plugs and fuel pressure

[rejracer27]

Hi, I am just wondering what kind of spark plugs have worked the best for everyone. My engine is stock except for some bolt on goodies and a 108 octane chip. I can't seem to find the right combination. Also I am lost as to how much fuel pressure I should be running. The car seams to E.T. faster at 40lbs than 50lbs but where should I be for performance and saftey. Don't really want to burn the engine down just yet, ya know.
Bob.

 

[johnnyttype]

Hi, I am just wondering what kind of spark plugs have worked the best for everyone. My engine is stock except for some bolt on goodies and a 108 octane chip. I can't seem to find the right combination. Also I am lost as to how much fuel pressure I should be running. The car seams to E.T. faster at 40lbs than 50lbs but where should I be for performance and saftey. Don't really want to burn the engine down just yet, ya know.
Bob.

do u know what kind of chip u have? that would help for the fp question. 42-43lbs. is what i run, per turbotweak instructions. spark plugs, i use cr43ts delco plugs .035" gap, work good. could go down to cr42ts if boost is above 23psi or so and close gap to .030-.032". hth

oh, and welcome, i see its ur first post

 

[ChevMCarlo84]

I run the NGK UR5's gapped to a tight .032".

Fuel pressure is typically set to the chip manufacturers specs. Typically 42-43# vac line off.

 

[tsaltario]

While on the topic of FP, can someone clarify something for me? When I turn my key to the "on" position, but don't start the car, with the line off, my FP is set to about 45.... After a couple of seconds, I hear the fuel pump shut off, (Since the car isn't running) and the FP drops to about 35.. When my car is running, with the line on, it's only at around 35 PSi.... make any sense?

 

[Underboost]

do u know what kind of chip u have? that would help for the fp question. 42-43lbs. is what i run, per turbotweak instructions. spark plugs, i use cr43ts delco plugs .035" gap, work good. could go down to cr42ts if boost is above 23psi or so and close gap to .030-.032". hth

oh, and welcome, i see its ur first post

+2

 

[Underboost]

While on the topic of FP, can someone clarify something for me? When I turn my key to the "on" position, but don't start the car, with the line off, my FP is set to about 45.... After a couple of seconds, I hear the fuel pump shut off, (Since the car isn't running) and the FP drops to about 35.. When my car is running, with the line on, it's only at around 35 PSi.... make any sense?

#1 When turning the key on accessory the pump energizes for 6 seconds then stops. Normal

#2 When turning the key off there is no pressure in the line so there's a check valve that keeps the fuel in the line for an easy start.

#3 Always have the car running when adj. the fuel psi reg with the line off. Once set slip the line back on. There's a vacuum and the gauge should read about 3lbs lower.

 

[Boost231]

i like NGK UR5 myself but do a search to see what you like

 

[mikestertwo]

+3 on NGK UR5's

 

[rejracer27]

The chip I am using is a thrasher. It may be getting to be old technology now but has worked very well in the past.
I run c12 fuel to avoid detonation. This plug changed has severly slowed the car down. The AC Delco's I was running worked waaaaaaaay better.
I am also still using stock injectors.:frown:

 

[rejracer27]

Hey, thanks for your reply and advice. I am using a thrasher chip, stock injectors and running C12 108 octane fuel. Perhaps the plugs should be gapped tighter?
Bob.

 

[johnnyttype]

any recent 1/4 mile times? boost pressure? what kind of plugs and gap are you using that have slowed you down? sorry, just need more info to help you out:smile:

 

[XLR8]

I use AC 43's.
If you don't have a scan tool get one - otherwise you just whistling in the dark.

 

[bmackinnon]

Swammi says.... Get a scan tool, and don't run the car hard until you do.... otherwise I see head gasket$ in your future.....

oh.... AC (C)R43s at 0.32", and whatever FP puts your 02's at 790ish with no knock on the scan tool.... usually around 43-45 line off.... depending..... and while u'r at it, buy a new O2 sensor, your gonna' need it soon running c16...

 

[rejracer27]

Hi all, well lets start with the plug gaps. I ran the gm recommended .035 gap. Didn't work. I had the Delcos that everyone now tells me to put back in and I will probably tighten the gap a little. The car ran .5 faster in the 1/8th with the old plugs. Scanner, what kind of scanner would be recommended. I need to tune this car. Oh, and I just installed a new poston's race gas O2 sensor so I should be good there. I have a race up coming up so I will post the results of a plug change and reduction in fuel pressure. If I buy a scanner I will go to the track for a little test n' tune. P.S. I hate losing so I need to go faster!!!

 

[johnnyttype]

P.S. I hate losing so I need to go faster!!!

i hear ya as long as your prepared to spend money, faster can be achieved! there are plenty of vendors on this forum that can help ya out so make sure you check them out i know i have!

if you want to tune your car there is a bunch of tech. out there now to do it. most of which can be found, among other good stuff too, at: FULL THROTTLE SPEED - Store Front Page

the scanner you get would be based on budget and goals. you could get a scanmaster for just little tuning or... a wideband o2, powerlogger w/laptop, fast xfi, Gen2 setup, etc. for more serious apps! hth