I have a pair of 425 hp 454's one does not time the same as the other. If I use the timing marks one engine has difficulty starting & backfires. If I time it by hand it seems to start/perform like the other.

I have used a dial indicator thru the oil fill caps on the two engines on the same rocker arm and find the timing marks are different in relation to the valve train.

Is it as easy as a slipped viberation damper, or could the person who built the engines have slip one tooth on the timing chains? If I had one motor off one tooth on the timing chains would it even run? Is there an easy way to check the viberation dampers if I pull them both off?

Find TDC on both, and mark the balancers. Then time it to where it is supposed to be using the new mark. If it runs fine, probably a bad balancer.

Thanks for the reply, but how do I find TDC with out pulling a head?

pull the plugs, disable the ignition spark, get a indicator to work in # 1 spark plug hole, run a piston up into it by rotating the engine by hand, remember what the reading was, mark the balancer, rotate the engine the other way until the indicator reads the same reading, mark the balancer, halfway between the two marks is TDC. It will be a little off, amybe a couple of degress, but at least you'll know the mark is close to the correct spot and you'll have the ability to determine if the balancer slipped or not. In fact, you won;t even have to run the engine. If you do the above, and the balancer mark is way off, you'll know the balancer moved.

Fred,

What do you recomend to use as an indicator?

For this exercise, just get something from Harbor Freight. But if you are going to start using a dial indicator a regular basis, get yourself something like a 711 Starret.

Fred, I have a Starret dial indicator kit with a flexiable arm that I use for misc . things, are you suggesting some sort of adapter that screws into the spark plug hole that will touch the piston as it comes up.....I didn't know harbor freight had that kind of stuff.

Are you absolutely sure that the distributors are installed the same? 1 notch off on one of the distributors will make the motor act like you describe.

Correct me if I am wrong, the rotor can be pointed simularly to the other engine, you are timing the points opening to TDC but by rotating the outer case of the distributor.

I have also noticed that with both engines at marked TDC the rotors point differently, I have removed the engines in question and find I cannot put it in so that the rotor points identically as the other. Thats how I came up with the viberation damper may have slipped.

This boat came to me in pieces with 2 rebuilt engines that were dropped in for shipping only. Engines meaning long blocks with pan and valve covers.

Use a magnetic base, and just stick the spring through the hole. Assuming you have iron heads so you can use the magnetic base. If aluminum heads, you may have to fab a bracket. All you are looking for is an equal piston top position when rotating the engine either way.

Come to think of it:
You could also simply take an old spark plug and weld a 2" 1/4" bolt on the end, screw it into the spark plug hole with the piston at the bottom, and then hand rotate CW till the piston touches, and the CCW till the piston touches. All you are looking for is the center, and you find that by rotating the assembly to the same position in two different directions, and dividing that by two.

As for rotor, it doesn't matter where it points, so long as the wires are in the proper order on the cap and #1 wire is indexed to the the rotor when it is supposed to be. You can have TDC rotor pointing at #1 cylinder, or anywhere you want, so long as you index the wires to the proper place. 28 degrees of advance to TDC is 28 of advance to TDC no matter where the rotor and #1 wire is. I hope I am explaining that in a way you can understand.