Timing Help on 355
 

Hey guys, I was wondering what my initial timing and total timing should be on my 355 small block. Its more of a street/strip motor.

It has:
Holley 600cfm double pumper
Comp Cam 292 Duration .501 lift
882 heads w/ 2.02 intake
~10:1 Static Compression
HEI Distributor w/ 45000V Accel Coil

Long story short, this motor would eat starters until one day it broke a nose cone and broke the teeth off the flywheel (TH400 tranny). I threw a CVR mini starter and retarded the timing to solve the issue. One day I thought I could put timing back into it by bump starting it (installed a ignition cut off switch to accomplish this) but a week later it ate the starter (I think it bent the starter drive). Needless to say I installed another CVR and dialed the timing back.

Finally I installed a harmonic balancer cover, timing tab, found TDC using a piston stop, and put the timing light on it (should of done this years ago when I first had the problem). Here's what I found:

With the timing I was running that did not cause the starter to kick back:
With vacuum hooked up
27 degrees initial to a max of 40 degrees
with the vacuum disconnected
27 degrees initial with no change with rpms (maybe a slight decrease at higher rpms)

Needless to say my mechanical timing is froze up (going to take the distributor apart tomorrow and take a look at it)

I put the timing it had before I retarded it, where it would cause severe kickback on startup, but had great performance
with vacuum hooked up
42 degrees initial (no wonder it was kicking back) and increased to 60
with vacuum disconnected
42 degrees initial with no change at all

(I'm guessing the reason there is no change in initial timing from vacuum advance to no vacuum is do from the fact the motor is only generating around 6 to 7 inches of vacuum at idle)

So I'm guessing once I get my dizzy fixed, my initial should be somewhere less than 27 degrees initial and should have 42 degrees total of advanced with vacuum disconnected. Does this sound about right? Thanks in advance. (Sorry bout the lengthy post)

Re: Timing Help on 355
 

This thread should tell you what you need to know

http://67-72chevytrucks.com/vboard/s...d.php?t=290498

Re: Timing Help on 355
 

Yup, that is a very well thought out post.

If your not going to remove / recurve the distributor,, the standard of 9-12 initial, and 34-36 total ALL IN BY 3400-3260 fits most every mild street driven small block out there. Usually set total and read where initial falls and it's in this ball park with a stock distributor. Most aftermarket distributors have 24 degrees of mechanical,, (but slow and late) But there is the trend,, 9-12 initial,,,, 34-36 total

Re: Timing Help on 355
 

Thanks everybody. I ended up buying a new Accel HEI distributor (the mechanical advance in the other distributor was froze up and one of the posts the mechanical advance connects to broke off). I set the total timing at 3000rpms to 36 and thats putting me at 20 degrees initial (a lot better than 42 degrees initial :lol:). Needless to say I shouldn't be having any more starter issues. I kept the factory springs in it since total timing is reached at 2700rpm by I might mess with them later. Thanks again.

Re: Timing Help on 355
 

Like everything Mr Gasket these days, the instructions for your Accel distributor SUCK @$$ but it's not surprising. Looked up th einstructions and it doesn't list the mechanical advance,, but I bet you need to drop your initial back around 12 and the total is not until up around 3800-4000. One way you can find out is run the rpm's up to 3000 and bl;ip the throttle while CLOSELY watching the timing. If it jumps up higher,, your not at the total. These things are a drop in for 99% of the street motors out there and 'typically' are set up with a factory advance curve. Means 4000ish before the total is all in. I think your asking for trouble at 20 initial!

Re: Timing Help on 355
 

You're right, I think the total is actually at 42. Don't know what rpm it is at when it reaches though since I didn't have another person looking at the tach. (Probably need to put some lighter spring in when I have time) She idles fine and I made some wide open passes shifting at 5000 and she is not pinging. Should I still be worrying about it? The motor has a lot of cam to it and it runs on the cool side no matter how hard I run it so I'm thinking that is whats allowing me to run so much timing. Does that sound about right? Thanks again for the help.

Re: Timing Help on 355
 

All I can say is 42° is a LOT,,, if you have really low compression and really good gas it is probably OK around 4000. But if the timing marks are right,, I bet it will make better power at 36-38 total. Watch the plug porcilin for hints of tiny splashed dots of aluminum. Inaudible detonation is still going to vaporize aluminum.

Re: Timing Help on 355
 

I agrre with Marv 42 is still too much . Make sure the weights on the new distributor are moving freely and you have enough spring to draw them back in when the motor is killed . Again adding spring weight will delay the advance so the lightest spring that will still pull the counter weights back .

Re: Timing Help on 355
 

Finally checked the plugs again after I've been driving it a while. Still look fine. One of these days I'll pull the cap and put lighter springs, just haven't had time because the dizzy is shoved up against the firewall from the motor being shoved so far back. I did check the weights on the distributor when I installed it, a lot better than the old one:lol:. Do have to say its a lot easier to start now not worrying about kickback.