Inliners International Forums General Discussion Engines Where to find piston and rods for 270 GMC

Yep that all makes sense, he said he would like to have the pistons before he bores it to get it exact. From what he can tell he said nothing has ever been machined on the block its probably never even been rebuilt. Would eggy know what pistons I could run like flat tops? My next question was getting a rear main seal that works well, I assume the Best gasket has a updated design that works better?

Many of the GMC engines required dome pistons because of their large combustion chambers to obtain their factory compression ratios. Just look at the pistons that came out of it to make sure you get the correct ones.

Ok so I called Tom Landon and he was very helpful told me to magnflux the head and some other good info will be looking for some pistons here first now. Need some 30-80 over pistons for a 59 GMC with small port head will try and find some NOS Zollners, also looking for a 302 intake and exhuast.

Why 302 intake & exhaust? Are you going with a 302 head? The small ports heads are plenty for the street. The small ports are not small rather the big ports are enormous. You may have a hard time sealing big port manifolds on a small port head. The gasket surface is pretty thin.

Small port it is then, I already have adapters for the big port to small port intake and thought the 302 2bbl would hop it up some and keep the stock look. Any good places to look for NOS pistons didnt see any on ebay.

If you can get to a counterperson who cares you may get lucky. AutoZone started by buying NOS parts from dealers & parts stores going out of business. There is still some stuff buried there. O'Reilly bought CSK (who bought dozens of smaller parts brands) and if you can get someone to get in touch with the Home base in Missouri they can do a lot. When I worked for CarQuest the computer searched the stock of every CarQuest store & warehouse in the country. A good counterperson at Napa can do the same thing. None of these places teaches their people to do this anymore. You might find some old guy that has been doing it a long time or some young person who likes to play with his computer. You machinist might have better luck because he will get to the commercial parts guy.

The folks on the Stovebolt website specialize in old GM trucks. Someone there might be able to help.
LINK TO STOVEBOLT

I will run around to the part stores and see what they have and post a couple WTB adds on the inline 6 websites.

Good luck to you. I hope you can find them. I know there is a set out there somewhere. What bore size are the one with the $1000 270?

Im not sure I can call and ask him. Same with the bearings he has.

Are the cam bearings in a 270 GMC the same as the chevy inline?

I think so. I'm headed out to the shop for a while and I'll check my old books.

That would be great thank you! Lifters look good I found 1 bent pushrod but other then that all seems to be going well.

OK, I found them in two catalogs and it's kind of interesting. I learned something. The Chevy 216 from '37-53, the early 235 '49-'54 (not the full pressure 235) & all the GMCs 228-302use the same cam bearings. The 235 & 261 from '54-'62 use a different set because the cam had larger journals.

I found this from both a Perfect Circle & Dura-Bond. PC # SH209S DB # CH-2

I wish you were closer. We will be touring the Dura-Bond plant in Carson City after our Chapter meeting next month. The guy who runs it is a member. Dura-Bond makes almost all of the cam bearings used in the US no matter what label is on the box they come in. It is an interesting process. I'll see if I can take some pictures.

Photo's Or even some Tech Info would be good to maybe post over in the tech.

Maybe tracked down some NOS pistons, but not sure if they are the correct ones, https://www.ebay.com/itm/284423525763 someone also said Federal Mogul 9845CP. A slightly narrower 1905CP fits some engines, 248, 270, and 302. Main bearings: F-M 697M but Im also not sure those are correct can anyone cross reference the part numbers?

Those may be a high compression version. I'm not sure. The pistons in my '57 270 are flattops. I don't know if that if stock? I built it in the late '70s. I think those will work for you and I'd grab them before someone else does. These and the ones with the other engine seem to be your choice right now.

I'll try to look up some some rod & main bearing numbers this afternoon.

I am worried about it not working correctly with my head, are you sure they will work?

I'm not sure but here are some links to pictures. And pictures of mine with what appears to be flattops. The dome pistons for the older heads are not like these.

LINK

LINK

Mine were also flat tops, I wonder if you could still run the domed ones and up the compression

I think they are a high compression set. The raised part goes up into the combustion chamber. I have no idea how much they would raise it but within reason more compression is better.

My Perfect Circle catalog shows these bearing numbers. A counterperson should be able to cross reference them if needed. Rod Bearings # CB427P Undersize P10 P20 P30 P40 Main bearing # MS428P Undersize P10 P20 P30 P40

Figured it out it�s for the 30-53 heads.

The other option is to use the old style head. The only dome pistons I have ever seen for the old style head had a full dome.

I wish I could find a 1959 part number reference searched the internet nothing, and my repair book for 1959.

Priced a set today with modern ring pack, domed version with .990 pin. Bore 3.915 cost delivered is 900. Also pricing for a bore in the 3.821 area is the same with a modern ring pack.

There were (3)different production changes involving connecting rods in the 270 engines. Knowing which version of connecting rod you have greatly affects rod bearing selection because of the tang width of the bearing needed and piston selection due to wrist pin diameter changes. You need to know which you have before you order any parts to verify you get the correct parts.

Those books are on the bottom of the pile I'll try to get to them tomorrow.

The rods are all the same length. The big piston pin were only 302 I think. Pretty sure the wide tang was only the later engines which is the number I posted. I'll see if I can find a Perfect Circle or Federal Mogal piston maybe TRW number.

