302/Cobra Engine Build

[Ted]

I figure we probably have some small block Ford experts around here.

I'm going to be building up a 302 for the Cobra replica. My plan is to start with a 302 out of a late 90s Explorer with GT40P heads. Port the heads, maybe new valves lapped in, add a new cam and carb and headers plus bore it 30 over and high compression pistons. Found a build minus the high compression pistons that was showing 375 HP on the dyno, which in a 2400 lb car is just fine, max power around 6k RPM. I've got an engine lined up for this, guy has to pull it for me. Stock rods and crank planned. Goal is a budget build.

I want an engine with a very lightweight rotating assembly so it's very rev-happy. I'm planning on aluminum flywheel, aluminum pulleys. I'm also going to go no power steering, basically just an alternator and (maybe) an AC compressor as I do expect to put AC in it (we'll talk about that later).

Plan is for hypereutectic high compression pistons since that should be enough for the horsepower I'm looking at and less weight for the rotating assembly. Also planning on an aluminum flywheel, which I've done on other cars and really liked.

I'm thinking about going with an electric water pump instead of mechanical. 15 years ago it seemed that electric weren't that great for street applications, but I think the quality has gotten better. What are thoughts on an electric water pump for street use with some track days? Track would be more higher speed time.

I've also considered knife edging/lightening the crank, but that's probably not something I want to do myself.

Any other suggestions for things to do or not do? Was thinking about a windage tray but I've read conflicting reports on 302s of that increasing power vs. not.

 

[SCCutler]

No way, no how, I'd do that build without power steering. Cockpit's tight enough without a big wheel, and a small wheel will be a beast at low speed.

How's that for going off-topic, first post?

 

[Ted]

No way, no how, I'd do that build without power steering. Cockpit's tight enough without a big wheel, and a small wheel will be a beast at low speed.

How's that for going off-topic, first post?

My plan is to use a power steering rack (2.5 turns lock-to-lock from early 90s Fox body, they make these new) and cap off the power steering ports. It's only a 2400 lb car. When my XJ-S started hitting the road its power steering was inop and that was a 4,000 lb car, I did just fine. Granted I was younger then, but Laurie thinks I'm better looking now and that should make up for it.

Because it'll have a rack designed for power steering, I could then add it if I wanted.

 

[Craig]

One thing I would do, is build it where it's happy on 89 octane fuel. If you are going have it on the road a bunch, the difference in fuel cost is probably worth it. Had a 64 Buick that didn't like anything under about 93 octane and it would tell you it didn't like the fuel if it was under that.
Personally, I'd be paranoid about an electric waterpump. Look at changing pulley sizes to adjust flow and hp requirements. You are going to have enough hp to do white knuckle rides, that losing a few for the reliability isn't a big thing.

Had a family friend that said the scariest thing he ever drove was a Cobra Mk1 with the 289.... His normal driver was a Jag XKE Mk3 with the V-12.

 

[Zeldman]

Forget 302.

Think 331.

The simple fact is that when you start adding up the cost of a good crank, rods, and pistons, along with the machine work to fit it into your existing block, it's just a few bucks more to go with a stroker and reap the benefits of extra displacement without having to deal with an engine swap to a big-block and all the headaches that brings (cooling, exhaust, and so on).

The 331 puts more torque on the table over a stock displacement small-block yet still offers the high rpm capability that the original 289 and 302 were known for. Essentially, the 331 becomes a nice middle ground of torque, horse power and rpm ability. Add the maintenance-free power of a hydraulic roller camshaft and be able to use pump gas for "stop anywhere" fill ups that I am guessing you are looking for.

A lot is available for the 302, just depends on how fast you want to go.

 

[mondtster]

You may be better off looking for the '95-96 GT40 heads instead of the 40Ps. The plug angles are different, potentially limiting your header choices.

In a light car a stock explorer motor with a cam will be plenty fun and easy to feed and care for. Otherwise you can get more aggressive with it but I don't see much point.

 

[Ted]

One thing I would do, is build it where it's happy on 89 octane fuel. If you are going have it on the road a bunch, the difference in fuel cost is probably worth it. Had a 64 Buick that didn't like anything under about 93 octane and it would tell you it didn't like the fuel if it was under that.
Personally, I'd be paranoid about an electric waterpump. Look at changing pulley sizes to adjust flow and hp requirements. You are going to have enough hp to do white knuckle rides, that losing a few for the reliability isn't a big thing.

