Big Block Chevy Intake decision
 

I am building two 468 motors for my 33 fountain. Comp. is a shade under 10:1. I am running a crane cch296 hyd/flat cam (.551/.573), GM990 rec port heads, Imco powerflo exh, and AED/Holley 850 carbs.

What intake should I be looking for/why? My head aches with all of the choices out there. Some say dual plane, others say single.

Thanks in advance- Bryan

what rpm range do you want to run in????Dual plane works good under 5300 single over ....my.02

I have read some good things about the air gap manifold great torque

I ran edelbrock victors on my 540's na's no trouble here.

I am also contemplating this decision. I have been running Weiand Stealths (dual plane) and happy with their performance, but my boats former life as a saltwaterboat destroyed them and need to be replaced.
Under the direction of JimV I am sticking with a dual plane for my 454's (468's). I am running 5200-5400rpm max. I am just curious about the RPM air gap, it appears it has the cut out plenum as the Stealth but also new technology of the air gap. also $10 cheaper. any extra info on head to head performance would be great.

Rookie DanB ran them on his warlock drop him a PM...hey your from my neck of the woods post a pic of your boat so I know who you are!!!

I would run dual planes due to the 850s. Dual planes can tolerate a little more carb than single plane. 850s are on the big side for 468s, but not too bad if used with dual plane.

BT :cool:

You want the airgap. Your CID and the expected RPM range of a Bravo drive you don't need the runner volume of the single plane stuff. The air gap is a good choice between a dual plane. .. you get that low end torque from the runner design. . .and the single. . .since the runners are isolated from the valley pan area the intake charge is cooler and makes more power. I would run a 1" 4 hole spacer with this also.

Chris
Stef's Performance

I have run the Performer and Air Gap back to back and saw no differance in performance. One did hurt the wallet more and required modifications to the 40 dollar inlet hose. I then ran a Edelbrock Torqer which made a big differance eliminated bow rise and took it up to the limiter with out having to wait for the boat to "air out". I also ran both an 830 and a 750 on each combo there was little if any differance there.
I port heads for as side line for a friends shop and have flowed a few single and dual planes and ported a few my feeling now is dual planes suck and I will most likely never purchase another.

Turbo,
I don't believe the the Torquer is available in a rectangular manifold. I was told that you could use oval port mainfolds on rectangular heads, but not vice versa.
I have used the Torquer II on sbc 350's in boats with great luck. If I was to go with a single plane it would be my choice. HP/TQ isn't in 7000 rpm range like most.

Turbo,

That is interesting. Let me know what single plane intakes work best. I have no. 2's and I want to rpm's around 5600

A good alternative to the Torquer, but in a rect. port version, is the Wiend Accelerator. It's the manifold used on the Merc. 420. It would be a good match for that cam. Just prop it to run over 5000 rpm.

Well. . .I work with Joe Petelle of HVH very closely. . .complete induction combinations. ..drawing from my experience with him and since he has designed some of the best flowing intakes in the performance industry. . .it would be my opinion to with the Air-gap.

Chris

by the way I'm running Edelbrock RPM's model 7161 oval port at 5100 and like it better than the single plane Merlin I used to run.... I traded it to JimV for some labor

Sut where did it make the power below 5500?? I want to stay around there....

I used the Vic Jr. Had it na and used it with a Pro Charger. I liked it in both set ups.

DAVE

I just bought 2 Dart intakes that are Med. oval that are made to cover a rec. port too.(Holley makes another like the GM one your boat came with but with Med ovol and enough material to cover the REC. opening.) Low end torque is not suposed to suffer too much and with the huge air gape and raised design top end is much better.Seems like the Manufacterers push the dual planes because even in a hot rod you need good response from the idle,,,in a boat you jump to 2500 or so when you hit it.(my humble opinion) I have also used tkr 2 but these WILL NOT cover a Rec. hole.

Merlin Single Plane is not good?
I don't know, just asking.

A single plane is the way I would go. RLW is correct in a Merlin single plane works great to about 540" max on a marine engine. Above 540 a single plane Dart would be better. I have no experience with Brodix, but I am sure they have great products as well. Another alternative is a Holley Strip Dominator oval manifold match ported to the 990 heads. This will give you great torque and all the benefits on the big end of a single plane manifold. For maximum performance consider a Wieand tunnel ram with dual 650 double pumpers. Better performance everywhere except right off idle. :D

Thanks for the help, everyone. I'm going to keep the 850's that came with it. I'm on a budget and want to work with what I have. I have Dart single plane (6204) manifolds that are oval port. These were on the old heads that came on the boat (peanut ports). I fiqured that machine work could make these Darts ok, but why not sell them and buy something that will compliment the motor combination. I want good, solid running motors. I'd like to see about 500 horse with my combo. I have heard from other friends that the Victor Jr. would be a good choice. I ask because I knew someone would have experience (good or bad).

tihs is a gm dual plane off of a 420 hp ls6 motor. bronze water passage. i am going with a holley 800 and that is a 2 inch spacer to go to holley from a spread bore. the motor is 540 9.8 block , 731 cam , canfield 310 heads. alot of work and i hope it pays off. not looking for more than 5500 rpm.

eric

Alright, I am going to search ebay for 2 single plane manifolds. I already have 2 dual plane that are more an eyesore than nonfunctional. I am going to run them back to back and post results. (Weiand Stealths vs. single plane Victor jr., X-celerator, or Torquer) I believe that a Dart or Brodix will push the power well out of the RPM range I am going to be using 5200-5400. I know that a Brodix works great a 6400 RPM's.

My boat has no problem with bottem end torque and pulls great till 4900. The last 300 RPM's is what I am looking for. It will only cost me a couple gaskets and some time to lay this question to rest for me.

