MorePowerPlease

O.K. I have a 98 corvette coupe. Let me start off by explaining what I installed.

Swapped out stock head for trickflow 215, 7.5 pushrods, harland rockers, SVO 30# injector, New rails and plumbing, Fast 90 w/ls2 ported tb. I also installed abear valve covers with catch can.

I was removing the oil cap with the car idling and I couldn't get the cap to come off, as I pulled harder air started too rush past cap. Put hand over opening and it is like putting your hand over the end of a shop vac hose (after holding it there for a few seconds).

Is this normal on a N/A LS1??

How much vacuum pressure is normal?

Car seems to run fine for not being tuned yet, but I am concerned about the amount of vacuum there is. Is this going to damage anything?? How would I even reduce it in a closed system like this??

Any input would be appreciated. Thanks

mrdragster1970

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Don't know anything about LS stuff. I do know they have a vent system & a regulator system for motors that pull too much vacuum. If the experts help you with an answer, there are ways to control it.

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3.4camaro

iTrader: (1)

there shouldnt be anywhere near that amount of vacuum in the crankcase.

I vote something is wrong with your PCV system.

1 FMF

iTrader: (1)

there's a pcv valve, should be in one of the valve covers, with a hose going from it to somewhere on your intake. I think there's a hose barb on the back of throttle body on the LS1. So when the motor is running, it sucks the crankcase of fumes for emissions. There needs to be another vent somewhere to allow air into the crankcase, otherwise the motor will suck itself. If no air is allowed in, the front/rear main seals on the crankshaft will want to get sucked in. Had a 99 camaro, an 02 now; don't remember where the vent hose goes to but it ends up at the air filter box- this is where the air is drawn into the crankcase to make up for what the intake sucks out via the pcv. You want to draw clean, filtered air into the crankcase, hopefully for obvious reasons. I've seen valve cover breathers for the ls1, you probably need one of these on your other valve cover, to allow air into the crankcase. If you can't remove your oil filler cap when running, that's a lot of vacuum and is not good. Any vacuum you can sense like that, is happening directly to your front/rear main seals and is not good.

MorePowerPlease

Hi dumbass here.

When I added the LS2 tb it does not have a air feed for crank system, so I had no incoming air (hence my new nickname).

I tapped into the air bridge (after the MAF) too pull the fresh air in. It is not recommended to just put a breather on as that air has not been accounted for by the Pcm.

Thanks J