nunus79

Is it time to step away from the Qjet and move on to a Holley? I got some baseline track runs in this weekend and experienced a drop of 0.4 sec & 4 mph since switching to the Weiand #7525 Team G single plane. I think the carb is running lean. I have a couple of richer metering rod sets to try and a richer hangar, all from Edelbrock’s limited selection. But here is the kicker, in Sundays paper Checker Auto Parts has a 10% off coupon for popular performance parts like CARBURETORS. Do you guys think I have a chance fooling with the Q-jet with such limited parts to get it close to right? Or should I just move on to a Holley with its more accessible selection of tuning parts?

Alwyn678

I like mine...a Holley750dp.......Man when it kicks in .......Better hang on

tsw71

Norris, The Qjets are damn good carbs, BUT I'll take a Holley over one everytime. It's probably more of a personal prefference than anything else. For your engine, I would go with a 650. Single planes do not respond well to over-carbing and 650 will be just about perfect. A 750 would feel good up top, but would probably cost you some low end torque.

Tom :cheers:

GWHITE75

If all you did was exchange manifolds, then you found a drop in the lower rpm torque range, causing the slower times, but the manifold will allow more air/fuel flow at higher rpm ranges than your old intake did, where it could be lacking in proper mixture. You might look at several items before discarding the rochester - distributor curve, plugs, timing advance and a richer mixture for the existing carb (ask Lars). I run holleys and have for some years now, but the rochester can work and it is pretty good for gas mileage, if you care.

The Dude

Q-Jets are wonderful and elegant carbs that work well on the street and that can be made top-notch performance carbs. That having been said I'm personally finding that the more I learn about and tinker with Holleys the more I like them. (More modular design with easier access to things, seemingly simpler construction, etc.)

Maybe it would be worth your while to get ahold of an old Holley of some type--a core, basically--and a good Holley book and spend some time diddling around with it. Even if you stay with the Q-Jet at least you've racked up some experience, right?


[Modified by The Dude, 3:17 PM 1/14/2002]

nunus79

Thanks for the insight guys.

The thing with the Qjet is that I see the end of the "tuning" tunnel as far available jets, hangars & rods go. The Holley opens up way more tuning opportunities. I secretly wanted to be like Nastee383 and be able to say I can run respectable times with the Qjet. ;) But unless someone knows where to easily get jets & rods for Q-jets, I'm seriously thinking of giving up.

Gwhite75,
My problems could very well be from misadjustments or from a poor intake choice. I cannot say for sure at this point. But my gut feeling is lean carb.

nunus79

I like your perspective :cool: :cheers:

mountainmotor

You are on the right track now! :)What fuel pump are you using? Next item would be to dump the quick bleed lifters :U
You did'nt by chance change the weight of your motor oil between this and the last trip to the track did you?That can effect the way those lifters operate.Check the Crane? site .They talk about not using them unless you are definatley over cammed which you are not.Can make for some detonation.

With your enthusiasum you will be in the 12's soon. :cool:

nunus79

Mountain
I'm using the Holley mechanical fuel pump 12-834??

I've tested the different weight oils effect on the Rhoads lifters and they respond for sure. I got a .1sec & 1 mph increase once, just by changing to a heavier oil at the track. This is what I was thinking, to compliment the effects of the lifters, I just installed 1.6 rockers on all valves. That way I should have regained most of the lift I lost at low to mid rpms and added lift to the top end. So much for my theories. LOL

The reason why I went with the Rhoads lifters with mild cam was to help build compression when I was running stock low-compression heads. All that has changed now, but I thought I'd test out my theory since I still got them in.

Tsw71 & you have me convinced that I need a new cam :lol: I'll tackle that one after I figure out the carburation.

mountainmotor

Quote:
"This is what I was thinking, to compliment the effects of the lifters, I just installed 1.6 rockers on all valves. That way I should have regained most of the lift I lost at low to mid rpms and added lift to the top end. So much for my theories. LOL"
Nope!
:nono:
Think along the lines of a Holley list # 4779 only :)


[Modified by mountainmotor, 4:03 PM 1/14/2002]

The Dude

Two words for you:

BONE
YARD

Just spend some time in the Chevy and BOP sections of the local recycling place. And don't overlook he trucks, either. Lots of different hangers, secondary rods, fuel line fittings, choke assemblies, etc., for just a few bucks each. You may even get lucky and find a couple or three good rebuildable cores, too. Q-Jets go for about $15 each from one wrecking yard I know of around here. Small parts? Sometimes they'll let you have them for free but don't try to walk out with them without showing them to the cashier first. That's sort of not too cool...

Les

I agree w/ everything that Tom said. If you can get a good deal on the Holley & for some reason you don't like it, which I doubt, you can always either keep it for future use or sell it for a small loss at worst.

1979toy

You can find guys that can tune either carb. Lets see, we know a guy in Denver that can tune a Quadrajet, and any performance shop can tune a Holley. Tune by mail or at home?
I'm currently installing an air/fuel mixture gage to watch my tuning progress. You might want to think about doing the same.
Does Maurice know about these plans? He might want to keep the fastest C3 on the island.

QuickVet

is that 4 tenths loss from your best or you average. you have to consider that if you are compairing from your best that is not very accuate. you need to compare from the average of your previous trips to the track and if you only made one trip that wont be a good enough thing to go by. you have to consider the weather and temp of the time you last went as well.

i would try a holley. get a 700-750 double pumper with machanical sec. :yesnod:

mountainmotor

1979toy,
The problem he is having can only be fixed by using a squarebore carb.It is an open plenum manifold that does not lend itself to the quadrajet as it promotes unequal distribution to the forward cylinders caused by the spreadbore design.Also because of the unequal lenths of the runners of the manifold a squarebore along with stagger jetting will provide optimum results.With the converter and gears he has along with the fact that he will soon change cams the 4779 Holley DP is the best choice.It can be tuned to provide great performance with his automatic.
One thing though.
Slicks are in the future

nunus79

I was just offered a 4160 Holley #80508 750 cfm vac secondary carb to try out by none other than Maurice. I guess he wants me to run better so that he can kick my butt again. :jester

I know squat about Holleys, so I guess this is my opportunity to learn some. I'm going to need all of your support & advice as I go thru this learning. I feel very fortunate & confident already from all of your response. Thank you everybody!

Oh and for the record, Cappy, or should I say "no-show" Cappy is the one with the fastest ET. :jester And 13.95-14.00 @98.7-99.3mph was the range of times I got on my last 2 track nights.