'70 Choke Pull-Off
#1
'70 Choke Pull-Off
I'm trying to identify the original style choke pull-off for a '70 W31 Q-Jet, 7040255. Any one what an original should look like? I've seen units that are entirely white plastic and units that are all metal. I also have an original '70 Chevelle Q-Jet and the pull-off is half plastic (white) and half metal (but unfortunately broken).
Thanks.
Thanks.
#4
#5
your vacuum break(pull-off) should be all metal. i should have the part number stamped into it(at least 5 digits). the bracket that holds it is considered a separate part, and has it's own part number stamped into it. since the brackets were all the same on Olds 4m carbs. during that era, that number won't do you any good. those vacuum breaks are quite hard to find, as nobody is making them now. the correct part number is 7040697 for the break unit only, the bracket and break assembly is 7026162.
bill
bill
#6
According to my parts book, the one for my application is indeed 7040697. I bought a couple of plastic aftermarket pull-offs, I guess that was a waste. Thanks Bill for the insight, I know what to look for now.
Brian
Brian
#8
Metal can for "exc. High Perf." apps
http://www.ebay.com/itm/CHOKE-PULL-O...449a69&vxp=mtr
Plastic replacement
http://www.ebay.com/itm/NORS-Choke-P...42c2e6&vxp=mtr
Here's the gray & black plastic unit I have seen on factory performance carbs of he 67 68 69 era
http://www.ebay.com/itm/VTG-NOS-DELC...c900d5&vxp=mtr
Save the above photos for your records.
Set up an epay search to alert you when things like this appear.
http://www.ebay.com/itm/CHOKE-PULL-O...449a69&vxp=mtr
Plastic replacement
http://www.ebay.com/itm/NORS-Choke-P...42c2e6&vxp=mtr
Here's the gray & black plastic unit I have seen on factory performance carbs of he 67 68 69 era
http://www.ebay.com/itm/VTG-NOS-DELC...c900d5&vxp=mtr
Save the above photos for your records.
Set up an epay search to alert you when things like this appear.
Last edited by Octania; September 1st, 2013 at 10:05 AM.
#10
The difference in all pulloffs to my knowledge is the size of the pinhole in the vac line tube. That orifice varies in size between various pulloffs and affects the rate of opening. Some serious tuners in the old days would drill them out and experiment with them. The length of the arm can vary between pulloffs, some have a hole and some an oval slot. Depends if it's a 4 BBL or 2 BBL and the make/model of carb. But...mostly it's that orifice diam, a 4BBL hi per and a 4BBL stock would have a different size and number, but look identical. When you buy a new pulloff now, they have like a universal orifice size to fit many aps, they might fit 15-20 GM aps that originally had different size orifices.
#13
Thanks Joe for sharing that insight. I'm going to speculate with a lower engine vacuum available the orifice might be larger and the spring tension lower--just a guess. Alternatively if the objective is to have the choke closed longer on the hi-perf engines than I guess the orifice may be smaller.
My car has a plastic pull-off currently. I'm not aware if the after market ever offered a metal one calibrated for the 70 OAI application.
My car has a plastic pull-off currently. I'm not aware if the after market ever offered a metal one calibrated for the 70 OAI application.
#14
Pretty much nobody is any fussier than I, and I wouldn't lose any sleep over not having the exact # dashpot. Joe is probably right, the sping is most likely different also. A replacement will do the job for you, nobody starts their W-car in Michigan when it's 25 below zero anymore. Finally, it's not a part you would be docked any points for at the OCA Nats or any judged show.
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davesdelta
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March 6th, 2007 11:18 AM