comments on 4165 holley carb

daveL82

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Apr 10, 2008
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I have a Rochester on my ZZ4 motor at the present time that hasn't been tuned on a dyno yet but does seem to run well on the street and track days.

I have 4 or 5 Holley 4165 spreadbore double pumpers including one of the ole 800 or 850 cfm versions for the big block.

These carbs are easy to swap with the Rochester but trying to decide it it's worth getting one of these carbs running on the vette. The 4165 has a side hung float so there is some concern during high speed corning during track days.

I did run one for a while but it would seem to cut out under hard braking.

Anyone have knowledge or opinions of these carbs?
 
I have one on my Vette and like it.

thum_5349050f376dc9f.jpg

However I have the same problem as you with it flooding out under hard braking. I've heard that there are several cures for it. I believe that the Holley fuel bowl vent baffle can be modified to work with the side-hung float. I think you can also connect the bowl vent tubes with a piece of tubing. I haven't tried either yet so can't report on effectiveness.
 
I think you can also get float bowls and metering blocks to convert to center hung floats and dual inlets
 
I think these are a little bit different than all the other Holley's, and the parts don't really interchange. Holley doesn't make a vent tube that actually fits. You MAY be able to modify the standard tube to work. I didn't want chopped up parts coming loose and floating around inside my carb.
When I adjusted mine to the correct float level, the secondary fuel bowl would flood the engine on hard brakeing.
When I lowered the float level, I thought I might run low durning long wot runs.
I went back to the Q Jet and it runs well.
 
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I think you can also get float bowls and metering blocks to convert to center hung floats and dual inlets
Yes, that's true. Actually Holley makes some models with the center hung floats and dual feed. I have one I thought I might use at some point. No 6213.

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Maybe Lars will jump in here. As I recall he doesn't care much for these carbs. One thing to keep in mind is that you can't switch boosters on them.
 
Actually, I've been able to get the 4165 and the 4175 carbs to run identical to the Q-Jets and the square-bore Holleys with a little tweaking and tuning. The problems during hard braking have to do with fuel in the bowl sloshing out the vent and flooding the engine - all you have to do is install a baffle to prevent fuel slosh from going out the vent. Other than that, the carb will run just fine.

Lars
 
So for the vent baffle it's the plastic insert that looks to be about an inch long?

Lars, Would you have any jet and power valve numbers for this carb on a ZZ4 motor, Doug Nash 5-speed for street and track days?
 
Lars, thanks for chiming in. I would be interested to hear your input on jetting and tuning my setup as well.

357 ci, 9.5:1, Comp Cams XE262, Weiand Action +Plus PN 8004 and Holley Model 4165 series PN R6210-3 with stock cowl induction hood and air cleaner, 4 speed Muncie and Hedman headers, stock '69 side exhaust.

Also, what are your recommendations for a baffle? To the best of my knowledge Holley only makes baffles for center-hung bowls.

And. . . if you ever decide to tune carbs again, I have Rochester and Holly spreadbores I would like to send your way.;)
 
You can run a "whistle" in the fuel vents, but I would still modify the vent tubes for racing: Your vent tubes are currently cut at a 45-degree angle at the top, and they're cut short. I'd remove the vent tubes and install slightly longer tubes. With the longer tubes (make sure they don't hit your air cleaner lid when the air cleaner is installed), you can clamp a 3/8" fuel line from the primary tube to the secondary tube in a loop. Snip a couple of holes into the hose at the top of the loop for vent. This will prevent any fuel from sloshing out of the vents and going down the venturi during hard braking.

For jetting suggestion I need the list number.

Lars
 
Lars, thanks for chiming in. I would be interested to hear your input on jetting and tuning my setup as well: Holley Model 4165 series PN R6210-3

The Holley 6210-3 is an emissions-legal replacement for the Q-Jet. The carb is smaller than a Q-jet, being only 650 cfm. As such, it is lean jetted for use on a stock vehicle, and it uses the close-tolerance 122-602 (size 60) jets on the primary side with 83 jets on the secondary. Power valve is an 8.5.

