GMPP vortec dual plane intake mani

Chevyforever

Veteran Member
Jan 4, 2011
1,351
Ontario, Canada
So it has an approximate carb pad height of 4.5" It appears that all the available alum. 4bbl intake manifolds to fit vortec heads have at least 4.50" tall carb pad dimensions.
 

Chevyforever

Veteran Member
Jan 4, 2011
1,351
Ontario, Canada
I was looking to see if there was a vortec aluminum intake manifold that had a carb pad height closer to 4". The tried and trusted Performer 2101 for Gen 1 heads carb pad height is 4.05" IIRC, it seems vortec heads need the extra height to work properly and or align w/ the ports ? I have a Jegs dual plane on my Camaro currently that is 4.67" tall and I am not really in love with it due to clearance issues.
 

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CorkyE

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Lifetime Gold Member
Nov 4, 2004
11,645
Ringgold, GA
I had an Eddy RPM Air Gap sitting on RPM heads, Holley 750 DP, NOS Cheater plate, Eddy drop base cleaner with 3" filter, all sitting under the hood. I removed nuts on hood scoop bolts that interfered, replaced with some thin ones I found, and dremel cut bolt flush with nut. With play dough around the air cleaner, my closest point was 1/4". YMMV
 

sandlapper

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Oct 9, 2020
1,187
SE CSA
So it has an approximate carb pad height of 4.5" It appears that all the available alum. 4bbl intake manifolds to fit vortec heads have at least 4.50" tall carb pad dimensions.
For clarity, do you require a Spreadbore flange? or, a squarebore flange?
Don't hold me to it, but seems there may be a squarebore or two that're lowest.

Note: In and of itself, that Angle created by A-B, will become a factor when fitment is very tight.
And, the larger the OD of filter top; the greater the significance of A-B Angle becomes.

Either Play-Doh or a wad of tin foil work.
 

Chevyforever

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Jan 4, 2011
1,351
Ontario, Canada
I am currently using a Holley 4160 square bore on the Jegs sq bore dual plane. I see there are now a couple intakes that are spreadbore with a carb pad height of .42" less than what I have on my car now. I will not ever cut or modify the hood on this Z28. I am the original owner since day 1, April 1980. My days of hood scoops etc are done, LOL. 14" dia a/cleaner with a 2.75" tall filter and 1" drop base rubs slightly. Clearance to top of dump tubes is terrible, had to lower them slightly.
A deeper drop base will accept slighty larger filter however that will do nothing for bowl vent tube clearance.
Seriously considering reinstalling original 5.7 / 350 engine and pulling this vortec/ comp cams/header equipped contraption out. Will drop from 330hp back to factory 190, but my wife will be happier with a quieter ride.
 

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Chevyforever

Veteran Member
Jan 4, 2011
1,351
Ontario, Canada
sandlapper, I appreciate your link to that Weiand 8121. I was on Summit this morning and looked at that intake but was mislead by their listing it as
Intake Style:
Dual plane
Basic Operating RPM Range:
Idle-5,500
Intake Manifold Height:
4.500 in.
Intake Finish:
Natural
Intake Material:
Aluminum

Again it is always best to go directly to the source mfr rather than a reseller for accurate info !
 

sandlapper

Veteran Member
Oct 9, 2020
1,187
SE CSA
sandlapper, I appreciate your link to that Weiand 8121. I was on Summit this morning and looked at that intake but was mislead by their listing it as

Intake Manifold Height:
4.500 in.

Again it is always best to go directly to the source mfr rather than a reseller for accurate info !

yup. Just as I had done w/ EB 2116 ... published info from EB site ... published info from Weiand/Holley site for 8121

OK I see you have have a squarebore ... that 8121 should be a help with the fit ... a wife's another matter.

perhaps someone here has one (8121 Not wife) that needs a new home? I do not.

FWIW, I've seen several GM Vortec heads with rams horn ex manifolds .... although it seems your log manifolds should fit vortec as well ... w/ wife in mind.
 
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