Holley model 4160, series 3310 carbs

[dcdoug]

Does anyone know what the differences are between the litany of series of Holley 4160, 3310 carbs? Holley's site isn't that helpful.

I have googled my 3310, which is a 3310-11 and other than a few references, I don't see much on it. I know there are a bunch of 3310-XX series carbs. Some seem to have only primary metering bodies and a secondary metering plate, while others have both primary and secondary metering bodies (mine is the latter). Any other differences? Anyone know anything about the 3310-11 specifically?

Works great, other than I may need to lean out the idle mixture a touch. Just curious about the differences.

[patrickt]

Originally Posted by dcdoug

Does anyone know what the differences are between the litany of series of Holley 4160, 3310 carbs? Holley's site isn't that helpful.

The Holley 4150 and 4160 are essentially the same, except the 4160 has no secondary metering block. If you take a 4160 and buy the kit to add a secondary metering block you have essentially turned it in to a 4150. If I recall correctly, it was about 1966 when the car manufacturers stopped using the 3310 as original equipment. When you bought the carb from Holley it was still referred to as a 4150 carburetor and it was 780 cfm. It had a "dash one" after the part number 3310 on the air horn and it had a secondary metering block (ID number was 7003, I think). Then about a decade later the 3310 model 4150 morphed into the 3310 model 4160 with a secondary metering plate and a 750 cfm rating. Every time Holley would make a teen weeny tweak to it they would up the dash number. Somewhere I have a description of what the tweaks were, but they're generally not as much as you would think, and 3310-11 is the current model.

[patrickt]

Holley hasn't updated their tech specs for the 3310 since generation 7. And generations 2 through 7 all have the same specs anyway. I think it's safe to say that a 3310-11 is still basically the same as the original 3310-2 that morphed in to existence around 1976. Here: http://www.holley.com/data/TechServi...%20Listing.pdf
There's still about a billion 4160s out on the road. I love mine. Works perfectly, easy to tune, tells me jokes when I'm driving, mows the lawn for me, etc.

[trularin]

One of the good things about your series is the factory installed the power Valve blow out protection. I have one of the older units that does not have this and have had to replace a number of power valves from the initial startup and tune.

The one on my car now I think it a -10.

Pat is right, there are little things like what I added, but bascially they are about the same.

Just my $0.02 worth.

[trularin]

Gee Pat, that looks nice.

Since yours mows the lawn, can you send it over my way in the summer?

One thing Pat didn't add was it is easy to work on.

[dcdoug]

Thanks! I am pretty happy with mine. Had it out shoveling snow for me in the alley since it wasn't busy doing anything on the car.....

What's the main benefit of the secondary metering block and the second idle mixture screw, by the way?

[patrickt]

Originally Posted by dcdoug

What's the main benefit of the secondary metering block and the second idle mixture screw, by the way?

The short answer is "if you car runs well, then there is no benefit to a secondary metering block." Secondary metering blocks let you change the jetting, but if your metering plate is "just right," then there's no point in changing anything. Personally, I like my 4160 along with the metering plate (which has non-adjustable metering orifices). 4150s also have dual accelerator pumps -- some people love that. BTW, some people just think that mechanical secondaries are inherently superior to vacuum secondaries, but I am of the opinion that a properly tuned vac secondary is just as good, and sometimes better, than a mechanical setup. Two idle screws are needed because there are two idle squirters for the two primary venturis -- (some carbs have four). Two are easy to adjust, and you move them in unison. I use a vacuum gauge, and have for decades, but I'll readily admit that an gizmo in your sidepipes to measure the burn is superior.

[patrickt]

Originally Posted by trularin

One thing Pat didn't add was it is easy to work on.

It's really easy to work on. I mean really, really easy to work on. Unless something's broken, there's really not much to it. Doug, since your car is running well I wouldn't even bother removing the sight plugs to check the floats (I'm worried you'll spill gas on the hot primaries). Just hook up a five dollar vacuum gauge like you see in my pic below, and then with the car warmed up and running, adjust the idle mixture screws until you get the highest vacuum. Adjust both screws the same amount. Then adjust your idle screw down so that your idle is at a rev that you like. Then do the idle mixture screws one more time -- some guys like to "enrichen" the mixture just a bit at idle after you've found the highest RPM setting. That can help for a smooth start. If you have a turkey pan that is not removable you're going to have a hard time getting the vacuum gauge on the manifold vacuum fitting that is under the front of the carb. The trickiest part of this whole exercise is just getting the vacuum hose on the fitting and not dropping the little black rubber cap that's on there down in to your engine. You can see in my pic another little black cap on the side of the carb just above the idle mixture screw. Don't hook your vacuum gauge on there. Here are the 4160 instructions:
http://www.holley.com/data/Products/...199R8108-2.pdf

[dcdoug]

I actually just sent my TP off to Mickmate today to make it "convertible" so it will be less of a PITA in the future to make tweaks. But right now it's easy so I thought I'd mess with it a bit. My guess is that I'm about 1/8 of a turn too rich, but I'll hook up the gauge and check it out after this rain storm passes next week.

[patrickt]

Originally Posted by dcdoug

... I'll hook up the gauge and check it out after this rain storm passes next week.

The readings and behavior of the needle of a vacuum gauge can tell you quite a bit about your engine. Astute followers of this thread will note that the needle in my pic is rock-steady.

