Holley 3310 780 CFM rebuilt vac sec first try starting

[Lexi]

If your carb doesn't have of these buy one. Youtube video for install. not mine.
https://www.summitracing.com/search...lve-savers?SortBy=Default&SortOrder=Ascending

Yep. You’re a mind reader. Thanks Fran

 

[Lexi]

Sure you got the timing right?

The timing was set last weekend with the 850 on it. Does swapping out a carburetor change the timing? Or is it just a matter of timing changes needed to match the carburetor? The guy that sold it said changing carburetors changes timing? I honestly don’t know; if anything thought it would be close enough to run with the new carb then dial it in? Any explanation is appreciated. Thanks

 

[Daves69]

FWIW, 2012 catalog..................

 

[Photon440]

The timing was set last weekend with the 850 on it. Does swapping out a carburetor change the timing? Or is it just a matter of timing changes needed to match the carburetor? The guy that sold it said changing carburetors changes timing? I honestly don’t know; if anything thought it would be close enough to run with the new carb then dial it in? Any explanation is appreciated. Thanks

A couple of reasons why changing carbs might require a timing change would be a richer or leaner mix than before, and ported distributor advance might come in at a different time. But it should be pretty close with both carbs.

 

[Lexi]

FWIW, 2012 catalog..................

View attachment 1094953

Thanks. At this point I have no idea what I bought. Can only go by what the sellers description was in the ad, and what I received. No numbers to reference as you can see choke tower was machined off.

 

[Lexi]

A couple of reasons why changing carbs might require a timing change would be a richer or leaner mix than before, and ported distributor advance might come in at a different time. But it should be pretty close with both carbs.

Thanks. That’s kind of what I thought. Will mess with it again in the morning

 

[MoparLeo]

Number one dirty word in anything engine related is "Rebuilt" 90% chance you are buying someone elses problem.
You will only know the true condition of a nib carb. So many things can be wrong and more then 1 thing can be wrong at the same time. No choke horn ?? And that will do what exactly for your car ?. Resell to the next guy and buy the proper part for your car and you can get exact, good info on proper tuning.
Like investing in stocks or opening a new business only buy what you are an expert on.

 

[forphorty]

Number one dirty word in anything engine related is "Rebuilt" 90% chance you are buying someone elses problem.
You will only know the true condition of a nib carb. So many things can be wrong and more then 1 thing can be wrong at the same time. No choke horn ?? And that will do what exactly for your car ?. Resell to the next guy and buy the proper part for your car and you can get exact, good info on proper tuning.
Like investing in stocks or opening a new business only buy what you are an expert on.

You can only know the true condition of "new in box" carb after careful inspection. Some new carbs occasionally (rarely) come equipped with metal shavings and/or incorrect machining. Choke horn? I usually chop them 'em off. "And that will do what exactly for your car?" Most of the time, probably not much.But I would expect some benefit if a person is required to run a short air cleaner on their car. I personally wouldn't advise the OP to sell his recently purchased carb just because it backfired once or twice.

 

[RJRENTON]

I understood some early 3310's were actually rated at 780 cfm. Later versions and those with a secondary metering plate were rated at 750 cfm. There was a way to visually confirm by looking at the inside of the carb, but I can't recall now what it was. Anyway, I do have a very old 3310 with secondary metering block and at the time confirmed it was one of the 780 versions.

The ad you posted suggests 2 metering blocks and changeable jets for the secondary side, so it could well be a 780.

The small pop and flames I'd attribute to a lean out condition because of the choke not being involved. In my experience a 50/50 chance the power valve was damaged. You should be able to still try and start the engine, but if the power valve is damaged it'll run richer than normal. I've run them with a blown valve for weeks until I could get to going through the carb. Idle would stink pretty good and sometimes the rich condition made it necessary to crank more than normal for restarting, but didn't do any real harm to anything.

The Holley model 4150 R3310-1 rated at 780 CFM is a great carb. Yes, it has a secondary metering block with replaceable jets AND A SECONDARY POWER VALVE provision, if former owner has not installed a power valve plug. It hss down leg secondary booster venturi. The "newer" carbs are rated at 750 CFM, model 4160 and has a secondary metering plate.
My experience is: IF a power valve has failed, due to a back fire, the result will be an extremely rich mixture, because manifold vacuum is pulling fuel directly out of the fuel bowl, thru the open power valve's vacuum passage, into the engine THRU the ruptured power valve's diaphragm. This extremely rich mixture usually results in stalling, black smoke exhaust and generally piss poor operation and is instantly recognisable.
Just my opinion of course.
BOB RENTON

 

[MoparLeo]

A new carb comes with
A) new parts
B) a warranty if something is wrong.

Caveat emptor
It is always easy to spend someone else's money and give advice that won't subject your opinion to any liability.
After all, these are just words typed on a site by who knows who. The Manufacturer at least has a dog in the fight and somehwhat of a reason to help you with a new product. But Once it is "Rebult" With who knows what parts, whether the carb is from the original or from boxes of spare or questionable parts, who owns it now.
Or send it to the experts here that seem to know how to "fix it" and try to get a guarantee it will be fixed. Ha.

