Engine has an MSD electronic ignition. Currently it's timed to factory setting. I think it may have too much timing in it. It doesn't feel like I'm getting all out of the motor at full throttle. Anyone have this combination and recommend an idle timing setting? I am scheduled for a dyno tune but would like to save the money if possible. Thanks!
I'd probably start with 12 on the crank. Put 21 in the distributor. I forget which color bushing thst is but MSD gives you a some nice advance curve charts. Get the advance in by 2500 or so. That should get you pretty close. Or you csn just lock out the timing and use a start retard box
Before you do that, do you have an MSD distributor? If so, you have an adjustable mechanical advance. Too many guys focus only on the initial timing and nothing else. That is a big mistake because as soon as the RPM goes above idle, both the mechanical advance and vacuum advance add timing. The important thing is to set TOTAL timing. Very easy to do if you know how to use a timing light to set it. Your thread title says 455 GS Stage1 timing, but once you change the distributor, the stock timing no longer applies. Distributors differed over the years with different mechanical advance specs, and as I mentioned before, if you have an MSD distributor, what is the mechanical advance adjusted to?
With any distributor and any timing setting your never ready to pack it up and call it good until you disconnect the vacuum advance and bring the motor up to 5000 rpm and confirm that no additional timing gets added above what you wanted to have. All too many motors have spit out connecting rods from this maylay and it so dam easy to check!
Steve, I wouldn't be free revving any engine to 5000 RPM. It takes 5 minutes to throw in a light pair of springs that get the weights to full extension at 2500 RPM or less. Set the total timing and then reinstall the springs of your choice. BTW, not sure we ever got a resolution to Stan's other thread, https://www.v8buick.com/index.php?threads/my-1970-455-gs-started-running-hot.368593/ I just looked through that thread and saw that the engine does indeed have an MSD distributor. The question now is, what advance limit bushing it has currently?
Thanks for all the info guys. I did replace the vacuum advance as it was shot but don't know what advance weights it has or what is needed for that matter. I would have to google it. I have to go out of town and will work on the timing next week. I will let you know what I find out. Thanks again!
Stan, In order to estimate where your initial timing will be, you need to know how much mechanical advance is in the distributor, then it's simple 1st grade subtraction. The MSD distributors use color coded advance stop bushings to limit mechanical advance. The bushings are Red-28*, Silver-25*, Blue-21*, and Black-18*
Well I set my total timing today to 30 deg. Which was about an 8 deg. change. Motor is a lot happier and pulls better. Thank you very much for all the help and advice!
I think you need to bump the total timing up a couple more degrees. 455's usually like 32-34* total timing - all in by @ 2500rpm.
Matt, Thanks for the info. I will check it again and see where it's at. Might be close to that. Car is running absolutely awesome! I'll let you know!
I did a final check of timing and at 2500 rpm it's at 33 deg. and running great! Thanks to everyone again for the help!
As long as it doesn't advance beyond 33*, that is great. All of the mechanical advance MAY not be in by 2500. That is the biggest mistake most make. If there is more mechanical advance left, it WILL come in at a higher RPM.
How would you know its coming in at a higher rpm. Would that mean its sticking or too heavy a spring?
