414 Dyno results: Missed combo?

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I like how that HP line goes up and up and then just simply hangs in there for a long duration. Killer torque line where she counts!
 
That motors swingin a big set of nuts!
Be interesting if a smaller venturi carb would up the
bottom end torque do to airspeed, might make a difference
across the whole rpm range.
 
longarm said:
That motors swingin a big set of nuts!
Be interesting if a smaller venturi carb would up the
bottom end torque do to airspeed, might make a difference
across the whole rpm range.
Click to expand...

The venturi on this 750 is already 1.375"--How much smaller would you want to try? J.Rob
 
RAMM said:
The venturi on this 750 is already 1.375"--How much smaller would you want to try? J.Rob
Click to expand...


Yep, that is smaller than a 4779 Holley IIRC. It flows more than a 4779, but the Venturi is smaller. That's why I don't like to call out carbs by CFM. Venturi and throttle blade diameter are much more important.
 
mopowers said:
No, the 4779 has 1-3/8" veturis as well.
Click to expand...


Hmmmm. My memory is shot to hell.

I'll take your word for now, but I'll look it up later.

I used to know all that off the top of my head. Evidently, that part died.

I doubt the carb RAMM used had the 1 11/16 throttle blades. Probably 1 3/4. Now I have to look at my carb and see what it is.
 
yellow rose said:
Hmmmm. My memory is shot to hell.

I'll take your word for now, but I'll look it up later.

I used to know all that off the top of my head. Evidently, that part died.

I doubt the carb RAMM used had the 1 11/16 throttle blades. Probably 1 3/4. Now I have to look at my carb and see what it is.
Click to expand...

1.75" throttle blades here. The question was about a smaller venturi though. J.Rob
 
yellow rose said:
Hmmmm. My memory is shot to hell.

I'll take your word for now, but I'll look it up later.

I used to know all that off the top of my head. Evidently, that part died.

I doubt the carb RAMM used had the 1 11/16 throttle blades. Probably 1 3/4. Now I have to look at my carb and see what it is.
Click to expand...

I hear ya. It doesn't help that every manufacturer's "750" (for instance) all have different specs.
 
Ah, the hell with port velocity and torque. What tire is gonna hook up 500+ anyway? Let it eat...Kill the low end and make power up top when the tires are planted.
 
Oh good Lord! No tire will but a good suspension will fix that. Then again, he's not launching at 500hp ether!
Next... serious comment...
 
rumblefish360 said:
Oh good Lord! No tire will but a good suspension will fix that. Then again, he's not launching at 500hp ether!
Next... serious comment...
Click to expand...

has 512ftlbs at 3600 rpm, might have 500 at 3000 even. i think a decent converter that still cruises well could have him "launching at 500+"

since we are talking "launching" i'm thinking torque here..
 
Just for reference:

4776 1.25 1.312 1.5625 600 CFM
4777 1.25 1.312 1.6875 650 CFM
4778 1.312 1.375 1.6875 700 CFM
4779 1.375 1.375 1.6875 750 CFM
4780 1.375 1.4375 1.6875 800 CFM
4781 1.5625 1.5625 1.7500 850 CFM

From Holley catalog.

List Primary Venturi Secondary venturi Throttle bore CFM


What this means is RAMM's carb is a 750 main body with an 850 base plate. Probably flows better than 900 CFM easy at 20.4 inches.
 
cookietruck said:
has 512ftlbs at 3600 rpm, might have 500 at 3000 even. i think a decent converter that still cruises well could have him "launching at 500+"

since we are talking "launching" i'm thinking torque here..
Click to expand...
Yup, tire fryer. A "street car" ain't hooking that up.
 
yellow rose said:
Just for reference:

4776 1.25 1.312 1.5625 600 CFM
4777 1.25 1.312 1.6875 650 CFM
4778 1.312 1.375 1.6875 700 CFM
4779 1.375 1.375 1.6875 750 CFM
4780 1.375 1.4375 1.6875 800 CFM
4781 1.5625 1.5625 1.7500 850 CFM

From Holley catalog.

List Primary Venturi Secondary venturi Throttle bore CFM


What this means is RAMM's carb is a 750 main body with an 850 base plate. Probably flows better than 900 CFM easy at 20.4 inches.
Click to expand...

Already told you it flows 865-868 cfm @ 20.4 dry. My friends QFT 750 flow 930-932 cfm--same measurements everywhere. Guess which one made more power on the dyno? J.Rob
 
RAMM said:
Already told you it flows 865-868 cfm @ 20.4 dry. My friends QFT 750 flow 930-932 cfm--same measurements everywhere. Guess which one made more power on the dyno? J.Rob
Click to expand...


Yeah, had to go back and look at post 42. Between trips to the porcelain throne and the internet I forgot you posted those numbers.

As you said before, the carb you have is more than plenty for that "asthmatic" engine.


BTW, did you ever determine why two carbs with the same dimensions had such a discrepancy in flow numbers?
 
yellow rose said:
BTW, did you ever determine why two carbs with the same dimensions had such a discrepancy in flow numbers?
Click to expand...

No never did but visually there is a difference in the "sculpting" between the old HP series and the new aluminum HP/XP series. Don't really care as there is virtually no difference in performance on the dyno or under the hood--don't care what the flow bench says. J.Rob
 
RAMM said:
The venturi on this 750 is already 1.375"--How much smaller would you want to try? J.Rob
Click to expand...
Just for chicks & jiggles, an off the shelf 650 double pumper, jetted accordingly of course. That is basically a 750 body w/an 850 base plate, how responsive to jet changes
was that unit? Oh, & I'd still like to see a pull w 1.6 rockers on the intakes :D!
 
RAMM said:
No never did but visually there is a difference in the "sculpting" between the old HP series and the new aluminum HP/XP series. Don't really care as there is virtually no difference in performance on the dyno or under the hood--don't care what the flow bench says. J.Rob
Click to expand...


I was thinking the boosters may be different.
 
Well, I am a nobody, but I can tell ya in my experience, it's almost impossible to over carburate a SBM
 
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