Timing problem?

[Ormly]

I replaced my 305 with a 350. I used the harmonic balancer from the 305.

My question: Is there a difference in degree location between the 305 timing mark that may be incorrect for the timing the 350? I would think not since they both have the same stroke of 3.48 but I do have a problem and I'm told there is a difference. Thanks for any help on this .

Orm

[Bill W]

I usually set the balancers side by side and check the marks in relation to the keyway. You then would transfer the old mark onto the new balancer or use both balancer and timing cover in a matching set so there would be no problems.

Bill

[Ormly]

Thank you, Bill. Since this was a long block replacement I had to use covers and such from the 305 along with the balancer. I had nothing to compare anything nor did I think there would be a difference seeing that the engine has the same stroke @3.48. I have a hard time believing timing marks could be different and no one [professional] was sure enough themselves to argue the point. I figured maybe the difference lay with diameter since the piston in the 350 is larger and the added weight would be consideration which would cause the timing mark to be different. But then perhaps the 305 would just have metal removed to lightened it if needs be. Either way the balancer would be different. BUT you are saying it's just the marks. Can you say how much difference there is in the location of the marks? I don't have a 350 balancer to compare to and I'm running but with some Carb or balancer [or both] problems.

Thanks for you kindnesses..

Orm

[Bill W]

Well, I'm no expert but I had to use a balancer and timing cover off a different year 350 than mine and the marks were in a different position compared to my stock 78 marks. To make it time correctly I needed to use the correct timing cover with the balancer to be able to use a timing light.

The balancer was the same diameter and thickness but the mark was in a different location the timing tab corresponded with it. Probably different due to accessories on the front of the donor engine and the ease of being able to look at the timing marks.

On your balance you could have slipped the outer ring?
What I mean is the inner iron ring and the outer iron ring are bonded together with rubber and over time the rubber falls apart and allows the outer ring to move which means the timing mark moves with it. This makes it all but impossible to time the engine with a timing light.

You could still time the vehicle with a vaccum gauge. Turn the disty until your engine runs smooth with the highest possible vaccum reading. Drive the rig and listen for pinging. If no pinging then your set. If it pings then back off a little and it should be fine.

Bill

[PHOENIX]

Originally Posted by Bill W

On your balance you could have slipped the outer ring?
What I mean is the inner iron ring and the outer iron ring are bonded together with rubber and over time the rubber falls apart and allows the outer ring to move which means the timing mark moves with it. This makes it all but impossible to time the engine with a timing light.
Bill

This is highly possible and something I have been trying to look into.

[Grim Reaper]

There are two different locations for the timing pointer. The 305 was straight up. The 350 may be 40 degreet to the right as facing the front of the engine.

[Bill W]

Doing some research I've found out there are three different pointer locations with corresponding balancer marks. 2 degress to the left of the keyway, 10 degrees, and 40 degrees. You need to use the corresponding pointer or timing cover to be able to time with a light.

Bill

[PHOENIX]

When I went from original 305 to crate 350 I used the same damper.
My father took my 305 damper down to gm dealer and compared to 350 damper.
Made the mark and we installed it. Mark has worked all this time, but I have recently found its different then when I found TDC with a piston stop (dont worry about this though, I have a few problems going on). HERE is a picture of the timing mark we made (called original in this picture)compared to the timing mark (called new in this picture) I found using piston stop. Im trying to find a picture that shows the difference between the original 305 damper and the triangle mark we made after comparing to the 350 damper.

If you set them down on a table and put the 305 mark at 12:00.
The 350 mark would be somewhere between 1:00 and 2:00.
Yes my 305 damper had the timing mark at 2:00 on the timing cover, not 12:00.
You can do the same as my father did and go to a local dealer and compare them.
Mark your own mark clean and fairly deep, then put some white paint in the groove you scratched so you can see it. If you dont put chalk or paint in there its hard to see when timing.

If you decided to buy a new damper they run about $110-120 from a gm dealer.
GM parts direct (.com) is cheaper at around $50-80 (not sure, I checked before) but they have a higher handling fee and from what I heard sometimes take a few weeks to ship. So if you buy new and in a rush go with the dealer or aftermarket mail order, if you have time to wait you can order gm original from gmpartsdirect.com and get it for a fair price.

[MylilBowTie]

http://www.chevyhiperformance.com/te...402/index.html

That might help to check the link out