DuPuis Family Cobra Build

[Fiveslide]

Your decision making and thoroughness during this build is impressive. Giving us your reasoning behind each choice is nice, I can't say I would make any different choices other than color, perhaps. Unless you're painting it blue, then I want a copy.

If you ever sell it, POA members get first refusal, right?

 

[PaulS]

However, I am thoroughly displeased with the bolt Factory Five provided. The hole in the bracket is 1/2" and the bolt they provide is 3/8". Looking at the geometry and what the bolt does this probably isn't an issue, however I'm going to be buying a 1/2" grade 8 bolt to replace it with and install. There have been several areas where I've felt the hardware was shorter than desired, but this one is the first where I've felt the diameter is too small, too.

.

The bolt is probably fine, I'm thinking 80% of the builders can't drill that hole accurately enough for FF to get rid of the slop and not get a ton of complaints.

 

[tmyers]

Valid points. Here's my view on K&Ns.

If you're using a car with a hot-wire MAF, then a K&N should never go on it. It will inevitably get oil on the MAF and then your car won't run right. I've had that happen on two vehicles - my wife's former Avalanche and also our BMW 740iL.

If you're using a car that uses MAP, Alpha-N, or some alternative MAF sensors (such as a Karman type) then a K&N can provide better flow albeit at the price of filtration. Whether or not the filtration causes a problem with engine longevity is debatable and also depends on the kinds of roads/conditions you're driving on. I ran a K&N on my 3000GT VR-4 for about 40,000 miles and it did provide improved airflow over the stock airbox with no negative side effects. The VR-4 used a Karman-style MAF. I have no idea how exactly that worked compared to a hot-wire, but it wasn't impacted by the K&N at all.

For the Weber-style induction on the Cobra, a K&N will be fine in my opinion. Yes, the filtration is worse than a paper filter. However the K&Ns will last forever, there's not much surface area (so I'll probably clean them very regularly) and the other alternative is mesh screens which basically just keep the rocks out. I'm not using a MAF sensor, it will either be MAP or Alpha-N (TPS based) EFI. So for those, I think K&Ns will be better than mesh screens.

Now time to get back out to the garage...

When I visited you there were a lot of gravel roads near your house. Do you have any concerns or plans on how to keep the dust out of the carbs till you get to areas of pavement?

Sent from my SM-N920V using Tapatalk

 

[Ted]

Congrats on making a cam choice. Going with Isky’s recommended lifters was a good move.

I think this cam will be fun. Specs here:

https://www.summitracing.com/parts/isk-381333

Note that it'll have a 108 degree lobe separation angle, so that should make it lopey witout being too wild, and with 1.7 instead of 1.6 rockers that should also get the lift and duration at 0.050" up a bit but still well within the safe zone for the heads and piston to valve clearance. I think it'll be about perfect, but we'll see. The timing gears I'm buying should also allow me to play with advancing/retarding the timing a bit if I feel I need to fine-tune the power curve.

It wouldn’t hurt to also double check the valve spring specs match the springs you got, and that the machine shop set them up with the proper closed height (closed pressure).

Good thought. I had called the machine shop yesterday to ask them to verify, and then I'll see whether or not I need to order new springs. Should've mentioned that I did that. If I haven't heard back I'll bug them tomorrow.

Been following along for a while and am kinda bummed no Webers, but I get it.

Yeah, I'm kinda bummed about it too. That said, the one thing that I was thinking is this car is going to be almost all electric with an electric water pump, electric power steering (at least probably), electric AC compressor, etc. So in some ways Webers and a ye olde distributor seems to go against the theme of the car. I'll find another car to do Webers on one day.

You do you on that gear drive! Hope you can hear it just enough.

I'm hoping. We'll see how it works out. The noise is part of it, but also eliminating one more area of miniscule slop. I'll be curious how responsive this is. I'm hoping sportbike level.

Can’t remember, did you have an exhaust figured out yet?

Yes. I have the FFR 351W headers as well as the side pipes that they include with all of their cars.

I’ll have to research some to see how that injection system is related to Megasquirt, never heard of Micro, but been away from hotrod stuff for a while.

Micorsquirt is more or less what used to be MegaSquirt'n'Spark 10+ years ago. It doesn't have the same level of features as some of the later MegaSquirt variants that they now sell, but for this car it does all I need just fine. MAP, Alpha-N, and it can control any of a number of electronic distributors or Ford EDIS. Part of me is also considering the EDIS from one of the later 5.0L Ford Explorer/Mercury Mountaineers since now I will have the means to control it. It does produce a better spark than a distributor, but it would have completely the wrong look. But that's something to consider. The Microsquirt is under $400 with a harness. I will have to do customizing on the harness but it's still in my opinion the best value out there, with a great support backing.

