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Taking apart my 351C 4V out of the Mach One I bought.
Looking at the heads and the condition of the valves but I don't have a book on clearances. The exhaust valves rock about a 1/16" when i wiggle them back and forth in the gudes. I move the valve just off the seat. Are Clevelands prone to excessive valve guide wear? Intakes are better, seats look good and there are no burned valves. What is the best way to measure valve stem to guide clearance?
Thx

<P ID="edit"><FONT SIZE=-1>Edited by whales on 03/26/01 05:56 PM (server time).</FONT></P>
 

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The wiggle you mention is excessive.

Clevelands are notorious for oiling problems to the crankshaft but I'm not aware of it affecting the top end. Some racers used oil drainback tubes to return the oil to the pan as it tended to pool in the top end. Also, external conections were done to supply oil to the crank from a special adapter near the oil filter. Your heads may just be worn out and not indicative of a particular problem.

Roller tip rockers will reduce sideload on the valve and are a good idea in the future after you've re-built them. (full roller even better).

As far as measuring valve stem to guide clearance lets call in Camachinist. I'm sure he'll be here shortly!

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valve guides always wear...easily and inexpensively replaced. but get rid of the 3groove valves and replace with some normal single groove valves.

1970 Fastback, 4V 351C, various colors with black interior
 

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Discussion Starter #4
Thx I have heard about those 3 groove keepers alittle confusing though you would think extra grooves would have more mechanical advantage holding a valve in the retainer. I put some oil on the exhaust valves and did the "wiggle test" ...my cheap version of a micrometer some improvment but not much. My real dilemma is sticking to my plan. I really wanted to wait and rebuild the motor next year after I spend money on all the goodies i want now but I'm thinking maybe i should just bite the bullet and send the block and heads off for machining...aughhh the american racing wheels and tires might have to wait!!!
 

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My advice on a Cleveland is NEVER skimp on the valvetrain. Do it once, do it right,...and wait on the tires. You'll feel better about it when you really need the motor.

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"If you're under control you're not going fast enough"
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Best way to determine VG clearance is to mic both the valve and the guide...

From your description, your guides are shot...

A machine shop can install bronze sleeves in the existing guides (not a whole new guide) to get you back in business....

I'd recommend a single groove valve if you're replacing yours...they are more secure than the 3 groove models...

If your valves are out more than .0005"-. 001" from top to bottom or out of round by more than that....get new ones...

FWIW, a properly machined C head won't have any more valve guide wear than an inline valve head....the geometry is designed to work with the polyangle valve design...
But, if stuff starts wearing, it can go in the toilet quick, especially with that 1.73 rocker ratio...

Post your prospective combo for the future and I can make some suggestions for equipping your heads to compliment it...there are also a number of 335 series gurus here who will be glad to help out....

Good luck!

Pat
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methinks Charles (roadracer) is drawing from some experience from the Cleveland heads on his Boss 302. I wholeheartedly agree - DO NOT be chinsy on the valvetrain, especially in the spring/retainer department. If you were to put that Cleveland back together now, chances are you may do more damage (ie broken spring, dropped valve) that will cost you a LOT more down the road....

randy

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TAke it from a guy who has dropped way too many valves into nice 351C's at 6000+ rpm. Yo udont' want to do that. The Cleveland (especially 4v) valves are huge...that means heavy too. But new single groove valves..I recommend Ferrea. They are beter quality than even Manley severe duty but won't break the bank (@ $18 each maybe). Buy a new cam and get the springs they reccomend...stick with Comp or Crower. Buy new 10 degree locks and retainers..and let the machine shop set up the valve springs uless you have a valvespring micrometer.

1970 Fastback, 4V 351C, various colors with black interior
 
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