Thread: 1929 Ford Model A Coupe Build

Tweet

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!