I'm sure this has been covered several times before, but I'll ask anyway. I am wanting to try a Holley carb for some "out of the box" gain in performance. I am currently running a Q-jet with the Performer intake, iron 72 Stage 1 heads, Popular Mechanics cam (232/244@0.050, 116 lobe centers), 10.5 pistons, and the MT repro headers with a 3" Headman X pipe exhaust system. The converter is a 2600 stall Street Edge, and stock 3.42 gears. I haven't had it on the drag strip yet, but want to buy a Holley to swap out when I do just to see the difference in performance. The car is not a daily driver, so gas mileage is not a factor. With so many choices, I don't know which carb to buy - 850 DP, 870 Street Avenger, 950 HP, vacuum secondaries or manual? Can someone please let me know what they recommend? I know the Q-jet is a great carb if John O. builds it, but I really want to try a Holley, and don't know which one to get. Thanks for any input.
I've had great luck with the 850 Double Pumper (4781, manual secondaries) in the past; unfortunately I have no experience with the others you mentioned. Devon
Thanks, Devon. I read that the manual secondaries were better for light cars, and the vacuum secondaries were better for heavy cars (my car is HEAVY!). Did you read the article on Richard Lasseter's car where Holley dyno tested three different carbs (870 Avenger, 950 HP, and 1000)? Any others have any feedback?
I have similiar setup and use 850 dp . On dyno 750 to 1050 are within 10hp of each other so go with what you can afford .
I've ruled out the Avenger, so it's between the 850 and 950. The 850 is plenty for what if I have now, but if I ever want to do some porting, then the more expensive 950 may pay off later.
I slapped on a 950 HP Series holley to replace my stock QJ and instantly picked up 8 tenths (went from 13.60's to 12.80's) My combo loves the Holley. Mine has mechanical secondaries, I like knowing all the blades are open when I stand on it :grin:
Now that is a great testimonial, Del. I can't wait to see the difference. Is your car a street car also? If so, how's the drivability with the 950 HP? Thanks!
Driveability is excellent, but theres no gas mileage improvement :grin: My car is a street/strip car. Its got mild ported heads, TA-310 cam, TA roller rockers, stock bottom end, SP-1 intake, and MSD Ignition. The car ran fine with the Q-Jet too, but it obviously needed something that the Holley delivered. I bought the carb new, and didn't jet it or anything, just bolted it on. A higher stall converter and better tires has put it into the 12.0's.
James i have 850 q-jet i sent it to JW he put it on the dyno on a level 1 motor the motor had a holley 950 on it then he put my carb on it made 4hp less. He said if he did'nt have to put a adapter plate on it might have done better.Just thought you would like to know.
Nya, nya...my car's heavier! I had great luck on my '67 Electra and '67 Wildcat. Still had a bit of off-idle bog when I mashed it until I went to 50cc accelerator pumps on front & back with a little cam/squirter tuning. Also I didn't have much more converter stall than what you've described, and the Electra was suffering from a 2.78:1 rear end! Sorry, can't say I've read Rich's article...sounds interesting. I love the mechanical secondaries, especially the Barry Grant Silver Claw (pre-Demon) I'm running now. Devon
When I switched from a 750 vac. sec. 3310 holley to my 950hp, my qtr. mile time went from 13.07 to 12.40 et. Best money for performance I've ever spent hands down. Looks like both our motors are somewhat similar. If you get the 950HP you won't be dissappointed. John.
Sounds like the 950 HP is my choice. Thanks for all the feedback, guys. If anyone is interested in the article Holley published about the dyno testing (of the three different carbs on RL's car), I have attached a link to it here . Make sure you click thru the "Slide Show" for all the results, pics, and dyno graphs. Enjoy!! Thanks again to everyone for the help!
