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Piston Tech.?

1K views 16 replies 5 participants last post by  Brian S 
#1 ·
Does anyone file and fit pistons? I see very little on this subject or I am not looking in the right place?
I am building a spare 351 Cleveland engine for my drag race car.I have had pistons custom made. I had a well known engine builder send in (I guess a mold of the inside of a head like I am using) to the piston manufacturer. I seem to have to be doing an awful lot of grinding,filing etc to these pistons to keep from hitting the head. Is this normal? I have never had pistons custom made before so I do not have anything to compare with. I have emailed the engine builder and he said this is a part of engine building. I always assumed you have pistons custom made so you do not have to do this. Is this normal? Can anyone guide me to an engine build forum with specefics on piston fitting?
Thanks for your time and input.
Regards
Steve
 
#3 ·
Wow! .100''.? This is such a trial and fit procedure. Is that .100'' clearance for the entire area of the piston? I have been using dykem blue on the piston then installing head without the head gasket and rotating to hear and feel the clunk. Then, remove head and grind spot on piston. This could take years? Is there anyplace I can go to website or books I can get on how to do this? I am having a hard time believing an engine builder would spend this much time massaging a piston.
Thanks
 
#4 ·
No,no, thats just the minimum thickness of the dome. The outside can be moved about anywhere it has to. If you can install the crank/rod/piston in the cylinder block. Install head with no gasket. Then turn engine over with no contact. You are in the ball park. Then you get to work on valve to piston clearance. .100" exh and .080" int. min..
 
#5 ·
I understand a little better now. I still believe I need to do too much to these pistons.
Thanks for your help Bob.
All the inquiry on this forum and I do not see much if anything on this. Am I the only one that has run into this or do not any of the members fit their own pistons?
Thanks again Bob
 
#6 ·
pistons

In todays modern performance world most guys will send the cylinder heads out and have them probed,/digitized, then they will use that program to machine the tops of the pistons for a perfect fit to the chamber....

I would say that if you have to fit all 8 pistons you are in for a bunch of work. Have you considered what static compression you are going to have when you are finished with this???? What are your goals for this engine???
 
#7 ·
Hi K-Star:
Thanks for your reply. My goals were to achieve about 13.5-1. I was wanting more compression as I am running alky. I originally had the mismatch of pistons for this block so I decided to have the pistons custom made and ordered by someone who knows race engines. I just assumed that a clay mold would be fabricated and sent to the piston manufacturer. If that was done that is where my questions lies. Why in the world would I have to do so much cutting on these? For once in my life I decided not to buy ebay pistons and have these made right. What was I thinking?
 
#10 ·
pistons

If it were me (as a engine builder) i would want to know there is a problem. I would go back to the guy and tell him what you found. If he is any typ of a reasonable person he should take care of it...I know i would...At the very least call ross's tech and find out if they know anything about it...

Keith
 
#11 ·
I have Ross custom pistons in my Hemi, (see my project journal) and although I ordered them through a supplier, I filled out the Ross custom order form.
Ross has a lot of questions that you need to answer, including intended use, gas or fuel, rod length, block height, compression ratio desired, and probably most important, max valve lift and when it occurs.
My pistons fit perfectly, and no modifications were needed. If you ordered custom pistons, and gave all of the correct information, they should fit without any "filing"....
If anything, my Ross pistons came in with valve reliefs that are probably slightly deeper than I needed with the cam I am using, but at the same time, I know I can go with a higher lift cam without any problems.
Ross did a great job on mine.

Steve
 
#13 ·
Hi Steve 392:
You have the confirmation I was looking for. So I guess I am not crazy? I did not think I should have to whittle this much off these pistons. I would have done all the leg work on the Ross site but the engine builder was selecting the cam and I just thought he would be the one to order the pistons. He had all specs and said he had the same head in his place so no need for me to send a clay mock up. Wow! What a mess.
Thanks
 
#14 ·
Piston Tech. Update

Just thought I would tell you what I found out. Called Ross and they said a mistake had been made and the pistons were made for a different Australian Head than the one I have. They are going to replace these or make the correct ones for my application. I also discussed the balance issue that I had of about 25 grams lighter and the rep told me that was a good thing.
Thank God for a GREAT COMPANY "ROSS PISTONS"

And thank you guys for all your help
Kindest Regards
Steve Leffler
 
#17 ·
The 3Vs and 302C chambers are almost the same size but slightly different shape. I hope all goes well with the new set and they arrive ASAP. I've heard of some guys waiting up to 6 months to have custom ones made.

If you want to share some build info with other Cleveland fans, go to my home page to find my engine tech forum.
 
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