Hey guys, trying to figure out what carb to go with on my street/strip 89 Iroc.

Motor will be:

L98 shortblock, LT4 hot cam, dual plane intake, Vortec heads, 10:1 compression, 2800 stall.

I would like an electric choke and am on a budget. Ideas or suggestions? I am thinking a 650 cfm carb would probably be perfect but have noticed a few of the budget carbs are either 600 cfm or 750, and I am guessing a 750 would be a bit much.

Thanks in advance!

 

I'm a big fan of Q-jets; once you get them dialed/tuned that is.

A Q-jet will offer all the CFM you're realistically ever going to need but will act like a small carb when you want it to.

 

If you street drive it regularly it's hard to beat a vacuum secondary carb. The two best are a PROPERLY TUNED QJet and a Holley 3310 (or one of the "tuner" carbs based on the 3310 design). They're both 750 CFM but the vacuum secondary design means it's basically impossible to over-carburate. You could put them on a stock 305 or a seriously built 454 and get great performance on both.

If you're more into racing and don't care about street manners, a double pumper is what you want. Something in the 650-750 CFM range would be fine, with proper sizing more important and application-specific. When in doubt, go a little smaller than what you think you need on a double pumper.

 

Thanks for the advice, so isn't the new summit carb based on a 3310?

http://www.summitracing.com/parts/SUM-M08750VS/

I was looking at the 750 Vacuum secondary Summit carb.


Also, I was looking at the new Quick Fuel Slayer series 750 cfm vacuum secondary:

http://www.summitracing.com/parts/QFT-SL-750-VS/

What are your thoughts on these two carbs specifically? I am leaning towards the Summit carb as it is about $50 cheaper and comes with the fuel bar.

Thanks!

 

A vacuum secondary carb isn't ideal. It has no benefits on the street, and will most likely be slower on the strip. A 650 double pumper would be about right, but a 750 wouldn't be too much.

Need more specifics on the intake manifold. "Dual plane" doesn't tell us much. Something along the lines of a Performer RPM would work well with the cam and the stall you're talking about using.

 

I am going to run either or a performer or performer RPM, I would prefer the RPM but one of my goals with this car is to retain the stock hood. My last car I had a lot of hood clearance issues when I put a carb in.

 

One other thing, I want a choke but don't want a manual choke, I don't see any mechanical secondary carbs that still have an electric choke. Thoughts?

 

A Holley will fit under a stock hood on a Performer RPM if you used a dropped-base air cleaner.

You can get an electric choke kit to convert a double pumper from manual to electric choke.

 

What is the downside of a vacuum secondary carb? I have never owned one, my last few motors have had a 650 Speed Demon and a 750 Speed Demon.

 

By their nature they can not open the secondaries instantly since they lack an accelerator pump on the secondary side. They supply airflow only based on engine demand (which is why it's basically impossible to over-carburate with one). In drag racing, with a properly matched combo, you want everything RIGHT NOW or it's too late. That's where a double pumper works best.

On the street where you're likely to be leaning into it in too high a gear and other oddball circumstances from time to time a vacuum secondary is more forgiving of those kinds of shenanigans without exhibiting bad behavior.

 

With 2800 stall behind a 350, you'd need a 1050 double pumper before you'd bog because of too much carb.

A 650 DP would be the best choice, but a 750 DP isn't too much.