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CarburetorsCarb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
After following the Holley tuning sticky last summer the car runs great on the primaries. Very efficient for a Holley! I have left well enough alone until today. Today I finally got around to wanting to fine tune the secondary jetting because at cruising speeds, when I stomp on it, it smells a little rich when the secondaries open. I wanted to jet it down two sizes and retest.
Thing is, when I take the bowl off it has a metering plate with no jets visable. Am I correct in thinking this style cannot be adjusted? It is calibrated from the Holley factory?
Next question is can it be converted to secondary jets?
Car is getting great fuel mileage. Around 25mpg if im easy with it, but Im thinking I can do even better leaning out the secondaries and might make more power in upper rpms too.
Sorry if these are dumb questions, Im learning.
EDIT: Should have mentioned carb is a 4160 600cfm VS
no problem. i'm running the same carb probably. i've got a 3310-4160. runs great for me. i added the 50cc accelerator pump and the QFT adjustable secondaries. never hiccups or stops pulling. been running 100 shot with it too.
different metering plate looks expensive (25-35$) when its a shot in the dark. I know when I was jetting the primaries, I had to buy 5 different jets smaller going through the tuning phase. I may look into the conversion idea though if its possible.
Ive never had it apart. Whatever came new in there. Seems like I read a while back about changing that spring, but when I looked at it I didnt see how to get at it.
It sounds like you might want to try the next lighter one. The yellow one or the green one. If you go too light, the sec will open too soon and it will bog.
It sounds like you might want to try the next lighter one. The yellow one or the green one. If you go too light, the sec will open too soon and it will bog.
Just to clarify, we are talking about where I have my finger pointed right? Also, there are four phillips head screws on top, but only three are accessible is why I said I remembered not seeing how to get to it...
Also, thinking of doing something like this to keep from having to pop that spring out multiple times. From what Im reading that diaphram will succumb to noobies like myself if it takes me more than a couple of tries...
Also, thinking of doing something like this to keep from having to pop that spring out multiple times. From what Im reading that diaphram will succumb to noobies like myself if it takes me more than a couple of tries...
that's a good price too IMO. i've changed springs many times but tried one of these adjustable vacuum secondaries years ago, and really like it. not too much to it, but it makes tuning very simple and quick. no problems with it.
that's a good price too IMO. i've changed springs many times but tried one of these adjustable vacuum secondaries years ago, and really like it. not too much to it, but it makes tuning very simple and quick. no problems with it.
I went ahead and ordered the adjustable one in the link above yesterday. I'm hoping to only pull it off once, and this looked like the best way to go about achieving that.
Sofa ruined me last summer in his sticky having me take the carb completely off like 3 or 4 times trying to get the transfer slots just right. Took me a whole year to want to mess with the secondaries..lol But guess what...It ran like a champ afterwards and still does. I will be kicking my self in the culo if this messes that up!
By the way, the carb is the newer all aluminum 80457SA
My 600 had a black spring from the factory. If that's the case with yours, it could be that the secondaries have never fully opened. I swapped from black (heaviest) to short yellow (next to lightest).
So I ordered the adjustable secondary from Holley (QFT) and it looks to be a quality piece. I also went ahead and took off the old one and popped it open and it had a silver spring in it. Thats a mediocre spring on their chart so it should have been opening anyways. Further reading about it however reveals it should have a checkball with a slot in the ball seat. Mine does not, it has a brass plug with a hole in it...weird
Oh well, Installing the new adjustable one now and will update on the ease of use and outcome.
Results are in. The new adjustable housing comes with a "purple spring" and couldnt be more accurate for my application. No adjustments were necessary, though adjusting it is a simple turn of a flat head screw to make the secondaries open faster or slower. Secondaries are now kicking in at about 3/4 pedal and the car just pulls hard after that with no ill exhaust smells. I'm guessing they never fully opened before because there is a HUGE difference now. I may test it by 1/4 mile speeds, but I dont think its necessary. Its running superb.
Thank you for your help guys!
I finally tried something I had previously only read about earlier today. I swapped in a lighter spring in the dizzy.....and WOW was I surprised what it did to the curve! Seat of the pants KIIIICK! Where has this little spring been, and why am I just now learning all of this?...lol
That said, after months I can let go—sometimes!