I have a 72 Monte that has basically sat for last 35 years,not even being started for the last 12. 63k on the clock.Was stored in a dry garage.I haven't attempted to start it yet,waiting on a new fuel tank.I was told this is a nylon coated timing gear?And they fail(the nylon)due to age.Replace it or leave it alone?I scoured the net,found nothing about the nylon.I don't want to get it in the engine if true.So if a tear down is in the works,do you just go ahead and pull the engine and install all new seals and gaskets?

 

If the car hasn't been started for the last 12 years, it probably wouldn't hurt to replace the seals and gaskets and maybe put a bit of oil in the cylinders and crank it over if it will, sometimes they will seize up from sitting if there is any moisture in the cylinder walls they will rust, hopefully this is not the case, but wouldn't hurt to at least check things over before you fire it up.

nylon is similar to plastic and with age it will get brittle and could break so probably not worth taking the chance, it would be a shame to ruin the engine on start up

 

Here is some reading for you with some pretty good tips for starting an engine that has been sitting

How to Start an Engine That's Been Sitting


5 Tips for Starting an Old Engine - HowStuffWorks


http://www.kaiserbill.com/Web-PDF/Start-Up.pdf

 

You can always try to move things a bit to see if it is seized by putting a big socket on the crank bolt and turning clockwise.

 

I just asked a Chevy guru,he says yes on the nylon gear.I am heading out to the garage and see if it is free.

 

The engine will roll over easily with a flexplate tool.I fogged it with WD and rolled it by hand(tool).Fresh oil and filter installed.I am considering a separate fuel container until new tank gets here.I really want to hear it run.The points appear to have a clean surface and plugs look great.Maybe get rid of the points and put a Pertonix in there?I know every time I get impatient,it comes back to haunt me.

 

The engine fired up after just a few rolls.No unusual noises and sounded great for a few minutes.It then got a rough idle and popping through the intake when revved up.I am afraid it lost a lobe off the camshaft.There appears to be 2 different camshafts available from GM for the L48 engine.The GM parts man is no help.My chevy guru neighbor says that one camshaft is for California emissions.It appears that the difference is in the closing of the valves before top dead center.One is 28 degree's,the other is 32.Anyone have any input on this?Called a leading cam manufacturer,the salesman wants to put a perf cam in it and frankly,didnt seem to know the answer to my question about those closing figures(even though they reproduce the factory grinds) and how it affects the engine and why.

 

Hmmm I wish I could help with this but I just went through this cam issue and got taken by a local engine builder I don't understand it well enough to give anyone advise.
I hope someone will post with some helpful information for you.

 

a little research says that one cam traps more compression on the later model open chamber head as used in 1971 and 72.the closed chamber head as used in 1970 had a much smaller combustion chamber and of course a higher compression ratio.it appears that the camshaft that closes further from top dead center traps more air.