263 L-8 compression ratio: how high can I go?

[37sedan_mod47]

I'd like to build a performance 263 straight 8 for my 1937 model 47. I've noticed that, unlike the 320, Buick did not raise the compression ratio much over the years. The last of the big 8s had compression ratios aproaching 8:1 while the small 8s stayed around 6.5:1, even in the early 1950s.

Getting an 8:1 to 9:1 comp ratio out of a 263 should be easy enough with some head milling and custom pistons, but would the block, head, crank, and rods hold up to the extra pressure?

Is there any one out there with experience in modifying the smaller Buick 8s?

[palbuick]

I would not build up your 37 motor, They have a babbit connecting rod, and might not hold up. Either convert to an insert bering or go to a 50-51-52 motor with the insert berings. The later Dynaflow motors had a highre compression over

the std trans models, this was done with a thinner head gasket. The 1941 Dual carbs will fit most all small series motors. Finding someone to regrind the camshaft might be difficult.

Wait for JT to jump in with more info.

Jim Schilf / palbuick@aol.com

[The Old Guy]

If you have a 263 to build, you have a strong engine. As Jim said" don't use the 37 as they have weak bearings". Joe Lunati of Lunati cams can grind a cam that will give you more lift . You do not want to add much in the way of duration,as the engine does not like RPM. You can mill .080 off the head without any problem, and the 41 compound carb unit is a cheap way to get dual carbs and exhaust. The 41 used a Y pipe to dump both manifolds into one, but it is really two 4 cylinder cast headers ,and you can run a pipe from each one.

Another BIG plus for acceleration is lightening the flywheel. It may be

possible to find an aluminum one ,but if not, you can have some weight turned off the stock wheel.

Gary Hart from Missouri set a record with a straight 8 at Bonneville a couple years ago in a 51 Buick sedan at 131.442 MPH

His phone number:417-742-4411 <img src="http://www.aaca.org/ubbthreads/images/graemlins/smile.gif" alt="" /> <img src="http://www.aaca.org/ubbthreads/images/graemlins/smile.gif" alt="" />

[Matt Harwood]

Raising the compression should not be a problem--I'm planning on milling a little bit off the heads to bump my '41's 320. Converting to the insert connecting rods is important, and if you go much above 8.5:1 compression, you'll need new pistons because the domes on the stock pistons probably won't hold up (I don't think I'd push one of these old guys much past 9.0:1 for reliability reasons). You can use a dual carb setup off of a '41 or '42 Special or Super, but you'll have to fiddle with the carbs because the engine in your car doesn't sit the same as it does in the '41s, and they'll be at a slight angle instead of level. But I've seen it on a '36, so I know it can be done. Contact Howard Camshafts for a regrind of the stock cam--they used to do a lot of high performance cams for the straight-8s, and can still regrind stock units. You'll also need some custom pushrods if you mill too much off the head and use a custom cam (which will have a smaller base circle than stock). I'd also recommend cleaning up the heads and exhaust manifolds, and polishing the combustion chamber. Using the '41 dual carb setup will also facilitate a dual exhaust system if you choose.

Hope this helps.

[37sedan_mod47]

Thanks for the advice and info. I am currently looking for a '50-'53 263 straight 8 for this car. The cost of converting to insert rod bearings alone is enough to warrant the purchase of a later model engine. I want to get any an all benefits from nearly 20 years of refinement as well.

Carburetion will be by dual Weber two barrel side drafts using a pair of custom manifolds. I've talked with some Weber gurus and they have recommended a set up which should give me peak HP between 3500-4000 rpm. Exhaust will be through a custom tube header into a single muffler and tailpipe, probably 3" ID.

New pistons are a must. Does anyone know if Egge makes a piston with a thicker crown for running at higher comp. ratios? Maybe they can machine me up a custom set?

I am looking for an honest 175 HP at the crank. Does that sound reasonable? The transmission will be a T-5 close ratio five speed from an F-body (Camaro) car. I will also be installing a 10 bolt GM axle and power disk brakes all around.

[Bill Stoneberg]

There is a gentleman here in Texas that has a 263 Straight 8 that has been taken apart and he has all the new parts needed to rebuild it. E-mail and I will give you his phone if you want it.

Also, If you have not picked up a copy of Clifornia Bill's book on how to Hot Rod 1950 engines, it is back in print again and available through Amazon. Here is the Link:

http://www.amazon.com/exec/obidos/tg/detail/-/1555611060/103-5299349-0547056

It has a whole section on how to build straight 8's.