Doomah

Ok let me try to explain my problem I think I know the answer but want to make sure I am on the right page, I am sorry if it doesn’t sound right

So I did my exhaust this weekend went from 2.0 pipes to 2.5 dual exhausts with new mufflers (dynomax from flowmaster). When I used to start my car from a cold start my coke with be on while it is warming up and when it would get warm I would tap the gas and it would lower the RPM and IDLE of the car and it would stay that way. Ever since I chance exhaust when I start the car everything would be the same it start off HIGH idle and RPM then I tap gas and it would lower but now when I go driving it will return to the higher RPM and Idle not as high as first start but still higher, so I put the car in park then tap gas and it would go back to lower IDLE but I would drive again and it will go back to high IDLE and it just keeps doing that.


I am thinking I have to re adjust the timing and idle cause of the new exhaust? I am going to try to do that but is there anything else it may be? Like something worst maybe carb went bad.

The setup of my car is 350 rockets, holly 600CFM carb, edelbrock performer intake manifold, MSD ignition blast 2 coils, and 2.5 exhausts.

In a week or two I am going to install a new cam and timing chain and lifter (this kit http://www.ebay.com/itm/COMP-OLDSMOB...ht_2940wt_1163).

anyways tks for any help

MDchanic

I'd take a look at the choke and see if you whacked anything while working on it, and sent it out of adjustment.

When it's warmed up and it goes back to high idle, is the choke all the way open, or is it partly closed?

- Eric

Hawghauler

It sounds like the choke is sticking. I would recommend cleaning it with carb/choke cleaner and adjusting it. Adjust it when the engine is cold. Vacume leaks could cause a high idle too. Make sure all the hoses are plugged in if it is not the choke. As have OCD when it comes to making adjustments under the hood. Adjusting carb mixture and checking/adjusting the timing is effortless and good therapy for the soul.

Doomah

Thanks for the reply's I am going to try to check that stuff on Monday tks again.

Sugar Bear

If nothing was knocked out of place, bent or twisted etc. going to a larger free flowing exhaust may have lowered the exhaust temperature providing less heat to the intake crossover. If less heat gets to the intake crossover and choke thermostat, the choke thermostat would not release as much as before allowing the high idle cam on the carb choke linkage to stay on.

Do you have a heat riser on one of the exhaust manifolds? Does it close when cold and open when hot?

Do as suggested by previous posters first, look for anything disturbed by doing the exhaust install, clean the choke linkage and make sure it moves freely. If this all checks out then I would reduce the tension/lean the choke thermostat slightly. Record the adjustments made in case they don't work so you will know how to reset them.