Don't read if you're close minded

-
I have only ever raced small blocks, but in virtually every car I have ever had( at the track) a bigger carb has always been faster and quicker.
Always.
The single exception was swapping off a 1025 race demon( 4150 style) and swapping on an 1100 pro systems dominator. In that particular case, the dominator wasn’t any better( or worse) but there were several factors that I think limited the viability of the dominator( one being adequate hood clearance, another being the adapter)
 
What find funny about this over carb debate is even the people that push smaller carbs generally over carb themselves, just about no one uses what the formula recommends, (cid x rpm / 3456) x VE% = carb cfm @ 1.5" hg.

A basic 5000 rpm peak hp 360 probably around 85% ve = 443 cfm
Same spec 318 = 390 cfm,
same spec 273 = 336 cfm
". 225 = 277 cfm
". 170 = 209 cfm

How many under 500 cfm 4bbl option are available to us ? Seems like the carb industry believes in over carbing.

Even a similar 440 = 541 cfm which is 59 cfms smaller than the standard 600 cfm carb that's recommended for mild small block applications.

Even if we crank hp peak to 6000 rpms @ 95% ve it raises up these carb cfm numbers 34% eg. 360 = 594 cfm that's a pretty healthy 360 (450 ish hp) and all that is recommended for is a basic 600 cfm carb so 90%+ 360 and anything smaller are pretty much over carbed, even a 440 @ same specs = 725 cfm less carb than most would run on milder smaller V8's. If 1.5" hg is the goal most of us are over doing it.
 
Last edited:
273 said:
What find funny about this over carb debate is even the people that push smaller carbs generally over carb themselves, just about no one uses what the formula recommends, (cid x rpm / 3456) x VE% = carb cfm @ 1.5" hg.

A basic 5000 rpm peak hp 360 probably around 85% ve = 443 cfm
Same spec 318 = 390 cfm,
same spec 273 = 336 cfm
". 225 = 277 cfm
". 170 = 209 cfm

Even a similar 440 = 541 cfm which is 59 cfms smaller than the standard 600 cfm carb that's recommended for mild small block applications.

Even if we crank hp peak to 6000 rpms @ 95% ve it raises up these carb cfm numbers 34% eg. 360 = 594 cfm that's a pretty healthy 360 and all that is recommended for is a basic 600 cfm carb so 90%+ 360 and anything smaller are pretty much over carbed, even a 440 @ same specs = 725 cfm less carb than most would run on milder smaller V8's. If 1.5" hg is the goal most of us are over doing it.
Click to expand...

Yet even a 340 came from the factory with a 800 cfm carb, didn’t it.
 
I think the videos are very interesting and I still don't understand the differentiator. Would be very nice to have had a MAP sensor for all the tests to try to gage if it was flow related.

However, kind of hard to argue flow on a "flow restriction" dual plane deal. Still not sure.

The other thing this test does is challenge dogma... which is always a good thing.

@TT5.9mag thanks for posting the graphs up. That's the key. It's not just a top end thing.
 
TT5.9mag said:
On the Dom he used an HVH 4 hole tapered 4150-4500 adapter and he said he’s never seen it loose power. It’s usually worth 10. So maybe it’s more the spacer than the carb.
Click to expand...
When I was in the building my 434 Brett Miller told me to go Dominator on a Dominator flanged intake. He also told me to not use an adapter on a 4150 intake, just stay with a 4150.
 
B3422w5 said:
Yet even a 340 came from the factory with a 800 cfm carb, didn’t it.
Click to expand...
The later thermoquad equipped engines did. One of the tricks I remember guys with the early 340 doing was installing the 750 AVS off a 440 on them, they always went faster.
 
Mean416 said:
@TT5.9mag thanks for posting the graphs up. That's the key. It's not just a top end thing.
Click to expand...
Even with heads flow on the dyno it show engines at least under 7000 rpm aren't as sensitive as people generally make them out to be, maybe on the street and or track might be a different story, but with over a hundred years of automotive racing if small was generally better 200-599 cfms we would of found that out to be true by now. And that the average person doesn't generally run anything smaller than a 600 cfm carb even on small stock/mild V8's. And 600 cfm by that formula roughly equals about 450 hp so if your making less than 450 hp and running a 600 cfm carb or larger apparently your over doing it.
 
justinp61 said:
The later thermoquad equipped engines did. One of the tricks I remember guys with the early 340 doing was installing the 750 AVS off a 440 on them, they always went faster.
Click to expand...
do you think any of that was a function of people not understanding or having the ability to tune the TQ?

