Idle Problems 600 Holley

Holeshot

Holeshot

New Member
:confused: Car Idles at 1300 in Park and 600 rpm in Drive.
7 lbs of pressure at Manifold in Park and 4 lbs in Drive.
Cam is 552 lift and 292 Duration with a 2800 to 3200 stall Conv.
Cam rated at 3200 to 7200 rpm.
Holley 600 cfm 41500 with 4.5 power valve and 66 jets.
350 Chevy 40 Over, 350 Turbo, with a 373 rear gear.
I lose Vacuum at low idle and lose brakes.:eek:
I have a vacuum can hooked up but it dosnt seem to help.
Any suggestions would be appreciated.:eek:

Kevin
kevinh11@charter.net
 
That is a problem with high lift cams...vaccum issues. May have to run either a mechanical or electrical vaccum pump. As far as idle...id put little bigger jets in here..and i run a block off plate for the power valve(i hate those things..if you run the block off plate..you must run a size bigger jet as well).
 
Thanks Racin90
Thats just what the guys at Holley said.
The guys at Jegs said I need a smaller cam.

Thanks again
Kev
 
Welcome..i had a guy..years ago..had a 92 chev 1/2 ton..put a 500 lift cam in his motor..idled rough..and wondered why the check engine light kept coming on. The engine..couldnt maintain a constant vaccum...ecm picked it up..and..walllaaaa...codes out the wazzooo..lol.
 
It a mystery why a big cam wont make any Vacuum.
I've tried to figure it out but I cant.
Thanks for your help. going to try the plug and jets today.
I'll let know how it works out.
 
It all has to do with lift and duration. the bigger the lift..the more air goes in..and exh goes out..duration means..longer duration for the valves to stay open..hence..engine doesnt pull a good steady vaccum. If you put a vac gauge on the engine..it would sit and flutter...alot. And when you put the car in gear..it would almost fall off..totally. Good luck
 
As far as your brakes go run a staight master cylinder no brake booster.there are lifters you can buy that will help give you vacuam at idle.
 
Aaron P said:
As far as your brakes go run a staight master cylinder no brake booster.there are lifters you can buy that will help give you vacuam at idle.
Click to expand...
Ahhh..yes there is. I dont know if a big cam will benefit that...but yes there are lifters that will help your problem if you dont wanna give up the cam. Consult your cam maker
 
Thanks Guys
All the info is greatly appreciated.
I'll keep you informed.
And I'm going to call Comp Cams today

Thanks again
 
Hey Guys

We put a new Cam in over the weekend and it runs great.
we put in a 504 lift 276 dur and it helped alot.
Thanks for all your help.

Kevin
 
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