i stepped up to 1 490 ex 501 int cam and put a 780 holley on it now it seems to idle rough but steady while the car is cold but once it comes up to temp it wont idle on its own you have to tend it.

i adjusted the idle mixture to find lean-best

it has to idle at like 1350 but i figured that was because of the bigger cam but once it heats up it wont even idle there

i know advancing the cam helps with low end torque, could this help my problem?

 

first we need the actual grind number or the cam part number like XE274H10 or whatever for the cam

as lift will tell us almost nothing about it and that XE274 i have idleing at 800 and can idle around 600 IE... you would need a pretty damn radical cam for 1300rpms at idle

why do you say it HAS to idle at 1350? will it stall if you turn out the idle screw any more?
with my T5 i like it around 850-700 rpm idle
what are you running for base timing? have you tried increasing it as by 1300 you are probably starting to pull in timing advance the engine could be wanting more base timing

no you wont "need" to advance that cam at all as it should run just fine with lining up the dots it might bandaid your problem but you would be losing out

 

Comp cams xtream energy XE284H cam

i tried throwing in a couple more degrees of base timing but it has a hard time starting i have more than enough starter though so i backed off the timing a bit.

i have the idle turned up to there because it wont really build steady vacuum until then the vacuum gauge would jump around and i thought the idle problem could be a vacuum problem

im at a loss right now and am considering just putting the old cam back in

any ideas?

 

you'll need at least 24* timing at idle to get that cam to run. Use manifold vacuum for your vacuum advance can to get it.
Then back off your throttle blades so you have a .060" gap there. You don't want an off idle bog.

don't adjust idle mixture for "lean-best" whatever that is. Set it for highest vacuum.

 

by lean best i mean i have the leanest setting for idle without going into a misfire. im not sure as to the exact timing, the timing cover i have does not have a tab on it. when i had the timing advanced a little bit when i was cranking it over it was firing too early and almost pinging

i was thinking maybe advancing the cam because i thought getting the valves shut sooner might help with the vacuum. also i thought maybe the valves werent quite closed when it was firing

im really at a loss right now, any suggestions would be great.

thanks

 

Get a timing tab on and get the timing set properly. You can't do any carb adjustments until the basics like timing and float levels are set.

 

ok, no no. You don't advance your cam because you didn't tune the carb or timing.

Put timing tape on your balancer, and set up your timing curve correctly. Someone else can jump in here and tell you exactly how to do it, but you don't just "do it 'till it pings". You have a "ragged edge" cam, so you need to get this exact.

oh, that cam has 4* of advance built in anyway, anymore and it'd run goofy.

Sounds like you're not sure of your valve set as well. Check your valve lash if you want.

 

i have timing tape on my balancer but my timing cover has no tab. the valves are set to zero lash plus quarter turn hydraulic lifter. float levels are set so fuel just trickles out of the sight hole when you wiggle the car slightly.

 

Okay, without knowing duration its all a guess, but I would start with 18" initial timing, but BE SURE TO REDUCE MECHANICAL ADVANCE or you will detonate and destroy your engine.

Also, you ned to adjust the throttle screw to about 1,000 RPM, and then tune the idle mixture with a vacuum gauge- you want the highest vacuum reading, which means probably richening it from where you're at.

all in all it sounds like you have no idea what you're doing and you realy need to find someone who is more knowledgeable to at least be there to walk you through your first time.

 

actually this is not the first time for me, it is difficult because i have no way to correctly time it, looking for help not criticism

 

you need to know where that timing is to start making any meaning full adjustments

 

Did you have to crank the idle speed up? You may be out of the idle circuit now. What's your vacuum at idle? What's the vacuum rating of your power valve. It's all about the tuning.

 

I wasn't trying to criticize, but tuning a car at idle is about the easiest part of tuning and if you don't have the tools/know how to do it right then you should probably have assistance.

And moving things around until it sounds right is NOT tuning. A lot of people think that if they have a distributor wrench then they can tune ignition, nothign could be further from the truth nor more dangerous.

 

Leaning out the idle just makes it worse. The leaner the engine is, the more unstable the idle will be. Adding a little more fuel for now may make it easier to keep the engine running while you get the timing squared away.