Had a family friend that said the scariest thing he ever drove was a Cobra Mk1 with the 289.... His normal driver was a Jag XKE Mk3 with the V-12.

This isn't going to be on the road a ton. If it gets 5,000 miles a year, I think that will be a lot. Our cars currently burn premium or diesel, so we're already used to being on the high side there. I'd rather have the more responsive power of a high compression engine.

The Type 3 E-types were pretty tame cars really. The V12 was always pretty neutered in its factory applications in Jags, and most of the E-types (if not all?) came with a Borg Warner 12 3-speed automatic, which made it even worse. I remember driving a customer's car when I was at the Jag shop and found it to be surprisingly underwhelming. The Type 1 I drove that had a 4.2 with triple SUs on it? Now THAT was fun.

Forget 302.

Think 331.

The simple fact is that when you start adding up the cost of a good crank, rods, and pistons, along with the machine work to fit it into your existing block, it's just a few bucks more to go with a stroker and reap the benefits of extra displacement without having to deal with an engine swap to a big-block and all the headaches that brings (cooling, exhaust, and so on).

The 331 puts more torque on the table over a stock displacement small-block yet still offers the high rpm capability that the original 289 and 302 were known for. Essentially, the 331 becomes a nice middle ground of torque, horse power and rpm ability. Add the maintenance-free power of a hydraulic roller camshaft and be able to use pump gas for "stop anywhere" fill ups that I am guessing you are looking for.

A lot is available for the 302, just depends on how fast you want to go.

My hope is to be able to reuse the stock crank and rods, which should be fine barring any issues with the . I'm not looking for a ton of power here, so stock crank and stock rods will be fine. Some people even use stock pistons in these applications, I'll just go with aftermarket for higher compression.

I'd thought about the 331/347 route, but really I'd like to make something that's rev-happy like my sportbikes were. Obviously it won't be quite that rev-happy (and I'm still talking about max power in the 5500-6k RPM range, figure I'd put in a limiter at 6500) but want it to be really responsive, and a lightweight rotating assembly is a large part of that.

You may be better off looking for the '95-96 GT40 heads instead of the 40Ps. The plug angles are different, potentially limiting your header choices.

In a light car a stock explorer motor with a cam will be plenty fun and easy to feed and care for. Otherwise you can get more aggressive with it but I don't see much point.

I'll look into that. I'll likely be going with the Factory Five headers, which I think solve those problems.

 

[Zeldman]

I'd thought about the 331/347 route, but really I'd like to make something that's rev-happy like my sportbikes were. Obviously it won't be quite that rev-happy (and I'm still talking about max power in the 5500-6k RPM range, figure I'd put in a limiter at 6500) but want it to be really responsive, and a lightweight rotating assembly is a large part of that.

That is why I suggested the 331 over the 347.

If you are determined to go with the stock crank, be sure to get it checked for straightness. Surprising how many are not. And I hope you plan on balancing the engine. Might not make a big difference in power but it will on longevity. Please tell us you are putting a clutch in it (with at least 6 gears) and not a automatic....

I think a friend of mine still has a clone Boss 429 sitting in his shop if you want a "real" engine.....

 

[FormerHangie]

I figure we probably have some small block Ford experts around here.

I'm going to be building up a 302 for the Cobra replica. My plan is to start with a 302 out of a late 90s Explorer with GT40P heads. Port the heads, maybe new valves lapped in, add a new cam and carb and headers plus bore it 30 over and high compression pistons. Found a build minus the high compression pistons that was showing 375 HP on the dyno, which in a 2400 lb car is just fine, max power around 6k RPM. I've got an engine lined up for this, guy has to pull it for me. Stock rods and crank planned. Goal is a budget build.

I want an engine with a very lightweight rotating assembly so it's very rev-happy. I'm planning on aluminum flywheel, aluminum pulleys. I'm also going to go no power steering, basically just an alternator and (maybe) an AC compressor as I do expect to put AC in it (we'll talk about that later).

