454 timing problem
 

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.

Fixx
 

Comp cams makes a tdc indicator that screws into the spark plug hole, i put a lock nut on mine so it dont wobble and gives a better tdc reading..if im checking tdc the only way to get a accurate reading it with a degree wheel..i always get rid of the factory timing pointers and go with a adjustable one so you can put the balancer mark @ zero..if your cams are not decreed the same it will put the distributors off of tdc also..

http://www.jegs.com/i/Comp%20Cams/24...0002/-1?CT=999

adjustable timing pointer..

http://stores.homestead.com/GEddings/Detail.bok?no=4

^^^ this!

Good call. Never saw those.

But yes, a degree wheel and adjustable pointer is best, but I figured he had his engine altogether and in the boat.

Fred, you are correct, the engines are complete and in the boat...and run a few sea trials. And to make matters worse, these teo 454's are in a 28 SS where there is no room to work on things.

If it turns out to be on the right engine, I will have to use cylinder #6 or spend the day R & R'ing exhaust.

I do like your weld a bolt idea...Thanks for the tip!

If the vib damper slipped, should I replace it, what if it slips again and I have to reset TDC?

Your thoughts............

Replace it. The rubber is supposed to be bonded to both sides and never slip. It's gonna come apart soon if it slipped. Not good in a boat.

Slip I might be able to deal with...fall off while out..not good.

Time to buy one for the boat, and something nice for the wife.

You can compare the 2 balancers by removing the front crank pulley(s) and scribing a line from the keyway to the edge of the balancer. Do this exactly the same on both engines balancer then compare how far the timing marks are from thier respective scribe marks.

Also, you can buy a piston stop for finding tdc as well. If you do it this way make sure you remove all the spark plugs so you can feel when you hit the stop. Otherwise you will plow though it.

This makes no sense. The distributor should be able to be dropped in so the rotors point the same. If it won't drop all the way down, then the oil pump shaft needs to be turned with a long screw driver so it dies drop down all the way.

It could be that the balancer has slipped, but it really sounds like the distributor is not installed quite right also.

+1

That is what I was describing earlier. The fact I couldn't position both rotors in the same place with both engines on the indicated TDC was the first tip I had a problem with the vibration damper. The second tip was that it was difficult to start and would backfire when relying on the indicated TDC.

I bought the boat with only 300 hours on the clocks, next to the boat was 2 freshly rebuilt 454 long blocks and boxes of various parts, some belonging to the boat, some didn't. It's a bit hard to believe the vibration dampers slipped in 300 hours, but who is to say they belonged to this boat.

Thanks for the tips, if I can scribe the dampers on the engines I'll try that too. The front of these engines are very close to the firewall......Cigarette 28 SS are pretty cramped in there.

I had one slip, cost me an engine because it was supercharged and more advance is not good. Anyway, I confirmed the slipped balancer by removing it and laying in on top of a new balancer with the keys lined up. It was off around 6*.

I might also suggest a compression test before you get too carried away. It is possible it has valve train issues with the popping and moving the timing just masks the problem.

It makes no difference if the #1 cylinder is at TDC for the distributor. The distributor should still drop down no matter what and in any position.

I agree with Griff. It sounds to me like you may be off a tooth on the distributor.

Also, some of the stock balancers had timing marks at 0*, and 30*. Watch for that too. You might be trying to set base timing at 42* instead of 12* if you were looking at the wrong timing mark.

Just on an off chance......these motors both turn the same way? I have counter rotating Merc 454's and the distributors turn the same way but they fire the cylinders backward. ie,normal firing order is 1 8 4 3 6 5 7 2 and reverse motor is 1 2 7 5 6 3 4 8. You can see where the timing would be different but close at the same time.
Just a thought.

I do understand the oil pump drive comes off the distributor, that isnt the problem, I have had the engines out for 3 sea trials, and had to set the timing by hand on this engine, the mark was about 30* off. It tells me the rubber in the damper has probably failed and the outer has slipped. I have heard of this but just never had it on my own engines.

My 28 has just poor access to the engines, it makes service very very difficult. Thanks to you guys I do have a short list ideas on how to check the ballancer this weekend.

These engines are standard rotation, the TRS drives handle the counter rotation