351 Cleveland max RPM
#1
Wink 
Hey guys,

Does anyone know what the recommended max RPM's are for the 351 Cleveland 4v? I have a 1971 Mach 1, and the odometer has no marking. I'm also asking this because I hear a lot of people say that these engines are known to blow up at high RPM's. How high is too high?

-Jonner B
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#2
Well as far as stock goes. I believe the Tach in the dash was redlined somewhere near 5700 RPM. I can guarantee you, it will go way beyond that. I had a stock bottom end, 2 bolt, 500+ HP. 351 Cleveland. That would burry an 8 grand tach and keep pulling. The FMX auto trans would shift it, before the engine ever quit pulling. So to put it bluntly. No the Cleveland is not prone to blowing up at high revs. Unless run out of oil, or severely neglected. They were virtually bulletproof. I drove mine like I stole it for 6 years, and never hurt it.  Cool

JTS
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#3
(12-14-2020, 03:51 AM)JTS71 Mach1 Wrote: Well as far as stock goes. I believe the Tach in the dash was redlined somewhere near 5700 RPM. I can guarantee you, it will go way beyond that. I had a stock bottom end, 2 bolt, 500+ HP. 351 Cleveland. That would burry an 8 grand tach and keep pulling. The FMX auto trans would shift it, before the engine ever quit pulling. So to put it bluntly. No the Cleveland is not prone to blowing up at high revs. Unless run out of oil, or severely neglected. They were virtually bulletproof. I drove mine like I stole it for 6 years, and never hurt it.  Cool

JTS

Hey JTS. Thanks for the response! Well that's good to hear. Mine is almost completely stock as far as I know, so I was worried that it wouldn't stand up well at high RPM's. It sounds like you've had good luck though! Thanks again!
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#4
Hey Jonner, You have to realize this was a long time ago. I should have  given you the reason I ended up with a 500 HP Cleveland to begin with. My 71 Mach1 was originally a 351 Cleveland, with a 2 barrel. Cool looking and nice driver. I changed the oil and found little hard pieces of something black. I looked at it and found it was pliable, as in not rock hard. I couldn't for the life of me figure out what it was. (I was 21) Well I started having oil pressure fluctuations on my guage??? I checked the oil several times always right on the full mark. I changed the oil again, found more pieces, and showed the pieces to my Dad. He also scratched his head. Well I was headed out of town a couple nights later and got up to about 70 mph, and Bang Bang Bang Boom Boom Boom. It shook the whole car. Thinking I had blown a tire I jumped out, and checked.  All the tires were up?????? What the Heck? Well I started it up and bang bang bang. I thought I've lost the timing chain and it's jumped time. Nope we went about a 1/4 mile and BBBAAANNNGGGG! it quit. Upon teardown I pulled the front cover and found the Ugliest milkshake I'd ever seen. It was a thick gray sludge right to the curve at the top of the oil pan and when I reached into the gunk I found a piece of the camshaft in the bottom of the oil pan. At least I know why it quit. It had broken a rod and slammed it into the block and eventually got it pointed straight up, and hit the cam killing it. So what was the little Black pieces? Turns out they were pieces of the valve stem seals. They had deteriorated and worked their way to the oil pan, and had stuck the oil pump, breaking the shaft. Which caused it to throw a rod. So I'd take a look at the valve guide seals as they can wreak havoc on an engine. 
 As Paul Harvey would say. And Now you Know the Rest of the Story!

JTS

 PS. There are a lot of things that can kill an engine. Lack of oil for whatever reason is a big one.
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#5
(12-15-2020, 03:25 AM)JTS71 Mach1 Wrote: Hey Jonner, You have to realize this was a long time ago. I should have  given you the reason I ended up with a 500 HP Cleveland to begin with. My 71 Mach1 was originally a 351 Cleveland, with a 2 barrel. Cool looking and nice driver. I changed the oil and found little hard pieces of something black. I looked at it and found it was pliable, as in not rock hard. I couldn't for the life of me figure out what it was. (I was 21) Well I started having oil pressure fluctuations on my guage??? I checked the oil several times always right on the full mark. I changed the oil again, found more pieces, and showed the pieces to my Dad. He also scratched his head. Well I was headed out of town a couple nights later and got up to about 70 mph, and Bang Bang Bang Boom Boom Boom. It shook the whole car. Thinking I had blown a tire I jumped out, and checked.  All the tires were up?????? What the Heck? Well I started it up and bang bang bang. I thought I've lost the timing chain and it's jumped time. Nope we went about a 1/4 mile and BBBAAANNNGGGG! it quit. Upon teardown I pulled the front cover and found the Ugliest milkshake I'd ever seen. It was a thick gray sludge right to the curve at the top of the oil pan and when I reached into the gunk I found a piece of the camshaft in the bottom of the oil pan. At least I know why it quit. It had broken a rod and slammed it into the block and eventually got it pointed straight up, and hit the cam killing it. So what was the little Black pieces? Turns out they were pieces of the valve stem seals. They had deteriorated and worked their way to the oil pan, and had stuck the oil pump, breaking the shaft. Which caused it to throw a rod. So I'd take a look at the valve guide seals as they can wreak havoc on an engine. 
 As Paul Harvey would say. And Now you Know the Rest of the Story!

JTS

 PS. There are a lot of things that can kill an engine. Lack of oil for whatever reason is a big one.

Hey JTS. Wow that is quite the story! I hope that doesn't happen to mine anytime soon! I am not hugely mechanically inclined, but my brother is - he could probably look at those for me.  And yes, I don't now much, but I definitely can see that no oil = big problem.  

Thanks again for the response!
-Jonner
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