Inliners International Forums General Discussion Engines Getting the most from 239 inline 6

Recently purchased a 53 Pontiac inline 6 with 55,000 original miles. I have two questions. The first is that it takes forever to start, would an electric fuel pump cure that? Second, how can I increase the performance of the engine or would I have to do a swap?
Thanks, John
PS New to restoration of autos,I am use to motorcycles.

John, your engine was pretty common years ago, but is rare today. I believe GMC used Pontiac sixes, back in the 30s, so they HAD to be tough. However, even stock parts will be hard to come by, these days....especially high-performance parts.

For your starting problem I'd check the obvious, first. Timing, points, plugs, and be sure the choke is closing when the engine's cold. A compression test will reveal a lot about the condition of the engine. I don't think an electric pump will help much, as long as the original is pumping OK.

As for increasing the horsepower, I'm afraid you'll find almost no speed equipment for your "Poncho". There are some things you can do to increase it's output, however, you'll probably have to make anything you use. I've seen two more flanges brazed to a stock intake, so two more carbs can be added, then a three carb progressive set up can be used. A set of headers and dual exhausts will increase the engine's ability to breathe, but you'll have to make the headers, or have 'em made. You can probably mill the head about .060 to increase the compression. Playing with the timing may yeild some more performance, too. Meanwhile, keep your eyes open for a nice 250 or 292 Chevy engine, so, if the old engine blows up, you'll have a more modern engine to install! I believe it would be almost a bolt-in.

Your '53 Pontiac six-cylinder flathead offers the same displacement as a '53 Ford flathead V8, with a larger bore and longer stroke, 3.5625 x 4. It will respond to the same kinds of modifications--overbore, milling the head, porting and polishing, oversize valves, regrinding the camshaft, increased carburetion--but the aftermarket speed equipment is not available, so it's a do-it-yourself operation, just as it was in the 1950s. We might think that one could achieve more low-speed torque more smoothly with this engine than with a Ford of the same vintage, but one can forget about high rpm. A 4.11 differential with overdrive would improve acceleration and offer increased flexibility on the Interstate. The effort and expense of a project like this would be rewarded by the admiration of a good number of us and by a personal sense of accomplishment. "Anybody" can swap in a 250 or 292, but the one who can build a "hot" Pontiac flathead and make it run well is a real hot rodder, not an imitation.

Pontiac-Oakland Club International (http://www.poci.org) is an excellent resource for parts and technical assistance related to these engines.

God's Peace to you.

d

I am pretty sure Vintage Auto Parts near Seattle had an Edmunds dual intake for a Pontiac flathead 6 at one time. The store has closed and the inventory was moved to Colorado, and the piece isnt listed on their website, but it has been a year or so since I was there anyway. The main thing is, there might be something out there, hard to find, tho!!

Nick

For vintage hot rod parts You might check with Brian's Salvage and Junk in Vallejo,California.Office number 1-707-642-5408 or home number 1-707-252-1409-------
EvilDr235

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Two types of people drive old cars.Rich people because they want to and poor people because they have to.
Remember EvilDr235 has a cure for Your sixness.

Thanks for the information. I planning on keeping the engine as "origanal" as in same block with A/C from Vintage Air (tis rather hot in San Antonio) and a 12 Volt system for some sounds. I appriciate the information and ideas.
John