Morning goons and goobettes.
Off to pull a 12er.
Anyone happen to have an original 427 Quadra jet for 68 vette laying around ?
This man is the absolute guru of carbs and i was thrilled for his detailed response to my email.
Lars said:
Hi Candie -
Good hearing from you.
I can't comment on EFI, as I've never played with the aftermarket units and have no experience with them. PerTronix, on the other hand, I can tell you is complete junk and nonsense. Horrible, unreliable stuff that serves no viable purpose at all. Keep your stock distributor with a good set of points correctly set up. Let me know if you need part numbers and specs. Don't let any mechanic talk you into doing the PerTronix swap - they are guys who don't understand points and are looking for the easy way out - they are generally idiots.
On the carb, here's the deal: The '68 427 Vette carb is a unique carb to that year and engine only. Junk cores are selling for near $1K, and good carbs are selling for $2K - $4K. Most of them are fakes. I've had customers find salvageable, original carbs for under $500. The key is to keep looking and try to find something that can be used. That car is worth the most with the correct carb on it. Do not consider the junk Edelbrock stuff - especially that horrible AVS carb. Those carbs are too small, and they will not bolt up to your spreadbore intake without an adapter, which will kill all performance in your car. I would set out on a quest to find a buildable, correct core. Some information attached that you may find useful.
The big block carbs are unique in that they have completely different air and fuel bleeds than the small block carbs. This allows the carb to idle with a small throttle opening to keep the idle circuit responsive and adjustable. If you are not concerned about the carb being "exactly correct," you can use any 1968 - 1974 big block Q-Jet. This will keep the engine looking "vintage correct" and you can hook up your choke and make it work by using the 1969 427 choke coil. Carbs in this year range all have the divorced choke system, and will interface with your intake manifold. You don't need a "Vette" carb: you can use any 427 or 454 passenger car carb (Impala, Chevelle, Camaro, Monte Carlo) and it will have the big air bleeds in it for minimal hassle in tuning and setup.
You can use a small block carb, but it will need significant "recalibration" in order to operate correctly on the 427. This will involve opening up bleed passages and fabricating custom air bleeds. The 1969-1970 Chevy Q-jets are visually almost identical to the '68. You have to know what you're looking for to tell the difference.
Should you want to use an electric choke, which would not be "vintage correct" for your car, you can use a 1976 - 1979 Chevy Q-Jet. This will require significant modification, and you may have issues with throttle linkage and fitment. But it can be done.
Do not buy a commercially built carb or any carb that is "pretty."
Tag me back if I can provide other info. Not sure what to provide for you since I don't know exactly what you need or where you're wanting to go with the car.
You have one more very economical option: There are 2 Q-Jet part numbers for the late 1970's Chevy heavy duty trucks. The HD trucks used the old-style divorced choke systems, and they mimic the 1968/1969 air bleed configurations, making them perfect substitute carbs for a vintage 427 or 454 big block. The choke pulloff systems are visually a little different from the '68, and the throttle levers are different from the original carbs, but they can be set up to run well. Good cores typically sell for about $50-75. The part numbers to look for are 17057213 and 17058213. There are a lot of them out there, and many are plain junk. But if you keep looking, you'll find a nice rebuildable one that can be used.
Lars