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I am restoring a 68 427 L36 4 Speed car. At some point someone must have replaced the carb. The one on it is 07029207 and based on my research it's for a small block engine. Suggestions for a replacement or other options
since I'm not spending the huge $$$ people are asking for the correct one. THANKS
Ok What mods are needed and is there a way to tell if it has already been modified ? THX
The member that replied (lars) is known as THE carb guru here. If you do not feel capable of tackling it yourself you may want to pm him. He rebuilds them and can set it up how you like. Many here have lars built/rebuilt/tuned carbs.
From: At my Bar drinking and wrenching in Lafayette Colorado
Originally Posted by Ky68Vette
Ok What mods are needed and is there a way to tell if it has already been modified ? THX
Highly unlikely that it has been modified (correctly) to mimic the big block carb specs. You can just measure the idle air bypass holes in the throttle plate to verify.
The differences between the small block and the big block carbs, and the mods that are done to turn a small block carb into a big block carb, are as follows:
.
Different primary jets
Different primary rods
Different secondary rods
IFRs changed from .035 to .039
DCRs changed from .052 to .055
Upper and lower IABs changed to 427 spec
Idle air bypass passages in throttle plate changed from .073 to .120
Additionally, the 1968 427 Vette carb is the only Chevy Q-Jet that has a reverse-rotation choke system. It uses a unique choke coil to operate the choke lever "backwards" using a "duck bill" choke counterweight. If your car has the original 1968 choke coil, you have to change it to a 1969-type coil to make a non-'68 Vette carb choke operate correctly.
1968 427 Vette choke system:
1969 small block carb system:
If the carb is running fine in its current condition, leave it alone and run it. It should run pretty good just set up to its stock small block hi perf specs.
Lars
Thanks....... Unfortunately the car is at the paint shop and every engine Picture I have just shows the Drivers side of the carb. It appeared to run ok but honestly after restoring the engine area I haven't driven it much cause it went to paint.
Have you considered putting the carburetor in a nice little box on your garage shelf? I have a 1968 427-4 speed Convertible and I switched my carburetor to a Holley EFI system and have been very happy with the way the car works after getting the EFI system setup.
My 1968 is still very original except it did not have the 3 deuces on it like it was made with. This engine works very well with the EFI system and it will start easier and even run in cold weather if you want it to.
I am using a Holley Stealthy Sniper EFI system that I purchased from EFISYSTEMPRO. They provide 24 months of support after the sale to get you through the setup stage. For me this was a lifesaver as I had lots of questions that were promptly answered by the staff. There is nothing done that is "permanent" so you can simply go back to your carburetor if you choose to.
The Holley STEALTH Sniper system looks very much like a carburetor and fits on the engine very nicely centered in the original carburetor location. My entire system was less than $1700 and it works great.
I have a collection of carburetors all missing their choke towers so they can flow lots of air. My biggest problems was cold starting my 12.5-1 compression 427 without using Ether and damaging the rings with its use. The cold starting function works like a charm and is very easy to adjust and set.
IF you want to stay with your carburetor then I too would send it to Lars. He is "The Man" when it comes to carburetors! That way you will have the right carburetor that works like it is supposed to for your 427.
Need Carb Suggestions
