Hey guys,

What carb would you reccomend to match my current set up?

Originally the GMPP 290hp 350.

• Dart SHP heads - 180cc intake, 64cc chamber 2.02/1.60 valves
• 1.5 full roller rockers
• Fel-Pro 1094 .015" head gaskets
• Stock L82 camshaft - .450/.460 lift 222/222 duration 114 LSA
• Performer RPM intake
• Stock bottom end
• TH350 Trans
• 3.55:1 Axle Ratio

I have the stock Q-Jet. Can I make that work with this set up somehow?

 

This is from GM as a starting point.
"Carburetor / Air Cleaner: A 670 cfm Holley four-barrel carburetor with either mechanical or vacuum operated secondaries and electric choke is recommended
for the 350/290 HP engine. Chevrolet Performance has a 670 cfm Holley four-barrel carburetor P/N 19170092 with vacuum
secondaries available."

Other parts are similar to the stock GM Crate (cam). Head specs are 64cc vs 76cc(gm) you have bigger vales but we are talking 10th's of inches.

The stock Quadrajet is around 750 CFM. (good choice to start with. You may need a adapter plate for your intake and possible hood clearence issues)

So for CFM anything in the 670-750 range. What I like to see in a carb is how easily I can make adjustments to AFR. Tunning is where you will get the best running engine.

Also from the GM Install manual. consider a torque converter change.

"When using the 350/290 HP engine as a replacement for
an original equipment engine, the performance intent of this engine should be considered. The torque curve is higher and
consequently may require a torque converter with a higher stall speed on automatic transmission equipped vehicles. Consult
with a reputable torque converter manufacturer for assistance in selecting the correct torque converter for your application"

 

The Holley 3310 is super versatile, but is a 750cfm...
I had a mild (300=325 HP motor for years in a '67 camaro. I ran a Holley 4777 (650 Double pumper), and absolutely loved it...I had a TH400 trans with a 2500 stall converter at the time. Ran it as my daily driver for years ('94-2001)...

unless you are spending a lot of time racing, keeping it in the upper RPM band, a 650 will suit you just fine.

 

Your Q-jet is more than adequate for your set up. Q-jet is up to 750 CFM, it will handle less just as well.
Is your performer RPM intake a spread bore manifold like the 7104? If not then an adapter would be needed. As cargotzman mentioned then you may run into fitment issues under the hood. Which ever way you go you'll have to be concerned with space under the hood.

 

As recommended by General Motors, the Holley 670 is by far the best choice for your setup.

For your engine, the Street Avenger series with electric choke, and vacuum secondaries is perfect.

https://www.holley.com/products/fuel.../parts/0-80670

You will find this carb very easy to tune with instructions readily available. Parts and accessories are plentiful and the carb is virtually bulletproof. It will last for years on the street or strip.

You can go with more, and probably even less. I run this carb on a more than mildly modified 383 with no issues at all.

If fact, I just increased my squirters to the next larger size and have realized an even greater performance boost off idle.

GM recommends Holley, and in the past installed Holley as standard equipment. It was good than, and better now.

 

Thanks for the input guys.

I ordered the 7104 performer RPM intake.

I'll see how it goes with the stock Q-Jet for now.

I can always look at switching to a holley later if the q-jet doesn't work out.

I will probably need to get a drop base air cleaner to get it to fit.

 

I run a Performer intake with q-jet and stock air cleaner on mine without any clearance issues. Two words on Q-Jets. "Lars Grimsrud"... This man does magic on Q-jets. He's a nice guy too.

 

That spreadbore intake you bought is really qjet only imo.

im a huge fan of holley but havent had good luck with the 4165/4175 that are spreadbore. ymmv.

You absolutely do not want to use adapter plates to go to squarebore.. Theyre terrible. Again... my opinion...

I agree 1000% with commander on his carb recommendations on this post and others ive seen. If it were me, I would go squarebore rpm and holley 4150 ultra street avenger 670. Its what I just did. in the mail now!

 

I have run this exact intake manifold with a Q-jet and run 11s in a full weight C3 with a 406 that I built.

 

The qjet will compliment this setup when properly jetted and adjusted. The cam is not too much for the stock converter; especially with the 3.54 gears. Stock converter in the C3 has plenty of stall. If you added much more cam, then I'd consider it. That 114 LSA will keep it very civilized; it will give up some bottom end power for higher rpm performance. I ran the Crane Energizer 272-H10 grind and it was a lot snappier, shorter duration, 110 LSA but had .454/.454 lift. Great cam!

If you haven't, get an adjustable vacuum can for the distributor and dial your timing (base/advance) in for performance. You get a cheap 40-50hp for $50 in parts. It will allow you to realize all of the benefit of your combo.

 

That manifold is q-junk only without an adaptor plate.

You will be limiting yourself in Carb choices unless you use a square bore. Square bore is much better.

 

Thanks for all the replies guys.

I know Lars has a few Q-Jet papers out. I'll look into those and see how I can go about tuning the stock carb for this combo.

Also, I do already have the 7101 Square bore Performer RPM. It's bolted to my Camaro with a holley carb. The 350 in the Camaro is pretty much stock, so I can swap that intake out if need be to run a Holley on my vette later.

 

I have almost your same setup (290 hp crate engine) but mine has Edelbrock heads and 1.6 roller rocker arms. I am running an Edelbrock 650 cfm Thunder AVS. This will match up with your Performer intake. Mine has great response.

 

I've run this exact manifold with both a QJet and a 4150 Holley - on a 383 and a 406 - and it works very well either way. Other suggestions to the contrary are not accurate, based on my experience.

 

Great, thanks for the info.

 

I would stick with the Qjet if in decent shape and send it to LARS for tuning. I have had a spreadbore Holley 4175 Q jet replacement 650 CFM since 1985 and it has been rock solid and perfect for all these years on the OEM L-82 and now on the L-82 355, AFR 180 heads, Roller cam, 10.2:1 compression...superb carb...Highly recommend the spreadbore Holley 4175 650 CFM vacuum secondary Qjet replacement carb.