How much do domed 2F pistons with a narrow combustion chamber on a F head raise compression - assuming I've cut .040" deep 45 degree chamfer on each cylinder from the head? (for details see 2F Block - F Head: Piston clearance and compression).
Domed pistons
- Thread starter NewFJFan
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- Thread starter
- #3
Thanks, very helpful.
Now I'll have to find domed piston Man-A-Fre volume... looking.
Now I'll have to find domed piston Man-A-Fre volume... looking.
map101
I have a new rebuilt 2F motor, 1978 block, purchased domed pistons, then had them ground accordingly to accommodate the small compression chamber of a 1980 head. Combustion ratio is now at 8.92 to 1. Put a stock camshaft, engine now has 500 miles on it and getting stronger. Put on a header and now FJ40 has very smooth power.
I have a new rebuilt 2F motor, 1978 block, purchased domed pistons, then had them ground accordingly to accommodate the small compression chamber of a 1980 head. Combustion ratio is now at 8.92 to 1. Put a stock camshaft, engine now has 500 miles on it and getting stronger. Put on a header and now FJ40 has very smooth power.
- Thread starter
- #5
Why grind the pistons?
I don't know much about such things but one would think the pistons are thin (moving part) and plenty of space on the head. Why grind the pistons and how much did you have to take off? Do you know the head number?
I don't know much about such things but one would think the pistons are thin (moving part) and plenty of space on the head. Why grind the pistons and how much did you have to take off? Do you know the head number?
map101 here. Domed pistons are the norm for 1975 to 1978. Prior to these dates and after flat topped pistons were used.
There is plenty of metal on the domed pistons to grind away needed metal to accomodate the newer heads. The reason you must remove metal is the make enough clearance for the valves and any excess overhang for the head decking.
I would suggest that if you want this done to go to a racing engine machine shop. They will be able to accomodate you on your project.
My engine was done by Rex Racing out of Sacramento, CA. Amazing service and work.
There is plenty of metal on the domed pistons to grind away needed metal to accomodate the newer heads. The reason you must remove metal is the make enough clearance for the valves and any excess overhang for the head decking.
I would suggest that if you want this done to go to a racing engine machine shop. They will be able to accomodate you on your project.
My engine was done by Rex Racing out of Sacramento, CA. Amazing service and work.
shaving head
Shaving the head will work, but in my case I was able to find a brand new 1980 head. My feeling is once you shave metal off you can not put it back on. My personal reason is that I am into my engine for the long haul and 20 years down the road I want all the metal i can left intact. Also, my head was a non-usa head. Came with no air injector ports.
Shaving the head will work, but in my case I was able to find a brand new 1980 head. My feeling is once you shave metal off you can not put it back on. My personal reason is that I am into my engine for the long haul and 20 years down the road I want all the metal i can left intact. Also, my head was a non-usa head. Came with no air injector ports.
Why not just get flat top pistons that were designed to go with that head and not mill anything
Ed
Ed
