The little plastic choke pull off in the front of the carb was busted into thousands of pieces upon delivery. I go to O'Reileys to buy one, and they show a metal unit (I think from Walker). WTH? Could this possibly work correctly, or are they just showing a part that I would regret buying?
Dan, I understand the plastic diaphragm is getting hard to find. It's desirable because the orifice can be enlarged to adjust secondary air valve opening rate. Check with Greg Gessler at www.gesslerheadporting.com as he should be able to help you out. Devon
Yeah Greg has them on his site. I just thought I'd try locally 1st, since it is only a $14 item. If NAPA doesn't have one tomorrow, I will order from Greg by Sunday...:beer
The Restriction On The New Pulloff May Have To Be Tuned To Your Engine. Since Manufacturers Vary You May Not Get The Same Secondary Opening Rate As The Old One. The Plastic Ones Are Easy To Drill With Wire Drillbits If The Restriction Is Too Small. If The Restriction Is Too Big You May Have To Plug And Redrill. Good Luck
Dan, if you're asking about how that diaphragm affects the secondary air valves, when you go to full throttle, intake manifold goes to near zero. Because that diaphragm has a very small orifice inside the vacuum hose nipple, it relaxes slowly which allows the q-jet's secondary air valves to open slowly as well. Tuning that orifice size helps you get the air valves to open fast enough to give you best acceleration without the dreaded bog. Devon
GP Sorensen Choke Pull-Off Part No. 779-030 Advanced Auto $10 Unless you have a very small drill bit set in .001 increments don't bother drilling it.
I just had my 7042240 carburetor rebuilt because it was starting to leak/flood. I attribute this to the ethanol in the gas. Last time it was done was by John Osborne in 2001. I made sure to tell the shop that I wanted my old pull off back, and they complied. I remember John citing one of the reasons he no longer rebuilds Q-jets is because you can no longer get the good pull offs. My carburetor runs great but I think I need to adjust the air valve tension because the transition into the secondaries is not as seamless as it was. I'll try adjusting the air valve spring first. If I can't get it the way I want it, I'll put the old pull off back on.
Just a note for drilling the restriction in pull-offs, plastic or metal. It is better to ream them with a small tapered reamer. You will find going from .016 to .018" may have a DRAMATIC change in the opening rate (for example). Take a small drill bit, about .030-.035". Very carefully on the shank end grind 4 "flats" 90 degrees from each other to a sharp point. The tapered flats should be apprx 1/4 from start to finish. Those little grinding/cutting wheels for a dremel tool work good for this, or a very fine bench grinder stone. Finish the sharp tip with a very fine sharpening stone. You now have a reamer that can be installed in a pin vise to custom set the opening rate anywhere you want it......Cliff PS: We sell the plastic pull-offs, any opening rate you would want. We also have a very tiny adjustable valve that can be installed (the restriction is drilled out in the pull-off) in line if you want the ease of custom tuning without removing the pull-off at all.......
I read one thing that Gessler does is he buys a handfull of pulloffs cause they're all slightly different. I took that advice and did the same. for 50 bucks I got four or five. Haven't tried them all out though to see how different they are yet though... A small reamer also sounds like something I need to get my hands on.
Sorry, no pics currently of the adjustable valve or the reamer. Contact us directly for parts, etc: http://www.cliffshighperformance.com/
