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kirks5oh

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guys, i'm having some minor issues with my '85 stang. it seems to be 'pinging' when i go WOT. it doesn't matter what the engine rpms are, when i punch it, i hear what sounds like a clattering coming from the motor. if i'm only 1/2 throttle it won't do it.

 

here's my set-up: 52k mile stock bottom end 5.0, with edelbrock performer intake, holley 585 carb, GT40 heads (upgraded springs??), crane roller rockers, e303 cam as far as i know.

 

i filled the tank up with 87 octane, and figured the car had too much timing for that octane (should have used 93 octane), so i backed the timing down to 10 degrees from 14. the plugs are autolite 104's gapped at 0.043", new distributor cap, rotor, and plug wires, fresh fuel filter. when i made those changes (decreased timing, lowered gap from 0.050 to 0.043"), the pinging stopped for a day, but now it came back. it doesn't seem to do it when the car is cold, either. i will add 93 octane as soon as the tank gets lower

 

furthermore, i took it on the freeway yesterday, and ran it pretty hard. i noticed that the car seemed to be running a bit hot when i was stopped at lights, or when i nailed it. when i got home, tons of coolant had been spit out of the expansion tank, and all the coolant hoses seemed tight as a drum, like the coolant system was pressurized or something. when the car cooled down, i had to add about 2 quarts of coolant to the radiator. oil looks totally fine. WTF?? blown head gasket?? how do i verify this?? could detonation have caused all this?? any help would be appreciated.

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I would doubt that detonation on a NA motor would blow a head gasket. I am wondering if you are lean. Check to see if there are air bubbles in the radiator.

 

i haven't changed the fuel pump yet--its the original pump, that might be my next step, as well as adding better gas.

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i recently swapped out whatever t-stat was in there for a 180 degree t-stat. i will be getting a new fuel pump later today.

 

haven't checked the timing at 3500rpms. right now its around 10.5 degrees, and around 30 degrees with the vacuum advance hose attached

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I would agree with most of the above. I would imagine a bad tank of gas would be the most likely cause if it has never done this in the past.

 

i don't know because i just bought the car recently.

 

i'm going to add some octane booster, and then blip the throttle cable to see if the secondaries open.

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didn't get a chance to start the car tonight, but i bought some octane booster, and will pick up my fuel pump tomorrow. i pulled the plugs tonight--some of them had a bit of the porceline chipped off (i'm assuming its from my shitty gapping tool puting too much pressure on the electrode). the #1 plug had a white/gray residue on the tip pictured below. other than that the other plugs looked fine

 

http://img22.imageshack.us/img22/1793/s3500136.jpg

 

 

as far as checking the secondaries, what's the best way to do this?

 

i'm assuming the primaries are labeled 1 below and secondaries 2?? with the car off, if i pull the cable, the primaries open and fuel is squirted into the primaries, but the secondaries stay shut. i'm assuming the car has to be running for the secondaries to open?

 

 

http://img22.imageshack.us/img22/8092/s3500060.jpg

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that pic is from when i first got the car. i've removed all the emissions crap, and fixed several vacuum leaks on the carb. the only vacuum tubes going to the carb now are from the master cylinder, the distributor, and the PCV (which was disconnected above at the time of that picture). every other vacuum connection has been blocked off--i'm going to take a picture right now.

 

so i'm not sure how the secondaries open?? when the throttle is wide open creating enough vacuum to open them??

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You can tell if your secondaries are opening by keeping them shut with a spring or other means. Test drive the vehicle. If performance is worse with the secondaries held shut, then they were opening when operating normally. Winging the engine in neutral does not work! Vacuum secondaries operate off engine rpm and load, not just rpm, and there just isn't enough airflow in a no-load situation to open the vacuum secondaries.

 

 

Holley makes about 4 different diaphragms. Even though one may look just like another, the link length can vary. This makes your secondary opening rate all messed up, because the spring is not acting on the diaphragm correctly. If your link is too long, the secondaries won't open all the way, no matter what spring you have installed. If your link is too short, the spring may not even touch the top of the diaphragm, which is not good.

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first pic is from the passenger side, shows everything plugged off. the remaining vaccuum lines on this side are to the PCV and back to the temp sensor on the back of the intake manifold.

 

http://img23.imageshack.us/img23/5323/s3500143.jpg

 

 

this shot is from the driver's side, you can see the vaccuum advance line coming from the distributor, and then the other hose going to the master cylinder

 

http://img23.imageshack.us/img23/79/s3500145.jpg

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going to change out the fuel pump, t-stat, and water pump tonight (timing cover gasket has been wet, and i know its about to go), as well as add octane booster and fill the rest of the tank up with 93 octane. if that doesn't cure the problem, i will probably just take it to a shop that does tons of carbed foxes--there are several in north tampa where i live
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tried some lucas octane booster and filled the other half of the gas tank with 93 octane--car still pinging, and coolant pressurized, but car did not run hot at all--ran less than midway on the temp guage. i'm going to change the fuel pump tonight, and the timing cover gasket/water pump while i'm there (gaskets are damp), and then take the car to a local shop later this week.
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Detonation could have put a hurt on the headgasket, are you losing any coolant other than thru leaks? Did you pull all 8 plugs and did they all look the one you have pictured?

 

Check your timing with another timing light. Whats the timing chain like, is it old or new?

 

Have you checked your rotor phasing in your distributor? Whats inside the cap look like, any oil?

 

Pulled a valve cover for loose rocker or broken spring?

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Is the car still pinging or does it have a wierd sort of hickup or miss to it now and then, fuel pumps are usally working or not working at all...

 

I had a similar problem and I got a new TFI module and pickup for the distributor and had Rob rebuild the distributor and the car runs like a top and even sounds a little better.

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