396/375 hp/motor issues

[Ed Wright]

Originally Posted by Adger Smith

Most of the cams goig flat I've seen do change the lash because the lifter always gets shorter. Put the vac gauge back in the tool box and use it to tune a car with a stock cam. You might need a smaller idle air bleed or check it for Vac leaks if it is lean at idle. If you have a PCV hooked to it like it was a stock car get rid of it or get one that is designed for low vac. Get an O2 sensor on it with some Data logging if you can't figure it out.

There ya go.

[njk53]

Make sure your headers are not leaking. We picked up a miss with an engine fresh off of the dyno and it turned out to be a leaky header gasket.

[Billy Nees]

Originally Posted by Adger Smith

You might need a smaller idle air bleed or check it for Vac leaks if it is lean at idle.

Not to oversimplify things but do you have a plugged idle air bleed?

[Mike Taylor 3601]

What Billy said,did you hear engine on dyno ?Has carb had fuel sitting in it since dyno?
Had BBC that was working on one time,idling sounded like carb or valve lash too tight,idled sound like was on 6cyl. all that was good,with idling tried to get feeler gauge in between rocker/valve would'nt go,shut off lash would check right, long story short tore down found lobes just strarting to go.

If have temp gun may shoot ex and find if one cyl. colder than others,no vac @ idle I would guess you are getting comp. back in intake,ethier valves being held open some reason ,bad lobes? bent valves?

Mike Taylor 3601

[Ed Wright]

Plugged air bleeds make them richer, not leaner.

[Billy Nees]

Originally Posted by Ed Wright

Plugged air bleeds make them richer, not leaner.

Ummmm, if the air bleed is completely plugged the idle circuit won't flow any fuel.

[Ed Wright]

Originally Posted by Billy Nees

Ummmm, if the air bleed is completely plugged the idle circuit won't flow any fuel.

The air bleed in the top of a Holley? Stick a tooth pick in one and see. Very rich, the air bleed won't bleed off any of the signal. Bigger bleeds=leaner.

[Jeff Lee]

Always go back to the basics!

[christopher teed]

thanks for the help so far...removed the carb and checked all the idle circuit for blockage etc.and checked the carb in general ..noticed that the diaphragm front pump... appeared to be sticking.changed it appears to run better...two things i really notice is the first is with the timing light ; at idle or throttle up the timing mark is steady ,then all of the sudden it jumps back about 20 degrees and then moves back to the stationary mark on timing tab this happens about every five seconds,,,the other is the fact that the bullet flat tappet cams is not much above the stock 396/375 cam...it does have a alittle tighter duration and a tight valve lash...but should have a good vacuum right at idle.....have drained the oil and removed the filter and will cut into the filter and see what is up.i live in orlando florida and the motor was dyno tuned on Bo Laws dyno by a guy named Dave Crunes ,Dave used to run stock eliminator years ago

[christopher teed]

well. drained the oil and cut away the oil filter to be on the safe side...everything looked good..drove the car down the road at 3000 rpm and up it runs fine...starting to think it may be a distributor issues..stock gm distributor with a advance curve kit and a pertronix ignitor ignition in distributor...have the same setup in my 396/350 camaro with no issues...will keep plugging ,but at low speeds and idle it runs and sounds like sh...will put my AFR innovative motorsports gauge on it ,and work on getting the air fuel ratio correct