Your decision making and thoroughness during this build is impressive. Giving us your reasoning behind each choice is nice, I can't say I would make any different choices other than color, perhaps. Unless you're painting it blue, then I want a copy.

If you ever sell it, POA members get first refusal, right?

Thanks, I'm glad that you're enjoying it and appreciate the compliment on the decisions. As an engineer these sorts of design decisions are what I've always done for a living, although mine have generally been limited to one particular system (engines and now avionics). What's been unique with this is having to make all the design decisions for ALL the systems in a complete car and the interactions that go with that, while trying to get as much of it right the first time as possible so as not to duplicate work down the road (although I'm sure I will). I am really enjoying it.

If I ever sell it I'll definitely let you all know first. That said, don't expect it to get sold anytime soon.

Color, I'm not going to go with the blue with white strips. Everyone does that and while on a vintage Cobra I would want to keep whatever colors it came with. For a replica, I more think that's where you can be more creative and go with whatever you want as if you were buying a new car. Plus my wife needs to like it.

Incidentally, the body color one of the easiest thing to change on the car later. If you really want you just pull the whole body off the car, buy a new one, and put it on, or just repaint the body. Obviously more to it than that but you get the idea.

The bolt is probably fine, I'm thinking 80% of the builders can't drill that hole accurately enough for FF to get rid of the slop and not get a ton of complaints.

Well, the bolt is also too short. You can't get the nut threaded on all the way, it goes about 3/4 of the way through the nut. I don't get the decision making there at all. And yes it is the right bolt - I verified in the instructions and parts manual.

When I visited you there were a lot of gravel roads near your house. Do you have any concerns or plans on how to keep the dust out of the carbs till you get to areas of pavement?

We live on a paved road and we don't have to drive on dirt roads to get anywhere we need to go. Sometimes dirt/gravel roads are the fastest way, but I'm not going to drive this car on dirt or gravel. I would be too worried about body damage more than anything. My beaters like the Mercedes I don't mind.

The K&Ns will still provide adequate filtration for the engine. Keep in mind that many people who run stacks or Webers either use screens or no filtration at all. I'm not going to do that. If the K&Ns seem to provide too much restriction I may come up with something else.

 

[tmyers]

That's good to hear.

Sent from my SM-N920V using Tapatalk

 

[SoonerAviator]

. . .Well, the bolt is also too short. You can't get the nut threaded on all the way, it goes about 3/4 of the way through the nut. I don't get the decision making there at all. And yes it is the right bolt - I verified in the instructions and parts manual.

Seems odd that they would ever design it that way. Any change the bracket is backwards or the differential has something non-standard about it? I would imagine others have run into this problem if that were the case.

 

[Ted]

Seems odd that they would ever design it that way. Any change the bracket is backwards or the differential has something non-standard about it? I would imagine others have run into this problem if that were the case.

I agree it's odd they would've designed it that way. The bracket is on correctly - not really a way to put it on backwards and even still the way that it is it wouldn't matter.

 

[-KLB-]

Is it bolting to a cast flange on the axle that may vary in thickness by model year?

 

[Ted]

Is it bolting to a cast flange on the axle that may vary in thickness by model year?

That is certainly possible, and may be it. Plus casting variations in general.

 

[Ted]

I have tracking numbers on some parts that will start to come in, so that's exciting.

I am back to thinking about another decision though, and that's power steering and power brakes. My plan up until this point has been to use vacuum power brakes with a kit that's sold. This kit was ordered several weeks ago, backordered, and promised it's "shipping soon" with no ship date. What I don't like about vacuum power is the booster is fairly large and it isn't designed to fit, so I then have to cut the frame and put in a bracket to make it fit. Another question is whether between the cam and the intake I'm using if vacuum flow would be sufficient anyway.

The power steering I've been planning on electric, which goes in-line on the steering column in the engine bay. I don't like that location for several reasons. First it's ugly when you open the hood, second it moves CG further forward with the electric box, third it puts this electric box designed to be mounted in an interior by the exhaust manifold. Seems bad all around. One person managed to set this thing up behind the dash inside the car successfully. What people generally say about power steering is that they like the extra caster it "enables" which makes the car drive better. Thing is, you can set caster wherever you want, it's just that the norm for non-power steering is close to 0 caster, which of course doesn't do much for tracking well, nor does it help with bump steer, which these cars are prone to.

This is ultimately a 2300-2400 lb car with components built for a 3500 lb car. The general consensus is that power steering and brakes make the nicer to drive, but that neither are required, and I have a manual rack. What I'm thinking of doing now is building the car without power steering or brakes and driving it that way. Changing either of these is not very easy with the body on the car, however I'm planning on driving the car in its "gel coat" form (not to mention go-kart form) for a while before doing paint and finishing putting the body on. Because of that, I have the option of more easily adding those things later. The confounding/difficult part there is that if I go non-power brakes then I have to make a change to the pedalbox for more leverage, which I'm not sure how reversible that is if I decide to later go to power brakes. I need to look into that aspect of it more, but this seems like it might be a logical experimentation. Something to think about...

 

[tmyers]

Does the builder have a forum where you could get opinions from other owners?

Sent from my SM-N920V using Tapatalk

 

[Ted]

Does the builder have a forum where you could get opinions from other owners?

It does. I quickly found out there is nothing useful to be gained by posting there.

 

[SoonerAviator]

Does the builder have a forum where you could get opinions from other owners?

Sent from my SM-N920V using Tapatalk

Or simply the opportunity to drive a non-PS/non-power brake model, and a PS/vacuum-assist brake model? Do they do any FFR car shows/get-togethers? Might be worth your time to meet up and check it out to see what you like in terms of steering wheel/pedal effort.

if it's me, I can deal with no power steering. I've driven many a C1/C2 Corvette and Nova without it. I wouldn't want to give up the vacuum-assist brakes though.

 

[Fiveslide]

It does. I quickly found out there is nothing useful to be gained by posting there.

I figured. When I said your decision making and thoroughness were impressive, that was compared to most people I've been around that build this stuff and other cars I've seen.

 

[Ted]

I figured. When I said your decision making and thoroughness were impressive, that was compared to most people I've been around that build this stuff and other cars I've seen.

The thing with the forums for the Factory Five builders is that most of it are people who lack a lot of basic mechanical ability or experience. Questions include "What am I doing wrong putting on this tie rod end?" answer: "You're literally putting it on upsidedown." Yes, an actual question. The standard person is someone who's only ever driven pretty refined vehicles and not something as raw as a Cobra.

The other subset are a few know-it-alls who get an ego trip over being "the gurus." They know the one and only way (in their minds) to build the car "right" and anyone who deviates from their way of thinking or wants to do something unconventional is automatically told they're an idiot.

What I've done a lot of is looked at archives in the forums to see what people say. When it comes to non-power brakes, people say it mostly comes down to brake pad selection and making sure the pads have been heated up enough. For power steering, it's not needed but people say it makes the car nicer to drive.

But, I know that my preferences are different from those of a lot of others, too.

So the more I think about it, the more I think that some experimentation makes sense, especially if the result is reduce weight and add lightness.

 

[PaulS]

The thing with the forums for the Factory Five builders is that most of it are people who lack a lot of basic mechanical ability or experience. Questions include "What am I doing wrong putting on this tie rod end?" answer: "You're literally putting it on upsidedown." Yes, an actual question. The standard person is someone who's only ever driven pretty refined vehicles and not something as raw as a Cobra.

The other subset are a few know-it-alls who get an ego trip over being "the gurus." They know the one and only way (in their minds) to build the car "right" and anyone who deviates from their way of thinking or wants to do something unconventional is automatically told they're an idiot.

What I've done a lot of is looked at archives in the forums to see what people say. When it comes to non-power brakes, people say it mostly comes down to brake pad selection and making sure the pads have been heated up enough. For power steering, it's not needed but people say it makes the car nicer to drive.

But, I know that my preferences are different from those of a lot of others, too.

So the more I think about it, the more I think that some experimentation makes sense, especially if the result is reduce weight and add lightness.

Hmmmm, kinda like aviation.

 

[Ted]

Hmmmm, kinda like aviation.

Pretty much, but I've been around here longer and have no patience to do that again.

 

[Ted]

I decided to go ahead and cancel my order for the power brake setup. I think what I'll end up doing is start off with manual brakes, try some of the better pads if I don't like the pads it came with, and then if I still don't like it after some experimentation, I'll switch to power at a later point in time.

What that means is I need to get the brake master cylinder for a 1995 Mustang Cobra and start putting things together.

Next question on the brakes will be getting some hoses and then also deciding what type of brake fluid I want to use - DOT 4, 5, or 5.1. Or maybe something else.

 

[-KLB-]

Hmm. As a teenager, I drove a 1700 lb car with no power steering, and no power brakes, and never felt like it was missing anything other than horsepower. Of course, you are talking about 40% more weight, parts that were not designed for this application, and actually will have horsepower. But yeah, given your circumstances, I would start without and evaluate which way to go.

