[Garrettsoler]

Hi everyone,

Working on a 1985 GMC c2500 with a sbc 350 engine. I've been trouble shooting a really rough idle that will just stall out and die. I took the carb off and noticed this piece on the intake manifold that was a little crooked (looks like it's missing a bolt). I attached a picture below, does anyone know what this is for? Can I just add a second bolt to the bottom to plug the hole?

 

[BogiesAnnex1]

That is a plug to block off the EGR valve passage for the EGR valve that someone deleted. In position I see in the picture that would be a large vacuum leak.

Bogie

 

[RWENUTS]

Not even close bogie!
it’s the choke stove adaptor on an edelbrock intake.
installed upside down.
for a divorced choke carb.

pic here.

Edelbrock Performer 2101 intake with Q-jet choke - CorvetteForum - Chevrolet Corvette Forum Discussion

C3 Tech/Performance - Edelbrock Performer 2101 intake with Q-jet choke - Hi all, Putting my 1970 L46 back together. Had it rebuilt and when that was done, he put an edelbrock performer 2101 on and I had the original Q-jet rebuilt and putting that on. Previously I had a Holley and never had a...

www.corvetteforum.com

 

[Garrettsoler]

I tightened it up and replaced the carb and now it's backfiring out of the carb. Any ideas why? Double checked and I don't have any crossing spark plug wires or anything. Was running fine last week besides dying at idle.

 

[RWENUTS]

Vacuum leak.
Likely on either side of the carb base.
You need one of these.

Carb Adapter #2732 for Edelbrock Manifolds Only, Square Bore-Spread Bore .100in

Edelbrock Square-Bore to Spread-Bore Adapter Plate for Edelbrock intakes

www.edelbrock.com

 

[BogiesAnnex1]

Not even close bogie!
it’s the choke stove adaptor on an edelbrock intake.
installed upside down.
for a divorced choke carb.

pic here.

Edelbrock Performer 2101 intake with Q-jet choke - CorvetteForum - Chevrolet Corvette Forum Discussion

C3 Tech/Performance - Edelbrock Performer 2101 intake with Q-jet choke - Hi all, Putting my 1970 L46 back together. Had it rebuilt and when that was done, he put an edelbrock performer 2101 on and I had the original Q-jet rebuilt and putting that on. Previously I had a Holley and never had a...

www.corvetteforum.com

So it is, need to slow down and really look or maybe time for new glasses.

Bogie

 

[Garrettsoler]

Interesting, well that's the machine shops fault he installed that onto the intake. What is this used for? Can I flip it over and tighten it down to stop intake leak? I have an electric choke on the carb by the way.

 

[RWENUTS]

Read the link to see what it’s for.
You can flip it over and bolt it down but you likely will need a gasket.
Like in here. Or make a gasket.

Replacement Choke Adapter Plate for #2101, #2104 & #3701 Big-Block Chevy

The Edelbrock Choke Block-Off For Small Block Chevrolet With #2101, #2104, #3701 Intake Manifolds

www.edelbrock.com

 

[BogiesAnnex1]

Interesting, well that's the machine shops fault he installed that onto the intake. What is this used for? Can I flip it over and tighten it down to stop intake leak? I have an electric choke on the carb by the way.

That should not present as an intake leak there should be no connection with that cavity and any vacuum source to the fresh charge part of the intake. That is a hot spot to either mount a divorced choke’s thermo coil or as a heat source for an integrated with carb thermo coil.

Its possible that a bolt hole penetrates an intake passage and leaks air so this thing should be secured. If the Edelbrock carb has a choke it’s most likely either manual or electric so for your application the exhaust hot spot serves no functional purpose so just close it as designed.

Bogie

 

[67jim]

Hi everyone,

Working on a 1985 GMC c2500 with a sbc 350 engine. I've been trouble shooting a really rough idle that will just stall out and die. I took the carb off and noticed this piece on the intake manifold that was a little crooked (looks like it's missing a bolt). I attached a picture below, does anyone know what this is for? Can I just add a second bolt to the bottom to plug the hole?

If it’s sucking vacuum, just put a bolt in it, if not don’t worry about it

 

[PHWOARchild]

You need to do a vacuum leak investigation. With the engine idling, take off the air cleaner and plug any vacuum hoses. Them place a hand over the carb air horn. If the idle smooths out and picks up, you have a vacuum leak.

 

[75gmck25]

When I converted from hot air to electric choke on my Quadrajet there was a port on the front of the choke housing that had to be capped. IIRC this port did draw vacuum, which is why the cap was needed. Maybe the cap is missing on your carburetor.

If you look at the docs for one of the electric choke kits it shows the port that must be capped.