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Jetting with high compression?

Old 08-03-2010, 07:17 AM
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Jetting with high compression?

A question for those of you running high-comp pistons: did you have to make any jetting changes related specifically to the installation of high-comp pistons? I realize that changing exhaust and cams,... will require a change in jetting but was wondering if keeping those airflow elements unchanged and simply installing JE pistons would require one to alter the jetting? I will be leaving the exhaust and other such things as they are presently when I get my engine rebuilt with the JE pistons and was wondering if I have to plan for possible jetting changes (am trying to assemble all necesary parts ahead of time so I don`t fall into a "backorder blackhole" once I get the process started).

thanks in advance
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Old 08-03-2010, 09:17 AM
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Mikstr, I'd rejet to be safe with larger mains and pilot jets and always run at least 93 octane pump gas to try to avoid a lean condition that might lead to detonation since you'll have HC pistons and stg1 profile cams.

Send Roger an email and ask him where to start out with the jetting so you aren't lean at all in initially. You can always lean it up from there to get your air/fuel mixture right...

Last edited by FL02SupaHawk996; 08-03-2010 at 09:18 AM. Reason: spell
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Old 08-04-2010, 06:28 PM
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I've not found that compression requires much rejetting. Depending on what other changes you've made the jetting requirements might be very close to what you had before. There's really only one way to know for sure - ride it. Just take it easy the first time out and see what's going on and adjust/correct as needed.
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