atkinsom

I'm starting to clean up the 1969 455 I have. In the process of pulling the timimg cover I noticed a bit of slack in the timing chain on the left side when facing the chain. The right side is tight with no slack. The chain is a double roller timing chain unit that looks very clean. The motor I was told has less than 5000 miles on it. I'm no expert on timing chains and just want opinions based on the pictures and video I've attached that the slack is acceptable for a double roller setup.

Thanks

rjohnson442

Take the fuel pump off then check for tension.

nofiveo

It's probably been line bored at some point.

boese1978

What would line boring do to affect the chain slack?

nofiveo

Line boring moves cam and crank closer.. thats why they make "line bore" timing sets, they have the chain length modified to take up the slack. Maybe someone else can elaborate more.

oldcutlass

Nofiveo could be right.

nofiveo

I noticed the Glyptal paint.. dead giveaway that it's been apart before.

atkinsom

Here are the specs as they were given to me. Maybe this might shed some light on the line bore comment and the timing chain slack. Maybe that's how it's supposed to be?

1969 455
Bored .040
1820 Engle Cam and anti pump up lifters
Hoskin Cylinder Heads Big Valve
.010-.010 N Crank Clevlite 77 Bearings
Mellings High Volume Oil Pump
Crank Pilot Hole for 4 spd
Advance Key Timing Chain
Oil restrictors installed
Edelbrock 04B Manifold

MDchanic

It doesn't say anything about it's having been line bored, but that is definitely more slack than you'd expect from a relatively fresh high-quality chain (low-quality is another story).

You may need to have the CLs of the cam and crank measured (or you could just buy 0.005" and 0.010" undersize chains, see if either one fits better, and return the one(s) that doesn't do the trick).

- Eric

atkinsom

I'll see if I can get a hold of the original engine owner (hopefully) and pose the line bore question and see if he can explain the slack.
I like your suggestion as well Eric.

64Rocket

That doen't seam to bad. I have seen worst. i'm sure everyone meant to say align hone. Align bore is a big job and usually done when new main caps are installed.

Gene

atkinsom

My brother spoke to the previous owner last night who's a super standup guy. He says the motor has less than 5k on it for sure and that the following was done.

He had the short block dunked and cleaned completely. Then he had it bored through the cam bearing areas to ensure that everything was straight and true prior to installing the new bearings. He said that you can have up to 1/2" of play or slop in the chain with no issues. All chains will stretch is what he mentioned and that he recommends I don't change it.
I understand what he's saying and his experience of 40+ years with Olds engines trumps me. Ultimately the question I have is with that kind of slop am I playing with fire but I also don't want to spend money where it's not needed. The motor is about 9.5-1 I was told but is a torque monster. Thanks again for any input. Like I always say I'm learning as I go along and having fun.

MDchanic

The important thing is that the cam is timed right with tension on the chain.

Degree it and see - it it's set up right with that slack, then the slack shouldn't be an issue.

- Eric