I need some help on a new Intake Manifold

[Caustic_Cobra]

I was curious if could get some advice from someone here on a new intake manifold.

I currently have a motor from Coast High Performance 393 stroker (351w and AFR 205 heads) that utilizes a Holley 850 and edelbrock air-gap open plenum manifold. Both the carb and manifold are too much for what I am doing with the car (i am not tracking or racing the car). So i have changed out the holley 850 for a 750 and things have improved. But low end driveability is still not there, along with getting gassed out of my garage during warm-up and idle.

I am thinking of moving towards a medium rise or low rise , dual plenum set-up that will help with better low end driving characteristics and not force my wife to wear a gas mask to get her to go driving with me. I also want to get away from the big oval air cleaner and a medium or low rise I am hoping will give me more clearance for an original round air cleaner, as there is no hood clearance for the stock air cleaner, currently.

What has been successful for any of you reading this note??

thanks for all you advice and help in advance!

[Three Peaks]

First off, the Edelbrock Air Gap is a dual plane manifold so your low end should be fine once you have the right carb and tune it correctly.
Which 750 are you running on your engine? What cam are you running? Have you had it dyno tuned and jetted properly for your set up?

I've heard from lots of guys that the 750 is great for the 393 at the top end, but loses the bottom end power. Just the opposite with the 650 DP or 670 Street avenger- great low end, but not enough top end.
I think a bit of tuning with your present set up will probably work wonders and give you the engine you thought you had.

For clearance on my 393 I got a dropped base 14" x 2" air cleaner . You can get the dropped base air cleaners lots of places. I found mine cheap on ebay, then bought a custom top to add a little bling to the engine compartment.

Bob

[Clois Harlan]

I have used the Edelbrock Performer RPM intake w/750 HP Holley with good results. I believe it is a 1500-6500 RPM intake which works great for what I want to do my coupe. However, do you have access to your cam specs? Your cam may dictate what intake you are required to use.

Ditto on the drop base air cleaner and I use the K&N Style breather top with the drop base.

Clois

[CobraEd]

What you are describing explains a rich mixture. you need to lean out your jets & idle. This is not a carb or manifold issue. I would set the idle jets first given what you are experiencing at idle in the garage and in low end driveability

[RedBarchetta]

I'm presently running the Performer RPM on my 392W stroker and have been wanting to swap to an Air Gap. Maybe there is a "trade" in here somewhere? And we're both in So Cal, too. E-mail me if you want to talk some more. See my gallery for very recent pics of the engine it's on now.

-Dean

[Rick Parker]

That's a real good opportunity for each of you, good luck to you both.

[Caustic_Cobra]

First off, thank you all for replying to me. I really, really appreciate it!

Bob and Clois, the manifold is a Victor Jr. 351W, a high-rise, open plenum with what I call an air-gap. Eventhough, it is not labeled as such, like the Edelbrock "Air Gap" line of intakes on their website. Maybe, I am wrong in my description...please tell me if so.

The motor has not been dynoed or tuned in that fashion, but a friend and I have timed and fooled around with re-jetting the carb. All with measured success.

The cam spec is as follows:
.555/.570 238/245 (110)

Dean, we just might be talking in the near future...

I need to mention that I am not a motor-head, but admire you all, that are and you all that have forgotten more than I will ever know. But, that is what makes Club Cobra so special, those with the knowledge and expertise willing to share and be patient with those less fortunate ones. For that, thank you again!!!!!

[Three Peaks]

Now that we know what your manifold is, we can probably make more sense out of it.

The Vic. JR. is a single plane manifold, unlike the "Air Gap" manifold, which is a dual plane. The Vic. Jr. , being single plane and higher rise runners, needs more velocity or RPM to wake it up, so performance will be weak below about 2500-3000 RPM or so. For your purposes, with that cam, the Edelbrock Air Gap, Weiand Stealth, or Edelbrock RPM will work great for you.

Give some serious thought to getting a good dyno tune once the carb/manifold issues are worked out. If you find someone who knows what he is doing, it will be worth your time and money I'm quite sure...

Bob

[vector1]

he has a 393, not a 351, so the vic jr might not be such a bad choice, plus the cam looks to be on the healthy side.

a dual plane rpm air gap will be snappier off idle but would prob give up to the vic jr above 3000 or so.

what are the specs on the carb, jetting and such. how much ign. advance at idle.

nice sized heads, big cam, i think you're going to have to live with the gas attack.

what is the vacuum at idle and cruise.

[RedBarchetta]

Originally Posted by Caustic_Cobra

...the manifold is a Victor Jr. 351W, a high-rise, open plenum with what I call an air-gap. Eventhough, it is not labeled as such, like the Edelbrock "Air Gap" line of intakes on their website. Maybe, I am wrong in my description...please tell me if so.

Hi Mike. The manifold that you just described (Victor Jr.) is indeed an open plenum manifold designed for more high rpm power (and a good one, at that). But since it's not the "Air Gap" dual plenum variety that Edelbrock sells, I wouldn't be interested in the swap that I mentioned previously. I just need to dig between the seat cushions and scrounge enough change to buy one.

-Dean

[ou812545]

I have a Polished Edlebrock Victor Jr. (351W) for sale if anyone is interested..
PM me if you are interested.

[Caustic_Cobra]

Thanks guys for all your help and thanks Rick for the PM's.

Bob, I think I will take a look into the RPM and Weiand as you suggested.

Dean, oh well. Looks like the both of us are going to be scrounging through the seat cushions.

If any one knows of someone in need of the Victor Jr. 351W and a Holley 850 dp...I going to have a good deal on the set!

Thanks again guys for everything, especially the advice!

[Three Peaks]

Mike,
Here are a few on corral.net
I think the last one on the list is an Performer Air Gap

http://forums.corral.net/forums/show...ht=351W+intake
http://forums.corral.net/forums/show...ht=351W+intake
http://forums.corral.net/forums/show...ht=351W+intake

Bob

[SF_SN888KE]

After the dyno tune and assuming you still need more low end performance, have you considered changing your rear gears? I have a SB 347 with 3.5 rear and TKO500 with a very tall 5th gear, something like .62 final and I tach under 2000 RPM at 70 MPH! (22 mpg on the freeway! ) I'm thinking of going to a 3.70 for better city perfomance

[Caustic_Cobra]

Thanks Bob,

I appreciate that. I think I will take a gander over at that sight and see. These toys aren't cheap and picking up a used one might do the trick. With a quick media blast, it will look like new!

Ron, I have the TKO 600 with a 3.73 rear and the .82 or .84 (can remember exactly which) 5th gear. It cruises nicely on the highway and mileage is decent, but the MPG isn't a real concern. The car is really for fun on the weekends. I fill it up once every couple of weeks.