All the timing sets i buy are too lose

Hi guys.

Ive spent the past 3 weeks searching for a single roller timing set for my 350. all the ones i buy are way too lose. I mean so lose their ready to jump a tooth

Am i the only one whos had this issue?

Cam or crank bent?

Erik the Awful said:

Cam or crank bent?

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How does one "bend" a cam or a crank? They are tempered steel, are they not?

My best guess here is that either the cam gears are heavily worn or they are not correct to begin with.

Uhm... I'll add this, though: We put timing sets on both of my Wife's POS's and they were TIGHT going on. Less then 1000 miles later, both chains have stretched and feel all dangly.

I guess if you wait long enough, you'll hear everything. What a bizarre problem... In fact, I have no idea what would cause this. A bent anything will be eazy to see.. just turn it over by hand (both crank and cam with the sprockets on, spark plugs out). The next thing would be the size of the sprockets, but I don't believe that has changed sense 1955. Please update what you find out. Stay with GM or Cloyes

You can buy .005” under timing sets (maybe tighter?) for blocks that have had the main caps line bored, since that process moves the crank closer to the cam slightly. Your case sounds a little extreme though.

Common to be loose. Not common to be so loose that they're "ready to jump a tooth".

Have your block, crank, and cam inspected by an experienced machinist.

Yes, cams and cranks can be bent. A careless crank grinder can cause problems by taking a bent shaft, and "grinding it straight". Sure--the main and rod journals can be ground so that they're aligned--but the crank snout is out-of-alignment with the journals since the snout isn't touched by the grinding wheel.

All it takes to bend a crank is detonation, or dropping the thing on the floor.

And it's not like GM is known for perfection on their machined parts to start with. "Factory tolerances" are looser than good aftermarket tolerances.

HawkDsl said:

The next thing would be the size of the sprockets, but I don't believe that has changed sense 1955. Please update what you find out. Stay with GM or Cloyes

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RockAuto shows different part numbers for TBI and Vortec timing chains, but they appear to have the same dimensions.

The only thing I can think of would be if you were mixing and matching pieces from different timing sets, and it sounds like you replaced the set as a whole.

Placing a crankshaft onto a set "v blocks" with a daily indicator and rotating the crank to measure any out of alignment. A hit or two with a dead blow on the high spots. Measuring the crank again for any high spots. And so on till true and no runout. If the crank snout, harmonic balancer shaft was far out of true, just turning the crank by hand would show a huge wobble.
As soon as any part is placed in operation, wear begins. Initial break'in till parts friction is reduced to the new static normal operating condition.
What gives you the idea that the chain is worn out or stretched? You say all the sets you buy are loose. What do you base this on. Do you measure the installed parts and are out of limits? Are ordering the correct parts numbers? Are looking for a problem that isn't their?
Chains don't stretch. They wear. Every pin, plate wears thru operation. Each thousandth adds up.
What kind of timing chain do you use? A double roller, Clothes type? A flat plate laminated type? The nylon delrin type gears that were to run quieter.
Have placed a straight edge vertically to see if the gears are in the same vertical plane?
Have looked in the GM service manual section on rebuilding the engine referring to service limits and assembly?
Without " being there" these are the conditions I would question to find an answer. Good luck.

This new smartphone keeps changing the words. Dail indicator. Cloyes timing chain.

The LT4/4.3 timing chain is like that. It sucks. For checking crank runout, I've set the crank in the block on the 2 outer mains, left the rest out, and measured in the middle.