I was wondering if you could take gmc 228 pistons and cut the pistontop and use as hi compression pistons in a chevy 235. does anyone know the distance from wristpin to crown on both. could this be a way to get the better gmc rods in a 235???
This is only what ive read but the benefits told are:Larger wristpin diameter,no wristpin clamp bolt,sturdier design,better for high rpm
Back when, the GMC rods might be fitted to a Chevy when making more than 200 hp.Custom pistons were used.This info is found in the old tuning guides by Bill Fisher ,Roger Huntington ,McGurk. The GMC rod is a bit thicker in the web with a larger wrist pin.Contary to what some think,all Chevy rods and cranks were forged,216,235 and 261. You could also use the stronger 261 rods in a 235,custom pistons needed due to the larger wrist pin.
Does anyone know about the pistons? I can get gmc 228 pistons for free but to order custom pistons is high $$$
Please doesnt anyone have the measurments for the 228 piston. ive searched the net and found nothing.
Unless you are really going all out with that engine (blower maybe), shave the head a bit and you will wake it up real well with carbs, exhaust and a cam. It will hold together if you are not going to keep it wound tight all the time.
You can't use GMC pistons in the 216/235/261 engine, period. Take a look at how the chamber relates to the piston and you'll know why... They have used 270 rods in the Chevy sixes due to the fact that they don't use a wrist pin clamp like the Chevy does, but I believe they require some modification to work. Not sure personally on that issue. The head flow on these engines is such that trying to spin them above 3800 isn't going to do much for you performance wise, so for a street engine I would suggest that you focus on making your performance below 3500.
Have you ever seen a high compression piston for a 235? Due to the unconventional combustion chamber design, the dome is all on one side of the piston top--it looks like a cat got into your garage and took a dump on top of it. No other piston will really work in place of it. You may want to try decking the block and/or milling the head for more squeeze. Keep in mind that since the intake valve is almost flush with the head surface, it will have to be recessed into the head the same amount that you take off of the surface, and that will necessitate a like amount of valve spring shims under the intake springs to keep pressures where they should be. A lot can be milled from a 235 cylinder head--I've got one that's been shaved .125 of an inch, and worked fine.
Here are 7" GMC rods fitted to custom Arias pistons. I bought this '54 261 bored out to 280 ci from a retired GM machinist. He told me the best of the best was used in creating the engine and he currently holds some 302 jimmy world record on the salt flats. The name brand parts list is as long as my arm and he claims 5k in parts and machining. Runs super as I travelled to MI with a machinist buddy to check out the engine before buying. He had her up on a test stand and it ran as smooth as I have ever heard an inline. So yes it can be done, yes I am very lucky, no I don't have deep pockets, the man is of an age when if he goes the wife would have sold it for pennies on the dollar. He has had this engine since, are you sitting down?, 1962 and I am lucky enough to be putting it in my ride until I p*** it on.
Thanks for sharing your knowledge. Cosmo49 do you have any picture of the combustion chamber? That engine looks really good.
http://s104.photobucket.com/albums/m177/49Cosmo/261/?albumview=slideshow This is all I have right now. the pictures tail off to another '58 261 I have and pictures of the development of the Edelbrock 2X2 intake.
Unfortunately so is Hans right. But sometimes they pop up. Not so many inline freaks here to compete about em....thankfully
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