How to limit total advance!!!!

[Dans66Stevens]

Ok I asked on the gear head bourd and no answers.
I have a 402 BBC with a tunnel ram and two 450 cfm Holleys.
My problem is with timing. If I set the timing at like 8% or 10% initial the boat runs like shit. This gives me around 38% total.
You guys will love this!!!! If I set it at like 16% {It runs like I Just Stole It}but this gives me like 44% total http://www.plauder-smilies.com/spiny.gif
Im wondering how I can run a initial of like 12% and a total of like 34% 36%...
The distributer is a Unilite....

[Dans66Stevens]

Is there away to change the amount of difference between to upper and lower #s

[triple x tx]

dan i would try locking the advance in the distributor and set the timing at about 34 to 36......so when you fire the motor it will have 34 degrees at idle.....something sounds strange in your setup

[Dans66Stevens]

When I say it runs like Shit.... It will start and run but won't idle. If you give it gas it has a huge flat spot. Then if you try to give it gas fast it will back fire out the carbs and quit. It has no power. If I advance it, it runs great.

[triple x tx]

is it vac. or mech. advance??

[Dans66Stevens]

mech....

[triple x tx]

lock the advance in it

[Kindsvater Flat]

Sounds like the harmonic balancer has slipped. I have seen that happen. My 440 did it and the numbers didn't jive. Showed that I was running 52 degrees of total timing.

[triple x tx]

i didnt think of that!!!!!!defintly worth checking into

[Costello]

Yes, TDC needs to really be TDC.

[Costello]

That was supposed to be thumbs up!

[blownschiada]

First check TDC is true second ditch the unilite run a msd,lock out the timing at 34 and buy a msd start retarder box to make for easy starting.Mine is running a crank trigger set at 34 with a start retard box and it is turn key.GOOD LUCK!

[Dans66Stevens]

Well I checked it once before and is was ok. I will pull it and check it again.

[PGF545]

Dan...there should be some type of limiter to stop the advance...ie http://free.***boat.net/ubb/redface.gifn factory GM dist there is a bushing that stops the weights, these bushings will wear out and cause the dist to advance too far, we had this problem on a street car on time....it had too much total timing but not enough initial timing, because we were pulling out the total and it was causing the initial to go real low. We replaced the bushings and that worked...you might have to rework the dist by either replacing the bushings, if they have them, or maybe looking to see how the advance is stopped. I have seen people weld the slots and remachine them or build offset bushings....or course this advice won't be worth anything if you lock the dist, but I thought I would offer some suggestions as a alternative in case you wanted a little advance.
Bernie

[FLYTE RISK]

Dan i agree with everything above but first you need to establish a true top dead center mark on your timing chain cover or pointer etc. Put a lock out in #1 cyl. with a degree wheel or sharpie ha ha turn it clkwise mark it than turn it countercw.. than split the differnce between the two...Once youhave established that, time it again, than see where your at.. I have also seen the rubber slip on a stock dampner lots of head gaskets later ha ha.....

[Oldsquirt]

One tip to add to what FLYTE RISK said. Once you establish your TDC mark, engrave index marks on the balancer hub and outer ring. This will allow you to visually inspect for movement of the ring relative to the hub. If over time you see movement, get a new balancer.

[dannyUALsanger]

I agree with most of what's already been posted, however, I have to add something else:
A lot of performance equipped engines, especially tunnel rammed engines, require an inordinate amount of initial advance to run properly. That being said, they still only need the normal amount of total advance, i.e. 34-36 or so degrees. This is where you have to adjust the amount of mechanical advance. Most distributors won't allow you to adjust mechanical advance unless you just lock it out or weld the slots and redrill.
I had this same problem with my Sanger and it's Vertex mag fired, tunnel ram 454. I needed to have different "advance plates" installed to limit my mechanical advance so I would see a total of 36 degrees. My initial is set at about 24 degrees. It runs great.

[Dans66Stevens]

DannyUALSanger...... I think you have hit the nail on the HEAD!!!! I have always thought this motor needed alot of initial advance. I never realized it was because of the tunnel ram. I thought is just the cam. Maybe its some of both???
Now Mallory Unilite Breaker less ignition. Is there a away to change the total advance. I have looked in it and don't see any weights. Am I missing something?

[Kurtis500]

It will start and run but won't idle. If you give it gas it has a huge flat spot. Then if you try to give it gas fast it will back fire out the carbs and quit.
? could be carb problems if not the ignition. Check for working accelerator pumps with appropriate nozzles and adjustments.
Vacuum leak?
Have you got it nailed down to just timing?

[Dans66Stevens]

Well im pretty sure its timing. If I advance the hell out of it. Lets just say it runs GEAT!!!!

[Kurtis500]

Most motors will smooth out when turning the distributor at idle. Locking it out would be a good idea. Still check the carbs if you can.

[dannyUALsanger]

Dans, I haven't ever seen the inside of a Mallory Unilite. My suggestion would be to go to their website and see if there is any info. At least you'll be able to get their phone number and call their tech line. They'll be familiar with what you're talking about http://free.***boat.net/ubb/wink.gif. I think that you've found the root of your "problem", though.