Hello all, I have a 305 bored .40 over in my 89 RS. It turns out good and runs good but I want it to run a little better. It has a Edelbrock Manual Choke 600CFM Cabr on it and I have a Edelbrock Electric Choke 750CFM sitting in the garage that is practically new. Which am I better off with?

My engine is a 305 bored .40 over with Vortec heads, Aluminum Edelbrock Performer intake, mild cam, double roller timing chain, and new lifters. Just laying that out for a better outlook. Thanks!

P.S. If I dont respond very quick it's because of computer issues

 

I'd say the 600. A 750 sounds like too much carb for a 310, tho a 650 would work well.

 

I have run both sized vacuum secondary carbs on my super mild 305 with stock TBI heads, Edelbrock EPS intake and mild GMPP ramjet camshaft. I feel no difference at all in idle quality or performance running the 600 vs 750 vac sec carb. I strictly bought the 750 looking ahead to when I put together a 350 or 383 for this thing in a few years like most people do. I have observed people tend to put a little money into the 305 first then end up yanking it for a larger OR more capable motor. So on that alone I am glad I chose the 750 looking to the future FWIW. I don't think you will see much of a performance gain at all going to the 750 from the 600 on the 305.

 

Alright, one last thing I need to know, which would be better as far as choke wise? The electric of manual? Also, I saw one of these cool cold air intakes for domestic carbureted V8's on Summit and was wondering if that has any advantage?

Cold Air intake:
http://www.summitracing.com/parts/spe-751k

Gonna post a photo I found of the Cold air intake as well for a better reference.

Thanks for the replies and help!

 

Choke I would go electric just so you dont have to remember to pull of the manual one.....

Cold air intake - that picture isn't a true cold air kit - its pulling warm engine compartment air in anyway...to be truly cold it would have to be pulling air from the outside perimeter of the engine compartment with a separator plate or in the direct force of air coming from the outside/ front of the car.

An old DRAG race formula is for every 10 degrees of intake charge temperature dropped - you get a 1% hp gain .......so on a 200hp motor if you manage to pull in 30 degree colder air you are only at BEST going to gain 6hp. 6hp in the quarter mile is only .06 better E.T. at ABSOLUTE best ...so really with a low HP motor the gains are not really worth all that effort or cost .

BUT

On my old 462 Buick the neatest thing I noticed in my own fashioned single headlight RAMAIR setup was that I dropped engine coolant temps a solid - repeatable 10-12 degrees going down the road at cruise. At idle it dropped nothing temp wise. So it can definitely drop engine cruise temps if done right and help you there from that aspect.

 

The formula is 1% power increase for every 7*F inlet temp drop. Other than that minor nit, what soothie said.

 

Choke wise, I run a holley 600 vac sec with manual, and honestly just leave it open 100% of the time. If I want to close it is have to pop the hood.. my last carb didn't even have a choke flap. Ran and drove just fine. Cold starts CAN suck..lol pump twice and crank, if no start then floor it and crank. Hold pedal down a little till things start flowin, and carry on as usual.

 

Use the 600. 750 is too much.
If you end up with another carb, use a 650 holley 4160 electric choke.

 

A stock 305 CCC Q-jet is 750 cfm......................

800 cfm on some stock 454 and 455s.............................

 

its NOT a cold air intake if it gets the air from right above the headers. and certainly not worth 150 either. cold air might be worth it if its got a box for the filter and an outside source for the air.


as far as the choke depends what you want to mess with. i dont like electric chokes because they tend to stay on longer than you need them and make it run bad if you want to race it, i only use the choke for a couple seconds when its cold. most of the time in the summer you dont even need it, and i live in a pretty cold area

 

A stock Q jet is also spread bore makes a big difference.

 

I thought the stock q jets were like 580 cfm or 600 cfm

 

Most sources quote a STOCK third gen 305 CCC carb is 750 cfm.

I have seen other sources quoting a L-69 CCC q-jet as a 650 cfm
unit but others here say that info is incorrect.

 

I may have my hands on a 600 electric choke my problem however is that the car was originally a Fuel injected v6. How would I go about hooking up the choke if it's electric? Any old positive wire OR is there a specific wire I should use?

Sorry for the delay my car about had a catastrophic wire fire due to the negligence of the previous owner.

I am gonna save my 750 CFM for the 400 I am gonna build this winter.

Thanks for the suggestion though!!!

 

Use a 550 or 600 cfm carb. You don't need anything higher. EVERYBODY overfeeds their cars!!!

 

bigger is not always better. this rule applys to; carbs,women power bills,tickets,ect.ect!

 

Anything that's hot only in the RUN position of the key. It draws very little juice (about 1A or so). On old cars that had hot air chokes (no choke heater power wire exists), I tap into one of the wires on the wiper motor that happens to be hot only in the run position. No need to drill holes through the firewall to get to the fuse block.

 

The difference in temperature is more like 80 - 100 degrees. Ambient on a warm day, say 75 degrees. Underhood temps, what does your thermostat run at? 180? 195? That's a good indicator of the underhood temp. Add the exhaust manifolds into that...
It's easy to see from that alone that the benefit of a cold air system is worth the trouble and expense. That the OEMs now go out of their way to build cold air intakes on their new vehicles is also telling.

 

Yeah a 750 is way too big for your 350. 550-600cfm is right on the money.

Any key switched 12 volt wire for the elec. choke. The wiper wire is a good one to use