Timing is everything

[jbweems]

Help!!!  I put a new cam, intake and Holly 670 carb on my 318.  Now I can't seem to get the timing set just right.   She is running a little hotter than normal and doesn't want to turn off when I kill the ignition switch.  What should the timing be set at?

Britt

[Plumcrazy]

Start by setting the timing at TDC, advance it until the rpm's no longer increase with more timing.  Then check the total timing advance with the vacuum advance disconnected.  You want about 34* to 36*.    If you have too much then the distributor will have to be modified to reduce the amount of mechanical advance it has.

Dieseling can be caused by too high an idle speed, but get the timing sorted out first before worrying idle speed.

[jbweems]

Thanks.  I'll give that a whirl.

[aifilaw]

It's a good ballpark, but especially with an after market cam there is no "use this timing number" It depends on many variables aside from the cam, and someone with the same cam may have a different timing set than you based on the cylinder heads quench and flow, et cetera. Best to use the method described above, and also do a search on the boards for timing threads and there's a couple that go into it in verbose detail.

[onebadmopar]

you say to advance it till the rpms wont go higher then leave it there?......after that  you still gotta adjust the idle right ?whats a good idle for a bigblock 500-550?

[Plumcrazy]

you say to advance it till the rpms wont go higher then leave it there?......after that  you still gotta adjust the idle right ?whats a good idle for a bigblock 500-550?

That will be about where you want to set your initial timing. You then need to check your total advance.  If it's more than about 36* you need to reduce the amount of mechanical advance in the distributor.

You'll have to experiment a little to find the right idle speed.  Obviously an auto trans car will need a higher idle speed.  And even all auto transmission cars will not be the same due to differences in the torque converters.

[onebadmopar]

im not running my advance most here said to plug it off and forget about it

[FLG]

Heres a good article on vacuum advance,

http://www.corvette-restoration.com/Tech_Papers/Timing101.pdf

I have mine hooked up to direct manifold vac and i find it runs alot better (especially at idle) then not connected or connected to ported. Also because the timing is advanced at idle it tends to run cooler because theres less heat thats allowed to soak into the cylinder walls. I cant say for a fact  how cool but some report up to 10 or so degrees.

[onebadmopar]

i redid timing and hooked advance up again is a little better im in the ball park now at least no noticable stumble off the line anymore i think now plugs may be messed up from it being on wrong timing and car not adjusted correctly once it cool i,ll pull them see what they look like

[firefighter3931]

Help!!!  I put a new cam, intake and Holly 670 carb on my 318.  Now I can't seem to get the timing set just right.   She is running a little hotter than normal and doesn't want to turn off when I kill the ignition switch.  What should the timing be set at?

Britt

What cam ? How much compression ? Elevated engine temps are a product of retarded timing....it probably wants and needs more base timing. 



Ron