Thread: 1929 Ford Model A Coupe Build

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Originally Posted by jerry clayton

Check frame specs at Wescottsauto.com


Tech section has detailed drawings of frames--------

Thanks for the link. Printed everything off and rechecked all measurements and for square. It's spot on. The only thing off is the bottom of the "C" channel. It's shorter than the top. I'm worried that when I go to box the frame, the inside is going to have a slight inward slant which could affect me later on down the line.

GeorgiaDad, I sincerely apologize for not replying to your post earlier. Somehow I missed the one from 2/7, and didn't see it at all until today's update. I'll try to answer your questions, best I can.

For the cruising rpm, I'd say that your 1800 to 2100 rpm is a good ballpark range. Ideally I like to be at the point on the torque vs rpm curve where the line is breaking over towards horizontal. If below that you're not going to have as much power to make a needed move or to accelerate quickly without changing gears, and with an automatic overdrive tranny you may be in that spot where it's going in & out of OD with very little throttle, which is annoying. My torque curve comes up pretty steep from idle, and at 2000rpm has tailed over and is nearly flat out to about 5500rpm, so I picked my rear gears for 1995rpm at 70mph, which I really like. As for the "gear calculator" site you found, I find it to be cumbersome with all of the info they ask for. I like to work with hard numbers, i.e. the actual diameter of the tire I'm running, or of the tire I've selected as listed by the maker. Places like DiscountTiresDirect or Tire Warehouse list the specs for the various tires they sell. Also, here's a link to a really handy listing of tires by wheel size that I've used a lot - http://tire-size-conversion.com/tiresizes/ Credit Ryan (40FordDeluxe) for that one.

I'd forget about the rear gear ratio at the junk yard and pick the rear end you're going to run based on track and strength, depending on the engine you're going to run. The Ford 9" has become the differential of choice for lots of folks, and you can either get one salvage or there are several places that offer them new, built to the width you want. That can be a big plus for a full fendered car, where tire position side to side is critical. On a hiboy you can live with an extra inch of width, where that may put you into the fenders on your car. Once you get the track decided you can replace the ring & pinion for less than $200 to dial in your rpm's. When you have your custom driveshaft made it's common to use different u-joint's front & rear to match the yokes. Don't get hung up on "all chevy" or "all ford".

I'm pretty sure that the S10 T5 Tranny is only rated for about 250 ft#, which is really pretty weak. You might be OK on the bellhousing to SBC interface - here's a reference that points to Gen I, II, and III engines sharing the same bellhousing pattern with the V-6 engines - Chevrolet Standard Shift Parts Interchange - Novak Conversions

On tire size, you're getting into an area of a lot of personal preference. I can't help with how much tire you can fit into the fenders, but someone else may know and be willing to share their experience. My approach would be to hit as many shows as you can, looking for Model A's that look right to you, and see what they're running. As Jack mentioned earlier, tires for 15" wheels are becoming less common, and sizes that were readily available five years ago are gone today, or only available from specialty suppliers like Coker Tire. Wheel and tire size is one of the most critical decisions that you are going to make to affect the "look" of the car, as they form the stance that makes or breaks the appearance. In my book you really do not want to simply install the Heidt's components and then try to make do with the wheels & tires. You will have some flexibility in the front end placement to affect ride height, but you need to have your wheels & tires figured out first, again in my opinion.

I think that the mismatch in top and bottom flange widths that you mention is not uncommon, and I assume that you're going to box the frame for strength so you can take care of that with the placement of the boxing plates, against the short flange, and butting the wider, right? At least that's what I would probably do without researching. Again, one of the other guys here can give you some guidance based on their experience.

Hope this helps at least a bit, and thanks for posting the update!

rspears, Thanks for the info. You gave me a lot to go over.

Per the rear end. I'm going with a Ford 9" rear end. I did some searching around and found a shop that does nothing but specialize in rear ends just 10 miles from me. I can pick up a Ford 9" from the savage yard. They will rebuild it and can cut it down to any width I want. So now at this point I need to decide on the best donner rear end. Also what rim size/off-set I'm going to use. Possibly a 3.25:1 ratio?

The transmission I have is a 5-speed manual WC B/W T5 #1352-175 from a 1988 5.0 Camaro. I only swapped out the tail housing from the S10 to move the shifter forward. Not the main shaft. I will either go with a GPS speedo or none at all.

I found a GM certified engine builder ~25 miles from me. He will build an engine to my spec's. I can even help build the engine. Since this will be a daily driver, I'm not looking to burn the tires off. But I do want the car to be able to get out of it's own way. He said we can sit down and plan the build out to match my needs.

For the front end, I have decided to go with a TCI IFS. The decision I need to make is chrome or no chrome. Being a daily, I'm wondering if polishing all of that chrome underneath is worth the hassle. But with wire spoke wheels, what is the non-chrome going to look like?

As per the frame. Ole Henry was quite the penny pincher. I was going over the frame when I noticed something. From the tip of the horns to about 3" past where the body bolts down is completely square. Top and bottom of the "c" channel is the same. But just past that point on both sides of the rail. The bottom rail angles in 3/16" making the bottom rail just a tad smaller than the top. Guess Mr. Ford was trying to save some steel cost. Not a big problem. I can square it up when I box out the frame.

