Need opinions/suggestions on intake/Carb selection

[highspeeddirt]

Here's what I have.. I don't know all the exact details on the engine in my car.  Just it was a fresh build when I got it.  It is a 360 with J heads. Torker II 340 intake and Holley 750 Carb. And headers.  It has a comp cams part# 20-223-3. Which cam card shows intake lift .477 exhaust lift .480, duration, intake 268 degrees,  exhaust 280 degrees.
I know the rpm range of the cam is 1600-5800 and the torker II is 2500-6000..
I'm just going to be using my car for street cruising and a little playing around.  Won't be taking it to the strip or anything.  My question is, How much difference would It make to change to a dual plane intake like a performer and maybe a 600cfm.  I really think this 750cfm may be too much.  I haven't done any tuning to the Carb,  but right now its running EXTREMELY rich. Can't hardly be around the car running cause it chokes you out.

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[Chryco Psycho]

I will bet the long duration cam is making it run rich @ idle so the cam swap would be a better investment .
 The RPM is a good intake , personally I WOULD USE THE AIR GAP  version if it is driven in good weather only but I doubt it will make a lot of difference for the $ spent .
 The 750 is not too big , the factory used a 800 CFM thermoquad on the 360 , you should be able to clean up the idle somewhat with some tuning , check your float levels & make sure you have enough vacuum to keep the power valve closed or swap it to a lower rating so it will stay closed at idle in gear

[cudabob496]

ya, before I'd start swapping parts, make sure everything is in proper tune, including the carb.
It might run great, but perhaps the carb jets are too big, or a float problem, etc.

[highspeeddirt]

Thanks,  I'll do some tuning on it.  Just didn't know if there would be much of a noticeable difference in the intakes.

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[highspeeddirt]

I'm going get the timing set right and work on tuning the Carb this afternoon,  any good suggestions on what jets are a good starting point for my combination?  I don't know what's in it now,  but would like a base line number in case they are way off when I open it up.

Thanks

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[Chryco Psycho]

Look at my tuning article in the archives
Jetting is one of the last changes & most carbs are set very close from the factory , it is far more important to check vacuum & make sure the power valve is staying closed at idle in gear if automatic , if your vacuum drops to say 5" at idle in gear you need a 3" powervalve so it will stay closed , if it is not staying closed the plugs will blacken & the idle will be very rich

[highspeeddirt]

Yeah I've been reading up on your tuning tips and am definitely going to take those steps.  My only concern,  is I know nothing about the Carb like if some has it majorly jetted up already.  And parts stores around here don't readily stock many "performance" parts

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[Chryco Psycho]

Not sure what 750 you have but I would expect to be in the 68-72 range for primary jetting , 78 or so rear , you can go to the Hollet site & look up factory jetting for the carb you have using the list # on the carb

[highspeeddirt]

Well,  I checked vacuum at idle in gear and had 7.5-8 inches.  Pulled the Carb apart and had a 7.5 power valve.  And 72 jets.  Holley site showed it came with 70. Being performance parts are hard to get around here unless you go to a performance specialty shop only open on week days.... Only thing I could find in the right direction I needed was a 5.0 power valve and they had one set of jets.  They were 68. I changed the power valve and still was bad rich, so I put in the 68's.  Its a ton better.  I could actually stand to let it idle in the shop. Also its a lot more responsive. Still seems rich but new plugs were starting to turn  brown.  Didn't get to drive it so still need to see for sure. I don't have headlights in in yet and got dark to quick with the time change.

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[Chryco Psycho]

AWESOME , the powervalve can be a problem & was in your case , glad you improved it that easily 

[highspeeddirt]

Thanks for the help Chryco...... I know That driving it will tell me more, but if I am pulling 8 inches of vacuum, what should I expect from dropping 3 on my power valve instead of 2 as you suggest?

[cudabob496]

These guys should have everything you need:

http://www.summitracing.com/

[highspeeddirt]

Yep,  summits got it,  jegs does too. Which I prefer. But don't have either here,  and didn't want to wait on mail order right now

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[Chryco Psycho]

the power valve adds extra fuel as the vacuum drops with the throttle opening , so now it has to drop a bit further before it opens but I doubt you would feel the difference as the vacuum will drop so quickly as the throttle is opened