which dual quad intake for the street
 

Hi all,
looking to put 2X4's on the old girl.... looking for some input on the differences between the 5450 Edelbrock (p65) and the Offenhouser 5499.
also, whats the difference between the 180 design Vs. the 360. Keep in mind, this is mostly street use.
FYI... my combo...
.060 428
455 crank/rods 10.2 CR
KRE D ports 290 port
Crane .041 clone
Rhoads V Max lifters
HS 1.5 rockers
M-23W 4 speed
3.31 12 bolt.
I have 2 Edelbrock dual quad carbs with linkage, fuel line etc already.

Thanks, Jeff

You will want the Edelbrock without question especially in light of your rear gearing in the car along with the slower port velocity of the 290 cfm heads below 3000 rpm.

In the mid to late 70s I had picked up a Offy 360 2- 4 bbl Q- jet Manifold and put it on my 3.55 rear geared stock 1970 400 in my GTO and within a weeks time I took it off and re- installed the iron stocker back on!!!

The Offy is way better than the E intake.It has the same carb spacing as the factory SD intakes.The factory air cleaners will fit.Try to avoid the E carbs.Early 60s AFBs are the best.For 625s The 3012s and as I remember the 2964 Buick’s are good.Maybe 61-63 on this site will confirm.For 750s the single quad 409s and the 3705s are great.Best of all are the real Pontiac SD AFBs.Tom

I am with Tom on this one. The Edelbrock intake jams the two carbs. together in the center of the manifold and makes it nearly impossible to get an air cleaner on it. Unless you use their own, goofy cheap looking junk. The Offenhauser manifold looks lousy at first glance and with it's tiny runners you would swear it couldn't support 400 HP. But you would be wrong. I am building an engine for a 62 Catalina right now and expect to make no less than 525 HP with one of these manifolds and a pair of clone SD-421 Carbs. The best possible manifold IMO will be the replica bathtub intake Tom is working on right now. I will switch to it when available and expect to gain another 20 HP or so with it. Plus the looks are nearly priceless. What are you putting your set-up on?

Opinion:

The Offy manifold is superior to the Edelbrock.

Neither one is going to work well on a Pontiac with the imitation carbs you mentioned, unless you REALLY modify the crap out of them!

Jon.

Tom's and mgarblik's comments are correct re the differences in carb spacing on the edelbrock vs offy intakes, and real afb carbs vs the edelbrock copies. Any late 50s-mid 60s Buick application afb is a better carb that the modern edelbrocks. Or you can use two Pontiac application AFBs. The offy intake places the carbs only 3/8" closer together than the real sd intake and you can thus make a setup look almost identical to the real sd setup with it, where the edelbrock intake jams them together.

But since you already have edelbrock carbs and linkage you can make a good performing setup that, way plenty of people have done it.

Here are two pictures of an offy setup using Pontiac application AFBs, with real sd air cleaners. The linkage is custom made.

I came back and edited this after I saw Jon's (carbking) comment. He was apparently typing his as I was typing mine. The edelbrocks CAN work and work well. You can walk down the pits at Norwalk and you will see dual quad setups on race cars with the edelbrock carbs on them and they go like stink. However, you can also get those carbs and never get them to work right no matter what you try to do. It is kind of a crap shoot with them. So if you already have them by all means try them. If you can't get them to work right you can always sell them and get a pair of Buick or Pontiac application AFBs. I will look at my notes and come back and share what jetting and metering rods I've put in sets I've done for people with your size engine.

For a 462 cubic inch engine start with .092 primary jets, .073 secondary jets, and .050x..060 metering rods, or .094 primary jets, .073 secondary jets, and .062x.068 metering rods. Actually you can use any size metering rods and use piRsquare to determine primary jet size, just have an 8-10 size difference between the small and large diameters on the metering rods.

I flowed all of the Pontiac Intakes produced from the early dual quad days, Edelbrock, Offy, etc on a Super Flow 1200 flow bench (lots of Flow bench flow capability and very accurate) and the stock Dual Quad Offy intake flowed quite a bit better vs the Edelbrock dual quad intake. Memory says the offy was over 20 cfm better per intake runner.

Joe C. ran one on his altered early tempest race car and picked up over the normal Pontiac Dual quad intakes. Well over a tenth if I remember correctly. Offy is better. Loren Budzinski posted the flow data at one time on the PY Board.

Tom V.

E clones race better than they street drive IMO.Tom

The E clones on my 409 have only seen dyno time so I can't say how the transition circuits are yet-maybe in the next year if I find a paint shop that won't put it in "paint jail". My 470/409 liked the 600s over the 750s. The Edelbrock intake flows way better than even the hi perf aluminum 409 dual quad and single quad intakes. I never flowed the Edelbrock dual quad Pontiac intake when I had one. M/T Pontiac cross ram does not flow as good as a single plane intake, but looks cooler!

Guys, thanks for all the great info.
I'll start looking for the Offy intake
61-63, I believe the carbs I have are the 1803s(500 CFM ,IIRC)
The jets/ metering you suggested would be good in those carbs, or should I get larger CFM carbs, then jet/meter accordingly.
Also, this is in a '65 GTO.

At least a pair of 625s

The jets and rods I stated are for 600 cfm carbs. I've never done any 500 cfm sets so will have to calculate the calibration for those. It you were doing a race car you could go a 750 cfm set for your 462 but for street I'd say 600 cfm would be best. Once you decide for sure what cfm carbs you will use put it on here and I will give you a calibration for them.

I ran an Offy with matched 63 Pontiac AFB's with carbking's kits on a 65 GTO for almost 10 years. (and rebuilt them per carbking's specs) After a short dial in period that ran like stink with no problems starting and running. Way easier than the tri-power that was on it.

How do the pre edelbrock Carter aftermarket stack up, i have a pair of 625 cfm carbs. I know this is the street section,but could they be made to support 469 at 6400 rpm for a race applkcation. Sorry for the hijack

My 462" liked the Offy intake with Carter 9605s (600cfm) AFB carbs. Gotta use the adapter plates for the large base carbs since the intakes were made for small base carbs.

Jeff Chmura Stray Cat makes a good point. If you go looking on ebay, craigslist, and other places for a used offy intake be sure to get one with the adapters already on it. You will see them offered without the adapters and you don't want that because the adapters will cost you almost as much as the intake new and they are almost impossible to find used. Just keep looking and one with adapters will turn up.

Bill I've only done sets using the original AFBs so can't help with your question. Perhaps carbking can.

I have used them both on everything from mild street to much more serious combinations. I like them both, but I give the Offy the performance edge. (although I have ZERO head to head dyno experience to back it up.)

Here is a pretty nasty 462 I build for my '40 coupe.

https://hosting.photobucket.com/albu...pskr1ezw1g.jpg

And, a healthy 389 for my 51 Merc. I made my own air cleaner base to get around the goofy carb spacing.

https://hosting.photobucket.com/albu.../merc11282.jpg

-Abone.

Holy huge picture, Batman.

Sorry about that.

-Abone.

I ran dual edelbrock 500s initally on my 432. Was just choking it. I ended up finding a pair of edelbrock avs2 650s and am now running these. Took some time and tuning but it runs like a raped ape!

I was running an edelbrock 2-4 intake on my previous 400 and can say that it has a lower carb mounting height so keep that in mind if hood clearance may be an issue. I swapped to offy 5499 and have way less hood cleance with the same air cleaners. I am now running 3.25" tall air filters on 6.375" diameter bases and I had to make custom bases cause my air cleaner lids are about 1/4" away from the hood.