91 l98 general info needed
Thread Starter
4th Gear
Joined: May 2008
Posts: 4
Likes: 0
91 l98 general info needed
just bought a 91 corvette with a blown head gasket...fixed and put back together and now....
idles @ 1000rpm?what should it be?
sounds like a large vacuum leak cant find one?is this injector noise?
never heard car before tear down not sure what to expect.... have worked on lt1 and sound very different... no time with a L98 until this one...
any info would be great going to try smoke test tomorrow....thanks to info from forum thanks this site has been a lot of help
idles @ 1000rpm?what should it be?
sounds like a large vacuum leak cant find one?is this injector noise?
never heard car before tear down not sure what to expect.... have worked on lt1 and sound very different... no time with a L98 until this one...
any info would be great going to try smoke test tomorrow....thanks to info from forum thanks this site has been a lot of help
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Typical idle is 700-800rpm.
Have you checked the vacuum lines under the plenum:
-two on right rear
-one at EGR Valve
-two at EGR Solenoid
Two on the TB:
-one large on right side
-one small under
Have you checked the vacuum lines under the plenum:
-two on right rear
-one at EGR Valve
-two at EGR Solenoid
Two on the TB:
-one large on right side
-one small under
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
As above, and you might also want to check for vac leaks at the runners etc. w/propane (un-lit of course). If all the above checks out, you could then look at re-setting the min. air on TB. If stock, the multec inj. are pretty quiet.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
"sounds like a large vacuum leak "
Almost certainly is one.As above ,need to check all connections and gaskets.
A piece of plastic tubing in your ear moved around intake can help to identify leak location.A lot more mating surfaces than LT1 intake
Almost certainly is one.As above ,need to check all connections and gaskets.
A piece of plastic tubing in your ear moved around intake can help to identify leak location.A lot more mating surfaces than LT1 intake
Safety Car
Joined: May 2006
Posts: 4,290
Likes: 140
From: Salem NH
This is going back about 8 years but, my SLP runners were right and left. If you tried to mount them opposite sides, you got a HUGE vac leak. Are the stock runners like that?
I think the stock runners might have an EGR passage, so you probably can't goof it up, but just my 2 cents.
Other wise, propane or carb cleaner to seach for vac leaks as suggested.
-- Joe
I think the stock runners might have an EGR passage, so you probably can't goof it up, but just my 2 cents.
Other wise, propane or carb cleaner to seach for vac leaks as suggested.
-- Joe
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Thread Starter
4th Gear
Joined: May 2008
Posts: 4
Likes: 0
thanks guys these all sound good i have done a visual on vacuum lines and fitting
tried the propane seemed to not work...pulled a vacuum line of fuel reg and put propane into it and idle did not change...
the idle setting #'s you gave really help and will try hose to ear trick...
will carb cleaner hurt the painted surfaces...i did paint and polish a bunch of parts and dont want to loss this work...
thanks for all your input
tried the propane seemed to not work...pulled a vacuum line of fuel reg and put propane into it and idle did not change...
the idle setting #'s you gave really help and will try hose to ear trick...
will carb cleaner hurt the painted surfaces...i did paint and polish a bunch of parts and dont want to loss this work...
thanks for all your input
Racer
Joined: May 2006
Posts: 426
Likes: 16
From: Concord CA
all you have to do is just spray a bit around one area at a time. Just be carefull around the painted parts...but yeah.. it could damage the finish if too much is used..
Could even be leak o-rings on the injectors..
Could even be leak o-rings on the injectors..
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
vacuum leak
my vacuum leak turned out to be the little 3 way vacuum check valve
at the back of the engine on the left side next to the distributor. The back side looked like it had melted and you couldn't tell from the front.
2. check the hose at the left side of the engine that goes to the vacuum reservoir and the charcoal cannister.
3. check the brake booster for the vacuum hose being cracked and rotted at the bottom.
check the booster inside the car by pressing on the brake pedal.
at the back of the engine on the left side next to the distributor. The back side looked like it had melted and you couldn't tell from the front.
2. check the hose at the left side of the engine that goes to the vacuum reservoir and the charcoal cannister.
3. check the brake booster for the vacuum hose being cracked and rotted at the bottom.
check the booster inside the car by pressing on the brake pedal.
Last edited by coupeguy2001; May 9, 2008 at 06:35 PM.
Thread Starter
4th Gear
Joined: May 2008
Posts: 4
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had a buddy over to do a smoke test and the car has edelbrock runners and the passenger side had a major leak at the lower intake will take apart later and see why....going away for a week tomorrow morning cant wait to see why?
