Just threw on some Jegs heads on my 350 SBC, And it starts up and stalls out due to a huge vacuum leak. Didn't notice it right away, but saw a gap on both sides of the intake, where it meets the heads

It looks like my Edelbrock performer EPS is not wide enough for the Jegs heads...

I called Jegs, they said that it is not a compatibility issue and implied that the deck might've been machined at one point (this is very possible) or the intake manifold might have warped. I had standard GM heads prior to this and never had any issues.

The previous owner possibly did some machine work.

If the deck has been machined, is there any way to fix this issue? A gap can be seen on the top and bottom of both sides of the intake.

Thanks for any help or suggestions!

 

Looks like you have heads that want a MUCH bigger intake than the stock replacement one you have.

Standard way of expressing such things is to use the FelPro intake gasket part # for the appropriate size. Your stock intake would use a FelPro 1204 gasket. Looks like the heads are set up for a 1205. (probably even says in the specs or owner's manual or something) REALLY BIG heads use a 1206.

Only problem you have is a parts selection mismatch. Get an intake more suited to your heads. Post the head part # and it won't be hard to pick one.

 

Thank you for your response. I used the gasket that was provided with the heads. But you're saying a FelPro gasket that is much thicker should fix it? To me it looks like the manifold is sitting to low... I guess a thicker gasket will move it up.

Here is what it came with. Thickness of the manifold gasket is .062"


Qty Item
2 555-514002 SBC 180CC 64CC SP 1.25"


1 555-210000 Int Gasket-SBC-Med Race

 

Yep, what sofa said.

Most of the 180-200cc aftermarket heads have bigger intake port openings, with the common size being fel pro 1205 gasket, and some being the 1206.

1205 gasket size... 1.28" x 2.09"
1206 gasket size.. 1.31" x 2.21"

Look on jegs site for info.. Here you go.

Jegs 180cc heads http://www.jegs.com/i/JEGS-Performan...d=#moreDetails

1.30" x 2.20" ports

Jegs 195cc heads
http://www.jegs.com/i/JEGS-Performan...d=#moreDetails

1.30" x 2.15" ports


eddy eps intake.... Port exit dimensions: 1.15" x 1.87".

eddy performer... Port exit dimensions: 1.14" x 1.88".

performer air gap... Port exit dimensions: 1.14" x 1.88"

performer rpm.... Port exit dimensions: 1.16" x 1.92"

Performer rpm air gap.... Port exit dimensions: 1.14" x 1.95".


I have Brodix IK 200 heads and my performer RPM intake just barely fits.

 

No it's not really the thickness of gasket in this case... "

Your intake will not work with those heads, no matter what gasket you use.

It's a mismatch between intake ports and head ports.

 

Here's your head port size:

From the specs for your heads, right off their web site, that you read, understood, asked questions about if you needed to, and compared to your other parts, BEFORE you bought them. Remember?

Looking at the port dimensions for your intake that NightRider posted, not hard to see what the problem is.

You basically have a GIGANTIC parts mismatch incompatibility. There's nothing "wrong" with any of your parts except that they are totally inappropriate to be installed on the same engine.

You need a race sized intake to go with those heads.

Looks like a Performer RPM is about the absolute bare minimum and probably still may not work, since not only do you have to worry about the port dimensions, but also, how far up or down on the surface the ports are located.

 

well damn... thank you guys for your help. The worst part about this is I called jegs before I ordered and they said that it would match up with my application... AND they are still saying that... I'll be sure to educate them in the same matter that I have been educated today.

 

Should've just bought the edelbrock heads...

 

Whats weird is it looks like the middle ports/gasket line up.. pull intake and compare port sizes. put a straight edge on intake to make sure its straight...but yeah, sofa and the guys are dead on otherwise. some knowledgeable ***** on this site.

 

now that i look closer... the first pic, the ports under the carb, you can see the gasket. that looks normal. then on the last pic, same spot but zoomed in, the gasket is gone now... did you pull the intake between pics? like the gasket got sucked in or something unless i am looking at it all wrong.

 

the first and last pic aren't actually the same spot. The first pic is toward the front of the intake, and the last pic is toward the back...

I'll definitely measure, but the port dimensions are way different... i'll need to find an intake manifold that would match...

 

ahh, i see now. i saw the sending line for your temp gauge in both pics...

 

Yeah unfortunately the "tech" guys aren't always quite as informed as you'd wish... that kinda leaves you in a bad spot, because most intakes that are likely to fit the heads, aren't likely to fit under your hood. Esp since you have a Firebird.

If you have their assurance that it will fit in writing (chat transcript for example) and pictures of what it actually does (doesn't), you'd have a pretty good case for a full refund. Trade em back in on something that fits better. The Edelbrock head suggestion isn't a bad one for example; not the "fastest" heads there are, but a VERY good choice for a nice street machine, and they FIT street-ish motors quite well. Dart would be another good choice, in their 180cc port size, such as part # 127122. http://www.jegs.com/p/Dart/Dart-SHP-...91309/10002/-1

 

You're very right sofa, those tech guys had to put me on hold like 5 times today and gave me very little ideas of what could be wrong. I doubt i'll get a full refund... We'll see what happens. Thanks for the suggestion on the Dart heads. I'll look into it if it comes to that. Thanks again for everyone's help.

 

The jegs heads flows great, flows better than the edelbrocks for sure and will make more power than the eddy or dart 180 heads.

You just need a bigger port intake. The performer RPM should work. Which also is the most common intake on builds using aftermarket 190+ cc heads

 

Jegs ended up sending an intake manifold and gasket (for free) that would fit properly. We'll see how that goes...
http://www.jegs.com/i/JEGS+Performan...13000/10002/-1

 

With that NEW manifold, it is still gonna have 3/10" mismatch on the top of the port.
Check the intake gasket against the manifold and the head before bolting it down.

 

okay will do, thank you

 

Did this intake work?