Plan is for hypereutectic high compression pistons since that should be enough for the horsepower I'm looking at and less weight for the rotating assembly. Also planning on an aluminum flywheel, which I've done on other cars and really liked.

I'm thinking about going with an electric water pump instead of mechanical. 15 years ago it seemed that electric weren't that great for street applications, but I think the quality has gotten better. What are thoughts on an electric water pump for street use with some track days? Track would be more higher speed time.

I've also considered knife edging/lightening the crank, but that's probably not something I want to do myself.

Any other suggestions for things to do or not do? Was thinking about a windage tray but I've read conflicting reports on 302s of that increasing power vs. not.

I wouldn't bother lightening the crank, I don't think you'd get much benefit for the money spent. If you want a snappy engine that likes to accelerate, I'd be more concerned about keeping the gas flow velocity up in the intake, and that's mostly a matter of not getting too carried away with the size of the intake ports, manifold and (ugh) carburetor.

Is someone experienced going to build this for you, or at least spec it out for you? Some combinations of parts just work better than others.

 

[FormerHangie]

That is why I suggested the 331 over the 347.

If you are determined to go with the stock crank, be sure to get it checked for straightness. Surprising how many are not. And I hope you plan on balancing the engine. Might not make a big difference in power but it will on longevity. Please tell us you are putting a clutch in it (with at least 6 gears) and not a automatic....

I think a friend of mine still has a clone Boss 429 sitting in his shop if you want a "real" engine.....

A light car with a torquey V-8 and a high drag coefficient ought to do just fine with five gears.

 

[SoonerAviator]

I'll look into that. I'll likely be going with the Factory Five headers, which I think solve those problems.

I'd still go with GT40 or any other straight-plug head. The angled plugs are a pain no matter the header design.

Honestly, I'd skip the 302 and go 351w, personally. Same block, higher deck, and the parts are pretty much interchangeable with a few exceptions. The later 5.0L used the 351w firing order as well. You can find 351w all over the place, and it's no more expensive to buy than a 302. It's free displacement, without needing a stroker set up. It can be stroked to a 408 if you really wanted to wind it up. If you do decide to stick with the 302, make sure you get one of the later models that has the provisions for roller rockers in the intake valley. The older 302 (pre mid-80's I think) did not.

Basics: whatever heads you use, get a 3-angle or better valve job done, and roller rockers (might check CL or eBay for some aftermarket aluminum heads). Nothing wrong with flat-tappet, but it adds to peace of mind if you're revving it to 5K on a track if it's got rollers in it to help combat valve float. I like the Edelbrock Performer RPM line of aluminum intakes and carbs. I run them on my 351w and it was a decent upgrade over the factory cast manifold both from a weight perspective and power.

If you're going to be keeping it non-EFI, I'd get a Pertronix dizzy at a minimum, MSD if you really want to track it often and take the abuse. No need to clean/set points all the time anymore.

Keep the belt-driven water pump. It's not going to rob much power and it pretty much bulletproof. Electric radiator fans are where manufacturers have moved away from the mechanical fans, which I'd agree with.

 

[GRG55]

...It's only a 2400 lb car. When my XJ-S started hitting the road its power steering was inop and that was a 4,000 lb car, I did just fine...

That's not really a valid comparison.
It doesn't matter if the power steering in the Jag is inop. Nobody expects them to start anyway.

 

[bradg33]

I'd just put a lawnmower engine in it; seems like a waste to stick a decent motor in it when you're just going to be watching my exhaust pipes fade into the distance far ahead of you.

 

[Mike Smith]

Mel Hambelton Ford, Wichita Ks. Call.......order engine....profit.

 

[Ted]

That is why I suggested the 331 over the 347.

If you are determined to go with the stock crank, be sure to get it checked for straightness. Surprising how many are not. And I hope you plan on balancing the engine. Might not make a big difference in power but it will on longevity. Please tell us you are putting a clutch in it (with at least 6 gears) and not a automatic....

I think a friend of mine still has a clone Boss 429 sitting in his shop if you want a "real" engine.....

Understood the 331 would be snappier than the 347, but you're still talking about increased displacement through a longer stroke, and an overall heavier rotating assembly. Now if the crank is junk, I may reconsider.

