I am sure that this question has been asked 137 times already, but:

What intake manifolds will fit under a stock '69 SB hood, using a stock air cleaner and a Holley carb?

Thanks in advance,
Kevin

 

I don't know about the stock hood because I went a head and put an big block hood on my '71 so that I would know that I would have enough room for an air gap intake and I also like the looks of the big block hood. I'm using a 750DP holley with the choke tower cut off and a air cleaner base for a mid 60's big block vette, 14x3 air cleaner. The filter and top are K&N. When I did the playdoe trick to see if the hood would close, it looked like I had about a little over an half inch from the top of the center of the air cleaner to the hood when closed.

 

Edelbrock RPM and Torquer (not Torquer II) are good choices for that lower hood if you want an upgrade from stock.

 

The Performer will fit fine with a stock dual snorkle air cleaner . For the Torker II, you will need a drop base air cleaner and 3" filter. It will still be close, but by torquing down on the wing nut a little, it will fit. Others have managed to fit the Weiand Stealth under there, but I'm sure you would need a lower filter element or different air cleaner to make it fit. The RPM will not fit unless you mill the choke housing and use a drop base with 2" filter.

 

Thanks for the assistance.

Will the same manifolds work with a Q-jet?


[Modified by Kevin Mason, 3:43 AM 5/15/2002]

 

The performer (2101, 3701EGR) will accept Q-jet and Holley. The most common rpm intake (7101) only accepts squarebore carbs (Holley, Edelbrock, etc). You can get a RPM intake that will accept a Q-Jet (7104), but it costs about $30 more.

As far as Weiand, the Action Plus accepts Q-Jet and Holley. But, I think the Stealth only accepts squarebore carbs(Holley, Edelbrock, etc), and I don't know of any Stealth that accepts Q-Jet. I could be wrong on this one, though.

Hope this helps!

 

Kevin - this is the clearance you will see with a Weiand Stealth and a Holley. Shotgun is right, the Stealth only fits square bore carbs. I'm using the LT-1 air cleaner with the standard filter over the Holley 4150.

 

BSieg: looking at the photo you posted, it appears that you have*zero* clearance. Am I correct?

Thanks once more, BSieg, Shotgun, and everyone else.

 

One should consider the entire flow path. Putting on an intake like the RPM w/o enough hood clearance & blocking the carb. intake is not the way to go.
It is possible to make Performers & Action+ work well beyond what many realize.

RPM will work on med rise 73-79 hoods.

:cool:

 

I have heard nothing but good things about the Action+.

Does it clear with the stock Q-jet? Thanks once more.


[Modified by Kevin Mason, 7:04 AM 5/15/2002]

 

This has been a much argued topic over the last couple years. 68-72 stock SB hoods have pretty much the same underhood clearance. The 72's I think might have a tad more room.

Here's a thread you might find useful.
http://forums.corvetteforum.com/zerothread?id=219513

Len


[Modified by 1970 Stingray, 8:23 AM 5/15/2002]

 

Ganey, Please elaborate.

Tom :cheers:

 

Hey Kevin - sorry it took so long to get back to you on the clearance. I have about 3/4 inch above the highest point of the air cleaner. It looks worse when measured against the fenders, but the hood does have a crown to it. No bumps or scrapes on the inside of the hood.

 

Thanks again, BSeig:

Does a Demon have roughly the same clearance as a Holley?

Ganey: were you referring to modifying the Performer or Action+ manifolds?


[Modified by Kevin Mason, 4:35 AM 5/16/2002]

 

Kevin
Both. Tom is aware of most of this & we have been discussing his setup privately. You might want to state your setup.

One should consider the entire flow path, heat reduction & velocity.
Some things that can be done:
Moroso has an intake valley heat shield. Some Corvettes came w/ a thick open gasket about 1/4" that could be used under stock Q-J carb. Then an additional 1/8" spacer could be added to the Performer for a total over stock height of about 3/8". All fitting under 73-79 med rise hood.
Holley & an aftermarket drop base will easily allow a 1/2 spacer + gaskets for a total increase in height to same as RPM. All fitting under 73-79 med rise hood.
The ports could be opened up & matched.
One could use spacers or the center divider could be cut down like the L-88 intake.

