hp difference between 600 carb and a 750.

[phenom08]

Track is allowing 750 carbs. Is it worth buying a 750? Running mostly slick 3/8 tracks. Motor is 358 with dart heads, dart intake, roller cam turning 7500-7700 rpm.

[perfconn]

358ci at 7700rpm needs 797.62 cfm so yes the 750 will make more power.

[merc123]

On my 355 with Vortec heads and 7200 RPM limit, we unbolted the 750 house carb on the dyno and put on a 600 and the 750 only yielded about 5 HP and TQ overall more than the 600. There were remarkably different power curves though and in some cases the 750 would have benefited more on one track while the 600 on another.

According to the calculators I would need a 739 CFM carb...

Just my opinion but getting a 5 HP gain isn't worth the cost of a new carb. You could put it in something else and achieve a better gain, like new tires or better shocks.

[50j]

What 600? What 750? Even if it was a 80540 600 HP it would run like a different car on the track with a good 750 on that motor. If it's a junker 1850 600 to a good 750 there's a bigger difference. Well worth the cost IMO.

[DANNY]

What 600? What 750? Even if it was a 80540 600 HP it would run like a different car on the track with a good 750 on that motor. If it's a junker 1850 600 to a good 750 there's a bigger difference. Well worth the cost IMO.

Heck yea, my first carb I got off ebay was a 700dbl pumper still had choke horn all I did was rebuild it and jet it. Later on I got a 750 HP on same motor talk about whoa! In my opinion carbs make a world of diff. If they were all that close no way would guys spend big bucks on some of them out there, we would all be getting our stuff from Autozone and O'Rileys

[phenom08]

My 600 is a 80540 that I sent to willys. The 750 would also be a willys only rule is baseplate size.

[50j]

In that case I would ask Willy's.

[merc123]

What 600? What 750? Even if it was a 80540 600 HP it would run like a different car on the track with a good 750 on that motor. If it's a junker 1850 600 to a good 750 there's a bigger difference. Well worth the cost IMO.

Both were custom built carbs from Stealth in my case.

[dynoman14]

Phenom,
If you cant make +50Hp with a 750 over a 600 there is a problem somewhere, either engine or carb. When we put a 750hp on a Hooters Cup engine we ran on dirt as a SPEC it picked up almost 40HP, and another 20HP with changing to bigger, longer tri-y headers.

Camshaft or Intake may be too small to turn up and use the extra cfms the carb provides.

Stealth builds some pretty wicked stuff so I am sure the fuel and air is available to make some power.

Just remember that most race engines require about 1# of fuel for every HP you make and when you want to make more HP you have to verifiy that the bigger carb is adequate jetted and air bleeded to make more power. Dyno sheet should be able to tell you this, if not your carb builder should have a fuel curve for the carb on your style of engine. I have about 10,000 different carbs I have run in the last 25 years and they all seem to like something different to make power. Similar carb styles and metering blocks are similar but most professional carbs are like fingerprints, no 2 of them are exactly the same.

I build my House Crate carbs 10 at a time and they all have slightly different booster signal and fuel pull from that. If you move a booster .010" in the venturi up or down or side to side you can vary fuel pull and air flow as much as 10% in just that one hole.

[50j]

Phenom,
If you cant make +50Hp with a 750 over a 600 there is a problem somewhere, either engine or carb. When we put a 750hp on a Hooters Cup engine we ran on dirt as a SPEC it picked up almost 40HP, and another 20HP with changing to bigger, longer tri-y headers.

Camshaft or Intake may be too small to turn up and use the extra cfms the carb provides.

Stealth builds some pretty wicked stuff so I am sure the fuel and air is available to make some power.

Just remember that most race engines require about 1# of fuel for every HP you make and when you want to make more HP you have to verifiy that the bigger carb is adequate jetted and air bleeded to make more power. Dyno sheet should be able to tell you this, if not your carb builder should have a fuel curve for the carb on your style of engine. I have about 10,000 different carbs I have run in the last 25 years and they all seem to like something different to make power. Similar carb styles and metering blocks are similar but most professional carbs are like fingerprints, no 2 of them are exactly the same.

I build my House Crate carbs 10 at a time and they all have slightly different booster signal and fuel pull from that. If you move a booster .010" in the venturi up or down or side to side you can vary fuel pull and air flow as much as 10% in just that one hole.

I think he's running gas.

[stockcar5]

Just remember that most race engines require about 1# of fuel for every HP you make

with comments like this its easy to see why everyone bashes on dynoman. more incorrect information.

[Racer18]

Phenom,
If you cant make +50Hp with a 750 over a 600 there is a problem somewhere, either engine or carb. When we put a 750hp on a Hooters Cup engine we ran on dirt as a SPEC it picked up almost 40HP, and another 20HP with changing to bigger, longer tri-y headers.

Camshaft or Intake may be too small to turn up and use the extra cfms the carb provides.

Stealth builds some pretty wicked stuff so I am sure the fuel and air is available to make some power.

Just remember that most race engines require about 1# of fuel for every HP you make and when you want to make more HP you have to verifiy that the bigger carb is adequate jetted and air bleeded to make more power. Dyno sheet should be able to tell you this, if not your carb builder should have a fuel curve for the carb on your style of engine. I have about 10,000 different carbs I have run in the last 25 years and they all seem to like something different to make power. Similar carb styles and metering blocks are similar but most professional carbs are like fingerprints, no 2 of them are exactly the same.

I build my House Crate carbs 10 at a time and they all have slightly different booster signal and fuel pull from that. If you move a booster .010" in the venturi up or down or side to side you can vary fuel pull and air flow as much as 10% in just that one hole.

Quit smokin your breakfast.

[50j]

So I just got one of the red marks today with a message that was obviously intended for someone else. Check your aim lol!

[chevy370lsx]

Take it for what it's worth, my flat tappet 377 went from 402rwhp with a 750 methanol carb to 453 rwhp with an 850 methanol carb.. Both were properly tuned carburetors using a wideband on the Dyno.

[merc123]

Mine was ran on 110 octane race fuel if that makes any difference to anyone. I didn't specify.

Also, my 600 has no problems keeping up with the 700 CFM carbs on the 400 block motors I run with. My motor is built to spec of the rules of that specific track as well as I'm sure the 400's are, or maybe even *gasp* "cheated" motors. So I'm guessing all of them have mismatched carbs to their engines and aren't running at peak performance. I'm sure a 40 HP difference would be noticeable.