How many rpm's does a 6 turn? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TwoFiftyShifter · 07-31-2010, 01:32 AM

I'm putting together my GMC with a 230, and was wondering about how many rpms it turns. I'm thinking of buying this 4k tach, how many rpms is safe for this motor? No more than 4000?

http://www.jegs.com/i/VDO/918/333353/10002/-1

bama63 · 07-31-2010, 01:57 AM

back in the day we used to spin em up to 7500 rpm at the local dirt tracks with a stock bottom end and they ran forever without problems. so i would think it safe to turn it more than 4000 rpm IMO

dnorris009 · 07-31-2010, 02:24 AM

Not sure about your 230, but with my 250 I'd have that thing
about maxed out most of the time.

**aerotruk63** · 07-31-2010, 06:34 AM

Running a six in my truck, it just pulls forever. You might consider a tach to 8000 RPM like in the old days! You might just fall in love with your six and want to build it.

*lakeroadster* · 07-31-2010, 10:08 AM

I had a '70 Nova with a 230 straight 6 that I drove back in High School, and an 8000 RPM SuperTach II is what I used.

As for max RPM if you look at an aftermarket camshaft from Crane they show the following:

Recommended RPM range with matching components
2600-3000 CRUISE RPM
BASIC RPM 2000-5000
Minimum RPM 1800
Maximum RPM 5400
Valve Float 6000
http://www.cranecams.com/?show=brows...tType=camshaft

I hope that helps.

NCD1966 · 07-31-2010, 11:01 AM

damn my old 250 ran out of breath above 3k

pmercer · 08-01-2010, 08:27 AM

I got a '61 gmc with a 235 engine, three on the tree, 390 gears, and it runs around 3400 rpms at 70 mph. I run it on the highway like that, but plan on changing it to 283/700r4 and rear end swap to +-350 gears over the winter. I find the gas milage very poor when the rpms are high, so thats why the swap.

Peter Mercer
St. John's, Newfoundland

07-31-2010, 01:32 AM	#1
TwoFiftyShifter Registered User Join Date: Nov 2008 Location: Gwinnett GA Posts: 1,803	How many rpm's does a 6 turn? I'm putting together my GMC with a 230, and was wondering about how many rpms it turns. I'm thinking of buying this 4k tach, how many rpms is safe for this motor? No more than 4000? http://www.jegs.com/i/VDO/918/333353/10002/-1 __________________ 1982 K10 SWB 1987 V20 - Sold - Doh!

07-31-2010, 01:57 AM	#2
bama63 Registered User Join Date: Jun 2010 Location: gadsden, alabama Posts: 468	Re: How many rpm's does a 6 turn? back in the day we used to spin em up to 7500 rpm at the local dirt tracks with a stock bottom end and they ran forever without problems. so i would think it safe to turn it more than 4000 rpm IMO

07-31-2010, 02:24 AM	#3
dnorris009 Registered User Join Date: Mar 2010 Location: Canton Ohio Posts: 109	Re: How many rpm's does a 6 turn? Not sure about your 230, but with my 250 I'd have that thing about maxed out most of the time. Last edited by dnorris009; 07-31-2010 at 02:32 AM.

07-31-2010, 06:34 AM	#4
aerotruk63 Check The Champ, Demonstrator Join Date: Jun 2009 Location: Montreal,Quebec Posts: 6,627	Re: How many rpm's does a 6 turn? Running a six in my truck, it just pulls forever. You might consider a tach to 8000 RPM like in the old days! You might just fall in love with your six and want to build it. __________________ 1963 *Chevrolet Truck* Literature LINK: https://picasaweb.google.com/113840717762774560215 YouTube Channel with 20+ Original *Chevrolet Truck* Salesmen, Mechanics & Service Department Training Slideshows. https://www.youtube.com/results?sear...otruk63&page=1

07-31-2010, 10:08 AM	#5
lakeroadster Account Suspended Join Date: Sep 2009 Location: High Plains of Colorado Posts: 2,485	Re: How many rpm's does a 6 turn? I had a '70 Nova with a 230 straight 6 that I drove back in High School, and an 8000 RPM SuperTach II is what I used. As for max RPM if you look at an aftermarket camshaft from Crane they show the following: Recommended RPM range with matching components 2600-3000 CRUISE RPM BASIC RPM 2000-5000 Minimum RPM 1800 Maximum RPM 5400 Valve Float 6000 http://www.cranecams.com/?show=brows...tType=camshaft I hope that helps. Last edited by lakeroadster; 07-31-2010 at 06:34 PM.

07-31-2010, 11:01 AM	#6
NCD1966 Registered User Join Date: Jun 2010 Location: Lafayette , La Posts: 404	Re: How many rpm's does a 6 turn? damn my old 250 ran out of breath above 3k __________________ 1966 Chevy C10 Stepside 355ci sbc with 3speed OD 2021 GMC Sierra 1500 AT4 6.2 1980 Chevy Camaro z28 383ci 1990 Chevy Suburban 350 tbi 2x4 (sold) 1984 Chevy C10 sliverado short fleet 1997 Chevy C1500 short fleet

08-01-2010, 08:27 AM	#7
pmercer Registered User Join Date: Oct 2009 Location: St. John's NL Canada Posts: 18	Re: How many rpm's does a 6 turn? I got a '61 gmc with a 235 engine, three on the tree, 390 gears, and it runs around 3400 rpms at 70 mph. I run it on the highway like that, but plan on changing it to 283/700r4 and rear end swap to +-350 gears over the winter. I find the gas milage very poor when the rpms are high, so thats why the swap. Peter Mercer St. John's, Newfoundland

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