Disappearing Carb. Fuel

[BRL]

Years ago I read in a car magazine that GM put a tin heat shield underneath their quadrajet intake manifolds to keep hot oil from splashing on the underside of the intake runners and disrupting fuel distribution, so I put one on an Edelbrock aluminum intake and engine ran noticeably smoother.
Of course I sold the car that had that intake on it because sometimes I do stupid stuff.
Anyway my fuel was disappearing from my Edelbrock 600 cfm carborator fuel bowls after a few days of sitting and I suspected it was either leaking down through worn jet needles or evaporating due to boiling away.
So I added one of those resin spacers to see if that would be of any help and the problem seems to have disappeared.

I'm only mentioning all this because I needed to let somebody know that my retired fat bottom doesn't just hop up under the hood anymore and next time I'll just live with the problem.

[LockDoc]

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I don't hop up under the hood anymore either, I just crawl in...
Making sure I have plenty of padding under me. And yes the spacers definitely keep the fuel from boiling in the float bowls. They can also help with vapor lock. I use the Phenolic ones, I think the last one I bought was 3/4 or 1 inch thick.

Here is an interesting read on them.

https://www.onallcylinders.com/2014/...uretor-spacer/
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[BRL]

Hey thanks for the reply and article, I found it to be an interesting read. 🙂

I just saw this spacer hanging on the rack at O'reilly's one day and figured it would help insulate the carburetor from engine heat, which it seems to do.

It is of an open plenum design and I would have preferred something with 4 individual holes for more bottom end torque, but it is thin so it's not adding much plenum area anyway and the engine seems to run smoother overall as well.

What really surprised me is the carb. is a square bore but the intake looks like it will accept a spread bore carb...when did I do that?

I'm not running any kind of adapter on it other than that spacer now but there are no vacuum leaks and the truck putts around town just fine for this old man.

[Sheepdip]

Put one incher on Otis after I got the A/C up and running, my problems on hot days at long traffic lights/trains went away along with an empty carb the next morning. They work.

[Rust_never_sleeps]

My qjet came to me with a tin shield between the carb and manifold. I'm told it's a Camaro part, but IDK. Gasket was literally stapled to this thing. PO never mentioned any hot start problems, so it must have worked

I'm adding a phenolic spacer instead

[BRL]

Ah Ha!
Found it!
Yea this tin plate was riveted to the underside of the Q-Jet intake manifold in the lifter valley and shielded the individual intake runners from hot engine oil being splashed up on them.
I went ahead and put it on an Edelbrock Performer intake and it did noticeably smooth out cruzing performance.
...and then I sold the dang intake.

[LNP]

You can buy lifter valley pans. They keep the hot oil off your intake and if a push rod or rocker was to break it would keep the lifter in its bore to insure good oil pressure.

https://www.summitracing.com/parts/m...iABEgLAy_D_BwE

[dmjlambert]

Did you take the shield off of the original intake manifold and put it on your Edelbrock one? Then you sold which intake, the original or Edelbrock?

[Steeveedee]

I put a 1/4", or maybe 3/8" spacer from Edelbrock on a car once. I guess their QC has improved since then. That thing leaked vacuum a lot. I was working massive hours in those days, so I just schmeared Indian Head gasket shellac on it until it quit leaking. I talked to Edelbrock about it and got less than satisfactory results. Their carb and intake.

[Rust_never_sleeps]

TBH, I've never seen the underside of my intake, could be anything hanging there

[jjzepplin]

I used to rebuild motors and I would take that shield off of the bottom of the intake and wow was there a lot of caked up oil in there. I would clean it out and re install it. I wonder how this would fit an aftermarket intake. Pictures of an install would be awesome. How did you attach it?

[KevinK7]

subbing...
Interesting topic (especially since I have an Edelbrock intake on a 350)...

[BRL]

Originally Posted by dmjlambert

Did you take the shield off of the original intake manifold and put it on your Edelbrock one? Then you sold which intake, the original or Edelbrock?

Yes I detached the shield from the original cast iron intake and reused the original rivets (they're kind of like little spikes) and then drilled four holes to stake the shield underneath the Edelbrock and eventually sold a car that had the Edelbrock intake and probably junked the factory intake.

[BRL]

Originally Posted by BRL

... and probably junked the factory intake.

OK you guys, I remember what happened to the factory intake...
Friend had a two barrel intake and already had a 4 barrel carburetor.
I explained that I removed the shield and he didn't care, so we wrer butting up the intake and was about to fire up the car, and one of us said "...where's the Cresent wrench?"
Yep, it was in the lifter valley/galley.
Thank God I'm not an airplane mechanic!

[Rust_never_sleeps]

Originally Posted by BRL

OK you guys, I remember what happened to the factory intake...
Friend had a two barrel intake and already had a 4 barrel carburetor.
I explained that I removed the shield and he didn't care, so we wrer butting up the intake and was about to fire up the car, and one of us said "...where's the Cresent wrench?"
Yep, it was in the lifter valley/galley.
Thank God I'm not an airplane mechanic!

This is why doctors do sponge counts ;-)