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Hey guys, I need some advise. When my Dad owned the 1979 sharp V hull Checkmate Persuader, the 454 HO (400 hp) and 12JF-A Berkeley "A" impeller spun up to 6000 rpm's at 63 mph. Now I drop a crate 502 w/415 hp with a 4800 Voyager rev limiter in the Checkmate. Now I'm lucky if I hit 45 mph.
If she's only 18' long and 1895 lbs, where'd my 18 mph go? With the new motor, I ought to be running an 'AA' impeller but....
Should I install a new cam so she'll turn 6000 rpm's and therefore push more water?
Do you have a ride plate or an intake grate, droop snoot or any other performance parts?
Just a thought 6,000 r's on an (A) is like 675hp. I think you have some major pump clearances to deal with first. Your 502 should make peak hp @ 5100-5200 r's. I would check my pump clearances, then dump the 4800 rpm limiter and recheck my timing to see if it is at 36 degs total. Then make another water test.
Jeff
Sorry guys, no performance parts...the intake grate is stock from our friendly neighborhood Checkmate Inc., and the droop snoot isn't compatible with the 12JF-A. But to the first guy, are there any after market stuff you recommend?
To the second guy...I appreciate your insight to my dad's 6000 r. Ever since you mentioned it, other sources confirmed what you said. His motor didn't have that much muscle. Silly question...but how do I make sure the timing's at 36 degree total?
You will need a timing light to do this task. Set the timing light to 36 degs then point it at your pointer on the harmonic dampener. The pointer and the timing mark on the dampener should line up with one-another. You need to know what rpm your distributor is fully advanced at. Say if (example your dist is set to 3000 rpm's to be fully advanced then you need to run your engine slightly over this to check your total. It is real easy to do. Most timing lights do come with instructions on how to hook up and use.
Good Luck and let us know how you come out.
Jeff
Hey Jeff, I appreciate your advise. I'm hopping on the computer here at work so sometimes it takes me a while to get back to you. But I'll try the timing light and get back to you.
- Admiral michael knight