If you have a performance vehicle with headers, good flowing exhaust, and a mild cam, I would bump that primary jetting up at least 3 to 4 jet sizes as a start. With a little bit of a cam, the 8.5 stock PV will open too soon, so I'd cut it down to about a 4.5. Take care of any hesitation/stumble issues by replacing the tiny .025" discharge nozzle with a .030-or-so. Be sure to crack the secondary throttle slightly using the secondary idle speed screw so that you are idling on the primary side with .020" or less of the transition slot exposed below the throttle blades - this is key to good idle and good off-idle throttle response.

Lars
 
Lars

I believe the 650 carbs I have are all List 6210 version but let me check.

The bigger version of the carb is really messed up and does nothing but flood the engine at idle. It's too big for the ZZ4 I believe so it's been in a box for the last 6 years. Picked it up at a corvette meet for $35
 
Dave -
Contrary to popular belief, a big carb will not cause an engine to run rich. In fact, the low metering signal to a big carb on a small engine causes the carb to run lean. I have test-run carbs from 390 cfm up through 1150 cfm on my 357 small block, and I have never had any problem running a big carb if it is correctly set up. Once a carb is over-sized based on the engine's needs, the carb will not deliver any more power than a correct carb, but it will not cause problems, rich running, or drivability issues. If your big carb is flooding the engine, the carb has internal problems that can be repaired. The flooding issues are not due to the size of the carb.

Lars
 
Lars, I agree about the carb size thing sorry I miss led you there. I think someone worked it over but not sure what has been done to it. I changed the jets, needle and seat and the power valve but not success so it went bax in the box. Thought about putting one of the 650 metering plates to see if that might help but never got to it.
 
Ok Lars, I have another question for you. There are several PN R6853 carbs listed on ebay right now. They are the competition/non-emission version. Would there be any advantage to starting with the comp version over the 6210? Or do you end up in the same place after tuning?

Also, would there be any problem using the standard jets rather than the close-tolerance?

Thanks for all your help so far.
 
The primary difference between the 6210 and the 6853 is the use of a secondary power valve on the 6853. The 6210 is jetted on the secondary side to compensate for no power valve (rich jetted), meaning that the secondaries on the 6210 are intended as more of an "on-off switch" with the mixture on the secondary side always being full-rich. This allows a street driven car to be inadverdently "tipped" into the mechanical secondaries at a low rpm without the car stumbling excessively. The 6853 will not go "full-rich" on the secondary side until you trip the manifold pressure below 6.5" Hg. This actually makes the 6853 a slightly more sophisticated carb, and it would allow you to run the engine at partial WOT (not fully open, but close) without the carb going to the full power enrich mode. This serves little purpose on a drag car, but can be a useful tuning parameter on a road course car.

Holley used the "close tolerance" jets on all of their emissions-legal carbs, because the flow tolerance variation on the standard jets is too large to produce consistent emissions. There is no problem using standard jets to tune a carb originally equipped with the close-tolerance jets.

Lars
 
There are days when you realize you have too much stuff

Lars, I went out to the garage and got the list numbers off 4 carbs and I think I have another one somewhere.

I have a 6210-3 that I bought from Summit 4 years ago. It ran good but seem to wnat to stall when you quickly let off the throttle.

I also have the following:

List 6211
List 6773
List 6497
 
You can run a "whistle" in the fuel vents, but I would still modify the vent tubes for racing: Your vent tubes are currently cut at a 45-degree angle at the top, and they're cut short. I'd remove the vent tubes and install slightly longer tubes. With the longer tubes (make sure they don't hit your air cleaner lid when the air cleaner is installed), you can clamp a 3/8" fuel line from the primary tube to the secondary tube in a loop. Snip a couple of holes into the hose at the top of the loop for vent. This will prevent any fuel from sloshing out of the vents and going down the venturi during hard braking.

For jetting suggestion I need the list number.

Lars
What is the best method to get the vent tubes out?
 
What is the best method to get the vent tubes out?

On carbs with the vent tube hole exposed on the underside, you can hit the edge of the tube with a pin punch to knock it out. With no access to the underside, you can grab the wall of the tube with a pair of needlenose vise grips and rock it back and forth until it comes out.

Lars
 
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