Which carb would you get?

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Coyote Jack

Coyote Jack

Member #55, I'm old
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After finding a couple of problems with the Holley 3310 750cfm carb I have now. I have come to the conclusion that I should either rebuild it or buy a new carb. Here are the specs on my setup.

360, .040 over
KB pistons, final compression 10.5 to 1
Magnum heads, 2.02 valves, ported to the max
M1 dual plane intake
Holley 3310 750cfm vaccumn secondary's
1" carb spacer
MSD Ignition, 6AL, Blaster 2 coil, 8534 Dist.
Comp cams Magnum 280H, 1.6 rockers, total lift .512
Dynamax ceramic headers, 1 5/8 primaries to 2 1/2" X-pipe, flowmaster 40's
TCI 2800 stall convertor
Fresh 727, reverse manual valve body, B&M Megashifter
4:10's in 8 3/4
SS springs, 002/003
26" M/T Sportsman Pro's
American Racing Outlaw 1 wheels, 15x8 rear, 14x6 front

What would you do and why?

Jack
 
I had a 3310 on my duster and like you was having some problems with it. I replaced it with an almost new (ebay) 750 mech secondary 4779. Like it a lot more. I'm sure that gas milage is down, but that wasn't ever much of a concern. I always liked the carter avs carbs i had on old musclecars. Next carb I buy might be an Edelbrock thunder series avs. Who knows?
 
What ever carb you comfortable with is what I would get. If you like Holleys and are OK with messing around with them, get one. Though I would not get a double pumper myself, a 750 vacuum is what I would be looking at.
 
Coyote Jack said:
After finding a couple of problems with the Holley 3310 750cfm carb I have now. I have come to the conclusion that I should either rebuild it or buy a new carb. Here are the specs on my setup.

360, .040 over
KB pistons, final compression 10.5 to 1
Magnum heads, 2.02 valves, ported to the max
M1 dual plane intake
Holley 3310 750cfm vaccumn secondary's
1" carb spacer
MSD Ignition, 6AL, Blaster 2 coil, 8534 Dist.
Comp cams Magnum 280H, 1.6 rockers, total lift .512
Dynamax ceramic headers, 1 5/8 primaries to 2 1/2" X-pipe, flowmaster 40's
TCI 2800 stall convertor
Fresh 727, reverse manual valve body, B&M Megashifter
4:10's in 8 3/4
SS springs, 002/003
26" M/T Sportsman Pro's
American Racing Outlaw 1 wheels, 15x8 rear, 14x6 front

What would you do and why?

After running my 388 on the dyno last friday and finding the 750 mighty demon to be just a tad to small on the top end - I recommend you buying the same carb for yours, especially if you are considering stepping up a notch in cam size. I run a 254@50 555 lift. I believe yours is a 230@50. If you upped to the XE275 and the 750 carb you would probably pick up 40fwhp.
Let us know what you decide and how it works.
Too bad you are so far away - I have a 650dp speed demon on the shelf that would work great with your present setup as it is meant for a cam with duration like you have now.
Click to expand...
 
Leo, far away is not a problem, as long as it's in Canada. LOL Going across the border is getting to be a pain. I am about as big as I want to get cam wise with these heads. Any bigger and I would be into new springs and cutting the spring seats. The CFM calculator I used said I should have a carb with 758 CFM. I am not sure about the speed demon as I have heard they are rated a little different.

Jack
 
Thought I read at the Holley web site they wet flow there carbs.
 
Jack,

That 650 speed demon may be just the ticket if the price is right. I know it seems small, but you'd only really lose HP above 5000 rpm and the driveablity would be awesome.

The speed demons have an idle air bypass screw, so can avoid drilling the throttle butterflys when running a big cam. Be sure to check out their website on how to adjust it. Barring that I would go with a 750 speed demon vacuum or mechanical. Barry Grant makes some great carbs. Kinda like how Holley should've done it!
 
