Head rebuild. Exhaust valves .001 off. Advice?
07-22-2011, 08:17 PM
#1
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Head rebuild. Exhaust valves .001 off. Advice?
Sorry if this is covered but difficult to find.
I have an 87 turbo with 90k miles and this is the first time the head has been rebuilt. The head shop says the intake valves are good but the exhaust valves are a thousandth off due to stretching and wear and I could be running the risk of the tops popping off down the road since they're a 2 piece. This shop is familar with 944 heads and I was referred to them my a certified Porsche mechanic.
The exhaust valves are $20 a piece, not that bad, but I don't have enough experience with 944 heads to know just how critical that dimension is. So, do I reuse or spend the extra $80?
Thanks in advance for the advice.
I have an 87 turbo with 90k miles and this is the first time the head has been rebuilt. The head shop says the intake valves are good but the exhaust valves are a thousandth off due to stretching and wear and I could be running the risk of the tops popping off down the road since they're a 2 piece. This shop is familar with 944 heads and I was referred to them my a certified Porsche mechanic.
The exhaust valves are $20 a piece, not that bad, but I don't have enough experience with 944 heads to know just how critical that dimension is. So, do I reuse or spend the extra $80?
Thanks in advance for the advice.
07-22-2011, 09:31 PM
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Sorry if this is covered but difficult to find.
I have an 87 turbo with 90k miles and this is the first time the head has been rebuilt. The head shop says the intake valves are good but the exhaust valves are a thousandth off due to stretching and wear and I could be running the risk of the tops popping off down the road since they're a 2 piece. This shop is familar with 944 heads and I was referred to them my a certified Porsche mechanic.
The exhaust valves are $20 a piece, not that bad, but I don't have enough experience with 944 heads to know just how critical that dimension is. So, do I reuse or spend the extra $80?
Thanks in advance for the advice.
I have an 87 turbo with 90k miles and this is the first time the head has been rebuilt. The head shop says the intake valves are good but the exhaust valves are a thousandth off due to stretching and wear and I could be running the risk of the tops popping off down the road since they're a 2 piece. This shop is familar with 944 heads and I was referred to them my a certified Porsche mechanic.
The exhaust valves are $20 a piece, not that bad, but I don't have enough experience with 944 heads to know just how critical that dimension is. So, do I reuse or spend the extra $80?
Thanks in advance for the advice.
07-23-2011, 10:27 AM
#3
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Sorry if this is covered but difficult to find.
I have an 87 turbo with 90k miles and this is the first time the head has been rebuilt. The head shop says the intake valves are good but the exhaust valves are a thousandth off due to stretching and wear and I could be running the risk of the tops popping off down the road since they're a 2 piece. This shop is familar with 944 heads and I was referred to them my a certified Porsche mechanic.
The exhaust valves are $20 a piece, not that bad, but I don't have enough experience with 944 heads to know just how critical that dimension is. So, do I reuse or spend the extra $80?
Thanks in advance for the advice.
I have an 87 turbo with 90k miles and this is the first time the head has been rebuilt. The head shop says the intake valves are good but the exhaust valves are a thousandth off due to stretching and wear and I could be running the risk of the tops popping off down the road since they're a 2 piece. This shop is familar with 944 heads and I was referred to them my a certified Porsche mechanic.
The exhaust valves are $20 a piece, not that bad, but I don't have enough experience with 944 heads to know just how critical that dimension is. So, do I reuse or spend the extra $80?
Thanks in advance for the advice.
944 valves are not ‘2 piece’ valves.
Real 944 turbo exhaust valves cost way more than $20 – closer to $120 each. The cheap replacement exhaust valves are probably not sodium filled.
If the valves tips are .001” high the most likely cause is the valves receding into the valve seats – the stock valves don’t ‘stretch’. .001” is not enough to worry about.
07-23-2011, 11:42 AM
#5
The stock valve retainer is 2 piece. I'm sure that is what they are referring to.
I think I paid about $50 each for my new "951" part number valves from pelican. The "928" part number ones have all the exact same dimensions but are just not sodium filled. Those are the ones for a 944NA.
The two piece Retaining clip would have to move about 3/4" to come out of the valve/sprng retaining set up. I can't see how .001 could make any significant difference on the spec I think they are referring to.
I think I paid about $50 each for my new "951" part number valves from pelican. The "928" part number ones have all the exact same dimensions but are just not sodium filled. Those are the ones for a 944NA.
The two piece Retaining clip would have to move about 3/4" to come out of the valve/sprng retaining set up. I can't see how .001 could make any significant difference on the spec I think they are referring to.
07-23-2011, 02:25 PM
#6
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The stock valve retainer is 2 piece. I'm sure that is what they are referring to.
I think I paid about $50 each for my new "951" part number valves from pelican. The "928" part number ones have all the exact same dimensions but are just not sodium filled. Those are the ones for a 944NA.
The two piece Retaining clip would have to move about 3/4" to come out of the valve/sprng retaining set up. I can't see how .001 could make any significant difference on the spec I think they are referring to.
I think I paid about $50 each for my new "951" part number valves from pelican. The "928" part number ones have all the exact same dimensions but are just not sodium filled. Those are the ones for a 944NA.
The two piece Retaining clip would have to move about 3/4" to come out of the valve/sprng retaining set up. I can't see how .001 could make any significant difference on the spec I think they are referring to.
I'm not sure whether he's referring to the retainer but he mentioned a couple times something about "if the head popped off the end down the road".
He said it should be fine but either wanted my okay or to know if I wanted new ones. From what you all are saying they should be fine though.
