383 no compression after head rebuild
 

Evening all.


I'm hoping someone can shed some light onto the problem I'm having getting this old girl running.


Background:

The car is a 1965 Chrysler Newport with a 383 2bbl carb and belongs to the kid across the road. He has been ripped off by all sorts of so called mechanics with this car, so I have stepped in to to save him spending any more money and to save him from scrapping the car.


Apparently the car was running, but suffering from a blown head gasket. He had someone replace the head gaskets but the car would not start at all afterwards. That was 2 years ago and in meantime other 'experts' have looked at it with no success.


The problem: All 8 cylinder have low compression, with readings of between 30-50psi and of course it won't start. With a lot of cranking and little fuel down the carb it will occasionally pop and almost ran for about 3 seconds, but just won't fire up.

I used two different compression testers and got very similar readings.


What has been done:

I pulled the heads, had them milled with new valves and guides and had the valves lapped - all by a very well respected engine shop.

New distributor, rebuilt carb, new battery, new fuel pump, new plugs, new intake gaskets, felpro head gaskets. The previous mechanic installed new push rods and also put in new lifters, but these were too short, so now the old lifters are back in.

With the motor cranking all the rockers move up and down. I get a bright white spark from each plug when I test those.


Question: Can the rings fail from siting after two years following a blown head gasket? Or are we looking at a timing chain issue?

The block is not cracked and holds coolant.


Your input is greatly appreciated, as the kids father has given him an ultimatum to get it running or it goes to the junkyard. That would be a real shame as it's totally solid (Las Vegas weather) with no rust and great chrome.


Thank you.

I think your on the rite track.... Check the Crank to Cam timing, I'm guessing that's where you will find the problem from what you have described..
Keep us posted....
For what it's worth... That compression is way to low.... And No, All the ring's would not have failed at the same time. The Compression should be around 125PSI.
I think your going to find the engine has jumped time... Re set that and before you put it all back together, recheck the compression…. Unless it bent all the rods or broke all the rings you should see the compression come back.

Just my guess... :)

Put a wrench on the crank bolt and turn back and forth, it will stop each way when it hits valve train resistance. 5-10 degrees is normal wear and loose, 15 degrees and over must be replaced. You can turn it back and forth with the fan if belt tight.

Thank you for your input gentlemen.

Today I pulled the timing cover off and found the chain to be very slack indeed. I now have a new one on order.
The timing marks on the gears were not quite lined up. With the crank at 12, the cam gear was about 1 or 2 teeth before 6. Do you think this would be enough to throw the timing off completely?
Of course, I guess I'll find out when the new chain arrives.

Thanks again, I'll give updates as I go along.

I don't think it should have knocked that much compression out of it... But lets see what happens... If it at least comes back to 70-80 psi it should at least start.. Wont be happy, But its a start.

As promised here is today's update.

So I installed the new timing set and set the marks as they should be (6 and 12) and set the initial timing with 15 degrees of advance and...........
nothing. She still won't fire up.
I will do another compression check this weekend and double check the spark and see how we go from there.

Let's see what the compression is.

You have checked the timing so ?? I would check the push rod length Maybe the valves are not closing properly ???

Evening Gents

Latest update for you. Virtually no compression when I checked this weekend, we're still talking 30psi as an average across all 8. So added a little oil down each bore and this bought it up in most cases to 50psi as an average, with a couple making 60 and others only increasing by 10psi.

I assume this would indicate bad rings. My neighbor who has been a mechanic since the 60's suggested that a carbon build up could case the rings to go bad after the motor had been sitting. Does that make sense?

This week I will put in some new lifters the neighbor above gave me and see if that makes any difference.

I wold have to agree.... Sounds like it has somehow knocked the rings out of it. Rust, Carbon, and Oil, and Sitting has probably got them stuck.

All 8 though? that seems very very unlikely
id be leaning towards a timing chain hopping a tooth and the valves closing at the wrong time or the pushrods being too long for the new valve seat depth and holding pressure/open.