Whay kind of idle should I expect?

[71green go]

Just curious...I have my engine running fairly good now but has a rougher idle than I thought....
would this cam cause a rough idle?

CAm card says Intake 507  running duration 270
                     Exhaust 515 running duration 278

                     Gross  cam lift     Intake 338 Duration@.050 226
                                            exhaust 343                     230
I have a CH4B Intake
holley 750 double pump
hooker supercomp headers
mild head work to steel head
wiesco forged pistons...
thanks!

Steve

[firefighter3931]

Steve, where is your timing set up at ?  Bumping up the initial timing will increase manifold vacuum and smooth out the idle. Depending on where it ends up you may need to limit the mechanical advance and adjust the speed of the timing curve. 

That is not a big cam....you should be able to idle nicely at 850 in gear.


Ron

[71green go]

Steve, where is your timing set up at ?  Bumping up the initial timing will increase manifold vacuum and smooth out the idle. Depending on where it ends up you may need to limit the mechanical advance and adjust the speed of the timing curve.  

That is not a big cam....you should be able to idle nicely at 850 in gear.


Ron

Ron...I set timing by ear basically, I just purchased a timing gun tonight as my old one just up and quit working

The car does idle in gear at around 900.....has great throttle response, and doesn't ping or bog with foot on brake and giving er lol, rear wheels break loose easily
However its not a very smooth idle, car shakes noticeably and engine shakes........was just wondering how smooth it should be
will set timing tomorrow evening...
I always am nervous about rocker adjustment as they are adjustable.....and wonder if they are off slightly would that cause a rough idle?

the kit I bought comes with timing light, compression tester, vacuum gauge and tach and dwell meter....now once I learn to use it all I will try and dial things in

[firefighter3931]

OK, now you got some tools 

Get the vacuum guage on it and adjust the timing up to 18* at idle and see how much the vacuum increases. Next, adjust the idle mixture for max vacuum and finally readjust your idle speed down to 850-900.

Once that is done map out the timing curve in 500rpm increments and record the results. It would be good to see what the total timing is and at what rpm it stops advancing. These results will determine if distributor mods are required.


Ron

[71green go]

K...put the timing light on the engine........set at 18 degrees , vacuum is about 10-12.....adjusting idle mixture screws seem to do nothing for vacuum increase

I am starting to think something Internal to the engine is wrong....has a noisy lifter at cyl number 7 ......

maybe cam was wiped during initial start-up .....didn't think so at time, but start up did not go smooth due to a bad base gasket sucking air and car would not keep running.....ran for a few moments then I put new gasket and car started right up

It has a terrible idle and cannot live with it like this...

all thoughts welcome.........really not looking forward to buying new parts and stripping engine down yet again

[firefighter3931]

K...put the timing light on the engine........set at 18 degrees , vacuum is about 10-12.....adjusting idle mixture screws seem to do nothing for vacuum increase

Steve, when you close off the idle mixture screws does the vacuum drop ? Does the engine want to die ?

If the idle circuit does not respond to idle mixture adjustments then the carb is an issue. Either you're running on the main circuit or the idle bleeds are clogged up. If the power valve is blown it will dump lots of extra fuel and make it run rough.

Does it smell rich at idle ? How do the plugs look ?



Ron