HISSIN50 said:An easy way to think of how Fuel pressure should react is to know that pressure basically goes up inversely proportionate to manifold vacuum.
Shane, do you plug the vac line to the reg when setting pressure? It makes a marginal difference (I dont think it matters here though).
That is pretty weird that you have more pressure with vac on the reg than with no vac. Kinda' backwards. If you put a handheld vac pump on the FPR nipple, does it hold vac?
Not sure on a Cobra, but on a GT, the stock pressure with the vac line off and plugged is ~39 PSI. Once the vac line is reattached, the FP is generally drops to ~32 PSI (varies if someone runs a cam with a diminished vacuum signal, etc). IIRC, anything at or over 30 PSI, with the vac line attached, is within spec.LoudToy958 said:What should pressure be at vac on psi vac off psi? I have it set at the normal 42psi vac on, but unsure what the static setting should be.
HISSIN50 said:Not sure on a Cobra, but on a GT, the stock pressure with the vac line off and plugged is ~39 PSI. Once the vac line is reattached, the FP is generally drops to ~32 PSI (varies if someone runs a cam with a diminished vacuum signal, etc). IIRC, anything at or over 30 PSI, with the vac line attached, is within spec.
Good call with the vac line sizing. My line was totally vulcanized (it actually had to be cut off and broke into sharp chunks.). I had some small line on-hand and tossed it on - not sure what size it was though. Like you, I like to run vac lines on the tight side.
Good luck with it Shane.
No, having the vaccumm tube off is the same as WOT (wide open throttle). It should never go higher than this in driving condiditons.
Swarzkopf - really sorry to get into your thread. Didn't mean to jack it. I hate when people do that.
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