not questioning the veracity of them going faster with the smaller carb, but merely wondering aloud if it was just because it was so new that the secrets had yet to be unlocked.
 
justinp61 said:
When I was in the building my 434 Brett Miller told me to go Dominator on a Dominator flanged intake. He also told me to not use an adapter on a 4150 intake, just stay with a 4150.
Click to expand...
I’ve heard the same thing repeated by many different people. But a Dominator on a dual plane was never even part of the conversation. I would guess 99.999% of the time when someone is comparing a 4500 to a 4150 all the intakes were single plane.
 
TT5.9mag said:
I’ve heard the same thing repeated by many different people. But a Dominator on a dual plane was never even part of the conversation. I would guess 99.999% of the time when someone is comparing a 4500 to a 4150 all the intakes were single plane.
Click to expand...

The first Doninator I saw on a car was a 454 and it had a dual plane intake on it. I think it was almost 2 tenths faster on the Dominator.

Back in the mid 1980’s and into the 1990’s I saw dozens of Dominators on dual plane intakes.

When there were no throttle stops or junk like that, to run a “super” class they would limit the power some and use a dual plane intake.

Now it’s nothing to see a 180 MPH Super Gas car.
 
junkyardhero said:
do you think any of that was a function of people not understanding or having the ability to tune the TQ?

not questioning the veracity of them going faster with the smaller carb, but merely wondering aloud if it was just because it was so new that the secrets had yet to be unlocked.
Click to expand...

The early 340’s didn’t have Thermoquads. I’m thinking 71 was the first year for them.
 
TT5.9mag said:
I’ve heard the same thing repeated by many different people. But a Dominator on a dual plane was never even part of the conversation. I would guess 99.999% of the time when someone is comparing a 4500 to a 4150 all the intakes were single plane.
Click to expand...
Yes, the dual plane slipped my mind, sorry.
 
Newbomb Turk said:
The first Doninator I saw on a car was a 454 and it had a dual plane intake on it. I think it was almost 2 tenths faster on the Dominator.

Back in the mid 1980’s and into the 1990’s I saw dozens of Dominators on dual plane intakes.

When there were no throttle stops or junk like that, to run a “super” class they would limit the power some and use a dual plane intake.

Now it’s nothing to see a 180 MPH Super Gas car.
Click to expand...
Were they using adapters or was there actually dual plane intakes with 4500 flanges?
 
@Newbomb Turk Quick google search came up with a few pics.
AE2382CC-C3B9-4C39-8783-CC4D4274F74D.png
A4A86420-50CF-42B4-92D0-18FF2706BD5D.png
B933CCC4-FDF9-4D73-A873-DDFAF2EDA984.png
 
TT5.9mag said:
@Newbomb Turk Quick google search came up with a few pics. View attachment 1716268565View attachment 1716268566View attachment 1716268567
Click to expand...
I like how the venturi's are closer to each corner of the intake ports..

Makes me think instead of a single plane would something like a cross between a single plane and kind of a mini tunnel ram with a large two barrel directly above the front and rear intake ports so basically a two piece 4bbl (inline) would work better than a 4 bbl straighter shot easier to make same length runners. And run the carbs side ways or even slightly crooked to get a even straighter shot.
 
Last edited:
As far as low-end vs CFM's (rating at least....:D ).....
In the worst-case scenario (meaning highway gears, stock converter).... my 360 Duster 60 ft the best with the 750 DP Holley and 750 DP Brawler. I tried a 600 eddy, 650 AVS II, 770 VS. As far as Double Pumper's and more CFM rating killing low end on a streetcar with stock converter (or next to stock) and highway gears just isn't the case in my opinion. I believe it's in the tune.
 
273 said:
I like how the venturi's are closer to each corner of the intake ports..

Makes me think instead of a single plane would something like a cross between a single plane and kind of a mini tunnel ram with a large two barrel directly above the front and rear intake ports so basically a two piece 4bbl (inline) would work better than a 4 bbl straighter shot easier to make same length runners. And run the carbs side ways or even slightly crooked to get an even straighter shot.
Click to expand...
That’s been done, or at least something similar. Lots of big hp guys used to run spit dominators on sheet metal tunnel rams. 4, 2 barrels. It was popular for big cu/in nitrous stuff
 
You must log in or register to reply here.
-

Back
Top