5800 RPM on a Cleveland?

MEDIK418 · 07-03-1999, 03:56 AM

I recently rebuilt a 351-C for our 82 GT. The machinist who I have a great deal of respect for recommended not going over 5800 rpm with the stock Cleveland valves and keepers. These are the ones with the multi-groove valve/keepers. His reasoning is that he's had only one customer who races a Cleveland and he takes his to 5800 with no problems so far. Has anyone had any high rpm experience with the stock valvetrain? I ask because we've had it to 5200 and it's still pulling HARD when we shift there. The cam specs show it to be good till just past 6000. It just seems a shame to waste free horsepower and those huge ports.

mach72 · 07-04-1999, 12:35 AM

The stock multi-groove valves are not to be used for high rpm use. They grip the valve stem loosely(to allow the valve to rotate for even stem wear) and have been known to cause "dropped valves". I have experienced this on an engine that was never pushed past 5500 rpm. I dropped a valve, put a hole in the top of the piston and cracked the block. This was while cruising along at a leisurely pace and not while racing. Although 2 years of hard use and street/strip duty played a part. The stock exhaust valves are of a 2 piece design and have been known to seperate under high spring pressures. I am presently rebuilding a cleveland for my 72 mach 1 and I am using stainless valves with single grooves and a completely new valvetrain. I feel that I have spent too much money on machine work to take a chance with the stock multi-groove valves. The stainless single groove valves can be purchased for about $200 from any mail order supplier or your local machine shop. Good luck, Tom

MEDIK418 · 07-04-1999, 01:16 AM

Thank you. I used Milodon stainless steel single groove valves on the exhaust but the machinist and I got mixed up on the valves he bought for the intakes. Basically, I had never seen these things before and he thought I knew what I was doing. . . . . So much for idle thoughts. I have noticed that Ford is still using the multi-groove valves on the 4.6. Anyway, I s'pose it's time to think about a valve change soon. Thanks again.

------------------
Father to two Teenage boys and four Mustangs. 71 Mach 1,82 GT/351-C, 85 LX trunk(my project), and one '89 GT

66fastback · 07-04-1999, 10:03 PM

Yes, the old multi-groove trick. They really don't hold up when you rev it up. Your right Medik, if you can't spin a Cleveland any higher than that, then you'll never experience what it's all about. I had a 4-barrell Cleveland once....Single plane intake and a huge Holley carb. It didn't even REALLY start to pull good until over 4 grand. Get yourself some good valves and enjoy some 7000 rpm pulls.

Mach · 07-04-1999, 10:05 PM

I bought a '71 351 Cleveland 4V in a box. Absolutly amazed me what this engine went through and came out "intact". Several of the valves have chips out of the stem face. I'm surprised one didn't get swallowed. The rockers were rough.

Can one say overrev?

The heads passed tanking, blasting, and fluxing.

Simply amazing.

07-03-1999, 03:56 AM	#1
MEDIK418 Registered Member Join Date: Mar 1999 Location: Amarillo, Texas, USA Posts: 780	5800 RPM on a Cleveland? I recently rebuilt a 351-C for our 82 GT. The machinist who I have a great deal of respect for recommended not going over 5800 rpm with the stock Cleveland valves and keepers. These are the ones with the multi-groove valve/keepers. His reasoning is that he's had only one customer who races a Cleveland and he takes his to 5800 with no problems so far. Has anyone had any high rpm experience with the stock valvetrain? I ask because we've had it to 5200 and it's still pulling HARD when we shift there. The cam specs show it to be good till just past 6000. It just seems a shame to waste free horsepower and those huge ports.

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07-04-1999, 12:35 AM	#2
mach72 Registered Member Join Date: Apr 1999 Location: Bixby, Ok USA Posts: 8	The stock multi-groove valves are not to be used for high rpm use. They grip the valve stem loosely(to allow the valve to rotate for even stem wear) and have been known to cause "dropped valves". I have experienced this on an engine that was never pushed past 5500 rpm. I dropped a valve, put a hole in the top of the piston and cracked the block. This was while cruising along at a leisurely pace and not while racing. Although 2 years of hard use and street/strip duty played a part. The stock exhaust valves are of a 2 piece design and have been known to seperate under high spring pressures. I am presently rebuilding a cleveland for my 72 mach 1 and I am using stainless valves with single grooves and a completely new valvetrain. I feel that I have spent too much money on machine work to take a chance with the stock multi-groove valves. The stainless single groove valves can be purchased for about $200 from any mail order supplier or your local machine shop. Good luck, Tom

07-04-1999, 01:16 AM	#3
MEDIK418 Registered Member Join Date: Mar 1999 Location: Amarillo, Texas, USA Posts: 780	Thank you. I used Milodon stainless steel single groove valves on the exhaust but the machinist and I got mixed up on the valves he bought for the intakes. Basically, I had never seen these things before and he thought I knew what I was doing. . . . . So much for idle thoughts. I have noticed that Ford is still using the multi-groove valves on the 4.6. Anyway, I s'pose it's time to think about a valve change soon. Thanks again. ------------------ Father to two Teenage boys and four Mustangs. 71 Mach 1,82 GT/351-C, 85 LX trunk(my project), and one '89 GT

07-04-1999, 10:03 PM	#4
66fastback Registered Member Join Date: Mar 1999 Location: Dallas, TX Posts: 208	Yes, the old multi-groove trick. They really don't hold up when you rev it up. Your right Medik, if you can't spin a Cleveland any higher than that, then you'll never experience what it's all about. I had a 4-barrell Cleveland once....Single plane intake and a huge Holley carb. It didn't even REALLY start to pull good until over 4 grand. Get yourself some good valves and enjoy some 7000 rpm pulls.

07-04-1999, 10:05 PM	#5
Mach Registered Member Join Date: Jun 1999 Location: North East Ohio Posts: 23	I bought a '71 351 Cleveland 4V in a box. Absolutly amazed me what this engine went through and came out "intact". Several of the valves have chips out of the stem face. I'm surprised one didn't get swallowed. The rockers were rough. Can one say overrev? The heads passed tanking, blasting, and fluxing. Simply amazing.