Yes, it will have a manual transmission, although it'll all but certainly be a 5-speed. Really doesn't need a 6-speed in it, and the T-56 is a hard one to fit in there. The car's small enough that it already has only about a 10" driveshaft.

I'd still go with GT40 or any other straight-plug head. The angled plugs are a pain no matter the header design.

Honestly, I'd skip the 302 and go 351w, personally. Same block, higher deck, and the parts are pretty much interchangeable with a few exceptions. The later 5.0L used the 351w firing order as well. You can find 351w all over the place, and it's no more expensive to buy than a 302. It's free displacement, without needing a stroker set up. It can be stroked to a 408 if you really wanted to wind it up. If you do decide to stick with the 302, make sure you get one of the later models that has the provisions for roller rockers in the intake valley. The older 302 (pre mid-80's I think) did not.

Basics: whatever heads you use, get a 3-angle or better valve job done, and roller rockers (might check CL or eBay for some aftermarket aluminum heads). Nothing wrong with flat-tappet, but it adds to peace of mind if you're revving it to 5K on a track if it's got rollers in it to help combat valve float. I like the Edelbrock Performer RPM line of aluminum intakes and carbs. I run them on my 351w and it was a decent upgrade over the factory cast manifold both from a weight perspective and power.

If you're going to be keeping it non-EFI, I'd get a Pertronix dizzy at a minimum, MSD if you really want to track it often and take the abuse. No need to clean/set points all the time anymore.

Keep the belt-driven water pump. It's not going to rob much power and it pretty much bulletproof. Electric radiator fans are where manufacturers have moved away from the mechanical fans, which I'd agree with.

I considered the 351W, and plenty are running them in their Cobra, so it's definitely a viable option (and one of the ones that's "endorsed" by Factory Five). There are two reasons why I decided against it:

1) The engine bay is designed for the 302 series. The 351W's extra deck height makes stuff more compact in there and thus harder to work on. I'm going to be the one building and maintaining this car, and because of that something that will be easier to maintain is preferable, and more space helps that. Of course if I do GT40P heads that is perhaps the wrong direction of ease of maintenance, but less stuff in the engine bay is better for it.

2) From what I can tell, the weight delta is on the order of 50-60 lbs between a 302 and a 351. I'm trying to minimize weight in the front to help handling, and really I'd like this to be a snappier car all around. I was planning an aluminum intake.

3) Looking at the horsepower/weight ratios of what I can achieve with a 302, there's plenty of power to be had there.

So basically sufficient power for what I'm trying to do with lower weight and smaller footprint makes me happy.

Good tips on the multi-angle valve job and roller rockers. The Explorer block I'm planning on using is a roller block to start and I was going to put a roller cam in it so I'm set there. If I can find a good set of aluminum heads then that might make sense as well. I did find a cylinder head machine shop locally that supposedly does very good work and figure I'd take the heads to them to get worked on. If I use the GT40 heads they'll need some work for porting as well as machining them for new springs, etc. If I can find a good price on some aluminum heads then that might make more sense, but it seems those are harder to come by.

I was definitely going to do an electric fan, so that's already in the plan.

I'd just put a lawnmower engine in it; seems like a waste to stick a decent motor in it when you're just going to be watching my exhaust pipes fade into the distance far ahead of you.

You wish, Vette boy. Game on. You'll be watching me fade into the distance when your automatic transmission overheats. Again.

 

[455 Bravo Uniform]

No electric water pump (cost, and no benefit in my opinion).

Keep your bottom end stock. No gain to be had there.

Hypereutectic pistons are more fragile than cast and forged. No reason to upgrade from cast, other than ego.

Focus on breathing: cam, headers/exhaust, intake, carb, cool air. Cheap and efficient gains. Match your rear gear and trans accordingly.

Drag racing and built (assembled) engines since 1983, for what my 2 cents is worth.

 

[SoonerAviator]

I'll take 50 cu. in. for 50lbs any day, lol.

 

[Ted]

No electric water pump (cost, and no benefit in my opinion).

Keep your bottom end stock. No gain to be had there.

Hypereutectic pistons are more fragile than cast and forged. No reason to upgrade from cast, other than ego.