[FWB]

the 4150 and 4160 are really very different patrick, the 4160 which is a universal type of 4bbl is what was used on most factory 427's one metering block and a single fuel inlet.
the 4150's are all not like the carb you pictured they also include the 1000 cfm and 1150 cfm dominator carbs. the BJ\BK holleys on 427 low risers and the BD\BC holleys on the med and high risers were all the 4160 type. they were one metering block. the two metering block type won't fit on the factory manifold. the 3310-1 is a 4160 the 3301 is also a 4160. one has a choke one does not

[patrickt]

Originally Posted by FWB

the 4150's are all not like the carb you pictured

That's not a 4150. That's my 4160, which is just like DCDoug's, a 3310-11.

[dcdoug]

OK, so I must have been hallucinating when I told you I had a secondary metering block. I don't, mine is a standard 3310-11. Maybe too many gas fumes.

I hooked up the vacuum gauge this PM and played with the idle mixture a bit. Leaned it out a touch (1/8 turn on both screws). Vacuum gauge bounces a bit as I have some roll to my idle. Should I turn up the idle to reduce the roll while adjusting the idle mixture so it is easier to see the gauge change?

Also, when I went to hook up the gauge, I noticed that the rubber cover to that front vacuum fitting was missing. I will get a replacement, but am curious as to what effect that missing cover has had? Car runs great, other than sometimes dieseling a bit when I shut it off, which is what I am trying to solve.

[patrickt]

Originally Posted by dcdoug

Also, when I went to hook up the gauge, I noticed that the rubber cover to that front vacuum fitting was missing. I will get a replacement, but am curious as to what effect that missing cover has had? Car runs great, other than sometimes dieseling a bit when I shut it off, which is what I am trying to solve.

You mean the rubber cover where you hook the vacuum gauge and that I said was really easy to drop and lose? If you don't have the rubber cover on it you have a pretty decent manifold vacuum leak. Your car will run rough -- you absolutely, positively have to have a cap on it. A leak like that can really make a difference.

Originally Posted by dcdoug

OK, so I must have been hallucinating when I told you I had a secondary metering block. I don't, mine is a standard 3310-11. Maybe too many gas fumes.

Yeah, I thought so.

Originally Posted by dcdoug

Should I turn up the idle to reduce the roll while adjusting the idle mixture so it is easier to see the gauge change?

Well, you can, so long as you re-adjust your idle back down to a good number after you have your mixture right. The theory being that the very best idle mixture will give you the highest vacuum because the engine is running the most efficiently. You can monkey around with it, and if it doesn't improve, monkey with it some more. You can't really hurt anything.

[FWB]

if you can verify the vacuum gauge is in correct working order, i would question the needle bouncing, how much is it bouncing, is it more than 1 in vac.your experiencing run on after the key is turned off. where is the timing set? is there fuel dripping into the plenum from the carb without moving the throttle? a fluctuation of 2 or more inches of vacuum can be a sign of valvetrain issues. broken springs or bad valve guides can cause a vacuum reading fluctuation. not trying to be an alarmist, and i have no idea how new or old your build is, but there seems to be more going on than having to adjust the carb.

[dcdoug]

I didn't lose the cap, it just wasn't there when I went to hook up the gauge. Maybe I knocked it off somehow when I took the carb off to remove the TP.

[patrickt]

Originally Posted by dcdoug

I didn't lose the cap, it just wasn't there when I went to hook up the gauge. Maybe I knocked it off somehow when I took the carb off to remove the TP.

OK, first thing you have to do is get a cap on it. You can't leave it open. Take the cap off the ported vacuum right above your passenger side idle mixture screw and put that one on it and then stick a piece of tubing or something over the ported vacuum fitting, even duct tape, to seal it up until you can get a cap from the auto parts store, take it for a ride and see how it runs. Just plugging that manifold leak might make quite a difference. FWIW, on my build, which is similar to yours, I run 13.5" of vacuum and the needle wobbles about an inch (meaning "one") or so. With the cams we're running that's perfectly normal.

[patrickt]

... and do I remember you telling me that you have yet to adjust your valves? If so, solid flat tappets that are out of adjustment can make your needle wobble.

[dcdoug]

Originally Posted by FWB

if you can verify the vacuum gauge is in correct working order, i would question the needle bouncing, how much is it bouncing, is it more than 1 in vac.your experiencing run on after the key is turned off. where is the timing set? is there fuel dripping into the plenum from the carb without moving the throttle? a fluctuation of 2 or more inches of vacuum can be a sign of valvetrain issues. broken springs or bad valve guides can cause a vacuum reading fluctuation. not trying to be an alarmist, and i have no idea how new or old your build is, but there seems to be more going on than having to adjust the carb.

Engine is about 8 months old and has 1,500 miles on it and was built by a professional who specializes in FEs and knows what he's doing. Checking the lash is on my list, but I would be surprised if there are any serious valve train issues. The needle bounces 1-2 inches of vacuum, mostly between 7-9".

[dcdoug]

Originally Posted by patrickt

... and do I remember you telling me that you have yet to adjust your valves? If so, solid flat tappets that are out of adjustment can make your needle wobble.

I was told that it was probably enough to do it annually and is on my list to do soon. My vacuum does seem quite low though. Thought non-emissions engines should be at 10 inches at least.