Thread: Flathead or late model

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I have a 41 ford coupe that was parked in an AZ garage since 65. I have the orginal engine,(rebuilt in 72 an never run) and a 'junk yard special, which was in car when parked. My question is should I keep the flatheads or convert to late model. My primary concern is hwy driving.

Lots of things to consider/be aware of.

When you say "primary", that imposes a lot of limits that don't favor the flathead. And I'm not an anti-flathead guy, just a realist.

First thing is there's at least a 50% chance that the block has/had cracks. If they can/were repair correctly that's not a disaster, but it has to be done right which = $. If it was rebuilt in '72 there's a good chance it was done "quick n' dirty" since that engine was very out of favor at that time. Or, in the hands of a devout restorer it may have been done correctly. Either way, if you didn't do it yourself, or supervise it personally, you really have no idea. How much of a gambler are you? Quick story. A buddy bought a very well restored '40 Ford a short while back. Supposedly everything was done, and done correctly. As it turns out the cosmetics were excellent, the engine ran well when he got it. After not very many miles it started to make a knocking noise. Kept getting worse. Once torn down it was learned that lots of new parts were put in a block that was loaded with small cracks (a common Ford flathead trait) that were either undetected, ignored, or who knows what. The block was junk.

Flatheads are also prone to overheating, again in part because of those cracks. But also, flathead rebuilders have learned that Ford wasn't real good about getting all the core sand out of the block cavities. It's not an easy thing to do, and not usually visible, so often in a "run of the mill" rebuild, it wasn't dealt with. In their day, high speed highways weren't as prevalent, so many of these old Fords were never run persistently on what we consider the highway, so it wasn't too much of an issue. Which leads to your needing to check the rear end ratio. There's a fair chance it's a 4.11, maybe a 3.78. Rare chance it's a 3.54. If you're ultra lucky you've got a Columbia two speed (overdrive rear axle). The normal gear ratios are intended for the predominant driving mode of the day; stop and go city or lower speed country driving. These engines don't like running 3000rpm or over for extended periods without sufficient modification.

Used as intended they can be a satisfactory power plant, but in modern terms that would be mild use. If it needs more work they can be an expensive rebuilt, $4-5000 is pretty common. With today's nostalgia craze there's a lot of interest in these engines, but don't let romance sway reality.

Bob, does the overheating cause cracks OR do the cracks cause overheating? Is a chicken just a way for eggs to reproduce?

I'd go with more modern power, for all the reasons Bob brought up. The flattie was a good motor in it's day, but it's day is long since passed. IMO, you'd be a lot happier highway cruising with a late model 302 or 351 Windsor powering the car.

I think Bob hit the nail on the head. It all depends on what style you are building. Do you want nostalgia , want something practical, or want something that drives like a modern car?

For Nostalgia, nothing beats a full dress flattie running through a pair of smithys. Both in tems of looks and sound. I've also heard that many overheating issues are the result of improper ignition advance/retardation, easy fix. Check out Flathead Jack's website. He discusses this condition in pretty good detail.

I'm in the same boat with you. I have a 59AB flattie and a SBC 283 sitting in my garage right now. Both beconning me to put them in my AV8. Both need rebuilding. I love the traditional flavor, but economic realities have me leaning towards the Chebbie. The SBC can produce twice the power for half the price, still be reliable and have a classic look using traditional dress up items. Small blocks are far from being unique however, and have garnered a "cookie cutter powerplant reputation" in certain circles, thus the disadvantage in the coolness factor.

I'm going to hang on to my flattie for afuture project when I have the $$$ to do it right.

Originally posted by robot
Bob, does the overheating cause cracks OR do the cracks cause overheating? Is a chicken just a way for eggs to reproduce?

Geez Mike, sorry, I must have missed your questions back in June. To both..............yes!


25th, welcome aboard. You're right, a properly dressed SBC is appropriate for anything resembling 1955 and later. Hope you'll not turn out to be another one-hit-wonder like the guy who started this thread.

I'm still here and most interested in everyones input. The '41' project is nearing the top of the list of 'I want to do's', if you know what I mean..... My current ideas are, 1st, check and see if the motor in the car will run. It was running when parked, but used alittle oil. 2nd, open the 'new' motor and see how time has treated it. (rebuilt in 79). I am leaning toward vintage, since the 'new' motor is orginal to the car, and done right, it would be a FINE weekend car. If it proves to be to costly to get a good motor from the 2, then I will go late model 351,,,,,but at that point how do I stop????? new frontend, readend, electric windows/door locks.....LOL Any suggestions on articles about motor swaps. Mostly interested in the electronic/computer requirements with a late model swap.
Thanks for the feedback
Geoff Jones
pioneerlogman@comcast.net
PS..I hope 1 flathead lives so I can try the 2 coil, double headed distributor,,,,and a 3 carb intake...:-) JUST FOR FUN

I have a friend with two 40s, a red two door and a black coupe. Both are built for long distance cruising. Small block Chevy, 700R-4 transmission, Mustang II front suspension, and parallel leaf springs and an 8" Ford rear axle. Both cars have air and cruise control. And both look super neat and very traditional.

And they drive them everywhere.

Email me for more pictures.

The other one.