Holley 3310 (750) or 850 Double Pumper?

Posted By: srunge55

Holley 3310 (750) or 850 Double Pumper? - 01/17/09 04:59 AM

I have both a 3310 vac secondary and an 850 DP. Which would you recommend for the following? This is a street car.

69 GTX convertible
440 (10:1)
Edelbrock heads (out of the box)
CH4B intake
Hedmen headers
727 (2500 stall)
3.55 SG
I haven't picked the cam yet but leaning toward the Lunati 60303 (226/234 at .050 .494/.513 lift)

Posted By: RapidRobert

Re: Holley 3310 (750) or 850 Double Pumper? - 01/17/09 05:46 AM

the 3310

Posted By: GTX MATT

Re: Holley 3310 (750) or 850 Double Pumper? - 01/17/09 06:18 AM

With that cam go with vacuum secondaries, I like the 850 CFM but with that cam you will have trouble at idle with a rich condition.

I think an 850 is perfect for a 440 but the double pumpers have a rich idle circuit which is great when you have alot of duration, helps it idle smoother, but with such a mild duration its just going to cause frustration with fouled plugs and a smelly car. Just my

Posted By: JimG

Re: Holley 3310 (750) or 850 Double Pumper? - 01/17/09 01:16 PM

Ditto the 3310.

While it's off, I'd recommend installing a quick-change cover for the vacuum secondary spring. If you need to tune the vacuum secondary opening (and you probably will), this turns a PITA job into something easy, plus you don't run the risk of tearing the donut gasket that NEVER seems to be available locally when you you need it.

Jim

Posted By: BSB67

Re: Holley 3310 (750) or 850 Double Pumper? - 01/17/09 02:03 PM

Certainly, you need to try them both. I've run an 800 DP on two different near stock 440s and they ran very well. The dual plane intake helps. Getting a clean idle might be an issue as others mentioned, but if you get that straightened out I think the 850 will have a slight performance advantage.

Posted By: srunge55

Re: Holley 3310 (750) or 850 Double Pumper? - 01/17/09 05:46 PM

Thanks for the advice.

Steve

Posted By: Pacnorthcuda

Re: Holley 3310 (750) or 850 Double Pumper? - 01/17/09 06:23 PM

Quote:

With that cam go with vacuum secondaries, I like the 850 CFM but with that cam you will have trouble at idle with a rich condition.

I think an 850 is perfect for a 440 but the double pumpers have a rich idle circuit which is great when you have alot of duration, helps it idle smoother, but with such a mild duration its just going to cause frustration with fouled plugs and a smelly car. Just my

Thats not my experience. I run the lunati 60303 cam in a 440, with an 850DP and an Eddy RPM. (I have a 4-speed, otherwise I would run a VS). Rich idle? Nope...actually very clean. I would suspect if one did experience a rich idle in this combo the transfer slot exposure would need to be adjusted.

Great street cam by the way.

Posted By: NTOLERANCE

Re: Holley 3310 (750) or 850 Double Pumper? - 01/17/09 06:51 PM

IMO, I would install the 3310 first. Tune the carb, get it running and see how you like it.

I feel the 3310 is a pretty basic, user friendly carb, for those who are a bit carb challenged. ( I admit to being a bit carb challenged at times

)

I have had a number of 3310 carbs and really liked them all.

Posted By: Dodgem

Re: Holley 3310 (750) or 850 Double Pumper? - 01/17/09 08:06 PM

Quote:

IMO, I would install the 3310 first. Tune the carb, get it running and see how you like it.

I feel the 3310 is a pretty basic, user friendly carb, for those who are a bit carb challenged. ( I admit to being a bit carb challenged at times )

I have had a number of 3310 carbs and really liked them all.

I second that but with 500 inches I'd give the 850 the old college try make sure it has a new power valve / valves and proper jetting. 80's front with a power valve and 88 without and the same on the secondaries. over jetting and bad power valves are the biggest issues on Holley carb

Posted By: 68KillerBee

Re: Holley 3310 (750) or 850 Double Pumper? - 01/18/09 03:10 AM

Hey,
I didnt know you have an x vert. my dads gotta 68. he's rebuilding his 3310 right now haha

Posted By: srunge55

Re: Holley 3310 (750) or 850 Double Pumper? - 01/18/09 05:37 AM

I just got it a couple months back. Traded my Demon. So your dad is running a 3310, is his a stock 440 or any performance upgrades?

Steve

Posted By: 68KillerBee

Re: Holley 3310 (750) or 850 Double Pumper? - 01/18/09 07:59 PM

Sounds like a good trade. You didn't happen to get this from a guy and it was painted black with goldflake....
i'll ask my dad next time i talk to him. he rebuilt it back inthe 80's ha

Posted By: srunge55

Re: Holley 3310 (750) or 850 Double Pumper? - 01/18/09 09:02 PM

Demon plus money. It was a fair deal. For him :-)
Yeah its black with silver stripes. Its been around for while, I'm sure you've seen it. I am working on repainting it now also going through the motor even though its fairly fresh.

Posted By: WayneM

Re: Holley 3310 (750) or 850 Double Pumper? - 01/19/09 03:22 AM

Quote:

Ditto the 3310.

While it's off, I'd recommend installing a quick-change cover for the vacuum secondary spring. If you need to tune the vacuum secondary opening (and you probably will), this turns a PITA job into something easy, plus you don't run the risk of tearing the donut gasket that NEVER seems to be available locally when you you need it.

Jim

Posted By: 68KillerBee

Re: Holley 3310 (750) or 850 Double Pumper? - 01/19/09 07:54 AM

Quote:

Demon plus money. It was a fair deal. For him :-)
Yeah its black with silver stripes. Its been around for while, I'm sure you've seen it. I am working on repainting it now also going through the motor even though its fairly fresh.

good stuff. i can't think of his last name. but my family has known that guy for quite a few years. my cousin bought a challenger off of him.
good luck with it

. can't wait to see it done

Posted By: Mr.Yuck

Re: Holley 3310 (750) or 850 Double Pumper? - 01/19/09 02:24 PM

neither, 750DP. Between the 2 I'd try the 850.

Posted By: Mr.Yuck

Re: Holley 3310 (750) or 850 Double Pumper? - 01/19/09 02:27 PM

P.S. I have had DP's on mild engines, and even a 750DP on a mild 340. Non of them idled rich or stunk of gas...I guess it's in how you tune it. IMO a well tuned mechanical carb is much more responsive than any vacuum.

Posted By: MrAngry

Re: Holley 3310 (750) or 850 Double Pumper? - 01/19/09 10:13 PM

my combo is very similar to yours... I went from an 850DP to a 3310 to an 800DP... 800DP is BY FAR the best in terms of performance. With the 3310 the car felt downright anemic.

Posted By: 383man

Re: Holley 3310 (750) or 850 Double Pumper? - 01/20/09 12:55 AM

I run an 850 DP on the mild 440 in my 63 and it works very good. It has a nice clean idle and still launches great at the track with no stumble at all. It is basically a stock 850 with the choke blade removed and jetted up a tad. I also drilled the squirters a bit but thats it. In fact the last time I went to the track I ran on the same plugs that have been in it for a year. DP carbs work great on auto's as mine and my sons cars are both auto's and he uses a 750 DP on his Dart. Either carb will work on your street car with 3.55's but if you plan to race it some I would go with the DP. Ron