I have a holley 650 DP on my car with milled choke towers, and some other work, it seems to idle all over the place. Anywhere from 900-1200+. It sometimes dies when I hit the brakes. The car does have a large cam (248/254 @ .50, .540/.568 lift on a 112). Is this to be expected with a cam like this? It is a real PITA, I never know where it will Idle. I have checked for vaccum leaks, but can't seem to really track one down. Any help would be great..TIA

------------------
Black 89 IROC...Mods: 355, 10.5:1 comp, Big Solid Crower Cam, TFS heads, Victor Jr, Holley, and a 5 spd...

 

how many turns out is your idle adjustment screw?

how tight is your throttle return spring?

do you have idle holes drilled into your throttle blades?

ODB

 

a 355ci engine with that much duration in the cam probably doesn't make much vacuum. making the idle circuit lean. drilling holes in your throttle blades will only make it worse. you simply need to richen up the idle circuit. any good carburetor shop should be able to fix the problem.

 

I have the Idle screws a turn and a half out on each side. I need to get a vaccum gage and tune it. Which way to richin the Idle screws?

------------------
Black 89 IROC...Mods: 355, 10.5:1 comp, Big Solid Crower Cam, TFS heads, Victor Jr, Holley, and a 5 spd...

 

WOW! That's a big cam, man. WAAAAY toooo big for the street!!! But very cool, just the same!!!!

You'll need to set min idle to somewhere around 1000-1100rpm. Engine will not like to idle below that no matter what you do... Too much valve overlap causing "false EGR" at low rpms, that's all. Turn up the idle screw that moves the throttle arm to open it up a little, until you cannot get it to idle below, say, 1000rpm and then fine-tune your idle mixture screws to get the max idle vacuum and them turn them back a little, if you even can with that cam. You'll have to run a little richre than stoiciometric with that cam.

That thing must rump-rumble-rump-rumble!!! I assume you drag it more than you "drive" it with a setup like that???

EDIT: the reason it dies sometimes when you hit the brakes is that the now "emptied" vacuum canister for the brakes is getting re-vacuumed, in laymans terms, which takes airflow away from your idle circuit in the carb, which can cause stumble and/or stall. No big deal and totally normal. There are even electric vacuum pumps and vacuum canister boosters you can install to alleviate this problem.

[This message has been edited by FastBroker (edited March 02, 2001).]

 

when the idle circuit is right. your motor will idle good at 850-950rpm. when i say good i mean consistent 850-950. it won't wander all over the place. especially since the car is a stick. you've got a good combination of parts. get it all dialed in and you could possibly have an 11 sec car.

 

Thank You to all who replied. Fastbroker, beleive it or not, I drive the car almost daily (gas hog and tempermental, but fun). I do have the Idle set around 1000 rpm. I took it to the drag strip this weekend, on street tires, through single 3in exhaust, tools in the back...etc, it ran back to back 12.90's @ 112.5 with 2.3 60 ft times and 0 tuning. I was pleased. Thanks again for all your help guys!

------------------
Black 89 IROC...Mods: 355, 10.5:1 comp, Big Solid Crower Cam, TFS heads, Victor Jr, Holley, and a 5 spd...

 

You'll get 12.10 next time. NICE run.

Whatcha get for highway mileage??? Is your tranny an overdriver or 1:1?

 

Thanks, highway mileage is not bad, Probably around 14, but in town and running around it is bad, like about 8 mpg (mostly cause I can't keep my foot out of it, and I probably don't have it tuned right). As far as the tranny, it is a WC T5, I never use 5th unless I'm on the interstate cause the engine lugs at anything under 2500 or so. What do you drive?

------------------
Black 89 IROC...Mods: 355, 10.5:1 comp, Big Solid Crower Cam, TFS heads, Victor Jr, Holley, and a 5 spd...12.90 @ 112.5 with a 2.3 60ft time on BFG radial TA's

 

I drive all kinds of stuff but not my Thirdgen much, lately. Too cold/snowy...

I like overpowered sleeper-type vehicles and that's pretty much all I drive/own. If it isn't overpowered when I buy it, I get it through emmissions first, then garage it and take care of the power-to-weight ratio thing myself...

It just snowed a foot here so my 350V8 Wrangler and 502/502 Grand Cherokee are putting in their dues while the 'maro and Vettes collect some dry-rot for a while. Just blew the front axle on the GC cause the all wheel drive front axle had enough. I just removed the front driveshaft and am still driving it in 2wd, not fun!!! Gonna sell both axles and upgrade to Dana 60 rear and a dana 44 front axle... 4wd stuff.

c-ya'

[This message has been edited by FastBroker (edited March 06, 2001).]

 

What is your e-mail fast broker? Mine is irocfast@yahoo.com

------------------
Black 89 IROC...Mods: 355, 10.5:1 comp, Big Solid Crower Cam, TFS heads, Victor Jr, Holley, and a 5 spd...12.90 @ 112.5 with a 2.3 60ft time on BFG radial TA's