Fred's 2375 Rebuild Thread Options

[friethmiller]

[A softball question for the Ninja and/or others]

This is the cam card that came with my 2357 engine, which was originally built by Rimco/Fat (long block) a few years ago. Can someone explain why with an intake/exhaust of 448, the lift was only set to 327 degrees? I'm about to rebuild my motor and a lot of focus will be directed at piston "deck clearance" and the valve train geometry that wasn't set correctly. Thanks.

[Jack Standz]

Just some thoughts and first impressions.

Those are KB / Keith Black cast hypereutectic pistons. Good pistons, but they don't have the scraper ring pinned. Not good. In addition, it looks like you have poor ring sealing,, excessive blow by & an overly rich condition. Maybe part build issues and maybe part break-in procedures - but see above comment about the oil ring not being pinned..

In/Ex lift on type iv rockers is approximately 1.3:1 (some say IN slightly more and EX slightly less). Then + or - 5% when you cut the pushrods to the correct length and get geometry correct. But, you had other more concerning issues with this build.

P toV clearance isn't usually an issue only @ TDC. For example on a 163/86b Webcam camshaft, the Pto V clearance gets closest around 8* ATDC (IIRC &YMMV). And, the valves might actually have clearance issues between the IN and EX valves (IIRC this cam can have this issue depending on how you set cam timing). So, be careful and mock-up and check everything.

This cam may not be what you want for your application, but it does have longer duration on the EX, which is what has seemed to work better with the limitations of the type iv EX ports. Maybe take a look at the Webcam 86b/86c too.

Cam thrust bearing problem seems like the cam was too tight (and possibly not aligned with each other) and should have been properly set-up during mock-up. You can take a glass plate and some valve grinding compound to clearance the thrust bearings. Seems to be a problem area too often, especially with double thrust bearings.

Did not use Curil T or K on cylinder to case sealing. Not a fan of silicone here.

Balance the entire rotating assembly, including clutch and PP.

FI could bring better performance after properly designed and dialed-in. However, you'll be fine with the carbs and manifolds you have, if properly tuned.

Good luck with getting your motor fixed! And Happy New Year too!!