Quote:
Originally Posted by Gach
If it’s that sensitive my guess is you got something else going on. Really I ran mine with no issue on 93 octane, for years. Here’s a possibility and I’ve seen this a more then a few times. Some times your running what you think is total timing 32-36 degrees, but if there’s issues with the distributor, for example you put a time light on it and say at 1500 rpms. Time in while it says 32-36 degrees But ! You bring it up to say 3000-3500 and it keeps advancing, I’ve seen the advance up to 50 degrees. But you don’t know if that’s happening say your first instinct is kicking it back 10 degrees then it feels sluggish. Just something did you want to check out and make sure that it’s not advancing. Honestly I never had any issues with my 69 Grand Prix 428. Running on 93 octane. Just a thought something you might want to check out.
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Hi Gach, in my first post of the thread I mentioned that the heads are 16 casting big valve, screw in stud 72cc (nominally) heads. I have not had the heads off of this engine. The engine, being a '68 428 originally in an automatic car came from the factory with either the 9779066 or 9779067 camshaft and the 1111959 distributor. When I got it, it had a 1970 RA III stickshift quadrajet - which was rather odd, but a windfall.
In the past, I put a timing light on it (I have a dial back light, so I can check the timing throughout the range) and it was in spec. During an inspection it was obvious that there weren't any missing bushings or pins in the distributor. Springs were stock, weights were stock. Vacuum can was fine and functioning. Could not find any problems with the advance mechanism at the time. Checked the balancer with a piston stop, and the balancer had not slipped (at that time). I don't now have faith that the elastomer is serviceable, and I expect to change the balancer as part of getting the engine back to running and reliable service. Again, it ran well with a blend of race gas and 93 octane, but sounded like ball bearings in a tin can with just the 93 at 9-10 degrees of timing. To drive it on 93, I had to retard the timing by 12 degrees from stock. Not fun.