 

[SoonerAviator]

Eh, Dot 4 or 5.1 is what I would run. Doubt you'd ever notice the difference between the two. I wouldn't bother with Dot 5, simply because if you had an brake fluid issue while you were away from the house, Dot 5 might be hard to find. At least with Dot 4/5.1 you could run whichever Dot 3, 4, or 5.1 fluid you found at the convenience store nearby to get you home if you had to.

 

[Ted]

Hmm. As a teenager, I drove a 1700 lb car with no power steering, and no power brakes, and never felt like it was missing anything other than horsepower. Of course, you are talking about 40% more weight, parts that were not designed for this application, and actually will have horsepower. But yeah, given your circumstances, I would start without and evaluate which way to go.

When I was a teenager the power steering didn't work in my 1982 Jaguar XJ-S for a while. It was annoying but that was a 4,000 lb car. I'm figuring at 2,400 lbs and with a purposely built manual steering rack with the right ratios I think this will be fine.

I've driven some cars without power brakes but not many. In this case I have brakes that were intended for a 3,500 lb car in a 2,400 lb car, and will do the appropriate modifications to the pedal box for the right ratio. I can then change things back if desired during one of the opportunities I'll have.

 

[Ted]

Eh, Dot 4 or 5.1 is what I would run. Doubt you'd ever notice the difference between the two. I wouldn't bother with Dot 5, simply because if you had an brake fluid issue while you were away from the house, Dot 5 might be hard to find. At least with Dot 4/5.1 you could run whichever Dot 3, 4, or 5.1 fluid you found at the convenience store nearby to get you home if you had to.

I'm leaning towards 5.1 for that reason.

 

[FormerHangie]

For a 2400 lb rear drive car, I think nonassisted steering and brakes would be fine, unless one of the drivers is a very petite female. You might not want to go too small with the steering wheel.

 

[Ted]

For a 2400 lb rear drive car, I think nonassisted steering and brakes would be fine, unless one of the drivers is a very petite female. You might not want to go too small with the steering wheel.

Correct, and my wife is not a wimpy woman as anyone who's met her can attest. The question more comes down to a question of what she likes in driving it vs. not. She'll get the opportunity to drive it with manual brakes and steering and then be part of the decision making process. My primary reason for wanting the power brakes and steering was to make it more to her liking, but this allows that option still.

The kit comes with a steering wheel and I'll start with that. It's on the smaller side. We'll see how the package works out.

 

[Zeldman]

Power steering is for turning the wheels when the vehicle is not moving. Once rolling it gets easy.

Just need to decide what steering gear ratio fits your liking.

Then again, with your engine choice you can steer with the rear wheels....

 

[tmyers]

Amen to that!!

Sent from my SM-N920V using Tapatalk

 

[Bill]

My dad inherited a 1960 Plymouth Savoy, 225 slant six, three in the tree, manual steering and brakes from his aunts estate. The brakes were drum all the way around.

It was a heavy car, but once I got used to it, no problem to drive that car anywhere. In fact, I savored in it’s simplicity.

 

[Bill]

My dad inherited a 1960 Plymouth Savoy, 225 slant six, three in the tree, manual steering and brakes from his aunts estate. The brakes were drum all the way around.

It was a heavy car, but once I got used to it, no problem to drive that car anywhere. In fact, I savored in it’s simplicity.

She was straight and clean, had a little over 17kmi on the clock when we got it. It was a nice car.

 

[Ted]

She was straight and clean, had a little over 17kmi on the clock when we got it. It was a nice car.

That is one cool machine!

Just ordered my polyurethane motor mounts, trans mount, and also the manual steering rack adapter from Factory Five. Their prices on all of those were good and I had a credit on file with them because of a screw-up they did with my initial order.

I probably am also going to order my fuel tank kit today with fuel tank straps so that I can work on the fuel tank next week when my wife is at work again. Seems like a good plan to keep things moving forward, especially since I won't have the camshaft to be able to build the engine.

 

[Zeldman]

She was straight and clean, had a little over 17kmi on the clock when we got it. It was a nice car.

Did this model have a ''squarish'' steering wheel.?? I remember my uncle had a model that looked similar and had that weird looking steering wheel. If I remember his was a mid 50's model with a Continental kit, and he drove it until '81.

 

[Bill]

Did this model have a ''squarish'' steering wheel.?? I remember my uncle had a model that looked similar and had that weird looking steering wheel. If I remember his was a mid 50's model with a Continental kit, and he drove it until '81.

Don't recall it being squarish, but it was huge. Lots of leverage for turning the wheels at parking lot speeds. It also had a climber speedometer, which was cool. Wish he didn't sell it.....oh well. Those slant-6's ran really well in the pre-smog era.

