Tuning Holley 4160 - advice needed!

[Dave Garner]

I have 600cfm Holley 4160 Quad barrel carb feeding my 302 recently fitted with a Comp Cams H282 hydraulic roller cam, Edelbrock RPM Performer heads & Inlet plus roller rockers.

I had the car up to the (only) rolling road in Cumbria and it is now running well but the chap who has the rolling road is very familiar with Webers - but not Holley's so is struggling a bit. At present the carb is running a bit rich below 4500 but more crucially running a little lean from 4500 to 6250 (as the cam, head and inlet really start to work together!). If we increase the fuel jet size we will run in to 'overly rich misfires' below 4500.

On a Weber you would reduce the size of the air bleed but this is fixed on the 4160 Holley - can anyone give some guidance on what to work with on the Holley to richen things up above 4500 rpm?

Many thanks in advance!!!

Dave

 

[Randy V]

The Holley 4160 series is a budget carburetor that is not easily tuned as the air bleeds are pressed in and not replaceable. They can, however, be drilled out or soldered shut and re-drilled (neither of which I would advise doing).

If everything else is in good working order I would
1) ensure that the primary throttles are barely open from the fully closed position and adjust the idle fuel mixture appropriately
2) reduce the primary jet size one jet size
3) replace the secondary metering plate with one that was two jet sizes larger (note that 4160s do not have replaceable secondary jets - which is why you will need to replace the metering plate which actually has the jet orfices drilled into it)
5) ensure that your power valve for the primary circuits is sized at least two inches of vacuum below the idle vacuum reading that the engine has.

If you really want to get more involved than this I would Bin the carb and replace it with a 4150 series carb with four corner idle and replaceable air bleeds..

 

[DaveM]

I would second all of Randy's comments. Standard Holley 4150's just don't have enough adjustability and 4160's are even worse. Basically only the main fuel jets are replaceable. Look at a Quick Fuel mechanical secondary carb. You can change everything - main fuel and air, and idle fuel and air jets. Don't know what they cost in UK, but Summit Racing has them for about $400 US.

 

[Dave Garner]

Thanks gentlemen! I will take your advice in relation to the Holley in the short term.

If I was to replace the Holley then it would be to go to a set of 4 twin Webers (and associated inlet manifold change) but I have spent my 'major upgrades budget' for 2013!

All the best

Dave

 

[Al Jones]

I second the motion for going to a Quick Fuel for reasons of adjustability. This is probably your cheapest and most effective course of action.

 

[Jac Mac]

Find a guy who knows Holleys!! Too check whether the air bleed problem exists rather than just guessing get some stainless safety wire in 0.025/0.032/0.040 sizes and make up some 'hairclips' so that the tip of the clip sits in the air bleed to reduce its size. If that cures the issue you can then make a permanent 'fix' by rivetting the hair clips to the air horn.

Having said that the quickfuel will have adjustability and features like 'idle ezi' to make life simple, as long as you buy a selection of air bleeds/jets etc at time of purchase.

 

[Robert May Eng.]

Carbs are just an organized fuel leak, if you are chucking money at a rolling road it might pay to go with throttle bodies and a programmable ecu. Just thoughts.

Bob

 

[Dave Garner]

Does anyone have a contact for a 'good Holley carb man' in the UK??

 

[David in Durango]

As Randy mentioned, it seems one would need air bleeds that are replaceble to fine tune. that is how I have done it.

good luck.

 

[Tony Hunt]

Does anyone have a contact for a 'good Holley carb man' in the UK??

Dave,
I know it's a bit far for you, but Frank Catt sorted out my Holley 4160 in a trice - once we'd sorted the fuel pressures.
Tony

 

[Mike Pass]

Talk to Kenny Coleman at Engine Data Analysis in Castlford. Top V8 and Holley man. Runs V8s and Holleys on the dyno every day so knows this stuff inside out.
Tel. 01977 516622.
Engine Data Analysis
Cheers
Mike

 

[Dave Garner]

Spot on! Thanks guys

Dave