Dyno, I'm trying to post a pic but like all other first time things I'm having a little trouble. If I don't get it posted by the time I get my boat out, here is a description. It is an '86 Scarab Panther all white with the red accent stripes.

I forgot, the heads that i'm using have 1.88/2.25 valves in them. Would that make a significant difference? I am cautious of revving too high. I want reliablility. I have also heard good things about the old GM dual plane (LS6).

I ran the Victor Jr. and had no problems.........

Ok. I have seen a couple of Victors. One the Victor Jr. I also saw one called the "2R" or Tarantula? I think that one is no longer made...

If dual plane is the hot set up, why do the 500hp's have a single on them.

Just stirring the pot :p

My engines have about the same set up as yours. I have Merlins on them. I couldn't be happier with the way they run.

Cuda,

What intakes do you run? What kind of hp would you guess?

I run the same intake as Open72 on my 515cu.in 9.5 to 1's with 850 holleys and they are just shy of 550h.p. i run the 741 cam it will Idle all day long. I don't run the motors over 5000 RPM.

Mark

Merlin single plane. The engines were originally 454/420's. They have been punched to 468, 10 to 1 compression and a bigger cam. I would guess 450 to 475 horses a side. Starts on first touch of the starter, idles great.

Thanks guys.

Ya I pondered this same question. So I pulled off the iorn dual plane and replaced it with a Weiand Excelerator. I like the fact tht it does not have a flat bottom in it witch aids in 2 things. It helps straiten the runners out and it decreses the volume of the plentum. I neaver had a problem planing off either but would like a few more RPM's up top. I have not ran it in the water yet but it has a quick responce on the garden house. :D

Rag's

The 500 hp motors are single planes.I would differently go single . most of your rpm will be from 3000 and up so your not going to loose much torque

Exactly. I'm gonna go with Victor Jr's.

Anyone have two they want to part with? The next selection is going to be valve springs...

I have heard that it is critical. Better to be a little stiff than a little soft (valve float is bad). High quality springs are a must due to the constant rpm.

Discuss...

You want a spring made from Super Clean Chrome Silicon, trade names are Cyloy, Pacaloy, Alpha, Nextec. The pressure of tool steel, the longevity of chrome silcon.

Chris

What are thoughts on these intakes offered on e-bay.
$165 regular $199 polished. Looks alot like the Victor jr's.

http://cgi.ebay.com/ebaymotors/ws/eB...471622480&rd=1

Also would you use a carb spacer with a single plane? I have a 1.5" spacer on my dual planes.
I read this on intake spacers and now a little lost.

"Spacers are very valuable tuning tools. But their use is for fine tuning a carb on a particular application.

You have 3 basic types of spacers, open, 4 hole and a shear plate.

The open spacer is to extend the plenium. This will have the effect of making a carb smaller in laymans terms. What it really does is by moving the carb further away from the vacuum source (engine)the carb will receive less "signal" thereby pulling less fuel from it. It will also increase the velocity of air supplied. If your carb is already too big you can see where this can hurt performance.

In higher RPM applications the increase in velocity can help. Still maybe not the best choice. This helps to explain why with a tunnelram and no spacers you get away with oversize carbs. The large plenium on a tunnelram pulls less signal so the carbs "think" they are smaller.

The 4 hole spacer will extend the length of the venturi's. This will help the carb get more "signal" almost as if reducing the size of the plenium. This is most useful if using a tunnelram or if the carb is borderline on too small. It will also increase the velocity of incoming air.

The shear plate considered "Top Secret" until the last year or so is just a 4 hole spacer with a series of larger steps counterbored on the bottom side of the spacer. It kind of reminds you of a bullseye target several counterbores getting progressively larger. These are used to help shear the air/fuel mix entering the plenium. By this flaring out on the bottom side of the spacer it will disperse the fuel more equally throughout the plenium this helps to ensure every cylinder gets the same air/fuel mix making more horsepower through equal tuning."

The copies of the edelbrock you see are Professional Products. these are Chinese copies. Manifold is a decent piece, kinda a hybrid of the Victor, Brodix, and Bowtie. Can have some bad core shift and would recommend a port match if using.

The intake track or the exhaust track work on pulses of air. These pulses have specific lengths based on CFM that make them more effiecent. These track lengths can be tuned for HP or Torque. A spacer can be used to get the proper pulse length for the intake track.

Most popular spacer now is the HVH Super Sucker, developed 25 years ago by Joe Petelle and outlawed by Winston Cup, this spacer corrects the fuel signal. When used with a 500 incher they are worth around 15HP over any other spacer.

Chris

Plus, Edelbrock is made here in the U.S. When I was younger, saving the ten bucks (or so) was the way to go. No more. Money needs to stay here...

Sorry, I'm passionate about that.

I was curious about carb spacers myself. I bought one Victor Jr. and looking for a second. After I get my motors up and running I may play with that.

I run the Air Gaps and 750 Demons on my 454/400hp Cyclones, can't tell you if they helped much over the original intakes or not as they were on the boat when I bought it, they do seem to deliver steady power all the way through the epm range though.....Fred

I think Edelbrock just started building rectangle port Torker II. As spacers go the ony one I have reciently tested that realy did much is the 4500 adapter to a 4150
base. Granted this was on a Ford small block. I have just gone through An RPM , a dual plane dual quad, and a Victor Jr. Tried them all with and with out spacers, 1" 4 hole, open and the 4500 adapter. The adapter beat them hands down.

Not to jump in on the post, but what intake would you guys run on an HP500.? Is there an improvement over the stock Dart manifold? Thanks.! This is an interesting post, cause I always thought on boats dual planes were the way to go.!:confused: