Blew head gasket
#47
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I would have to respectfully disagree. Last year I finally replaced my stock injectors. Not because they failed in any way, but because they were pushing 20 years old. I was running 50psi of fuel pressure, but they never let me down or failed to keep me plenty rich at 22psi.
Since I was replacing them anyway I went with 55's and dropped my fuel pressure into the forties but it runs exactly the way it did on stockers with 50psi and ARC2 controlling them.
YMMV, only relating my experience.
Since I was replacing them anyway I went with 55's and dropped my fuel pressure into the forties but it runs exactly the way it did on stockers with 50psi and ARC2 controlling them.
YMMV, only relating my experience.
#48
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Originally Posted by billindenver
I would have to respectfully disagree. Last year I finally replaced my stock injectors. Not because they failed in any way, but because they were pushing 20 years old. I was running 50psi of fuel pressure, but they never let me down or failed to keep me plenty rich at 22psi.
Since I was replacing them anyway I went with 55's and dropped my fuel pressure into the forties but it runs exactly the way it did on stockers with 50psi and ARC2 controlling them.
YMMV, only relating my experience.
Since I was replacing them anyway I went with 55's and dropped my fuel pressure into the forties but it runs exactly the way it did on stockers with 50psi and ARC2 controlling them.
YMMV, only relating my experience.
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#52
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Yes, stock fuel pump. 46psi with 55# injectors. 50psi with stock..IIRC At the time I was tuning based on what the A/F meter told me...and I turned up the pressure until it would remain rich enough wide open. When I put the 55lb's in I put the fuel pressure guage in as well. Pretty sure it was 50 psi on the stockers.
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Originally Posted by billindenver
I would have to respectfully disagree. Last year I finally replaced my stock injectors. Not because they failed in any way, but because they were pushing 20 years old. I was running 50psi of fuel pressure, but they never let me down or failed to keep me plenty rich at 22psi.
Since I was replacing them anyway I went with 55's and dropped my fuel pressure into the forties but it runs exactly the way it did on stockers with 50psi and ARC2 controlling them.
YMMV, only relating my experience.
Since I was replacing them anyway I went with 55's and dropped my fuel pressure into the forties but it runs exactly the way it did on stockers with 50psi and ARC2 controlling them.
YMMV, only relating my experience.
Is this a common experience or is it just that some springs may be a little fatigued with age?
#55
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do you have any way to monitor the percentage of duty cycle your injectors were (or are) running?
i ask this because i do have that ability, and i have seen how stock injectors hit 100% duty cycle at 18-19psi of boost.
i ask this because i do have that ability, and i have seen how stock injectors hit 100% duty cycle at 18-19psi of boost.
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Originally Posted by Geneqco
Have you done any head work? I've been told that at around 17 to 18 psi you can start to get valve float at high rpm with the stock valve springs. I recall a thread where I think ST confirmed he had experienced this.
Is this a common experience or is it just that some springs may be a little fatigued with age?
Is this a common experience or is it just that some springs may be a little fatigued with age?
I'm getting old so my memory could be off a bit.
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I do recall reading about the head float but that was at substantially higher boost. The valve float at around 17+ psi was an independant observation IIRC. It could have just been that the springs in his particular head were a little fatigued if this is not a more general problem.
I also know of some who have turned their boost up on occasion to mid 20's without issue.
I also know of some who have turned their boost up on occasion to mid 20's without issue.
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Originally Posted by nize
head float is probably due to knock, not boost psi.
can you guess how much psi is generated from the cylinder combustion?
can you guess how much psi is generated from the cylinder combustion?