Mach 1 RPM...

[keith1562]

The 351cj in my 72 Mach1, is freshly rebuilt. I'm taking it easy for a breakin period. When rebult I included flat top pistons, slightly hotter cam and I even sprung for balancing the rotating assembly. Once broken in, what is a safe red line for my cleveland?
Thanks for any input,
Keith

[Steven Harris]

I had a similar built 351C back in high school in a 70 GT Torino. The man that built the motor told me it would rev to 8,000 and to hold it to at least 6,000 before shifting for ultimate performance.

I think I did rev it to at least 7,000 one or two times but usually shifted at 5,500 because I could not afford a rebuild. It ran like a scalded cat and never came apart.

So that is not a professional opinion just a personal experience. We have several professionals here who will be much better informed than I.

So, how do you like the performance so far?

[JTS71 Mach1]

I had 71 Mach1 that had a 351 Cleveland that was about 500 Hp it had all the good stuff in it. I had a stack of reciepts for over $2500.00 in 1979. It had 12 to 1 compression and a really snotty Sig Erson cam with the closed chamber 4 barrell heads and It would bury an 8000 RPM tach and keep right on pulling, That is until the govenor in the trans would slam it into 2nd gear. ( second gear lasted 2 weeks). I turned this engine way past 8000 RPM constantly, and drove the car for 6 years and never opened the motor. I've run a lot of high performance engines over the years and I believe when built right the 351c is just damn near the best out there. Lets see a Chevy lover build a 500 hp small block and get it to last for more then a week or 2. Fat Chance!

[Steven Harris]

Pretty much the same build as the one in my GT Torino mentioned above.

[JTS71 Mach1]

Yeah I'll bet it was a Beast JTS 71 Mach1

[keith1562]

I had a similar built 351C back in high school in a 70 GT Torino. The man that built the motor told me it would rev to 8,000 and to hold it to at least 6,000 before shifting for ultimate performance.

I think I did rev it to at least 7,000 one or two times but usually shifted at 5,500 because I could not afford a rebuild. It ran like a scalded cat and never came apart.

So that is not a professional opinion just a personal experience. We have several professionals here who will be much better informed than I.

So, how do you like the performance so far?

I'm still breaking in the motor after rebuild , I haven't taken it past 3000 r.p.m. . In a couple hundred more miles, I'll see how she really runs. The mechanic who built it (30 years experience) talked me into having it balanced, he said that clevelands really start to pull above 5000 r.p.m., I can hardly wait!

[JTS71 Mach1]

He isn't kidding thats where the big valves and ports really start to breathe and it's hang on for dear life from there. ENJOY! I know, I've already been there! JTS 71 Mach1

[keith1562]

I had 71 Mach1 that had a 351 Cleveland that was about 500 Hp it had all the good stuff in it. I had a stack of reciepts for over $2500.00 in 1979. It had 12 to 1 compression and a really snotty Sig Erson cam with the closed chamber 4 barrell heads and It would bury an 8000 RPM tach and keep right on pulling, That is until the govenor in the trans would slam it into 2nd gear. ( second gear lasted 2 weeks). I turned this engine way past 8000 RPM constantly, and drove the car for 6 years and never opened the motor. I've run a lot of high performance engines over the years and I believe when built right the 351c is just damn near the best out there. Lets see a Chevy lover build a 500 hp small block and get it to last for more then a week or 2. Fat Chance!

When you say the govener slammed into second gear. This is the first I've heard of a govenor. Was it set-up with a C-6 or toploader?
Just curious,
Keith

[JTS71 Mach1]

It was an FMX automatic. But I believe most automatics have a govenor. You just never hear of anyone talking about them. Which is partly due to the amount of RPM you have to turn to activate the govenor, the engine was past 8000 RPM when it happened. And most cars from the Factory never see that kind of RPM, so most people don't even know about them. When it happened to me that first time I was clueless. (and21) My Dad told me what it was. JTS 71 Mach1

[keith1562]

[quote='Steven Harris'Pretty much the same build as the one in my GT Torino mentioned above.

the advice from Steven Harris seems to make alot of sence. 5,500 redline with an occasional push to 7000 or 7500. I just spent $7200 on my rebuild. I couldn't afford to do it again. If the engine grenaded it would break my heart, as well as wallet. If you're wondering why the rebuild cost that much, there's good reason. I'm a disabled cancer survivor and I just can't do the heavy work, so the local shop got the job. I really trust them. On a lighter note I've really been enjoying driving it. I can only drive about 45 minutes at a time. But each time I do it takes me straight back to 1980!
Keith

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[quote='Steven Harris'Pretty much the same build as the one in my GT Torino mentioned above.

The advice from Steven Harris seems to make alot of sense. 5,500 redline with an occasional push to 7000 or 7500. I just spent $7200 on my rebuild. I couldn't afford to do it again. If the engine grenaded it would break my heart, as well as wallet. If you're wondering why the rebuild cost that much, there's good reason. I'm a disabled cancer survivor and I just can't do the heavy work, so the local shop got the job. I really trust them. On a lighter note I've really been enjoying driving it. I can only drive about 45 minutes at a time. But each time I do it takes me straight back to 1980! It runs circles around my 69 cougar with a 351w, but the cat makes a great daily driver.
Keith