Hey Guys,

My 76 with a 383 is having all sorts of what i think are timing issues...curb idle just stalls, seems to run fine at high idle and when the car is moving, but pretty much stalls at lights, etc...

Just replaced the edelbrock 800 with a Holley Ultra Street Avenger 770, the edelbrock had been sitting some time when the previous owner with the car outside, needed a rebuild so just replaced it with the Holley. Checked the vacuum and it pretty low, when I can keep it running, about 7 or 8 the cam is kinda big so not surprised with the low vacuum... I know the carb needs to be adjusted but I really think its more of a timing issue... initial is around 14 and total @ 38. Replace all the vacuum lines and checked for leaks.. did not find any.

Here are some specs:

Like I said 383, Comp Cams 235/249 @ 50, MSD 6AL Box, MSD Street Fire Dizzy have not changed any springs and running with ported vacuum, Patriot 195 CNC heads.

Any help would be greatly appreciated...

 

Connect the dots.

 

Here's what I just posted on a similar thread here in this section:

When you run a big, lumpy cam, the initial timing setting and the total length of the mechanical advance curve becomes much more important than on a near-stock engine. On a mild engine, you can get away with initial timing anywhere from 4 to 14 degrees, as long as you limit it to 36 total. As the cam gets bigger, the mechanical curve needs to get shorter, and you have to run a bunch of initial timing. With that cam, make sure you have at least 18 degrees initial timing - you can even go 20 - with a short, 18 degree long advance curve to get the 36 total.

With vacuum advance, make sure you're running the soft "B28" vacuum can, and make sure it's hooked up to manifold vacuum. Your distributor has the "B26" vacuum can in it, so it won't work with your engine setup - change it out with the B28. In its stock form, the B28 vacuum can will pull in about 17 degrees of vacuum advance (same as the B26), which is too much. Either weld up about .060" of the end of the limit slot or slip a piece of tight-fitting rubber hose over the actuation rod, making sure the hose does not rub hard against the sides of the limit slot. You want to limit the vacuum advance to about 12 degrees. By making the slot shorter or the rod travel shorter, the total 12-degree vacuum advance also comes "full in" at a lower (numerically lower) vacuum level. This will get your actual timing at idle up to about 30 degrees (18 initial plus 12 vacuum), and this will really help your manifold vacuum at idle and your idle quality.

Once you have that done, change out your distributor springs and finish setting the thing up right, including setting up the correct throttle blade angles and transfer slot exposures on that carb - that's also key to a reliable idle speed.

Lars

 

Thanks.. I know I was pretty much stating the obvious... just wanted to make sure I was heading down the right path...

Will find a B28 vaccum and try it out along with the limit.. thanks!!!

 

Where is the Patriot Head factory ?

 

C'mon, Wayne... I'm sure they have patriots in China, too...!

 

Lars, do you know how much help you give us guys, 'us' being people trying to learn and do things for ourselves? I'm just fine tuning my 383 and your information will be used here too - and that's not the first time for me either. So I'm also happy to see you on this forum.

Bud.