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Discussion Starter #1
Hey guys I just got my truck back on the road (pulled my 4bt from the 89 ranger and put it in a 2001 ford expedition). And I can't remember what rpm my pump ran to. I sent the pump to a shop to get an unrelated fuel issue sorted. Now it seems to be hitting 3200 rpm and feeling like it's hitting the wall. I thought I had it spinning to 3500 before.
What is everyone running for rpms in there 4bts?

I know spinning a diesel that high might be counter productive in the tq and hp department but mine felt like it was still building power(and boost). It's possible my tach was out tho...
thoughts?
 

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There are several different governor springs. A quick Google search showed up to 4200 RPM. 3200 RPM is the "traditional" governor spring. Nascarmark sells this one:


I have a 3400 spring in my VE pump, only because the 3200 spring was back ordered. I don't rev my engine that high.
 

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Discussion Starter #3
gottach didn't know there was a 3400.
People are saying on other cummins forums that with the "366" spring (3200 rpm) you can actually spin to more than 3200. Not really sure why that would be, but it might explain why sometimes it feels like it hits 3200 and stops and why sometimes it goes higher.
 

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Discussion Starter #4
gottach didn't know there was a 3400.
People are saying on other cummins forums that with the "366" spring (3200 rpm) you can actually spin to more than 3200. Not really sure why that would be, but it might explain why sometimes it feels like it hits 3200 and stops and why sometimes it goes higher.
I'm still working out all the bugs as I get this truck fully in daily driver mode so we shall see after some more testing
 

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In my 8K truck I normally shift between 2,300 and 2,500 if I'm really flogging it I might see 2,800 in the 1st-3rd.
When in direct and OD I never see north of 2,250 but that is just more than 80mph and as geared 33's and 3.55's when passing at speed it does the best in OD vs. Direct, the noticeable loss of torque above 2,200 rally hurts getting back on the right side of the line.
 

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Discussion Starter #6
In my 8K truck I normally shift between 2,300 and 2,500 if I'm really flogging it I might see 2,800 in the 1st-3rd.
When in direct and OD I never see north of 2,250 but that is just more than 80mph and as geared 33's and 3.55's when passing at speed it does the best in OD vs. Direct, the noticeable loss of torque above 2,200 rally hurts getting back on the right side of the line.
What spring do u have?
 

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The "366" spring, it seems to keep full fueling to at least 2,800.
 
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