I'm just a couple of days away from having the frame sandblasted. I was going to spray the frame down with weldable primer when it came back. But I'm not so sure now. I've been reading a lot about Southern Polyurethanes, SPI.. I'm going to contact them and see what they recommend. Has anyone else used Southern Polyurethanes products? What did you think of them?

Time for an update.

I got the frame back from the blasters. It came out really nice.Nice clean steel is so nice to work with.

For the boxing plates. I bought mine from Wolfs Metal Fabrication. The ones I bought have holes predrilled. 1928 - 1931 Model A "Drilled" Boxing Plates - Wolfes Metal Fab In hindsight, I should have used the solid plates and just drilled out where the body bolts go.


My TCI IFS arrived. I went non chrome. Going to have it powder coated to mach the frame.


Wanting to flatten out the back axle hump some. I went on a search for a new rear brace. Just about everyone I found said "for use with our frame". All of which have been narrowed. Not wanting to narrow my frame, I decided to make my own using 3"x2" tube steel. After taking careful measurements it was time to cut the steel. I needed to make 22.5* cuts. My portaband will cut deep but not wide. That left using the sawzall. First thing I did was set up a mockup of what I was trying to do.

From there I made a jig using some steel I had laying around.

From there I used a 9" blade in the sawzall and took my time cutting.


After cutting I then tacked welded each section together. Making sure each one was square and at the proper angle. The bottom is a nice straight edge. From left to right it's off by .3*, I can live with that.

It's going to my friends shop to be tig welded then off to the sandblaster before being installed on the frame.

I picked up a Ford 8" rear end from a '70's Maverick. The fit is perfect. It's at the blasters now. I'm going to replace the axle's with Mosers just to be safe. The differential is at Vanishing Point Race Cars. They are replacing the ring and pinion for me. Going from a 2.79 to a 3.25 gear ratio.

Originally Posted by GeorgiaDad

Going from a 2.79 to a 3.25 gear ratio.

Very strongly recommend using a 3.80 gearset.
http://www.currieenterprises.com/ces...e.aspx?id=1173

Ideal final drive first gear ratio should be between 10.0:1 and 11.0:1. With a 3.80 rear gear and a 2.73 first gear, the first gear final drive ratio would be 10.49:1.

Combining a 3.80 rear gear with a 0.73 5th gear will result in a 5th gear final drive ratio of 2.77:1, which is about as low (numerically) as I would want to go with a low-torque motor. Use a ~28" rear tire (the bigger the rear tire, the better the car will look, up to about 28/29 inches. Using tires taller than that may make the car look dorky.)

With a 2.77:1 final drive 5th gear ratio, 28" tire and a cruising speed of 65 mph, the crank speed would be 2,164 rpm's.

Build the motor between 8.0:1 and 9.5:1, with an ideal SCR of ~8.75:1. Use a cam with intake duration of no more than 200 to 204 degrees @0.050" tappet lift. Many fellows forget that you must match the cruise rpm's with the cam timing to get the cam into the lower end of its operating range at cruise. Such a cam as I'm recommending here would cruise at ~1800 to 2200 rpm's, allowing you to accelerate smoothly from 55 mph in 5th gear (1,831 rpm's). It would create a DCR (Dynamic Compression Ratio) of right at 8.0:1, which, when combined with a tight squish of 0.035" to 0.045", would allow the use of lower grade pump gas without detonation.
http://www.crankshaftcoalition.com/w..._compatibility

A 350 built with 64cc heads and 22cc pistons would have ~8.7:1 SCR, just about ideal for this combination.
https://www.uempistons.com/index.php...9cd4d2555812d4

.

Just FYI if you're not familiar with those "banger" motors, you can get good $ for them if they run good.
Motor trans & radiator can bring you $600 to put towards your project.

DO NOT TOSS IT!

That being said, good luck with you're build, I'll be following along.

Wow, I haven't posted an update in a while. Things are moving a bit slow lately. Been too darn cold in the garage a lot of nights. So here's where I stand.

I have the engine mostly rebuilt. I'm holding off on the carb, fuel pump and headers until I get the engine set in place permanently. I'm going back and forth on a couple of items. I'm leaning towards going with an electric fuel pump vs. mechanical. Also leaning towards a carb vs. EFI. Not sure I want to go through the headache of setting up an EFI for a daily driver. I've also decided to remove the mechanical fan and go with an electric radiator mounted fan. From my calculations it should let me move the engine 1 1/2" forward. I need all the room I can get. Going with a Walker radiator.


I have the rear suspension fabbed up. Took a lot more work than I was expecting. The rear has been powder coated and is at the shop being rebuilt at the moment.


Put the front clip together with some temp tires. I'm happy with the way it turned out. Had to modify the front fender brackets but it wasn't too hard.


So at this point I've got the front modded up to check for fittness. I'm waiting on the new radiator to arrive before I start finalizing everything. so far I'm happy with how thing are going. I just wish it would warm up.