Hey I am trying to time my car after a cam swap and I just can't get it right. I am ending up with 35* initial timing just to make it idle. I know the piston and balancer are on TDC......I am using a proform HEI Vac. Advance. I thought at one point the Dist. was off a tooth but I still had to put 30+ base to get it to run. I am also running a MSD 6al




Thanks
Brian

 

you can't have it off a tooth, lot of people say it but it doesn't work that way. you're checking with vacuum line off right? idle speed set correctly? not advancing on the mechanical side? sure you have the right timing tab and dampner?

 

Yeah nothing has changet except I went from the LT4 cam to the LT4 Hot cam. Same damper......timing tab& chain cover. I am only getting 7 to 10 inches of vac.

Yeah I have the advance line off. It is running VERY rich throwing carbon out the exhaust. I know that the dots were lined up from the cam and crank gears. What do you think could have went wrong?


Brian

 

BTT

 

Are you sure your balancer hasn't slipped? That's all I can think of at 2am. No vacuum leaks? you should pull way more vacuum than that with the hot cam. I'm trying to think of adjusting the valves incorrectly could cause any of your problems, but it's too late for me to think that much. Those are the only 3 things I could see going wrong right now..or was that 4..

 

no vacuum leaks. sure the valves are set right?

 

It sounds like the new cam might have been drilled wrong and setting up the dots on the sprockets didn't set up the cam timing properly.

If you have to advance that much, it sounds like the valve timing is so far out, that the valves are openning too soon, to allow normal firing.

That would also explain the mess coming out the exhaust, the valve will be opening way early on the combustion stroke.

I'm assuming you put the woodruff keys in the damper and the two sprokets, they have to be there. If the damper ever slips, it can only happen if the keys are left out.

It is easy to check the cam timing. Take off a rocker cover and put a clock guage on the number one valve. Then rotate the engine to see if it is openning when it is supposed to.

Yours would not be the first cam to be made wrong.

 

Oh yes, and you wont get enough vacum if the valves are openning too soon and blowing back into the inlet, before sucking from it. Also they close too soon before they have had a full suck.

It does sound like the valve timing is way out. And with the only change being the cam, it looks the most likey problem.

 

Well guys we are getting closer with your help......I did find a valve I think was too tight. I got it right and we are much closer. How much vac. should I have at idle? (LT4 HOT CAM) I did put new roller lifters in......so now that I have them good and oiled up I will wait until it cools and hit ALL the valves again.


Thanks ALL!!!!!!!!!!:hail: