The Stovebolt Site Forums The Shop Area Engine Shop 302 Jimmy

Hello to all. I am a newbie here to the lists but have lurked in the shadows from time to time, just reading and learning. I'll get right to the point today as I need to get going here. I recently aquired a BIG Jimmy six (302 to exact, military version) yesterday I took it apart to see how things look inside. It looks very good considering the age and all. I did find a problem with a piston though, actually two pistons. It seems 3 and 4 have bad bushings on the little end of the connecting rods. I am confident a machine shop can fix these for me. The thing I am not sure what to do with yet is the number 4 piston itself has some big issues. It seems the wrist pin keeper had come out on one side of the piston and the other side was all beat up. Portions of the piston that retain the keeper are gone!! So... I am going to need to aquire another piston to fix this most cost effectively or buy a new set of pistons at a lesser cost efficient fashion. Any feedback out there on a source for single pistons for the 302 GMC engines. Maybe someone has a set that is already broken and they would like to let go of anther single piston. I am pretty sure they are standard bore. I need to clean the tops to verify. I will be in search of rings and main/rod bearings too eventually. I know Pattricks will carry some of the stuff I want as well as Kanter Automotive. I want to test the waters here to see if any of you "Bangers" have any other leads for me. Thanks for letting me ramble on here. I probably had too much coffee this morning!! Individuals???...Army Surplus???...Other Bolters??? I am on the hunt!!Let me know.... Rick

I see various singles on eBay frequently, but they are not easy to find and take a lot of looking. Have you checked with Stovebolt Engine Company?

No Kook, I have to admit I have not done a bunch of checking yet. I will do so this week and see what I can drum up. Thanks for the tip. Where on e-bay would one look for pistons?? I have never seen any listed that I can recall.

I have several old, used sets. I can check for you, be patient. This would probably get you by. What kind of condition is the cylinder in?

Try Egge Machine . If they don't have them in stock, they can make you some .

OOoo! EXCELLENT link there long motor man! Thanks.

If two pistons are fubar, plus a3rd lost a pin retainer, I'd give serious thought as to whether the other three as "good as new" or about to go south, too.

Matching compression ration, weight, etc makes it harder to find "a few" pistons. Get a set, it'll be cheaper overall. Patrick's has better-than-OEM for decent prices.

Cheers!
George

Nope, sounds like it's toast, you outta just scrap that thing, tell ya' what I'll do I'll come pick it up for ya and take care of it.
You ever get the casting number off it? Lets see it..
MONGO

Before looking for pistons, I suggest doing some measuring. The results will determine what size piston you need.

1) Be sure to mic your old wristpin, 302s used two different pin sizes .990 on earlier 302s, 1.050 on the later ones. Larger rods can be bushed down to the small size but not vice versa.

2)Also it would be wise to check wear and taper in the cylinder bores to be sure that the block won't need an overbore. I'd be surprised if there were no scoring damage from the pin keeper failure.

GMC 302 pistons can be hard to find and expensive. The rings are an old wide style and often cost more than the piston itself, if you can find them. Good Luck

Shop Shark KCMONGO is in the hunt for some fresh meat or somethin'!! Ya sure come on over and pick it up!! Funny!! I have taken the block to a machine shop after checking around fro some used pistons. A couple of guys ahd some and I appreciate their efforts in hunting them up, but after looking carefullt at the cylinder walls I feel it best to get the overbore and a fresh set of pistons also. The shop I am working with deals with JE pistons in the race engines they buils, so I will most likely have some JE pistons made. The cost is going to be nearly the same as those offered by Patricks and Egge Machine. With the added benefit of the shop offering some warranty for the the JE brand. Although I suspect there will be no cause for needing a claim of any nature. I do not intend to run the H, E , Double golfsticks outta this engine. I want more power to tow with and make some long distant runs if the desire comes up. I am excited all the same. I will try to keep those interested up to date on my processes. I was sorta thinking about putting a Paxton type supercharger on it though. That would really bring the old beast to life!! Pricey I would bet too!!... We'll see on that...

Don't tell anyone but Egge makes Patrick's pistons

In the past I and others have had problems with Egges pistons....Patrick yelled a lot and they are better but check em...really check em

Setup a dial gauge and surface plate and with the rings off check the cam grind for flat spots!

I'm using Ross but there's nut'ing wrong with JE
and others making forged pistons

In any case measure measure measure!!!!!