Camshaft Guru; Tell me where to start with jets

[Flying Undertaker]

Lynn: My biggest concern is the 2 Quarts fuel dilution of the oil, that's a lot of fuel! Check your fuel pump, they've been known to fail and dump fuel into the oil from the fuel pump mounting area of the block. As for jets, I'd stick with 72 in the primary side until you get the engine to idle correctly, possibly reduce the secondary side to 72 in the future. New Camshaft specs are not too radical for a DZ engine as the original cam specs are .485 lift on both intake & exhaust sides with 254 degrees duration at . 050 lift. with a 114 degree lobe separation to allow better idle for emissions and 50 state usage. The newer cam is 236 degree duration at .050 lift, 18 degrees less. Disassemble the carb and clean with a bucket type carb cleaner, later using spray cleaner through carb metering block passages and air bleed and passages in the main body. Reassemble carb making sure to use correct metering block gaskets (most kits have 2 different style gaskets). Stay with the factory power valve values until you get the carb to idle smooth enough to obtain vacuum readings with a good working vacuum gauge. Adjust power valves to be between 1 to 1 1/2 inches below vacuum reading at idle in neutral. Always use NEW power valves unless you have a tester to insure that the power valve diaphragm wasn't damaged due to backfire as the original carbs did not have a check ball to prevent backfire damage. Ignition timing seems to be fine as is. Always use full intake manifold or carb baseplate vacuum advance hookup to canister on distributor, stay away from ported vacuum. Good luck, keep us updated on the progress. Don.

[x33rs]

Something else you can do Lynn that I check with all Holley carbs here is flatness with the metering blocks.

I noticed you mentioned a large internal fuel leak. If you already checked the obvious (blown PV, transition slots not overly exposed, or dirt in needle and seat) and you're still having a serious flood issue, I find a warped metering block often a cause, especially on these 50 year old carbs. Meter blocks that aren't sealing properly cause all kinds of wonky idle issues and internal fuel leaks.

Holley used to make a tool to bend the meter blocks back into place. Yes sounds crazy but this was a problem even back in the day. I have one of these tools in a box somewhere I haven't found since I've moved but it's just as easy to chuck it in a vice.

What happens over years of cranking on the float bowl screws is that it draws in the corners of the meter blocks. If you run a straight edge across the block you'll find a lot of them bowed in the center. You can carefully chuck it in a vice in such a way to apply pressure and gently bow the meter block in the other direction, and let it rest for a few minutes. It's okay if it now bows slightly the other direction. It will push and seal in the center of the gasket better, and saves some of these hard to find meter blocks.

I also run a straight edge across the face of the carb, and often find the corners of the carb pulled out from the bowl screws. I lightly run a fine file across the face until I see the file contacts the entire surface, then clean and blow out all passages as necessary. I find this is most often the cure for old carbs that most people removed long ago for poor running problems they could never figure out.
Hope that helps.

[Steve Shauger]

Originally Posted by Flying Undertaker

Lynn: My biggest concern is the 2 Quarts fuel dilution of the oil, that's a lot of fuel! Check your fuel pump, they've been known to fail and dump fuel into the oil from the fuel pump mounting area of the block. Don.

I agree, two qts of fuel most likely came from the fuel pump leak into the block. If that much fuel had come from the carb, the cylinders would be washed and the car would be burning oil due to piston ring wear.


Lynn keep an eye on the fuel in the oil issue....