 

[Ted]

Alright, crowd-sourcing time here.

One of the design decisions I have to make before too long is gauges. I'm having a hard time figuring this one out. There's a billion different gauge styles out there. The typical one that everyone goes with is the Cobra look-alike gauges sold by either Factory Five, Speedhut, or a few others. The Factory Five ones look the best, and include the reverse rotation (counter-clockwise) speedometer that was what Cobras and other British cars commonly came with at the time.

Even though I'm a Jaguar guy, that Smith's style gauge (Smith's made the original gauges) I don't feel really do it for the car with what I'm trying to accomplish. My goal with this is a blend of classic and modern. Also, the original gauge set includes a clock - the most useless gauge one could possibly have on a Cobra. I don't care what time it is, unless it's my lap time on a track! I also think the reverse rotation speedometer is something that is sort of a novelty that has no practical value.

I do like the Autometer Sport Comp gauges. At this point they're sort of dated but they're classic and have a great look about them.

So now, I'm turning to you all for suggestions as maybe some of you have ideas that I haven't seen before. Here is what I'm looking for in terms of requirements:

- The factory holes for speedo and tach are 4". I want a minimum of 4" diameter for speedo and tach. 5" is preferred, I like big there, but I can live with 4"
- The other gauges are 2 1/16". Ones that I need are oil pressure, water temp, fuel level. Ones I also want are oil temp and fuel pressure
- I want a GPS speedo since then I don't have to screw around with speed sensors
- I want the 2 1/16" gauges to be "full sweep" (270 degree sweep). The fuel level I don't mind being 90 degree sweep, but I hate 90 degree sweep for any engine related gauges. I want as much resolution as I can get
- 2 5/8" or alternate sizes are acceptable for the alternate gauges
- An integrated shift light into the tach would be nice, but not required. Alternately I could go with an external shift light. Again, not required

Here's what an as-delivered gauge set looks like, although the gauges this guy used are not the FFR gauges, they're some alternate kind:

Another idea that intrigues me is the idea of using some sort of digital racing-type instrument cluster. Something like this (picture for example, not necessarily something I want specifically):

The problem I see there is having something that will fit in the dash and still be readable. The Cobra dash is not ideally set up from a readability perspective, hence why you have the normal layout of the speedo and tach visible through the wheel and then the other engine gauges more centered.

The other thing I'm trying to get away from is spending $1k on a gauge set. I think that's a silly amount of money to spend. Now I do want gauges that look and perform well, but it doesn't seem like that's a reasonable amount of money to spend. I'd like to spend closer to half that or less. There are gauge sets out there that accomplish that, but I'm also looking aestheticly correct for what I'm doing.

Like I said, the goal is a modern recreation of a classic, so it should have an appropriate blend I think, erring if anything on the modern side. Because the primary colors of the car are going to be black with red accents I don't want white backgrounds on the gauges. White lettering is fine. Needles I can be more flexible color wise.

So, PoA, post some suggestions.

 

[jsstevens]

Just remember GPS Speedo will only give you ground speed. No wild swings when you break the tires loose.

 

[tmyers]

I would need to see some pictures to weigh in. I think the digital looks nice but not sure it would fit with the Cobra style.

Do think about what it is going to look like at night too, as in what colors you want to see glowing from your dash board.

I like simple style.

Sent from my SM-N920V using Tapatalk

 

[Ted]

Just remember GPS Speedo will only give you ground speed. No wild swings when you break the tires loose.

I have thought about that and I'm fine with it. There are a lot of benefits to GPS speedos. Negatives too, of course.

 

[tmyers]

Regarding the Speedo. I am not sure what my son's Speedo was connected to, but calibration was a simple connection of two pins on the back, drive a measured two miles and connect the pins again. This allowed an easy way to recalibrate if gears were changed or different size tires were introduced. The issue with his installation was that no one had the forethought to install a simple momentary push button to make re-calibration easier

Sent from my SM-N920V using Tapatalk

 

[Bill]

I'd go with the digital TFT display. It ain't no classic car anyway, I'd have more fun programming and playing with the digital gauge.

 

[TCABM]

Having used a Koso digital gauge package before, I would not go that route.

First and foremost, aesthetically it doesn’t meet your desires. Second, it’s a compromise.

I’ve had good success with auto meter before and there’s a wide selection of styles and colors to meet your desires.

 

[SCCutler]

Gauges:

I'd go Stewart-Warner Deluxe. Simple, clean.

https://www.stewartwarner.com/products/deluxe/

 

[455 Bravo Uniform]

I vote for Sport Comp. That’s my era.