Holley 3310-1
Thread Starter
Advanced
Joined: Apr 2008
Posts: 71
Likes: 0
Holley 3310-1
Can someone tell me please what power valves are appropriate for this carb? As some of you may know, this carb has 2 power valves, one in the primary metering block and one in the secondary block. I read some where the stock configuration was (72 front jets 10.5 PV, 76 rear jets 8.5 PV). It would seem like a bad idea to have the secondary power valve open before the secondaries do. The proper way to size the front power valve is to take a vacuum reading and cut it in half (12" vacuum = 6.5 PV). But there is no such explanation for sizing the rear power valve that I know of. Anybody got any ideas?
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
Can someone tell me please what power valves are appropriate for this carb? As some of you may know, this carb has 2 power valves, one in the primary metering block and one in the secondary block. I read some where the stock configuration was (72 front jets 10.5 PV, 76 rear jets 8.5 PV). It would seem like a bad idea to have the secondary power valve open before the secondaries do. The proper way to size the front power valve is to take a vacuum reading and cut it in half (12" vacuum = 6.5 PV). But there is no such explanation for sizing the rear power valve that I know of. Anybody got any ideas?
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
Thread Starter
Advanced
Joined: Apr 2008
Posts: 71
Likes: 0
I'm with you midyear, anytime the 3310-1 is brought up in conversation it confuses the crap out of people. It is not an ordinary 3310, 4160, 750cfm carb. By the way, my motor is a basically stock LS-5 with headers and exhaust. What attracted me to by this carb was its originality. It has the #'s correct metering blocks and was jetted 72,76. I have never seen the type of power valves it had though. They are stamped on the side, in the flats were you unscrew it instead of on the metal in front of the diaphragm. One is stamped 105 (10.5 I assume) and has small holes instead of a window. The other is stamped 2 and has small windows. I'm fighting this carb loading up and I'm considering putting these power valves back in. The diaphragms look good and they have good movement. They should be good right?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
yep..another way is before you tear the carb apart, screw in the idle adjustments closed, if it still runs, the front pv is blown, tough to do on the rear though.... btw the rear pv only works along with the vac secondaries when they are partially open....
Le Mans Master
Joined: Nov 2008
Posts: 5,691
Likes: 12
From: columbus oh
little mouse.....i am quoting holleys numerical component parts listing for the 3310-1 model 4150 780 cfm.... re build kit #37-1084...this kit is exclusive to that 780 carb because it contains the two proper pv's ...a 10.5 for the front and an 8.5 for the rear.....the bigger valve is used in the front for early power enrichment (higher vacuum) because that model is metered on the lean side....they tried to make this an economy oriented carb and it falls short on some mills....the pv in the rear is a neat idea because it allows leaner jetting in the rear which is actually a part of the idle circuit too...it needs less fuel at an idle, trying to achieve even more economy, kind of contradictory of a performance carb....
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
little mouse.....i am quoting holleys numerical component parts listing for the 3310-1 model 4150 780 cfm.... re build kit #37-1084...this kit is exclusive to that 780 carb because it contains the two proper pv's ...a 10.5 for the front and an 8.5 for the rear.....the bigger valve is used in the front for early power enrichment (higher vacuum) because that model is metered on the lean side....they tried to make this an economy oriented carb and it falls short on some mills....the pv in the rear is a neat idea because it allows leaner jetting in the rear which is actually a part of the idle circuit too...it needs less fuel at an idle, trying to achieve even more economy, kind of contradictory of a performance carb....
Now I can only go with the carbs I have had apart or what the holley book says ( assuming no misprints or screwups )
To the OP unless you have extreme good idle vacuum hauling
a heavy trailer with the vette lol. I suggest you use a 6.5
if need be richen the primary jets up from the 72s if you have a very big cam very low idle vacuum then you will need something lower then a 6.5.
So lets see you stick in some reall small jets then try to fix it under
load with an earlier opening 10.5 fuel enrichment valve.
Last edited by Little Mouse; Oct 3, 2009 at 03:54 AM.
Race Director
Joined: Feb 1999
Posts: 16,978
Likes: 7
From: In Dreams There Is Truth Ohio
3310 A and 3310 1A primary 10.5 secondary 8.5
3310 2a primary 10.5 secondary plate
The above per Holley Illustrated Parts and specs and initially this carb was used on the 396 425 hp Corvette
Mouse, reason you've seen 6.5 inch valves, is that guys ditched the 10.5 and put 6.5 inchers...I've purchased countless of 3310's from swap meets and almost everyone had 6.5 inchers, some had 8.5's but I never eveer came accross a 3310 with 10.5 in the primary
3310 2a primary 10.5 secondary plate
The above per Holley Illustrated Parts and specs and initially this carb was used on the 396 425 hp Corvette
Mouse, reason you've seen 6.5 inch valves, is that guys ditched the 10.5 and put 6.5 inchers...I've purchased countless of 3310's from swap meets and almost everyone had 6.5 inchers, some had 8.5's but I never eveer came accross a 3310 with 10.5 in the primary
Last edited by GDaina; Oct 3, 2009 at 12:39 AM.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
[QUOTE=GDaina;1571697542]3310 A and 3310 1A primary 10.5 secondary 8.5
3310 2a primary 10.5 secondary plate
The above per Holley Illustrated Parts and specs and initially this carb was used on the 396 425 hp Corvette
Ok the 3310-1 does have a 10.5 valve MY BAD.
All my carbs were metering plate 4160s they have the 6.5.
why would you need a 10.5 power valve even the jets are the same
72s as the 4160.
you have a light weight car 427/425 hp, solid cam probably
13 inches of vacuum a 10.5 power valve, insane.
I see the later 750s all have a 6.5 power valve that makes sense.
3310 2a primary 10.5 secondary plate
The above per Holley Illustrated Parts and specs and initially this carb was used on the 396 425 hp Corvette
Ok the 3310-1 does have a 10.5 valve MY BAD.
All my carbs were metering plate 4160s they have the 6.5.
why would you need a 10.5 power valve even the jets are the same
72s as the 4160.
you have a light weight car 427/425 hp, solid cam probably
13 inches of vacuum a 10.5 power valve, insane.
I see the later 750s all have a 6.5 power valve that makes sense.
Last edited by Little Mouse; Oct 3, 2009 at 02:07 AM.
