[blackadder]

Been thinking, perhaps to much. I have an Offenhauser 2x4 spreadbore low profile manifold that has 2 Edelbrock Competition 625 CFM equal bore carbs. I also have the conversion plates for the manifold. I was thinking that putting this on a 428 bored to 433 and running 1970 64 heads with a pretty basic rebuild (No fancy porting or anything) and a 068 cam might be a bit overcarbed?
This would be for street use and not driven to hard on a regular basis. I was looking at a pair of these as a replacement. I think they would be far more functional for what is planned. Any thoughts?
https://www.holley.com/products/fuel...parts/VK060100

[25stevem]

I don’t foresee any benefit to switching unless your current carbs do not function properly.

[Skip Fix]

Is the carb spacing on the manifold even wide enough to fit to Holley styles?

[tom s]

I run a 433 with a 068 car and 96 heads with a 2-4 repo Bathtub tunnel ram with a pair of 750 pontiac SD 421 carbs with progressive linkage.I think you will like your intake with a pair of real Carter 625-750 AFBs with progressive linkage.My tunnel ram is better to drive than any tripower I have ever run.2.68s in the back with a 3.42 first ST 10 and can cruise on the highway at 1800-2000 with no effort.I have had tripower flat style 2-4s with a pair of pontiac SD 625s and both 2-4s deove more EZ than the tripower.FWIW,Tom

[tom s]

DONT let Skip talk you into Holleys!PLEASE!Tom

[b-man]

Your 625 cfm carbs are not too big, no need to put much smaller 450 cfm carbs on it.

For a little perspective, the factory dual quad 265 and 283 SBC engines were equipped with Carter WCFB 4-barrels rated at around 385 cfm.

[Tom Vaught]

Agree with what all have said to date.

Not sure of these latest 450 cfm carbs but the previous ones were a poor alternative vs the 600 cfm holleys or the Edelbrock 625 cfm carbs. Maybe they are better today but in past years they were not matched well with Progressive Opening, (one carb then sometime later the second carb).

Remember the carb is going to take what it needs, (even with a linkage where both carbs open the Primaries at the same rate at the same time).

The 625 ~ cfm carbs were fine carbs for dual quad applications, years ago, if tuned properly.
I gave away a set of Holley 450 cfm carbs (for free one time) as I just wanted them out of the house and they came on a Pontiac Offy intake.

Tom V

[blackadder]

Thanks for all the replies. I am convinced to stick with what I have then. Wanted it more for something different as I already have a tri power as well as a 70 455 HO manifold and Q Jet. May never run the 2x4 but nice to know it will be ok with the carbs as is. I have a few engine options to try it on when I get to that point. Also have the 389 my car came with as well as a 65 421 tri power engine as well as the 428.

[Charlie Brengun]

I have an offy intake with two Holley 450's on it. No choke and it runs pig rich. I've sort of made up my mind to go a single holley 750 vac sec but haven't done it yet (as I have other things to address first).

Anyway the way my car is currently with the two holley 450's, it isn't very useful for a street application, although I do have to admit it came with a distributor without a vacuum advance (unilite) and that also doesn't appear to be the best of choices.

[25stevem]

If you want to improve things then sell the Offy 2-4 intake and get the Edelbrock 2-4 .
It has far better drivability and yet the same top end power from what I have seen if that matters to you.

[tom s]

Steve,with ALL due respect the E 2-4 intake is not as good as the Offy!The E intake has the carbs setup like a chevy and the Offy they are setup spacing wise as the factory 2-4 intake.Tom

[Tom Vaught]

Originally Posted by 25stevem

If you want to improve things then sell the Offy 2-4 intake and get the Edelbrock 2-4 .
It has far better drivability and yet the same top end power from what I have seen if that matters to you.

Originally Posted by tom s

Steve,with ALL due respect the E 2-4 intake is not as good as the Offy!The E intake has the carbs setup like a chevy and the Offy they are setup spacing wise as the factory 2-4 intake.Tom

I have flowed both intakes on a Superflow 1200 bench and the Offy is quite a bit better for flow vs the Edelbrock. Also Track times are a bunch better.

I have helped several members with tuning at the track on the Offy vs the Edelbrock intake and the Offy was ALWAYS better on the quarter mile track.

So I agree with Tom S on his post (as I have done back to back testing on the same intakes on the same day on on the Norwalk Ohio track helping members who wanted the comparison. We did not do a drive-ability test so you may be correct on that comparison.

Tom V.

[blackadder]

Lots of info here and I believe I will stay with the Offy 2x4 with the Edelbrock carbs for the 428. I am first going to do the 65 421 with a 65 tripower set up first unless I find I need pistons during the tear down then priorities may/will change.

[25stevem]

A local guy who use to live near by had a Pontiac street rod he built from a kit.
The 389 motor he started with had the Offy 2-4 on it at first and when the Edelbrock 2-4 came out he wanted to try that.
We put it on with the same two carbs he had been running with the Offy and for the average street usage the car was intend for the drivability was without question better.
If your motor is 428 cid or better then the Offy would be a better choice above 5000 rpm.

[carbking]

Originally Posted by 25stevem

A local guy who use to live near by had a Pontiac street rod he built from a kit.
The 389 motor he started with had the Offy 2-4 on it at first and when the Edelbrock 2-4 came out he wanted to try that.
We put it on with the same two carbs he had been running with the Offy and for the average street usage the car was intend for the drivability was without question better.
If your motor is 428 cid or better then the Offy would be a better choice above 5000 rpm.

Not an argument; but this is the first time in all the years I have done multiple carbs to hear that someone had better results with the Edelbrock 2x4 than the Offenhauser 2x4 ON A PONTIAC!

The Chevrolet folks do seem to favor the Edelbrock.

Jon

[25stevem]

What I replied with likely has to be viewed with the perspective that this 389 we did the swap on still had its 068 Cam in it guys.

Are you folks willing to then argue that the 2-4 Edelbrock is not even as good as the current plain old Performer up to 5200 rpm, because that’s what some of you seem to be leaning towards, or am I reading too much into all of this commentary?

[tom s]

I have been a 2-4 pontiac guy since 1963,over the years I have run pretty much all of them except a Warrior and a Gutsram.I have raced them and drive them on the street as I have 2 on my cars right now.The E drove OK with the same factory 421 AFBs but did not race as well.The factorys IMO have always been the best.The 991 was always a good street driver and good race UNTIL the 859 came out and then the Bathtub after it.I have converted a couple Bathtubs to late style over the years,I have a converted 859 right now.The factory seemed to get it "right" with carb spacing,runner length and carbs.Everyone has been afraid of 2-4s on the street but not tripowers?3 carbs to deal with instead of one?What am I missing?The world likes one carb and that is fine but 2 good carbs and a good intake will drive as well as a single and potential for more HP has been increased.ANYONE that endes up on the southern left coast is welcome to drive any of my cars and many have.Pro Stock cars used 2 carbs for a reason.The factory got it right way back in the early 60s with the dual plane 991 with progressive linkage and the SD AFBs and though the years I have never found anything as good right out of the box for good street manners and HP potential.FWIW,Tom