Secondary transfer slot idle setting

[Hotfingrs]

You can buy a cam assortment kit. But first, is your engine stumbling or hesitating?? This will dictate what you need to do. If it takes off then dies, then takes off again under acceleration, you're not getting enough of a shot of gas...put a larger squirter in. If it dies as soon as you nail it, then takes off, too much gas, smaller squirter. Play with squirter size first. Holley rates their accelerator pumps by the amount of gas they will squirt with 10 pushes of the pump. Most don't really need a 50cc pump. You really didn't say if you were having a problem in this area, only observations on differences....

[Michael C Henry]

I have just reassembled the carbs, and cleaned the plugs, and set the float levels.The carbs do not sit level the engine is almost level so the manifold has the carb secondaries down in the front.I have two of the cam assortments sets to chose from. and all the stuff to back to 30 cc pump if advised to.I'm getting tired of cleaning fouled plugs. waiting till tomorrow to fire it .Have to push it outside,prewarm the oil.The outside part is incase the fireing it turns out to be litteral.

[Michael C Henry]

The setting the initial idle by the transfer slot worked great .The engine idled at near 600 rpm.Problem even with new 3.5 pv's it loaded up and fouled the plugs on a ten minute drive.When I got it into the garage the front primary carb had gas fume clouds inside and appeared wet.I can check the diaphrams and they don't leak. The old original pv's leaked vacum , a slow vacum leak ,less than perfect. How can you check to see if the valve is actually sealing off the gas flow?
If it isn't the pv not sealing than I'm lost. I'm going to end up going to a pro.I'm not rich and allready have a load of parts.

[rdorman]

You could always block off the power valve and see what happens. Beware that under heavy load the car will be lean.... so don't get on it!
Rick

[Jack21]

Mike,

You're running way too rich. And if your engine isn't pulling enough vacuum to keep 35 PV's closed, I'm surprised the e4ngine runs at all.

If your PV has 2 gaskets on it, remove 1. The PV could be pushing against the main body, and lot allowing the metering block to seal.

In fact, at this point, replace the PV with a PV plug (a Holley part) just to isolate problems. No getting on it!

While, we're at it, we're going to install another diagnostic. The main body has a small hole at the bottom of the primary power valve vacuum chamber. Thread this hole, and install a setscrew in it to plug it. Don't thread the corresponding hole in the baseplate so the setscrew won't back itself out. This will cut off the manifold vacuum from the power valve, AND the accelerator pump transfer passage just above this vacuum chamber, to the squirter check valve, and squirter.

An undocumented problem I've found on more than one Holley (some old and worn, some right out of the box). The primary power valve vacuum chamber draws fuel from an improperly sealed accelerator pump transfer slot where the metering block joins the main body. This gives a characteristly rich running engine, and stumble with any throttle application from off-idle, to cruise.

Extra fuel short circuits the accelerator pump squirter, and enters the engine through the power valve vacuum chamber passage in the main body, and throttle plate.

If blocking off the power valve vacuum hole seems to cure engine richness, and throttle stumble (because the squirter is now delivering good fuel shots), this may be the culprit.

Holley 4165's & 4175's have a small brass tube with rubber "O" rings on either end, that are fitted between the metering block, and main body.

The main body may be warped requiring it to be filed, or milled flat. A small casting irregularity in the metering block, or main body may require better sealing. Drill out the main body a short way into the transfer slot, with corresponding hole or chamfer in the metering block. A piece of brass tubing is then tapped into the hole in the main body side. A tight fitting "O" ring is then installed over the tube. Remove the piece of metering block gasket where the O ring goes. As the metering block is assembled on the main body, the O ring compresses, sealing the accelerator pump transfer channel, and power valve vacuum channel.

Remove the vacuum channel set screw, and replace the power valve. Power valve value = 1/2 idle vacuum + .5.

Pick up a Holley setup and tuning manual or two.

[Michael C Henry]

Before it went sour I had judged the vacuum to be a little better than 10. The original pv were 7.5g,they leaked a little vacuum but seemed to work.I was told about the air bleeds again today.At this point I don't know where to run.I'll lookat everything again.

[Jack21]

Mike,

We didn't just dream up these suggestions and remedies. AND, neither are we loaded with spare cash.

There are several good Holley references on the market that run $12.99 - $19.99. You really need to start there.

30 year old motors with 2 x 4 setups are not the easiest things to deglitch.