carb adapter/ spacer flow questions

owen1980

Veteran Member
Jun 23, 2004
429
Brownsburg, IN
I am trying to catch up on knowledge of carbs quick, I went to a GM sponsored automotive tech school and was a dealer tech for 6 years. I only had one car with a carb (first 1980 Z28) and mainly only read GM high tech performance mags. I had always planned on putting an EFI engine in my current 80Z but I bought my friends ZZ3 with a Holley. It had a 1" spacer on it, when taking it apart for inspection I noticed the GM intake is a dual pattern design. To me it looks like the spacer could cause a disruption of flow into the manifold because of the blocky design of it. I was thinking of running an adapter for 4150 to spread bore like this http://www.jegs.com/i/JEGS-Performance-Products/555/15440/10002/-1
. The Z will not see much track time mainly street fun, anyone have any issues with 4150 spacers on a dual pattern intake?
The biggest factor will be fitting it all under the stock Z28 Air Induction hood.
20170408_080817_zpsj2yibvoy.jpg
 

80sz

sup
Feb 2, 2014
3,989
Buffalo,n.y.
Which carb are you using? Stock 80 or a holley? The one you listed would be fine for stock but you are going to be pretty tight to the hood... If it fits. You'd most likely have to ditch stock air cleaner. I was able to fit stock air cleaner to the holly but I had to put a 1/2" plastic spacer from the lid to top of carb,then it was to tall to fit under hood.
 

owen1980

Veteran Member
Jun 23, 2004
429
Brownsburg, IN
Whatever model Holley this is.
20170325_161456_zpsqwhy8esp.jpg

This is what my friend had on it running consistant 13.20's in his 73 Nova.
I figured I might have to ditch the stock air cleaner anyway.
 

80sz

sup
Feb 2, 2014
3,989
Buffalo,n.y.
Model # is stamped on front of choke assembly. A double pumper mechanical secondary. The spacer is not needed for the intake. One you listed is for a quadrajet to square bore
 

owen1980

Veteran Member
Jun 23, 2004
429
Brownsburg, IN
I had rebuilt my original quadrajet years ago but since the ZZ3 I bought was running at peak performance it would be stupid not to use the Holley that was on it. It is hard to not have all the data from sensors to look at like modern EFI engines to see the differences carbs and spacers make.
 

80sz

sup
Feb 2, 2014
3,989
Buffalo,n.y.
The spacer will take the air stream and allow it to make the turn into the heads smother at higher rpms. It keeps the flow from smacking off the bottom of manifold . It also allows for a bigger plenum which also aids in mixture. If you decide to get a spacer a open hole wood one works well. In theory a 4- hole will promote more venturi speed . This allowing for better throttle response. It's a trial and error best left up to a dyno to figure which one works best.
 

80sz

sup
Feb 2, 2014
3,989
Buffalo,n.y.
I'd save some cash and put the holley on and see how it runs. That looks like a spacer on it already? I'm not to familiar with that intake tho. The divider just looks low to me.
 

owen1980

Veteran Member
Jun 23, 2004
429
Brownsburg, IN
The pic in first thread is the 1" aluminum spacer that was already on it. I was just showing how much of the dual pattern intake inlet it covered up, creating a sharp edge for the air/fuel mixture to go around. Intake is the standard Chevy performance dual plane intake that was on the ZZ3,ZZ4.
 




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