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thought of new pistons for the 248 straight 8


Guest buickkuhn

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Guest buickkuhn

I am thinking of possible getting new pistons for my 1941 buick 248 straight eight. I am looking for what you out there have used in the past and how much you milled the head/ gasket thickness to work with new pistons. I am trying to get all the info before I am actually ready to rebuild the motor this winter . If you have pictures that would be helpful too . The original with the combustion ring and the negative space seem to be the faults so this is what I am asking about . Is it worth the extra cost to get new and did they work out well for you .

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I used standard repro pistons in mine. I wish I had "warmed up" the engine some. Hindsight!

If yours does not NEED re boring, I am not sure new pistons would improve performance any. If re boring is needed, check it out.

A lot of discussion on the straight eight forums on Teambuick.com.

Ben

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Stock rebuilds seldom result in significant power increases, by observation. What they do is improve the ring sealing, correct for various seal leaks, "renew" dimensions for the valve guides/seals, engine smoooothness, etc.

Just some observations . . .

NTX5467

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I'm pretty sure there's only one type of piston being made by the aftermarket unless you have something custom made. From the factory, they varied by year, but the application lists all seem to suggest that there's one piston for all 248s. I put standard pistons (.060 oversize, since my engine had already been rebuilt once) in my '41 Century 320 when I rebuilt it. I also milled the head a bit to get up to about 8.3:1 compression, added insert bearings, a re-ground cam (I have an NOS Howard cam from the '50s still in the box, but I couldn't bear to use it, so I had it duplicated), and some mild valve work like hardened seats and a 3-angle valve job. On these cars, there's not a lot of big performance to be had if you're using the stock manifolds, which are the limiting factor. Custom manifolds will result in significant power gains, but there's no need to go overboard with modifications if you're keeping the originals with their 90-degree turns.

I am shooting for 200 horsepower and 300 pounds of torque from my Century, and I think I'll be close with the modifications I have. They are all invisible and from the outside it will look completely stock, but it should be a great driver.

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Guest buickkuhn

I would like to drive this as much as I did my 65 ford fairlane after I rebuilt that , some better gas millage would be a added bonus too . Thanks for the info

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There's a book I found a good while back on modifying Chevy and GMC inline 6-cylinder engines, in the pre-V8 times. LOTS of interesting information, including mixing nitro with gasoline and "3/4 race" camshafts. There's a chapter on the inline Buicks, too. It's in reprint and you can probably find in at Amazon or similar. It's in paperback now.

Increasing cam "open time" can somewhat compensate for poor cylinder head flow and such. Still, as mentioned, factory manifolding seemed to be more about "looks" than otherwise, back then, compared to more modern times. Reducing the internal rotating mass, custom manifolding, some type of fuel injection, modern ignition system, and improved exhaust components might make some people be surprised by an older Buick with such an engine. Have to be a coordinated and synergistic approach for the best results.

Just some thoughts . . .

NTX5467

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I'll be running 100% stock intake and exhaust manifolds and Stromberg carbs. I may cheat a bit and upgrade the exhaust to 2.25 inch pipe, which I doubt anyone will notice but it may flow a little better. But my goal is to have a completely stock looking engine bay with just a little more horsepower on tap. There's a certain fellow locally who claims his '41 Packards were the fastest cars on the road that year. I am to demonstrate otherwise...

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Don't forget to "massage" the venturi clusters and related surfaces in the throttle bores of the carbs. Just a little light file work on the casting flash areas might help things a little bit. When I did that on the OEM AFB on my '67 Chrysler (which had full manual secondaries and NO "flow valve" (as Chevy versions did), I achieved a slight bog off-idle at WOT which wasn't there before. Must have found some more air flow somewhere. I always liked a part-WOT off-idle and then full WOT as the rpms built, before the shift . . . which seems to work better.

How IS the project progressing? Also curious.

Enjoy!

NTX5467

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  • 4 months later...

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