 

[Xp29h]

I’ve seen where people clean up a dirty carb and dirt and grime will get into those tiny air bleed parts on top of the carb. Some will have removable and size differences to help with rich / lean issues. Yours does not. I would take it all apart make sure those are all cleaned as well as everything else. Make sure gaskets are correct and parts are what they are supposed to be for that carb. As it’s used from a Chevy guy, you never know!


Ok more like it’s just used!

 

[Lexi]

The Holley model 4150 R3310-1 rated at 780 CFM is a great carb. Yes, it has a secondary metering block with replaceable jets AND A SECONDARY POWER VALVE provision, if former owner has not installed a power valve plug. It hss down leg secondary booster venturi. The "newer" carbs are rated at 750 CFM, model 4160 and has a secondary metering plate.
My experience is: IF a power valve has failed, due to a back fire, the result will be an extremely rich mixture, because manifold vacuum is pulling fuel directly out of the fuel bowl, thru the open power valve's vacuum passage, into the engine THRU the ruptured power valve's diaphragm. This extremely rich mixture usually results in stalling, black smoke exhaust and generally piss poor operation and is instantly recognisable.
Just my opinion of course.
BOB RENTON

Thanks Bob. I always learn from your posts regarding the Holley 4150, 3310, etc. Appreciate your thoughts. I will update my recent findings on this thread soon.

 

[Lexi]

A new carb comes with
A) new parts
B) a warranty if something is wrong.

Caveat emptor
It is always easy to spend someone else's money and give advice that won't subject your opinion to any liability.
After all, these are just words typed on a site by who knows who. The Manufacturer at least has a dog in the fight and somehwhat of a reason to help you with a new product. But Once it is "Rebult" With who knows what parts, whether the carb is from the original or from boxes of spare or questionable parts, who owns it now.
Or send it to the experts here that seem to know how to "fix it" and try to get a guarantee it will be fixed. Ha.

I typically never buy anything used ir rebuilt, and agree with you on having leverage when buying new. This was somewhat an act of desperation, in that I had a 780 on the car that performed flawlessly, that was replaced a couple years ago with the Ultra XP, which was a nightmare, stuck needle/seat, crap inside the carb when new, as mentioned above, and other issues. Resolved, but it wasn't exactly easy, as they then claim the carb was used, etc, but ended up making good on it, with a replacement, brand new. Anyhow, it's more than the car needs, so I want to go back to the 780 Vac secondary, and regret giving my original one away. Life lesson. Thanks for everyone weighing in. The subject carb of this thread has stirred up a conflict between myself and the seller, so it's getting interesting now. Will post what I have learned soon.

 

[Lexi]

So, overdue update on the 3310-EH 780? carburetor I needed help on. First of all, was able to get the car started and running after changing the front squirter from the .025 originally supplied to a .030 first try it fired right up for a few seconds then stalled, like the previous attempt, but on the second attempt no pop, and was able to keep it running feathering gas until it warmed up to full operating temp. Checked and set timing. Seems ok, but after a quick drive it’s obvious it will need some tuning, to get it smoothed out, responsive, etc. A friend who’s very good with Holley carbs, offered to help me get it straightened out, has a box full of everything needed to experiment and offered to come over to help me out. Unfortunately I had to postpone due to sudden and unexpected health issue, so after I get myself re-tuned, he will come over to assist with the carb tuning. I was going to return the carb to the seller after reading the posts here, raising the questions on what the darn thing is, etc. I have little knowledge on Holley part number/ designations, and I bought it based on the ad description. I kept asking the seller for any additional information and part numbers. All he offered was that “3310-EH 780 CFM”, along with his comments about me being a moron for not knowing what it is, based on that nomenclature, no extra charge for his insults. I tried researching further online, but it was difficult finding that exact designation on web searches. I finally found a hit on the exact description 3310-EH in comments from a YouTube video stating it was a special 780 made for Chevy paired with a specific intake. Here is a copy of what I found:

At this point, I can only assume it’s a 780, could be a 750, but at this point if I can get it tuned as good as my previous 780, it won’t matter to me. I just want to cruise the car occasionally, no racing, and have some decent performance, so I can leave it on the car and sell the 850 XP, that is too much for my car, to someone who needs it. I appreciate all of the knowledge and suggestions from everyone who weighed in on my original problem. I’m looking forward to getting back to speed and see what my buddy can do with this thing in the coming weeks. Any comments, confirmation of the info in the YouTube post is appreciated. Thanks guys

 

[RJRENTON]

