I bought a NOS Solo 665 last fall with the intentions of building it with a Dolmar 7910 topend. I bought the topend and it's just been setting there. I finally got around to mounting it to see how much needed removed from the squishband, since the 665/681 has a 2mm longer stroke. Then it set for several more weeks. Friday I had Nik, @FATGUY , mill a slot in my PVC mandrel to accept a cutting tool. It requires taking .060" out of the squishband, with the use of the thinner rubber coated Dolmar gasket, for a final squish of ~.020". Without having raised the exhaust up, compression is 235 PSI. However, the exhaust is way down at 108.5°. I don't have an accurate measurement yet, but it looks like it will take about .130" just to get it up to 100°. It may end up higher.
I have some questions on the bottom end. I don't recall the details, but I thought I had heard of multiple issues with 681 cranks. On the other hand, a couple reliable sources have run these as high as 240+ compression and even on nitrous with no issues. I'd rather true and weld the crank now though if there might be issues. Does anyone have the lowdown on if there are crank issues with these?
Crank bearings... Am I correct that the flywheel side is a 6202? How about the PTO side? Is it a proprietary bearing? I'm toying with the idea of putting ceramic mains in it, since this is a fun build for myself.
Are the main bearings, seals, and crank gasket the same as the 7900/7910?
I'd appreciate any info you guys might have on these. If not, I'll fill in the blanks as I go.
I have some questions on the bottom end. I don't recall the details, but I thought I had heard of multiple issues with 681 cranks. On the other hand, a couple reliable sources have run these as high as 240+ compression and even on nitrous with no issues. I'd rather true and weld the crank now though if there might be issues. Does anyone have the lowdown on if there are crank issues with these?
Crank bearings... Am I correct that the flywheel side is a 6202? How about the PTO side? Is it a proprietary bearing? I'm toying with the idea of putting ceramic mains in it, since this is a fun build for myself.
Are the main bearings, seals, and crank gasket the same as the 7900/7910?
I'd appreciate any info you guys might have on these. If not, I'll fill in the blanks as I go.