I have a 84 z28 and I have done a engine swap from the 305 that was in it to a 355ci. that is slightly built a mild cam,flat tops,headers,Wiend stelth intake,600cfm edelbrok carb.and preformance ignition system. I just recently installed the ignition system and the headers and now iam at the point of tuning the D--! thing. What should I start at for the base timing and what should the total advance timing be? I have been having a hard time getting it where it doesn't pre-ignite or knock. I would appreciate some help! Thanks NORT

 

From my experience, I always started a 0*, and advanced it a little bit at a time, just to be safe, I wouldn't do more than 8* for now, eventually, you can go higher, 12 is probably about all your gonna safely get out of it, maybe a little higher, I may be wrong on some things, but that's just from my experience.

 

Nort,

I'll presume you do not have an ECM with knock sensors, and a host of other "smarter than we are" electronic gizmos designed to squeeze 30 mpg out of a 350.

It's an old-fashioned 355 with carb, right?

12* initial advance, 38* total advance, all in by 3000 RPM. Change advance springs (lighter) if needed to get the advance in quickly. this builds power.

OBTW - a little more overlap in a cam helps fight detonation; it will bleed off low-rpm compression.

and.....sell the Edelbrock to some less knowledgable person and replace it with a Holley 750 vacuum secondary unit. It's their #3310 carb. It's worth 25 HP over the 'brock.

Also, it's tuned from the factory to work perfectly on that 355 you built. Good luck.

BOR

 

I concur, SELL the Edelbrock ASAP, I had one, they suck a fat one.

 

here's my timing problem. i have a crate350HO(base model) with hooker headers, holley 750 vacuum second, base ignition. i can only gain 10-12 degrees on my advance. i have changed the springs and achieved the advance earlier, but if i set it at 12 degrees base, i only get 22-24 total. when i set the timing, i disconnected the vacuum advance and plugged it, set the timing(12 degrees) and then hooked the vacuum advance back up. when i did this, my base timing shot back up to 30 degrees.?

let me know,

thadd

 

Hey its been a long time sense I posted that question, but thats cool. First I think that you may want to drop the base timming down just a little to start out with, 12 degrees is about the max that you can run and all motors may not like it as much as others. As far as the timming jumping up when you plug the vacuum back in , I don't think that your suppost to do it that way . I belive that you leave it unhooked to check your total timming. The vacuum advance is really only for the low end around town stuff anyway. I don't even have mine hooked up, you are suppost to get better gas milage with it buy what the hell. I have been told that you should try for around 36 to 38 degrees total at 2500 to 3000 RPM. Mine has never timed right because I don't really have the right balancer on the motor when I get the motor to run right it say (with a timming light) that iam running about 60 degrees of timming and that just isn't really possible. The way that I have been tunning the motor is pretty much by ear, I take the timming up to where I just get a slight knock and then back it back down from there. I know it isn't the proper way to go about it but it does work.It takes a little time and you may get your fingers a little hot messing with the distributor. As you know the little springs in the distributor are what let it advance faster or slower, I havemedium light springs in mine and all of my timming is in by 2500. I know that I haven't anwserd your question very well but I hope it may of helped some. Later NORT