As previously noted by others, and your article, the origional Holley 780 CFM was designed for GM's 427/425 HP application. The after market Holley 780 CFM, was an adaptation of that GM design, modified to include the bolt on Mopar throttle cable bracket and the Ford C-6 auto trans downshift lever and spring. This carb was designated by Holley as a model 4150 R-3310-1 and flowed (advertised) 780 CFM. It has down leg secondary booster venturi, secondary metering block with a removable secondary power valve. The carb had an adjustable hot air choke coil, PCV and both manifold vacuum and venturi vacuum spark advance ports. The choke system was convertible to either electric or manual operation with a Holley kit.
The present day Holley is a 4160 design model R-3310-2 or -3 or -4 using a secondary metering plate and straight secondary booster venturi, with a slightly smaller secondary venturi dimension. The user could always add the secondary metering plate with screw in jets in lieu of the fixed orifice plate as origionality supplied to approximate the orifice dimensions, to make tuning easier.
The origional 780 CFM R3310 and the -1 variant are available on eBay and the net. The subsequent variations are available as new and both old and new designs have vacuum operated secondaries. The double pump proponents have their preferences as well. IMO....The Holley R3310 is an EXCELLENT carb suitable for almost all applications. Plus, Holley carbs are easy to tune, with most parts readily available. Just thinking out loud....
BOB RENTON

 

[Bobzilla]

So, overdue update on the 3310-EH 780? carburetor I needed help on. First of all, was able to get the car started and running after changing the front squirter from the .025 originally supplied to a .030 first try it fired right up for a few seconds then stalled, like the previous attempt, but on the second attempt no pop, and was able to keep it running feathering gas until it warmed up to full operating temp. Checked and set timing. Seems ok, but after a quick drive it’s obvious it will need some tuning, to get it smoothed out, responsive, etc. A friend who’s very good with Holley carbs, offered to help me get it straightened out, has a box full of everything needed to experiment and offered to come over to help me out. Unfortunately I had to postpone due to sudden and unexpected health issue, so after I get myself re-tuned, he will come over to assist with the carb tuning. I was going to return the carb to the seller after reading the posts here, raising the questions on what the darn thing is, etc. I have little knowledge on Holley part number/ designations, and I bought it based on the ad description. I kept asking the seller for any additional information and part numbers. All he offered was that “3310-EH 780 CFM”, along with his comments about me being a moron for not knowing what it is, based on that nomenclature, no extra charge for his insults. I tried researching further online, but it was difficult finding that exact designation on web searches. I finally found a hit on the exact description 3310-EH in comments from a YouTube video stating it was a special 780 made for Chevy paired with a specific intake. Here is a copy of what I found:

View attachment 1098029
At this point, I can only assume it’s a 780, could be a 750, but at this point if I can get it tuned as good as my previous 780, it won’t matter to me. I just want to cruise the car occasionally, no racing, and have some decent performance, so I can leave it on the car and sell the 850 XP, that is too much for my car, to someone who needs it. I appreciate all of the knowledge and suggestions from everyone who weighed in on my original problem. I’m looking forward to getting back to speed and see what my buddy can do with this thing in the coming weeks. Any comments, confirmation of the info in the YouTube post is appreciated. Thanks guys

I ran a 3310-1 without a choke for years on the street. Excellent carb.
Your problem right now is your technique. A cold engine does not run well at idle. Even with a choke carbs use a fast idle setting for warm up. Feathering the throttle is wrong.
I suggest this routine:
1. Before attempting to engage the starter, just give one or two slow presses of the pedal to operate the accelerator pump.
2. Hold throttle steady around 1/4 open.
3. Engage the starter and it should fire up. Do not feather throttle. Do not return it to idle.
4. If it is revving too high, above 2500 rpm, slowly back off the throttle a little, but not feather and do not return it to idle.
5. Once it runs for 30 seconds or so, return the throttle to idle and see if it stays running.
6. If it stalls, turn idle speed screw in an 1/8 turn and try the whole procedure again.
Once it stays running you can tune the rest of the settings, but you will always need to start it this way since it has no choke.

 

[Lexi]

I ran a 3310-1 without a choke for years on the street. Excellent carb.
Your problem right now is your technique. A cold engine does not run well at idle. Even with a choke carbs use a fast idle setting for warm up. Feathering the throttle is wrong.
I suggest this routine:
1. Before attempting to engage the starter, just give one or two slow presses of the pedal to operate the accelerator pump.
2. Hold throttle steady around 1/4 open.
3. Engage the starter and it should fire up. Do not feather throttle. Do not return it to idle.
4. If it is revving too high, above 2500 rpm, slowly back off the throttle a little, but not feather and do not return it to idle.
5. Once it runs for 30 seconds or so, return the throttle to idle and see if it stays running.
6. If it stalls, turn idle speed screw in an 1/8 turn and try the whole procedure again.
Once it stays running you can tune the rest of the settings, but you will always need to start it this way since it has no choke.

Thanks so much for your input. Appreciate your help. I too have been chokeless with this car since 1981. Pretty much followed same procedure to start it,as you described. Manual choke was disconnected after engine build with the car being mostly a show and go car. More track time than street. Only driven on the street to get to various car shows, before quitting racing altogether for the typical life changes, and not long after, not much showing, and driving. Parked and garaged for many years. Perhaps “feathering” wasn’t accurate in my description but once I got it running, full temperature i had to tap gas pedal to prevent stall. We did reset idle speed screw, and retired pretty easily. No time to dial in, or play with it further as I needed to drive it to muffler shop, and didn’t want to risk any issue driving it there, so threw the 850 back on it just to get it there and back. Didn’t have the chance to do it, as I have some unexpected health issues that need fixing, but will be back to getting the 3310 running as it should as soon as I can. Thanks for weighing in.