Speed Demon, its the only new design for a carb, vastly superior to all the other 40 year old designs.
 
Jack, I think any carb in the 750cfm range will work fine. You just need to do a little tunning.
 
Holleys have some issues but easily solved ones usually. Most main bodies are not flat on the metering block surfaces which means they need truing with the proper file for aluminum. Many also don't have air bypass holes drilled in the pimary throttle plates which makes getting proper idle mixture on a cammed engine nearly impossible due to transfer slot exposure. The baseplate mating surface of the main body may also need filing on the screw hole areas to assure proper gasket seating. The baseplate itself may need filing if someone has over torqued it on a thick gasket.
 
Hey Jack, If my experience is worth anything, I changed from a 750 speed demon with vacuum secondaries to a 750 demon double pumper straight out of the box and it runs beautifully. Adjusted the idle mixture and haven't touched it since. Also added a fuel regulator and set for 7psi.

Terry
 
388dart has kindly offered to let me try his 650 dp speed demon. That along with some other pointers make me hopefull to get my problems resolved.
The impression I am getting from my current carb is that the primaries are working fine but when I stomp on it it works like it is only using the primaries.
As near as I can figure this is all part of the build process. You have to allow for getting them sorted out.

Jack
 
Yes you need to sort them out.

In my experience though the larger carbs have improved low speed drivability. The exact opposite of what the current thought is.
 
flyboy01 said:
Speed Demon, its the only new design for a carb, vastly superior to all the other 40 year old designs.
Click to expand...


The Demon carbs are just massaged Holley's, nothing new. Most of the parts are interchangeable. Barry Grant got his start tweaking Holleys much the same as Proform or Quick Fuel and just evolved into manufacturing his own version of a Holley.

I have a 725 Road Demon and it's the worest carb I have ever tried to tune, constantly chasing it. Got so frustrated I went back to a basic Holley 4160 600 cfm carb, tweaked the main jets and set the idle mixture and have not had to touch it in two years.
 
There sure is some good info here!! Thanks guy's :thumbup:
 
I had a 3310 with a Proform main body on my 360 and it did ok. A buddy of mine had a 750HP for sale, so I swapped the 3310 off and put on the 750HP. I gotta tell ya, it woke this motor right up. So either the 3310 was too small, tuned wrong or the 750HP is just one hell of a carb. ;-)
 
All carbs, like anything have their advantages and dis-advantages but I myself like Holleys and the Holley types. Like Adam said any carb around the 750 range tuned right will work pretty well.

Chuck
 
Coyote Jack said:
388dart has kindly offered to let me try his 650 dp speed demon. That along with some other pointers make me hopefull to get my problems resolved.
The impression I am getting from my current carb is that the primaries are working fine but when I stomp on it it works like it is only using the primaries.
As near as I can figure this is all part of the build process. You have to allow for getting them sorted out.

Jack
Click to expand...
maybe this is a stupid Q, but have you tried different springs in the secondary vacuum thingee? (brain fart)
 
The vacuum pot had a leak that I was able to fix. They now seam to open but there are other issues with this carb. It at the very least needs a rebuild, so I am exploring all options to get the performance where it should be.

Jack
 
I am considering buying a Holley 670cc Street Avenger. They are not as adjustable but are suppose to be dependable. Just need to come up with the cash. They seem reasonable at $370. Has anyone heard good or bad things about this carb?
 
The Street Avenger series of carbs are actually more easily adjusted than the sub ject carb of this thread.

Where the #3310 is a series 4160 which does not have a metering block on the secondaries and does not accept replaceable jets the Street Avenger Series is a 4150 series with a secondary metering block which allows for jet changes and it also comes with the quick change secondary cover to allow easy access to the springs.

FWIW, the Street Avenger carbs are rated by measuring the flow wet where as the older 3310 750 was rated with dry flow. These two carbs are very close in capabilities.
 
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