Intake manifold and bad vacuum

[Bundy]

I'm having issues with my Atomic EFI, was running great now it's running like shit. Called MSD and they said vacuum... well since only my brake booster runs off the manifold I could see it wasn't that.

However I noticed at the same time I developed a leak from the bellhousing so I am thinking I could have blown the rear gasket on the intake manifold and I am leaking oil and have a vacuum leak as a result. I sprayed starter fluid in an attempt to ID it but there was no change... is that because there are no runners that close to the back? Would it still affect how the engine runs?

 

[stlo]

Does it run good at start up and then runs like shit say once the motor warms up?

 

[broncnaz]

How much vacuum are you pulling? rear intake leak doesnt mean you have a vacuum leak although it could. Might try unhooking the vacuum booster to see if that helps any cause if its leaking a little it could bleed off vacuum. You may want to check the timing as it effects vacuum quite a bit.

 

[Bundy]

It ran fine until I rolled it a month ago so something ain't right.

It starts cold like shit and the A/F is ridiculously lean- 34:1 ish. If I change the cam setting on the computer (3 settings street-stock/mild cam/performance) from stock to performance it starts to even out and get to 13.5-14:1.

I'll check the timing and block off the brake booster vacuum line and see if I get a change.

Thanks for the ideas guys!

 

[6t6bronco]

Have you changed the fuel filter since you rolled it?

 

[garberz]

I won't say what I think it is Ryan, you already know what I'll tell you to check.;D

 

[broncnaz]

while it probably wont cure your oil leak you may want to retorque the intake. I've had several new intake installs that required retorquing after a few runs. seems the new gasket along with the heating and cooling process lossens things up. probably since the torque on intakes is not that high to start with.

 

[Bundy]

I won't say what I think it is Ryan, you already know what I'll tell you to check.;D

I'll check the batteries Mark but they were replaced pretty recently!

I'll go check the intake bolts, didn't think of that. I have a vaccum gauge but never have used it. Can I just hook it to the brake booster's port and read it from there? What should it be pulling?

 

[Bundy]

I got the vacuum gauge on and it read around 2-3 psi (or 17 Hg, whatever that is). The 17 reading was in the green part of the gauge so is that good?

I'm running Windsor Jr heads (iron) with the Edelbrock performer intake (iron) and my old school World Products paperwork says to use the infamous Felpro 1250. However last year I called and asked World Products and they said to use the FelPro 1262... which had WAY too big of runners and gave me a massive vacuum leak. Then I went with the stock 302 felpro 90361 and it ran well for a year but ever since I rolled it's been shit... I'm wondering if the impact could have broken one of the seals around the intake ports?

Anyway, I know the 1250 and 1262 (specified by World products) won't work and 90361 may not have held up so I am going to pull the intake and buy the Edelbrock recommended gasket #7220 and hope for the best.

 

[garberz]

"HG" is inches of Mercury. 17" is fine. Batteries are good. What the hell are they talking about?

 

[Bundy]

"HG" is inches of Mercury.

I know we probably created the standard system just to piss the rest of the world off, but inches of mercury? Who comes up with this shit?

Since that is an acceptable reading I can rule out the intake gasket being the culprit? I checked the timing and it was advanced at around 14 degrees which is the last place I set it (and it was running fine)