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My engine has a stock bottom end, mild cam and upgraded stainless steel valves/seats etc.
Engine has roughly 60,000 miles, done over the span of 18 years since it was rebuilt.
What sort of revs are high enough to blow the cobwebs out, but low enough to avoid bouncing valves off the pistons?
I'm looking for a conservative figure to keep in mind as I look at the tachometer climbing. 6,000 rpm?
Last edited by Toploader (6/01/2023 8:19 PM)
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You are looking for an opinion. I'll offer mine. If you like to drive it, limit yourself to 5000 rpm's. If you like to work on it, go ahead and regularly take it up to 6500+. After 18 years and 60,000 miles, I would expect a bit of relaxation in the valve springs that would encourage me to be conservative about how high I would wind it up.
Of course, if you have your dream engine on a stand in the shop.....
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TimC wrote:
You are looking for an opinion. I'll offer mine. If you like to drive it, limit yourself to 5000 rpm's. If you like to work on it, go ahead and regularly take it up to 6500+. After 18 years and 60,000 miles, I would expect a bit of relaxation in the valve springs that would encourage me to be conservative about how high I would wind it up.
Of course, if you have your dream engine on a stand in the shop.....
Fair call... It's not quite the daily driver, but close enough. I have plans for another rebuild, but that's probably 5 years away at least. The engine is still strong and compression is good. I just want to keep it healthy and prevent carbon build up.
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I would expect if your engine is capable of actually reaching 5,000 rpm, that would be a good limit.
4,500 is probably safer and more realistic.
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MS wrote:
I would expect if your engine is capable of actually reaching 5,000 rpm, that would be a good limit.
4,500 is probably safer and more realistic.
Thanks MS. I will keep it around that sort of RPM.
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Consider that on a stock non K code 289 max power was made at 4,800 RPM. Reving it much past that makes no sense. For maximum performance you want to shift at an RPM to where after the shift the engine is at or near peak torque. That's probably closer to 4,500.
The bottom end of the 289 has the ability to rev to 8,000+ RPM because the stroke is so short. However max engine speed for a given engine is a function of the cam and valvespring package the engine has. Even most hot street cams aren't going to be designed to rev past 6,500 RPM. That super high winding stuff is for race cars and like TimC said, will require considerably more periodic maintenance.
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Above 5 grand I start hyperventilating !
To "blow-the-cobwebs-out-of-it" you don't need to take it up to 100MPH.....
Just 'wind-up' 1st-2nd-3rd gear . I wouldn't go above 5000 (maybe 4500)
Wind-it-up....then let it back down to 2500rpm then shift to next gear. Doing that let's the engine vacuum pull oil up on the cylinder walls ( and let's YOU sorta catch-your-breath)......
6sal6
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I just built my 289 that is 60 over and its balanced and has polished rods. It will get right up there to 5K in a blink of 2 eyes and would likely go more but I limited it to 5 with a 5K tach. I just like knowing it could but rarely go past 4K. After all its got 2.80 buts and a C4. And getting 18 on reg is enough for me.
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My rev limiter is set at 5000 . . . . . I can’t ever remember hitting it!😇
I’m kinda like Sal, my sphincter really tightens up going near that.
In my biking days red line was almost a daily necessity.😱
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Right now the AOD is my fuse. On the wood it will shift to 2nd at 4200, third at 4K and fourth at the same. I figger I can do that with no worries about breaking things.
BB1
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