KB piston to wall clearance?

Does anyone know for sure what the piston to wall clearance is for the old kenne bell 2362p pistons in the picture?:

 

But, the piston in question is not "budget super lite", it is forged super lite?
Then there should be clearance .0060-.0070?

 

Yes, these are the old Sealed Power/TRW forgings. Have them in my car now...0.006" piston to wall is where mine are if I remember right.

Devon

 

I have the same pistons without valve reliefs, mine are .030 over, set at .0045 piston to wall clearance.

 

.0040 or .0060?

 

Careful, you have your decimal place in the wrong spot.

Your question should be 0.004," or 0.006"?

If advised that 0.004" is the way to go, do it. Personally I think anywhere in between that to a max of 0.006" will be fine. NOT 0.060" !!! That's ten times too much!

Devon

 

If it’s got 5/64” compression rings the clearance is .003”.
The last time I used this type of TRW pistons I knew the motor would easily top 580 Hp so I stepped up the clearance by .001”

 

Sorry, my typo. Off course 0.0040" & 0.0060"

 

I set my TRW/Speed Pro 4032 pistons at .0035 if I remember right.. Proper clearance depens on bore an type of alloy.

 

This piston is a 50+ year old design. Sealed Power / TRW . It is a very dense and heavy forging. That has an extremely low expansion rate. It is NOT like a custom forged piton alloy. Lost count of how many engines we built using these pistons.
At one time they were available in the 70'S for $100.00 and went up in the 80'S to $150.00 a set from California Discount Warehouse. And they were referred to as "Budget Forgings". But eventually the cost became $550.00 a set. No longer cost effective. You can run these pistons as tight as .0025 Because they do NOT expand like a custom forging. The ones we build decades ago at .003 are still running TODAY. MAX clearance service limit for this piston is .0045-.005 . We restored a STAGE 1 Convertible a few years back that was shipped to us from the UK. And were told "You won't have to rebuild the engine it was rebuilt and only has 1500 miles". Firing it up and it was LOUD. So upon father inspection. And disassembly. It was discovered that these pistons were installed at .008 and were rattling themselves to death. And seven of the pistons had cracked skirts. Just ready to come apart and destroy an original matching numbers Stage 1 SS block. Good thing we caught that !!! These pistons used to be available in all the popular over sizes. The nice thing about the Standard version was that it was a few thou bigger so even if you had a 455 block with 100+ K miles you could still retain the standard bore and hone the proper clearance. These pistons might be discontinued now ? And when they were still available of the last ones there were only available in .030. I think we still have a number of set in stock along with a bunch of cams and every other part in stock to build and assemble a 455. We would probably build .0025-.003 clearance with these pistons for quietest operation, longest life, and least amount of blow by. Like we have many times. But we don't tell anyone what to do. And we would NOT build one with .005-.008 clearance. It is good thing that engine built in the UK did not break the piston skirts and come apart and destroy the SS block !!!



View attachment 661260

View attachment 661260

 

Here is picture of the newly rebuilt matching numbers engine that had the .008 rattlers . Now running with pistons at proper clearances.

 

Many thanks for the information. We have a stage 1 kenne bell engine restoration. In the 80's, the connecting rod and the block fell apart with it. The block had been delivered to the scrap yard by the previous owner. This set had 7 pieces of intact old pistons and one new spare piston. The engine was made entirely with kenne bell parts in the 70s and we are now restoring this in Finland
Apparently that .0040 clearance reported by Kenne Bell.... and Larry is correct?

 

I have a number of sets of those pistons NOS. The instructions that come with the pistons recommend .0025 for piston to wall clearances. We have built many of them at .003 and they are still running well for decades. WE don't tell anyone what to do.
Just what we do. It is totally up to each individual to decide what they want to build their engine combos.

 

Went into the storage room to get some parts. While there we have a number of sets of these TRW/Sealed Power pistons stacked up. I took a picture of the piston number on the box that has the recommended clearances. We usually set them at .003
But it is up to users discretion and preference as to what they want to set the clearance at.

 

We gave the machinist a value of .0028-.0033" measured from the piston pin height and he was ok with that. Thanks.

 

Hope the rebuild process goes well.