Carb Choice

[dobie]

Hoosier's recent thread got me thinking. I went out to my spare room and looked around for my extra carbs. Currently I have a 650 DP which runs fine honestly. I also have a 700 DP which I just can't get my car to like. As Hoosier described, the car bucks and bounces, and doesn't start nearly as easy. I found a 750 Holley with vacuum secondaries. The current 650 and 700 both have manual secondaries.

Performance wise, which might be the better choice? The current 650 DP with manual sec., or getting the 750 w/vacuum sec. rebuilt? I'd love to use a bigger carb, but my past experience with the 700 DP leaves me a little leery to mess with something which is currently running well enough.

 

[mannye]

I don't know much about this stuff, but it seems to me that you have to have the cam to match the carb. I've heard of "overcarbing" an engine, but I don't know enough to elaborate. Maybe someone that actually knows what he's talking aboot can chime in?

 

[dobie]

I would tend to agree. Here's my current specs: 383, MP dual plane intake, .488/.491 split profile cam, Hooker headers, 3.91 rear end, 4 speed, no power anything. The heads were shaved .020 and gasket matched. The pistons are stock low compression ones, so I'm guessing comp. is now around 9.0 to 1.

 

[mcmopar]

The 750 with vac. secondaries would work well on that setup. I'm running #74 jets on the primary side on mine. Not sure on the secondary side but I think they are #78. Yes, I have a secondary power valve on mine. It runs so well that I am hesitant to put the 850DP on it.
As you say, though, its running well enough now so why mess with it? You are probably a little down on power but unless you are thrashing it all the time it may not be worth the time and trouble of messing with something else.

 

[SomeCarGuy]

That is a nice carb to run.

I think it would be worth it, but you may lose some MPG and possibly some low end. My experience has been the mid range picks up with a 750 on a 383.

 

[dobie]

Good deal. Thanks for all the help.

 

[Basketcase]

but unless you are thrashing it all the time it may not be worth the time and trouble of messing with something else.

naw....not Steve...NEVER......... :acme:

 

[dobie]

:devil:

My latest MPG figure was 7.5, so what's that say...........


:cheers:

 

[ACME A12]

The 750 with vac. secondaries would work well on that setup. I'm running #74 jets on the primary side on mine. Not sure on the secondary side but I think they are #78. Yes, I have a secondary power valve on mine. It runs so well that I am hesitant to put the 850DP on it.

That 850 DP probably wouldn't deliver enought fuel without some modifications...since you must have extrude honed all of the idle circuitry on the 750 to get it to dump all of that raw fuel when you're cruising at 2 mph...couple of spark plugs in the tail pipes and they'll make you the President of the Pharaohs Car Club... :lmao:

Just teasing...of course... :acme:

:jester:

 

[Basketcase]

[couple of spark plugs in the tail pipes and they'll make you the President of the Pharaohs Car Club... :lmao:



:jester:

he tried that with his work car. The Sherriff didn't think too much of it....but it WAS a great way to slow people down..... :jester:

 

[ACME A12]

[couple of spark plugs in the tail pipes and they'll make you the President of the Pharaohs Car Club... :lmao:



:jester:

he tried that with his work car. The Sherriff didn't think too much of it....but it WAS a great way to slow people down..... :jester:

I was :acme: John...but it is a helluva idea for Steve's work cruiser...

:jester:

 

[Roadcuda]

[couple of spark plugs in the tail pipes and they'll make you the President of the Pharaohs Car Club... :lmao:



:jester:

he tried that with his work car. The Sherriff didn't think too much of it....but it WAS a great way to slow people down..... :jester:

Now that would have been fun to see!!!! :devil:

 

[mcmopar]

The 750 with vac. secondaries would work well on that setup. I'm running #74 jets on the primary side on mine. Not sure on the secondary side but I think they are #78. Yes, I have a secondary power valve on mine. It runs so well that I am hesitant to put the 850DP on it.

That 850 DP probably wouldn't deliver enought fuel without some modifications...since you must have extrude honed all of the idle circuitry on the 750 to get it to dump all of that raw fuel when you're cruising at 2 mph...couple of spark plugs in the tail pipes and they'll make you the President of the Pharaohs Car Club... :lmao:

Just teasing...of course... :acme:

:jester:

:lmao: :lmao: :lmao: Keeps all you tailgaters off my backside!

 

[dobie]