The Stovebolt Site Forums The Shop Area Engine Shop 1938 GMC Flathead vs. Chevy 216

Just came across some info that says GMC light duty pickups came with Olds/Pontiac flat-heads in them from the factory. It suggests that GMC started entering the light duty truck market they didnt have suitable engines and they didnt want to put the Chevy 216 engine in bcs of the low oil pressures so they opted to for the Olds/Pon 6's.

Just for my own curiosity what are the pro's and con's of the two engines. I don't know much about flatheads so what are some characteristics of both the engines side by side how would they preform, and what are the attributes of each, I don't plan to replace my 216 but I'm just curious

The Olds sourced 213/230 L-head engine used in 36-37 had bearing inserts and was a full oil pressure engine. These engines had different cams, distributors and carbs than the car engines. The Pontiac 221 engine was used in 1938 and I have no idea why GMC used that engine, maybe supply issues with the Olds engine?

Not to hijack the original question, but here is a parallel thought I've question I've had in mind for a while.

Why did Chevrolet opt to stay with the low-pressure/ babbit bearing 216/235 for so many years?

Conventional wisdom, both today and apparently at the time....seems to be that full pressure oiling and insert bearings were "better" from a user and maintenance perspective. Both of those features, in one form or another, were common several years before Chevy retired the engine and moved on to the full-pressure design.

Was it purely cost avoidance? Or was there some other motive? Did the 216 hold some little-known advantage over other engine designs of the period?

GM still tries to market the GMC as upscale to the Chevrolet truck. Putting a bearing insert full pressure was GM's way of saying yes they share sheet metal and other parts but the heart of the GMC is what makes the GMC better. It is what we call marketing today salesmanship back then is my guess. Jeffrey

We can guess though not know.

Waiting for the old tooling and production line to wear out before replacing.

Felt truck buyers were old fashioned, conservative, not accept change well. Thus lose sales.

Keep Chevrolet behind the times so there would be a real reason to step up to the other GM divisions and justify spending more money for a Pontiac, Olds, Buick, GMC.

Preferred to reinvest profits in other ways/divisions. Jeffrey

What is actually the difference between babbit bearing and insert bearings and why is one better than the other?

Few people can pour Babbitt these days. Because few do it, when it is done it's quite expensive to do. Also Babbitt is softer than modern bearing material so consequently it doesn't last as long. Babbitt

Read the link given by Tiny - it is a good read.

Babbitted rods have the bearings as an integral part of rods. Ultimately, when the clearance between the "bearing" surface and the crankshaft gets too large, you have to replace the rods (to get new babbitted bearing surfaces ($$). If the rod-bearing journals on the crankshaft have to be ground, you need new rods/babbitts. There are also adjustment issues that required care and skill (and, luck).

Precision insert rod bearings allows bearings to be replaced when they wear, and allows rod bearings to be replaced if the crankshaft has to be ground due to wear.

Thanks for the link Tiny, I might have come across that article before I guess I really didn't understand the difference bcs I'm still learning

We're all still learning my friend. Those who think they know everything are called politicians.

All good theories.

Perhaps the war slowed product development. Or maybe the war left Chevrolet with a surplus of 216s to sell through after the war, thereby reducing their motivation to move on to a full-pressure design.

Whatever GM's reasons were, the 216 surely stood the test of time pretty well, in spite of its limitations. I'm amazed at the countless stories here of them being revived after 30-50 year naps.

Here's another way too look at it, and how it was explained to me. GM used a "tier" system of how their vehicles were priced/sold, with Chevrolet at the bottom, Cadillac at the top. New technology or mechanical improvements would always be sold on a higher up the ladder brand first, for the most part. With Chevrolet being the bottom rung brand, it got upgrades and improvements last. That's on top of anything they could do to make them cheaper/easier to manufacture. As mentioned in an earlier post, GMC was considered an "upscale" truck, so it got engines from the higher up brands. Plus, when they did design their own engines, they got the improved mechanicals and technology, and a higher price to go with it.

ok just hypothetically, does anyone know if one of the flathead 6's would bolt straight in and replace a chevy 216 in a 39-46 era truck

....and lets take this a step further, lets say we did swap in a flathead, could you mount a T5 up to it, just like you can with the 216, as the article on this site explains?

I understand the differential branding strategy. What's peculiar to me is that it took so long to move on to full pressure/insert bearings. 1939 for GMC and 1953 for Chevy. That's a long time, even if you are the entry level brand. Customers must have not cared too much, I guess. They sold a lot of cars.

I even have a 2 carb intake for one.

You could probably swap in a flathead engine from a GMC to a Chevrolet, but it would not be a drop in deal, motor mounts are not the same and you would have to adapt the carb linkage from the GMC. Don't know about the T5 or not, GMC and Chevrolet used the same transmissions in the small trucks, so it might.

I might have to keep that in mind for down that road, I think that would make interesting combination.