Focus on breathing: cam, headers/exhaust, intake, carb, cool air. Cheap and efficient gains. Match your rear gear and trans accordingly.

Drag racing and built (assembled) engines since 1983, for what my 2 cents is worth.

This will be a used engine out of an Explorer with over 100k miles on it, not new. So you'd just leave the bottom end alone? I'm aiming for 11:1 compression. Would you shave heads to achieve that instead of changing pistons? I was figuring on boring it 30 over since it probably is at a point where it could use that and figured at least new bearings while in there. The heads will have to come off to get machined anyway - need bigger springs to support the cam.

Cool air I'm planning on. The Cobra kits have a functional hood scoop, and I figure I'll put on an air cleaner with one of those air cleaner lids that is also an air cleaner. Maximizes the total area thus reducing restriction.

 

[Ted]

I'll take 50 cu. in. for 50lbs any day, lol.

It depends on the application. In a truck or a muscle car, absolutely. This is neither.

 

[Mike Smith]

Ted, since you totally ignored my other post (insert sarcasm emoji), I will assume you want to build the engine because you want to build the engine? Because you really cant build one for what you can buy one for. When you factor in part cost and machine work, much less if you put any value on your own time. Plus, with a Ford Racing crate engine you can get a 2/24 warranty.

 

[StevieTimes]

I'm sure I'm oversimplifying... but why not just buy something like this?
https://www.ebay.com/itm/2015-Ford-...126529&hash=item48af563376:g:NTwAAOSwjiFbO2uR

Isn't that 435 horses, and you are done building the 302...?

 

[jsstevens]

I think building the engine is part of the point.

 

[455 Bravo Uniform]

This will be a used engine out of an Explorer with over 100k miles on it, not new. So you'd just leave the bottom end alone? I'm aiming for 11:1 compression. Would you shave heads to achieve that instead of changing pistons? I was figuring on boring it 30 over since it probably is at a point where it could use that and figured at least new bearings while in there. The heads will have to come off to get machined anyway - need bigger springs to support the cam.

Cool air I'm planning on. The Cobra kits have a functional hood scoop, and I figure I'll put on an air cleaner with one of those air cleaner lids that is also an air cleaner. Maximizes the total area thus reducing restriction.

No, but I’d go back stock on the bottom end unless a Ford guru says otherwise for 6k rpm. Recondition your rods, new ARP rod bolts, clean/turn the crank if it needs it, with appropriate bearings.

On the pistons- I would only mill the heads for compression if not contraindicated by a Ford expert. Not sure what kind of geometry issues or leaks or weakening you run into doing that with the 302. Size the thickness of your head gaskets accordingly. If the valve seats are sunk/cut, you’ll lose some more compression there. 11:1 you’re better off forged (may be no cast options). Detonation gave hypers a bad name in the past (they shatter catastrophically).

I assume you’re going with a manual trans, which will give you some options with going to a hotter cam without as much worry about fuel mileage or matching torque converter, tire size, and rear.

This should be a fun ride!!! Pics mandatory.

 

[mondtster]

This will be a used engine out of an Explorer with over 100k miles on it, not new. So you'd just leave the bottom end alone? I'm aiming for 11:1 compression. Would you shave heads to achieve that instead of changing pistons? I was figuring on boring it 30 over since it probably is at a point where it could use that and figured at least new bearings while in there. The heads will have to come off to get machined anyway - need bigger springs to support the cam.

Cool air I'm planning on. The Cobra kits have a functional hood scoop, and I figure I'll put on an air cleaner with one of those air cleaner lids that is also an air cleaner. Maximizes the total area thus reducing restriction.

Personally, I'd just leave the bottom end alone as long as things look ok on inspection. You really can't build an engine for what you can buy a new one for these days and with only 100k on a late model engine (that has been running EFI its whole life) you should be good for a while as long as the oil was changed.

Although not totally the same, this is my buddy's car. At the time of the video it literally had a stock cast piston 351 shortblock with 130k or so miles on it and 200k GT40P heads on it. He ran in the mid 9s for several years with that setup. The block and crank live on, without ever seeing a machine shop and ran high 8s with a single turbo and still runs low 9s with twins. So no, I don't think you need to rebuild the thing unless you buy a piece of junk.

