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By admin, November 2, 2006 4:36 pm

((((part 2 of my first question)))I’m still having problems setting the timming on my 455 olds engine?

OK guys every thing you have told me i’v tryed…And yes I’m running a msd 6al box and a msd distributor as well as a accel super coil…I’v tryed setting it by ear ….It’s one way or the other to hight or to low… There is just no happy spot ….Yes my cam is in right … IS IT posible that i have a fucked up timming chain i don’t mean with the cam gear …with the crank gear.. i thinking that maybe it was marked wrong when it was made…and just maybe my crank timming it in the negative rang … if that was the case i’d have to run higher ignition timming to make it run and that would make the engine ping… WHAT DO YOU GUYS THINK??????

I own a shop, a drag car & truck, and build engines. I think you have a messed up harmoninc balancer, and your marks are off due to it slipping on the rubber its mounted on. Lay your hands on a piston stop, and find the true TDC of your #1 piston. Turn the engine in one direction until the piston stops against the stop, make a mark on the balancer, and then go in the other direction until it stops against the stop again, and make another mark on the balancer. Measure the half way distance between the two marks, and you now have your true TDC of the #1 cylinder. Does it align with the scale on the timing cover? Probably not. Measure the distance of each mark on the scale, and find your timing marks, or get a tape that has the scale to attach to your balancer. You can also get a cover that bolts over your balancer that has many marks on it from Jegs. If you find the true TDC then you will know the skinny on your crank gear. Some gears have different slots for advancing or retarding the cam timing by moving the crank gear. I’m sure you know about this already. You are going to have to figure your mechanical timing, and check to see what it all adds up to be, and then see how far out there its going at 3,000 rpms with the vacuum cannister hooked up. I’m thinking you may have too much compression. If you will go to this site:

http://www.kb-silvolite.com

and they have a compression ratio calculator that you can enter all your spec’s into, and come up with the true compression ratio of your build. You may have to go with some thicker head gaskets to lower the ratio some before it will quit spark knocking. You should be somewhere between 34-36 degrees of total timing, and with 93 octane fuel it should run ok, but the use of octane booster may be a reality if the compression is too high, and this is what it sounds like to me. I base this on years of building race engines, and my experience with this issue. Think about this; If you were off on your gears, the timing marks would be way off when you attempt to time it with a light. It would be so far off you couldn’t get it to run at all. I think; the reason you can’t find a happy medium is; in order to overcome the compression ratio you are having to lower the timing to where it doesn’t want to run, and when it does run its way too high. I hate to say it, but this is a classic sign of an engine with too much compression for pump fuel, so your options aren’t many. You can either run octane booster, and live with it, or lower the compression by using thicker head gaskets, but you will want to make sure they match your bore, as this will leave a space that can cause spark knock later when it gets a few miles on the build. I hope what I’ve said makes sense to you, and that it’s been some help to you.
Oh one other thing; Put a vacuum gage on the engine, set your timing to the best vacuum, and then back it off just till the knock goes away, and it can still be started when its hot without it grunting. This is a good method of timing one for street use. You are dealing with a distributor that is meant to be ran wide open, and may not want to work for street use too well. It is also possible the distributor may be bad. Get a handle on your compression, Get your total timing dialed in, and see what the vacuum gage says about your engine. You may even have a bad vacuum leak around the intake some place, and it won’t run at lower ignition timing due to the leak. Either way, a vacuum gage can tell you many things about your engine. The other thing I go by is what the spark plugs look like, but of course everyone has their own methods, and what works best for them.
Glad to help out, Good Luck!!!

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