I'm freshening a 396/375 horse for a friend of mine. It has 11.1 compression, rectangle port heads & intake. The original Holley carb disappeared many years ago. What size shoud I go with on this thing? I'm sure this engine will spin to 6000-6200 rpm's. Is a 750 or 780 too big? what about a 650? This will go in a 4 speed car so I'd stick with a square bore, vacuume secondary. Would a Mechanical secondary carb make the car bog if you stick your foot in it while the revs are too low?

 

The 750-780 Vac secondary is similar to stock. It is hard to overcarburate when using a vac secondary.

The car will be more responsive with a 4 speed (especially if it has some gear eg. 3.73 - 4.10) with a mechanical secondary carb. It will bog if the carb is to big or the rpm is too low. If using a dual plane intake the carb size is more forgiving as well. I've had good results with a 750 & 800 DP on mine w/ a dual plane intake & 4.10 gears.

Hope tihs helps.

 

Thanks for the advice, Lonnie. For ease of driveability, I'll probably have him stick with the vac. sec. carb. I feel much better about ordering the 750 now that I know that over carbing is not too much of a concern.

Thanks again!!!

Matt

 

I ran a mechanical secondary on a 396 Nova with an M20 & 3.31s. It was boggy if I wasn't careful about rpms/gear selection. Carb was on car when I bought it, replaced w/780 vacuum secondary, and I was much happier. I run a 780 on my 71 now with a 400 sbc/auto/3.42s and it runs like a champ. Just get a secondary spring kit to tune for earliest opening that is driveable, and convert secondary to metering block if you want to tune it.

 

Thank you for the info, Angel. I appreciate the driveability experiance!

I think that the 750 VS carb will be what we go with.

However, here is the next dilemma. From what I can see, Holley only offers the 750 VS carb with an electric choke in the shiny finish. They offer it with a mechanical choke in the classic finish. How do I get the classic Holley olive green colored carb with an Electric Choke????

Matt

 

If I'm not mistaken, you can buy the electric choke conversion kit.
Also, you should double check... I think the electric choke IS available on the old style finish.

BTW, don't be so quick to turn up your nose at a manual choke.

They're actually kind of nice and not particularly difficult to use. They're also more "period correct", and they work quite well.

 

I was looking throughthe summit catalog and didn't see a listing for the classic finish with the ele. choke. I'll have to call Holley and check. The guy at Summit wasn't sure.

The car is already wired for an ele. choke so for ease of use, I'll try to stay with that. I know that manual chokes are pretty easy to use.

As a side note, I am dissapointed with the Edelbrock carb that was on the car. Anybody else have feedback on Edelbrock carbs? Anytime you have to make a quick stop, or sharp turn, the car will sputter, and most of the time it kill.

The tunability of the Edelbrock was extremely easy, but it is not without it's faults.

Matt

 

Sounds like float level is off. One of the reasons I prefer Holleys is the ability to adjust the floats externally, or pull inlet needles right out the top for cleaning if trash ends up in the seat.