 

[Ted]

Ted, since you totally ignored my other post (insert sarcasm emoji), I will assume you want to build the engine because you want to build the engine? Because you really cant build one for what you can buy one for. When you factor in part cost and machine work, much less if you put any value on your own time. Plus, with a Ford Racing crate engine you can get a 2/24 warranty.

I missed it, oops.

Whenever I do the math on a crate engine I figure it depends on what you're doing. In this case I've got an engine lined up for $300. Sell some of the parts I don't need and the engine should cost me around $150 let's say.

Pistons/rings/bore 30 over/cylinder work, should be in it for maybe $2k for the long block (I'd hope less) for something that makes around 375 HP. Looking at Summit:

https://www.summitracing.com/parts/mll-bp3060ct/overview/make/ford

Is the closest I can find, with a good bit more. If you have a suggestion of where else to look I'm all ears. But @jsstevens is also correct that building the engine is part of it.

I'm sure I'm oversimplifying... but why not just buy something like this?
https://www.ebay.com/itm/2015-Ford-Mustang-5-0L-Engine-Motor-8cyl-OEM-46K-Miles-LKQ-184049405/312179307382?fits=Make:Ford|Model:Mustang&epid=9021126529&hash=item48af563376:g:NTwAAOSwjiFbO2uR

Isn't that 435 horses, and you are done building the 302...?

The new 5.0 "Coyote" engines aren't the same as the old school pushrod 302. Don't want one of the new engines.

 

[mondtster]

No, but I’d go back stock on the bottom end unless a Ford guru says otherwise for 6k rpm. Recondition your rods, new ARP rod bolts, clean/turn the crank if it needs it, with appropriate bearings.

That's too much money wasted on stock rods and ARP bolts. I'd either reuse the rods as is or buy a cheap set of imported aftermarket rods. You can buy them cheaper than a machine shop can rework them for, plus you'll get floating piston pins that way.

On the pistons- I would only mill the heads for compression if not contraindicated by a Ford expert.

I wouldn't mill a GT40 or 40P head because the deck surface isn't terribly thick to begin with.

 

[Ted]

No, but I’d go back stock on the bottom end unless a Ford guru says otherwise for 6k rpm. Recondition your rods, new ARP rod bolts, clean/turn the crank if it needs it, with appropriate bearings.

On the pistons- I would only mill the heads for compression if not contraindicated by a Ford expert. Not sure what kind of geometry issues or leaks or weakening you run into doing that with the 302. Size the thickness of your head gaskets accordingly. If the valve seats are sunk/cut, you’ll lose some more compression there. 11:1 you’re better off forged (may be no cast options). Detonation gave hypers a bad name in the past (they shatter catastrophically).

I assume you’re going with a manual trans, which will give you some options with going to a hotter cam without as much worry about fuel mileage or matching torque converter, tire size, and rear.

This should be a fun ride!!! Pics mandatory.

Yes, either a TKO or a T-5. Still debating which.

Personally, I'd just leave the bottom end alone as long as things look ok on inspection. You really can't build an engine for what you can buy a new one for these days and with only 100k on a late model engine (that has been running EFI its whole life) you should be good for a while as long as the oil was changed.

Although not totally the same, this is my buddy's car. At the time of the video it literally had a stock cast piston 351 shortblock with 130k or so miles on it and 200k GT40P heads on it. He ran in the mid 9s for several years with that setup. The block and crank live on, without ever seeing a machine shop and ran high 8s with a single turbo and still runs low 9s with twins. So no, I don't think you need to rebuild the thing unless you buy a piece of junk.

Thanks, good insight on that and so maybe I don't need it. Either way I'll have to pull the heads off and can see how the bottom end looks. If it looks good, maybe I just do some work elsewhere. I like high compression engines and am not doing forced induction. A quick Google says I should be able to shave the heads and get around 10:1 without messing around with changing pistons or rings. I could start off with a compression check and see if that looks good, and if that and inspection makes me believe I can leave the bottom end alone, shave the heads and just take what I can get there. That'd certainly save some money on the build.

Edit: I see you don't like shaving GT40 heads.

 

[SoonerAviator]

11.0 compression? I'd shoot for 10-10.5 unless you want to cart race fuel everywhere. 10-10.5 should be able to run on 91/93 octane without issue. 11.0+ starts running into detonation/pinging in certain situations.

