What Carb do you guys run on the 383??

[67chevemall]

I need help chosing a new carb.
I had a 600 holley for years that was ok
The Edelbrock 1406 just isn't cutting it. I don't like it.

Any pics or suggestions would be great......

I like the demon series.....
And the 4150 Holleys look good too....

anybody

[70rs/ss]

Just for a driver? 750 edelbrock. I plan a 750 double pumper, but mine is in a "fun" car, not my DD. What's wrong with the 1406?

[muscletrucks]

The best carb for the torquer 383 is a Holley 670 Street Avenger. This with a dual plane intake and the numbers show you can't do any better. It hits the sweet spot. Rodney

[Billla]

Originally Posted by 67chevemall

I had a 600 holley for years that was ok
The Edelbrock 1406 just isn't cutting it. I don't like it.
I like the demon series.....
And the 4150 Holleys look good too....

CFM = ((CI x RPM)/3456) x VE, if you figure 383 HP then you don't need more than 600 CFM until past 6000 RPM. You'd have to turn it to 8K to need 750 CFM.

There's nothing wrong with the 1406 - if it's not "cutting it" then it's not working, configured or tuned correctly. I agree that the Edelbrock Performers, Holley Street Avenger or Street Demons are the best choices for a daily driver.

A mechanical-secondary carb is a racing carb, not a street carb. You give up driveability and fuel economy for instant acceleration performance - if that's a good trade-off, then cool - otherwise tune what you have.

[HoupPhotography]

X2 ^^^

[67chevemall]

I have tried everything I can to get it to run nice again.
It has been sitting for a few years now so it is even harder.
I thought about taking it to the engine shop down the road, but hate
to leave the truck anywhere.
I think it could be the dizzy and timing more then the carb.
Just want to get the right carb on there before I take it in.
I can flat bed it to a place next town over where they would
tune it up nice, and dyno it all on a Saturday where I can "hang out"

I could tune the 1406 but I like the holleys much better.Want to go back.
I have a brand new 1406 I would trade somebody to get me going.

Your right I don't need Mech Sec. at this point.
The truck is just for Sunday runs for now.
What is the holley Vac Sec # for 650 carb?

?? spring is here and I'm still in bed: go time

[BurnoutNova]

Originally Posted by Billla

A mechanical-secondary carb is a racing carb, not a street carb.

sort of, your right about fuel economy. i'd say some machanical secondary/ double pumpers are racing carbs. the ones with no chokes, and huge acelerator pumps and/or dominators. alot of cars came with them from the factory, and the one on my nova is a out of the box 650 DP, and it runs around great on the street. no driveability probleoms at all. it does like the gas though.

[Billla]

Originally Posted by BurnoutNova

sort of, your right about fuel economy. i'd say some machanical secondary/ double pumpers are racing carbs. the ones with no chokes, and huge acelerator pumps and/or dominators. alot of cars came with them from the factory, and the one on my nova is a out of the box 650 DP, and it runs around great on the street. no driveability probleoms at all. it does like the gas though.

Even the ones with chokes are really racing carbs; the driveability problems of quickly-opening secondaries get covered up by a big shot from the accelerator pump.

The most common "big" carb was the Holley 780 which was a 4150 vacuum secondary carb with a secondary metering block in place of the standard plate - like a 3310 today. Even the LT-1/ZR-1 used this carb. As far as I know (and I ain't the expert ), the only factory Chevy mechanical secondary carbs were used on the 302 cross-ram and the ZL-1/L-88...not really street engines ;-)

As noted, it's really just a choice - if immediate accelleration is your bag, then that's the one area where a mechanical secondary carb will shine.

[chevy72blu]

Originally Posted by Billla

Even the ones with chokes are really racing carbs; the driveability problems of quickly-opening secondaries get covered up by a big shot from the accelerator pump.

The most common "big" carb was the Holley 780 which was a 4150 vacuum secondary carb with a secondary metering block in place of the standard plate - like a 3310 today. Even the LT-1/ZR-1 used this carb. As far as I know (and I ain't the expert ), the only factory Chevy mechanical secondary carbs were used on the 302 cross-ram and the ZL-1/L-88...not really street engines ;-)

As noted, it's really just a choice - if immediate accelleration is your bag, then that's the one area where a mechanical secondary carb will shine.

The 4150 780's are great carbs... I had one built by a guy I know (modified bleeds, air horn/choke tower delete, etc ect) for my BBC. Suposedly they will flow 810 cfm. They are pretty sought after as corvette restoration carbs.

[Billla]

Originally Posted by chevy72blu

The 4150 780's are great carbs... I had one built by a guy I know (modified bleeds, air horn/choke tower delete, etc ect) for my BBC. Suposedly they will flow 810 cfm. They are pretty sought after as corvette restoration carbs.

Most definitely - I have 3 of these; one LT-1 original from 1970 and two reproductions that were available directly from Holley in the early 80's. I also have the LT-1 intakes to match; 1 original with a late '69 cast date and two reproductions available from GM also in 80's.

The original stuff is going into a factory correct (but with a refit roller cam ) LT-1 I'm building...slowly...for my '69 Corvette. The others I'm just holding in trust for the right project. I love this setup for a hot 425+ HP GEN I.

