bluestang65
New member
I hate to say how much more I love building SBF, Modular and even the new Coyotes. This is a rant. If you can get through it, I'm actually asking for help.
Build is a 250 with the CI head and EFI.
I ordered a set of custom pistons and they came out with the compression distance at 1.600 instead of 1.511. When you buy custom pistons, you sign a waiver that you own them. Fault is on me because I just send them a link and asked them to make me a forged stock piston for a 4.1L Ford. Gave them the specs from summit racing including the 1.511 compression distance, but there's no way for me to prove that.
According to my calculations, that makes distance below deck .034" using 9.469 distance to center, 5.881 rod length and 1.955 (half of stroke). The machine shop kissed the block deck, so it's probably closer to .030" if I'm lucky.
Plug it all in and assuming the small side of CI's estimates for the heads of 48cc and I'm over 11:1. I haven't cc'd the heads yet.
I am building a cool-sounding, EFI, fun, street engine and I don't care about performance too much, but clearly the temperament of this engine doesn't match what I'm trying to do.
I'm pissed and venting a little. Help me come to some working solution...
New pistons - $500 sucks and of course the same 'no guarantee we do our job right' exists.
Copper head gasket - .094 gets me in the 9.5:1 but I've called 2 places and keep getting "huh, what motor... oh here it is... it's a 300, right?" I don't think I can explain to another human being what this engine is. I'm not keen on using these, but if somebody knows a source, lmk.
MLS - expensive but cheaper than new pistons, I guess. Did CI ever get Cometic to start making gaskets for these motors or is it a straight custom job?
Custom rods?
New cast pistons - bite yet another bullet and snag a cheap set of cast pistons just to get this job done. It's an NA build, but the idea of cast pistons isn't exciting. Plus, the block was machined to the piston's specs so it's set right at 3.710 instead of adding a couple thousandths to accommodate the .030" oversized pistons.
I could shave a little off the pistons like maybe .010 but this relies on also being able to squeeze a little more out of the heads. Anybody know if it's possible to get a few cc's out of the heads? I'll have to double check what's left to work with in the combustion chamber anyway.
I know we are building a dying breed here, but they built more than one of these motors, so it shouldn't be a total one-off. I'm about to put this whole mess piece by piece in the classifieds.
Build is a 250 with the CI head and EFI.
I ordered a set of custom pistons and they came out with the compression distance at 1.600 instead of 1.511. When you buy custom pistons, you sign a waiver that you own them. Fault is on me because I just send them a link and asked them to make me a forged stock piston for a 4.1L Ford. Gave them the specs from summit racing including the 1.511 compression distance, but there's no way for me to prove that.
According to my calculations, that makes distance below deck .034" using 9.469 distance to center, 5.881 rod length and 1.955 (half of stroke). The machine shop kissed the block deck, so it's probably closer to .030" if I'm lucky.
Plug it all in and assuming the small side of CI's estimates for the heads of 48cc and I'm over 11:1. I haven't cc'd the heads yet.
I am building a cool-sounding, EFI, fun, street engine and I don't care about performance too much, but clearly the temperament of this engine doesn't match what I'm trying to do.
I'm pissed and venting a little. Help me come to some working solution...
New pistons - $500 sucks and of course the same 'no guarantee we do our job right' exists.
Copper head gasket - .094 gets me in the 9.5:1 but I've called 2 places and keep getting "huh, what motor... oh here it is... it's a 300, right?" I don't think I can explain to another human being what this engine is. I'm not keen on using these, but if somebody knows a source, lmk.
MLS - expensive but cheaper than new pistons, I guess. Did CI ever get Cometic to start making gaskets for these motors or is it a straight custom job?
Custom rods?
New cast pistons - bite yet another bullet and snag a cheap set of cast pistons just to get this job done. It's an NA build, but the idea of cast pistons isn't exciting. Plus, the block was machined to the piston's specs so it's set right at 3.710 instead of adding a couple thousandths to accommodate the .030" oversized pistons.
I could shave a little off the pistons like maybe .010 but this relies on also being able to squeeze a little more out of the heads. Anybody know if it's possible to get a few cc's out of the heads? I'll have to double check what's left to work with in the combustion chamber anyway.
I know we are building a dying breed here, but they built more than one of these motors, so it shouldn't be a total one-off. I'm about to put this whole mess piece by piece in the classifieds.