Here is a Link to a thread on the HAMB . LINK It shows the full dome piston used with the Old open chamber head & the H head. Below in the thread there are drawings of the dome piston in the old chamber and two flat top pistons with the 302 head, D chamber. The late 270 head is more like the 302 head than the open chamber but not the same. The pistons you found will not work with the old head or the 302 head. I believe they are late 270 aftermarket high compression pistons.

Jim Carter used to sell them on special order. He may be able to help. LINK

I can get the rod number to your guys tomorrow, I am learning a lot thank you guys so much! ! push rod is bent but lifters look good still. I will probably end up ordering custom pistons. Who still makes them Ross?

Patrick's used to sell Venolia forged pistons and still may. The Venolia pistons have domes specific for the GMC heads and you can buy direct from them also. Verify your forging numbers on the rods to make sure all rods are the same and don't assume they are original to the engine. After 80 years of existence, anything could have ended up swapped and changed in it from mechanics just trying to get the vehicle back on the road. My Sealed Power book shows the evolution of the changes in connecting rods and the big pin was common to both the 270 and 302, since those two engines were the only ones remaining at the end of the production years. There are several different forging numbers for each style of rods produced, so if you're still in doubt, just get your machine shop to confirm the ones you have.

I did not know that about the big pin. Pin size is a problem when trying to find off the shelf pistons.

There is nothing wrong with good used pistons. These long pistons tended to wear on the skirts and knurling was used to improve the fit. Old techniques work on old engines.

If you order custom pistons you will likely reduce the rotating weight a lOT.

Venolia is out of business about 2 years. As said before. I can order them direct thru Ross. Have some ordered now. Priced a set today with modern ring pack, domed version with .990 pin. Bore 3.915 cost delivered is 900. Also pricing for a bore in the 3.821 area is the same with a modern ring pack.

He's trying to determine which rods he has, either the big pin or small pin. Small pin is .990 same as BBC....

Looks like Patrick's may have withered away as well...where does the time go?

Correct, then it is just a matter of tear down and measure. If he has big pin, the rods could be rebushed to the .990 pin.

If you're referring to Patrick's in AZ, he's been gone for a while and Mother Trucker Trucks in AZ (JoeM) pretty much picked up after him but not sure exactly what he carries. If anyone would like JoeM's email, ping me in a PM and I'll provide it to you. This is also something I would probably call Jim Carter and speak with either Jim or John, either of them will most likely know and possibly where you can get parts if they can't get them for you.

JoeM is a standup person, in my experience. I purchased a ring/pinion from him for my '46 to convert the torque tube over to 355:1, and was sitting on those for about a year when I switched plans and decided to use a '55 Series 2 rear axle so I could swap the trans to an open driveshaft. He exchanged them for me to a 3.38:1 set for the Series 2 and didn't charge me. And some irony in how me and Joe met, we were both run off from the VCCA Forums for discussing swapping a ring/pinion in my '46, they told us that was supposed to go in the forum where "Hot Rods" would post. Both of us banned without even a PM from the moderator, no warning, nothing...Joe was actually more furious about it than I was, if that is even possible...

I would give JoeM a call first, to see if he could help, and Jim Carter after that. Joe might have the rods you need. Short of those suggestions, I'd go to the H.A.M.B. as that's where you find the guys that would be doing this type of stuff to their 270. I could be off there though...But the few folks here that tried to help you are some of the others that would know, so the H.A.M.B. may not be of any more help.

Yeah I knew Mother Trucker is on the HAMB. I thought for sure that Phillip was going to take the reins from Patrick and carry the torch....

Phillip really got wound up when Speedway screwed with Patrick over the Fenton brand. That took a lot out of Patrick too. Not the first to get bulldozed by Speedway. I did quite bit of business with Patrick & Phillip and never had a problem, other that getting off the phone. These days $900 is a reasonable price for custom pistons.

Yeah, Patrick was very proud to have the Fenton line, he knew Fenton personally and had an agreement to use his name. Speedy Bill was a snake and like you say, bulldozed them out of it. I also witnessed Vic Edelbrock almost break Speedy in half at the Hot Rod and Restoratuon Show in Indy one year over Speedy knocking off the original Slingshot Flathead intake Vic's dad designed. I wished he would have, for Vic Jr to have been in his 70's at that time, he was 6'4 and Speedy was built like Pee Wee Herman, he deserved it....

I still haven't looked at the rod number yet, but was searching forms and found out you can do a "full flow" is it worth doing? Also is it possible to do a one piece seal by some machine work? Just thinking if im redoing the engine I should do all the modern upgrades I can.

There also used to be a link on here to an internet article, I think it was Webrodder, about how to do a one piece rear main seal conversion on a Stovebolt. Provided you can find a seal that has the correct ID dimensions for the GMC crank, and the block and rear main cap has adequate material around the seal area to allow machining for that, then it could be done.

I had to di the full flow filter conversion on my 270.



I have heard of using a Chrysler one piece seal but was never able to find the details. It does involve quite a bit of machine work. Best Gasket makes the best rear main seal I have ever used. It comes with a template for trimming to make sure you get the right amount of squish on the seal.

Ok I think I�ll just keep the rope seal if they make a good one. Any specs on the full flow conversion?