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#1 |
Registered User
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Location: Bradenton, FL
Posts: 1,036
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Max RPMs for a 402
What is max RPMs for a stock 402?
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1970 CST/10 402,700R4,3:73 posi,AC,PS,PB,TLT,PW,Buckets with heaters |
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#2 |
Registered User
Join Date: Oct 2008
Location: Marianna Arkansas
Posts: 7,269
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Re: Max RPMs for a 402
In stock form I'd say you are running out of fire and fuel about 5000 or a little less. The ignition isn't gonna let you rev too high with points bounce and on top of that by those rpm's the fuel is gonna be running out.
On the other hand I had a modified 402 in and old Chevelle, and I kept a 7600 rpm chip in the rev limiter. |
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#3 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: Max RPMs for a 402
On the dyno my 402 nosed over around 5100 and was all done by 5500. That's with a =slightly= better than stock cam. So if you're stock, at 5250 I'd say shift it. Even 5000.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#4 |
Registered User
Join Date: Mar 2013
Location: Campbellsville, KY
Posts: 888
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Re: Max RPMs for a 402
Valve float and pure air intake capability should limit it to not much over 5 grand, but I've heard tell of GM performance cam kits for 427's back in the day that advertised "Guaranteed satisfactory operation up to 9,200 RPM" - the rotating assembly of a big block Chevy is no weak piece.
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Alex V. ------ 1967 C10 Suburban, 350/NP435, Green/Green, PS, PB, HD cooling, charging, shocks, and springs. 1985 GMC C3500 SRW, Sierra Classic, 454/TH400, white/blue. |
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#5 |
Registered User
Join Date: Mar 2016
Location: Long Island NY
Posts: 598
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Re: Max RPMs for a 402
My thoughts exactly. It's a truck motor and the valve springs are over 30 years old so I can't imagine it being any good over 5 grand. I'd limit it to 5,000 unless you upgrade the valve springs, cam and intake.
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#6 |
Local Detroit diesel nut!
![]() Join Date: Apr 2008
Location: Burlington, WI
Posts: 175
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Re: Max RPMs for a 402
When the valves start to float, shift, than make a mental note to shift 100 RPM earlier the next go around
![]() I am guessing that around 4500 the engine is done as far as power and torque are concerned!!! Mike
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Nothing cool anymore, I am old and boring.... |
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#7 |
Registered User
Join Date: Sep 2015
Location: danbury, ct.
Posts: 568
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Re: Max RPMs for a 402
Exactly my thoughts on that 402.. Every engine is different. Without running your engine myself and getting a "feel" for it there is no way to say for sure. With that said I totally agree with Mike. It is my opinion a bad idea to upgrade the top end of an engine for more RPM without upgrading the lower end. Bad things do happen...
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#8 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: Max RPMs for a 402
Why speculate? Here's a picture. This is with the stock 396/325hp cam (instead of the 396/310hp stock cam).
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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