It depends on the application. In a truck or a muscle car, absolutely. This is neither.

I dunno, plenty of Cobras had 427's with well over 400HP and close to 500ft/lbs of torque. It would be interesting to see identical setups aside from 302 vs 351w to see if the added torque from the 351w manifests itself in a useful manner. Like I mentioned in the original Cobra thread, it'd be hard for me not to have a 427 crate motor or a 5.0 Voodoo engine in a FF kit. Just for the knowledge that there's far more power under my right foot than should be legal, lol.

Either way, a properly built and sorted out 302/351w will have enough power to be a blast in a FF Cobra.

 

[mondtster]

Thanks, good insight on that and so maybe I don't need it. Either way I'll have to pull the heads off and can see how the bottom end looks. If it looks good, maybe I just do some work elsewhere. I like high compression engines and am not doing forced induction. A quick Google says I should be able to shave the heads and get around 10:1 without messing around with changing pistons or rings. I could start off with a compression check and see if that looks good, and if that and inspection makes me believe I can leave the bottom end alone, shave the heads and just take what I can get there. That'd certainly save some money on the build.

Edit: I see you don't like shaving GT40 heads.

Personally, I don't think compression makes as big a difference as people believe it does. Look at the stock class racers that are restricted to factory compression ratios, factory heads, intakes, and carburetors. They're also restricted to stock lift cams but duration is open. They'll run decent times even with all that stock stuff. Turn some RPM, make some power, and do it with cylinder head work instead of bottom end work. I wouldn't run a turbo on something like you're working on either.

I can probably count on one hand how many engines I've "built" for cars. For car projects I typically buy good condition junkyard motors to clean up and inspect, then run them. It's a boondoggle to do much else these days.

 

[Ted]

Personally, I don't think compression makes as big a difference as people believe it does. Look at the stock class racers that are restricted to factory compression ratios, factory heads, intakes, and carburetors. They're also restricted to stock lift cams but duration is open. They'll run decent times even with all that stock stuff. Turn some RPM, make some power, and do it with cylinder head work instead of bottom end work. I wouldn't run a turbo on something like you're working on either.

I can probably count on one hand how many engines I've "built" for cars. For car projects I typically buy good condition junkyard motors to clean up and inspect, then run them. It's a boondoggle to do much else these days.

In the worlds I've been working in, there's always been no real need (or desire) to open up the bottom end. No aftermarket options there really and so it just doesn't make much sense.

When I've played around with compression on dynos I've noticed a difference, but there is that question of effort and cost vs. reward. If the bottom end checks out good as pulled then just focusing on the heads is an appealing way to go to keep things simple and reduce cost. And if 10-10.5:1 is about all I should aim for in that setup anyway for detonation purposes, then that makes the head only plan a pretty good one.

 

[mondtster]

When I've played around with compression on dynos I've noticed a difference, but there is that question of effort and cost vs. reward. If the bottom end checks out good as pulled then just focusing on the heads is an appealing way to go to keep things simple and reduce cost. And if 10-10.5:1 is about all I should aim for in that setup anyway for detonation purposes, then that makes the head only plan a pretty good one.

To be clear, yes you will see a difference with a change in compression ratio. The 150 and 160hp Lycoming o-320 is an example of that. What I meant was that I don’t feel that increasing compression will net you enough of a difference in power for the effort invested.

A compromise might be to install the short block as is with the head work and bolt on mods done and see what you think. If you aren’t satisfied you’re not really out anything since you were going to do the head work anyway.

 

[James_Dean]

I dunno, plenty of Cobras had 427's with well over 400HP and close to 500ft/lbs of torque.

Either way, a properly built and sorted out 302/351w will have enough power to be a blast in a FF Cobra.

500hp and 550 lb ft. pushing 2900 lbs is a good time.

 

[Ted]

500hp and 550 lb ft. pushing 2900 lbs is a good time.

Now we’ll have to race our Cobras as well as our airplanes.

I predict you’ll win both, but I’ll still have fun losing.

