Dome top pistons in a flat top piston 2F.

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PG45er

PG45er

10 Year
Joined
Mar 19, 2015
Threads
22
Messages
388
Location
Prince George ,BC,Canada
I have a Canadian 2f with the flat top pistons that I am rebuilding for my 1977 FJ45. I know it is original block and head with the flat top pistons, as are the other two 2f's I have. I also know that the US models may have had dome top pistons for those years. My engine needed boring so I ordered new pistons and the ones the supplier got for me (ITM ENGINE PRODUCTS) are domed, not flat like original. Apparently these are the only ones listed for the 2F. Can any of the engine gurus out there tell me if I will have head/valve clearance issues if I use these?? If I can use them should I be concerned at all about increased compression ratio?? I'll post in the 40 section as well.

Thanks
 
Last edited:
Splangy said:
Which head casting number do you have?
Click to expand...
Thought some pics might help.
Thanks
Combustion chamber.webp
numbers 1.webp
numbers 2 .webp
Piston 1.webp
Piston 2.webp
 
The 11101-61010 head is a closed chamber intended for flat-top pistons.

I had always heard from rebuilders that the domed pistons were the ones harder to get, and that the flat-tops were more readily available.

Guess different countries look at this differently. BTW, nice, clean-looking head.
 
Bear said:
The 11101-61010 head is a closed chamber intended for flat-top pistons.

I had always heard from rebuilders that the domed pistons were the ones harder to get, and that the flat-tops were more readily available.

Guess different countries look at this differently. BTW, nice, clean-looking head.
Click to expand...
Thanks for confirming that Bear. I've got my supplier taking another look for flat tops. I was was looking forward to finally being able to put my engine together after waiting 6 weeks for boring and new pistons but I guess it will be a while yet.
 
Bump

I"ve got my flat top pistons. The block was bored .050 over for the dome tops, so I checked the fit of the flat top pistons in the cylinders. They meet the manual specs, 2.4 lb to pull the .002 strip gauge. The rings I'm not 100% sure on...ring end gap in the manual says .008-.016 for 1st and second ring. I've got .020 on the top ring and .017 on the second ring?? My machine shop guy says he is comfortable with that.

Thoughts???? Opinions????
 
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