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any one using the Holley Quadra-jet replacement carb? thinking about using one on my LS-5 any one here got one of these carbs? I dont plan on ever showing my car again, so it having a Q-jet is not that big of a deal. the only thing is the Holley is a 650cfm an the Q-jets are 750? would that mater on a 454?
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Re: quadra-jet replacment
i have rebuilt Q jets for people who have had holley replacements on their cars and trucks with the deal if they did not like the Q jet better after my rebuild i would rebuild their holley replacement carb free. NEVER had to do one!!!! -
Re: quadra-jet replacment
I have used the 6210 650 CFM double pumper and the 6211-6213 series 800 CFM double pumpers. They run great, the main drawback is that being double pumpers, the arm for the secondary pumper interferes with the 1" diameter crankcase vent tube on the bottom of the 1970 style double snorkel air cleaner housing. If you want the stock look, you have to pick up a 1973-74 double snorkel base (on e-bay about $75) and use the 1973 style vent tube setup.
650 vs 750 CFM is essentially a wash as Holley rates the carbs at 1 mmHg pressure drop and Rochester used 1.5 mmHg for the 4 barrels (if I remember correctly).
In addition, if you go with the 800 CFM carbs, as with all double pumpers, you shouldn't smash the throttle wide open at low RPM or you may get a bog.
Hope this helps,
MarkComment
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Re: quadra-jet replacment
Lyndon I replaced the original quadra-jets on my 68 327/350 4sp CR 370 rear and on my 70 350/300 turbo with 308 rear back about 1973. I have accumulated a lot of miles on my cars with the Holley 6210 650 double pumper spreadbores. They have not been trouble free, but power valves will rupture and fail. I really like the performance of the Holley on the 68 being able to manually control the application of the two huge secondaries. Another thing I like about the Holley spreadbore is after letting my cars sit for a couple weeks with engine starts, it is so easy to put some gasoline in the front vent tube priming the front with fresh fuel, press the accelerator and the cars start like you just turned them off. I let the 68 go undriven for 6 months or so and it cranked up like it had just been run the day before, starter just barely turned the engine and it was running using a sample of gas from my lawn movers gas can. The leak down of fuel from the quadra-jets into the intake was reason enough for me to switch.Comment
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Re: quadra-jet replacment
will the stock air cleaner fit on the Holley? on the 71 it is a duel snorkle type.Comment
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see my post above
If you use the double pumper it will not fit. If you get the later vac. secondary type, it probably will but I have never used that.
MarkComment
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Re: see my post above
will the open type like on a LT-1 an LS-6 work then?Comment
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only the 1967 L88
The high rise BB through 1969 open air cleaner had the 1" crankcase vent tube pointing straight out to the pass side and connected to the elbow in the valve cover with a short straight rubber tube. That style will not work with the low rise intakes as used stock on your 1971.
The low rise BB air cleaners had the vent tube pointing back at about a 45 degree angle and this hits the pumper arm on the carb regardless of whether it's an open or closed type element.
The 1967 L88 base has no vent provision as they used a road draft breather so it will work but you have to stick in one of those aftermarket type breathers in the valve cover.
If you want the closest look to your original dual snorkle air cleaner, use the 1973-74 style. The stamped housing is identical to the 1970-71, except the crankcase vent goes into the back side of the housing through one of those plastic filters like on later cars instead of through the bottom of the housing. Just put your original lid on it. You will need to buy the tube from Paragon - about $15. Or, you can just leave the plastic breather filter out of the air cleaner housing and use a breather in the valve cover.
MarkComment
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Re: only the 1967 L88
thanks for all the info I think I will just get a jobber rebuild from auto zone are advance auto for bout 150$Comment
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Re: only the 1967 L88
Lyndon I have the dual snorkel air cleaner on my 70 and I used it after the installation of the Holley 6210 double pumper. I would have to look at it to be sure but I did not modify it much. I did do something to it. I have not used the 70's dual snorkel for years because I bought a new GM drop base open element type to use on top of my ZZ1 crate engine with a new Holley square bore 650 double pumper. I do remember denting in the fresh air tube on this base just a little for clearance.Comment
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