 

[Crane Pilot]

Dump the 302 and go with a de-stroked 351w. Do forged pistons and not hyperutectic I'm not a fan of those in a sport engine. The one issue I can think of using a 90's vintage block is the matching of oil and water ports and jackets to the heads. A 600 lift cam with an intake to match the cam. I second the hydraulic roller cam. It gives good response and very docile for occasional street use. I built a big block 460 bored 40 over and to make a 472 with iron dove c heads that have been ported and polished and also shaved .030 to raise the compression up a little. I'm only doing about 500hp but I built it as a torque monster since I'm spinning 47in tall tractor tires with 2.5ton military axles. Sorry, back on topic I believe the 351 dimension wise is just a hair bigger than the 302. And even though the possibilities are almost endless for your build the only limiting factor will be as in other things is the size of your wallet. Oh and do not I repeat do not go without power steering. You can easily do a hydraulic power rack and pinion for cheap. If you want a vintage look with a new advantage look into a Holley EFI. It looks like a carberator but is fuel injection. Just a few of my suggestions.

 

[Mike Smith]

Ted, how many AMU’s do you think you are gonna spend on this engine?

 

[FormerHangie]

11.0 compression? I'd shoot for 10-10.5 unless you want to cart race fuel everywhere. 10-10.5 should be able to run on 91/93 octane without issue. 11.0+ starts running into detonation/pinging in certain situations.

I dunno, plenty of Cobras had 427's with well over 400HP and close to 500ft/lbs of torque. It would be interesting to see identical setups aside from 302 vs 351w to see if the added torque from the 351w manifests itself in a useful manner. Like I mentioned in the original Cobra thread, it'd be hard for me not to have a 427 crate motor or a 5.0 Voodoo engine in a FF kit. Just for the knowledge that there's far more power under my right foot than should be legal, lol.

Either way, a properly built and sorted out 302/351w will have enough power to be a blast in a FF Cobra.

There are guys who build cars with huge motors and huge brakes and huge sticky tires, and wind up with a car that is brutal and not very satisfying to drive. For track day and street use you want something with enough power but not so much that all you do is turn the car until it's pointed at the next corner and step on the pedal. Balance is the key to a satisfying car for Ted's intended use, and I think he's on the right track. Lap times aren't important, driver satisfaction is.

Also, power and weight cost brake pads and tire rubber to run.

Speaking of track days, @Ted DuPuis may want to check with some of the organizers of track days in his area (Heartland Park? Hallett?) to make sure the roll bar he's getting is acceptable. From the pictures it looks like a good one.

 

[SoonerAviator]

There are guys who build cars with huge motors and huge brakes and huge sticky tires, and wind up with a car that is brutal and not very satisfying to drive. For track day and street use you want something with enough power but not so much that all you do is turn the car until it's pointed at the next corner and step on the pedal. Balance is the key to a satisfying car for Ted's intended use, and I think he's on the right track. Lap times aren't important, driver satisfaction is.

Also, power and weight cost brake pads and tire rubber to run.

We’re talking about a 351w vs a 302, lol. It’s not like I’m suggesting he shoehorn a blown 460 in it. You can do a mild amount of work to get a 302 to 350HP, or a mild amount of work to get a 351w to 400HP. The cost is the same either direction you go, so why not get a bit more bang for the buck? You don’t see Chevy guys recommending a 305 over a 350 for the same reasons.




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[FormerHangie]

We’re talking about a 351w vs a 302, lol. It’s not like I’m suggesting he shoehorn a blown 460 in it. You can do a mild amount of work to get a 302 to 350HP, or a mild amount of work to get a 351w to 400HP. The cost is the same either direction you go, so why not get a bit more bang for the buck? You don’t see Chevy guys recommending a 305 over a 350 for the same reasons.


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What's the weight difference?

 

[rtk11]

I would second the use of a 351 Windsor and bore and stroke it. Or as suggested above, de-stroke it if you want higher RPM operation. The 351W has only 1” taller deck height than the 302, but offers a lot more torque from the displacement.

If you’re just looking for high rpm, high horsepower, would you consider the Coyote motor and have 435 streetable, reliable horsepower? If you want the lope from a crammed engine, the Coyote has plenty of programmers that can program in the lope.

 

[SoonerAviator]

What's the weight difference?

We covered it earlier, but 50lbs is the general rule.


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