[67chevemall]

The most common "big" carb was the Holley 780 which was a 4150 vacuum secondary carb with a secondary metering block in place of the standard plate - like a 3310 today

Just caught this one...... the carb that came on the engine was exactly that
vacuum sec with a mettering block on the secd's and it had a choke installed.
and it was a 4150.

So maybe I should look at the 3310


hummm?

[space]

Originally Posted by Billla

CFM = ((CI x RPM)/3456) x VE, if you figure 383 HP then you don't need more than 600 CFM until past 6000 RPM. You'd have to turn it to 8K to need 750 CFM.

There's nothing wrong with the 1406 - if it's not "cutting it" then it's not working, configured or tuned correctly. I agree that the Edelbrock Performers, Holley Street Avenger or Street Demons are the best choices for a daily driver.

A mechanical-secondary carb is a racing carb, not a street carb. You give up driveability and fuel economy for instant acceleration performance - if that's a good trade-off, then cool - otherwise tune what you have.

Interesting thread.. I just purchased a 800 Holley double pumper because I was told by 3 different race shops my hesitation @ WOT was due to my Edelbrock 750 single pump not being able to throw enough fuel. Different jets were experimented with at different timing settings to no avail. Any comments on this?

[Billla]

Originally Posted by space

Interesting thread.. I just purchased a 800 Holley double pumper because I was told by 3 different race shops my hesitation @ WOT was due to my Edelbrock 750 single pump not being able to throw enough fuel. Different jets were experimented with at different timing settings to no avail. Any comments on this?

It's a broad question with no simple answer as every engine is different. How were they determining it was fuel starvation? Was this on the dyno?

If it's sudden WOT (drag racing) then this is more about secondary opening than the pump shot...

[space]

Yeah it was on the dyno. I also switched to a mechanical secondary as it was opening up late. It happened anytime I put it to the floor.

[70rs/ss]

Originally Posted by Billla

CFM = ((CI x RPM)/3456) x VE, if you figure 383 HP then you don't need more than 600 CFM until past 6000 RPM. You'd have to turn it to 8K to need 750 CFM.

A mechanical-secondary carb is a racing carb, not a street carb. You give up driveability and fuel economy for instant acceleration performance - if that's a good trade-off, then cool - otherwise tune what you have.

This formula is theoretical assuming a set of peramiters, but it is good for a starting point (buy by no means the absolute). As any modified motor will accept more fuel up to a point over the theoretical formulas suggested number. A BIG carb on a nearly stock anything isn't going to work, but a BIG carb on a motor that can handle it is OK. I daily drove a warmed up 350 with a holley 750 double pumper wth no drivability issues for about 5-6 years, heck I even had to have the car emissioned in Tucson. To say that DP are racing appl only is a little too far to the other side of of the dicussion with they are great for a dd 290hp 350 on the other extreme. There is a point in the middle of stock and full on race engines and the double pumper does fine there. An Edel, Carter, Stret Avenger, etc work good and give great drivability and decent MPG but a double pumper will put down more power on a hotter motor at the sacrifice of MPG. Just so nobody thinks I am biased, I own three Edels from 600-850 cfm, as well as an 850 Demon DP, and an 850Holley DP. I use the 750's mostly on hopped up 350-383, and the 850's on my BBC 454-496.

[Billla]

Originally Posted by 70rs/ss

As any modified motor will accept more fuel up to a point over the theoretical formulas suggested number.

To say that DP are racing appl only is a little too far to the other side of of the dicussion

a double pumper will put down more power on a hotter motor at the sacrifice of MPG.

As usual, I find myself on the other side of this discussion. I'll note that I disagree with virtually all of this and move on

[BurnoutNova]

Originally Posted by Billla

As usual, I find myself on the other side of this discussion. I'll note that I disagree with virtually all of this and move on

i'll agree with this...you dont gain any power richening your fuel mixture... so more fuel can hurt you.

a bigger carb doesnt always mean more fuel either, CFM is air, not just the amount of fuel you consume

[Billla]

If you must have a Holley, then the Street Avenger is your carb.

Always timing, then carb for tuning...

[muscletrucks]

Like I said.......................

[Billla]

Originally Posted by muscletrucks

Like I said.......................

Hey - didn't mean to not give you your props! Exactly like the man said in a prior post

[muscletrucks]

No problem, your tops with me!

[wibilly]

i never cared for holly carbs but love my street avenger

[BarryB]

I am planning on putting a 750 spread bore Holley on my 383 stroker motor. I might have to jet it down some but what is the point of having a stoker if your going to putt around in it.????

[67chevemall]

I have a weiland square bore manifold. Would this be the problem with the 1406?
I took a few of your guys advice and bought the bigger thinker gasket from summit.

I put the carb on last night.
I am going out to blow out all the fuel lines and get some fuel up there.
see what happens this time.
It has been a while.

I like the looks of that avenger. thanks for that tip.

[bryanw1968]

I am not a holley guy anymore but when I had my 383 I ran a 780 and it was perfect!!!
A think a 650 is just not enough carb especially when we're talking about holley's.
If you're talking a Demon it's different. They underrate their flow numbers quite a bit. My BG650 DP flows 725cfm. I attempted to run a BG750DP on my pretty punchy 355 and it was WAY too much carb. My .02 cents......

Good luck,
B