Curtis (mountainmotor) is aware of all this & has made several comments, some next.
mountainmotor
Putting a RPM or Air Gap RPM under a hood like yours will require milling the choke tower off a Holley carb to maintain 1 inch or so clearance between the carb and the filter top.Too close for me and makes a Qjet out of the question.Yes one of the members is running a Air Gap with a hot cam ect.It is a new combo and the RPM is falling off at 5k.I wonder why?The Performer can and will make great power with everything else in order combination wise.I don"t know what carb you are wanting to use but thought I would bring this up now,not after the fact.I know for a fact they will support 400hp.
If need be for a little more top end power one could modify the center divider to near Air Gap Specs.
In an all out effort and in most combinations the modding of the center divider of the little 180 degree or some call them dual plane manifolds can pull the power back into a comparison with a taller RPM manifold or the tad bit shorter but very good Weiand Stealth.That manifold gets overlooked as an alternative to the RPM.
by Curtis

PS Curtis (mountainmotor) & I agree on this. Expect that there are others aware of these things & maybe they will comment.

 

Hi Ganey,
I've got a Performer manifold & Q-jet with the 1/4" open gasket under it. If I fit a 1/8" spacer (assuming the cleaner still fits under the hood) what sort of improvement would be expected? (Other main mods:
K&N filter in std. dual snorkel cleaner, 1:1.52 Magnum rockers, Moroso valley baffle (mainly to hold the lifters in their bores if something disasterous happened up the top end), 2 1/2" dual pipes, open mufflers (Monza) :D, 210/216 .440"/.454" cam & stock CR, heads & manifolds (at the moment :( ))
Would a spacer be worth the bother with the above mild setup?
:cheers:

 

Another thing that can be done esp. in the south is to block the heat risers.
This is understood i.e. standard procedure (to me) & left it out.

Paul
You may not be able to squeeze it in your 81. It can help to keep the carb cooler which you probably don't need in England. One has to experiment w/ spacers to see what works best on his combo.

 

Ganey, thanks for the advice!

For your edification, my setup at this point is essentially stock carb, stock manifold.

I am looking to replace the manifold and carb as a system. I'd as soon keep the stock-sized K&N filter for airflow reasons, and I was looking at a Holley or Demon carb with a Weiand manifold. The car is a '69 350/300, so what will fit under the '73-'79 hood may not apply.

Although it does not relate directly to the clearance issue, I have a mild cam in, forget the specs, and shorty headers. Need steeper rear end gears at some point to match the cam, and full-length headers.

 

"In an all out effort and in most combinations the modding of the center divider of the little 180 degree or some call them dual plane manifolds can pull the power back into a comparison with a taller RPM manifold or the tad bit shorter but very good Weiand Stealth.That manifold gets overlooked as an alternative to the RPM."

I have a Weiand Stealth and notice that the RPM is falling off aroun 6200 -6500 with my new heads. Explain the modding of the center divider? Are talking about opening it up?
Thanks

 

Ganey,
Thanks for the reply.
You're not wrong there! Hottest day of the year today (26C), probably a bad day in your winter?
What I've done for carb cooling is to leave all the rubbers out from around the rad, & remove the a/c condenser. Still runs at around 180 & I've hopefully got a cooler airstream running through the engine bay. Might find that the engine runs hot once the cam is broken in & I start doing decent speeds, but it's fun experimenting :)
Another question on manifolds:
Some, like the std. L81 one, don't have waterways to the rear of the heads. Therefore the hot coolant circulates through the front of the manifold, keeping it hotter than the rear? Wouldn't this cause the front cylinders to run a bit leaner than the rear ones? Or is it the case that the manifold is at the same temp throughout? Just wondering.
Thanks
Paul