Good compression/no compression

[mjroads]

I've read through many posts trying to learn as much about this as possible. A few days ago I bought a '64 Monza with what I was told a '66 140hp engine in it (2 carbs). Ok here's what I know.. It runs hot on the left side and runs cold on the right side. Even the exhaust is hot on left, cold on right. The carb on the left has good suction but the right carb has almost none. The fuel line and stone filter to the right carb is clear. I have superior carb rebuilt kits on the way from Clarks. I read on here that this problem is likely a carb blockage on the right. I will rebuild them both when the kits get here. The problem I just discovered is this. I did a compression test and found the 3 cylinders on the left were 170-180 and the cylinders on the right were 0. The car starts and idles fine but can't be driven because when the accelerator is more than gently pushed it pings heavily making a lot of noise. (So I stopped right away) It doesn't leak oil that I can see but I did notice the thermostat was soaked in oil when I was underneath. Any recommendations would be appreciated! I was hoping this wasn't going to be a massive project.. :)

[UNSAFE]

It is very uncommon for all three cylinders on one side to have zero compression due to a mechanical problem !

To properly check the compression the carbs must be fixed in the open position and all of the spark plugs should be removed and the coil grounded or disabled .

It is possible that the right side carb is completely closed and that could account for the lack of compression and the poor running .

As big of an air leak that would be caused by bad rings , head gaskets , or valve problems you would be able to hear something awry .

Block the carbs in the open position and try the compression test again with all spark plugs removed . Crank the engine over the same amount of turns on each cylinder .

Four strokes is about right .

[MBlaster1]

Hi you said that you had 140hp with 2 carbs a 140hp should have 4 carbs also sounds like the engine needs a rebuild. Sorry to tell you that could be the head though.

[mjroads]

Ok, I had forgotten to disconnect the coil, so I was hopeful that would change my result. I completely disconnected wires and unplugged distributor wire. I redid the test but had the same results. I blocked open the carbs, had all plugs out and cranked 4 times. Let me point this out.. when on the side that does have compression, the car sounds like its trying to start. On the other side it sound different, more like its just spinning. I know that isn't great lingo but maybe that observation will help those with more experience than me. I agree that it does seem suspicious that the whole right side isn't showing compression and the other side is great.

MBlaster, that's what I told him too but he insisted it was a 140. I'm just going to assume from now on it's a 110 as I knew it was. That's why I pointed out it only had 2 carbs. I am hoping it's not an engine rebuild in my future.. :(

[terribleted]

Remove the right carb and recheck compression on the right just in case. Assuming the right is still zero remove the right valve cover and see if by some chance the rockers are adjusted way loose or tight. Do this by using the shop manual valve adjustment procedures but only adjust the right side valves, hopefully you will gain some compression on one or more cylinders. If you still have zero on any of the right side cylinders and have not yet found a cause the next step would be to pull the head and see what is up in there (perhaps a dropped valve seat that disintegrated and blew pieces into the other cylinders that are keeping valves open...or other multiple issues causing the compression loss).

[mjroads]

Ok, good ideas.. I'll pull the carb tonight and go from there because I have to go into work for a couple hours. I have the 61 manual and 64 supplement, will there be any differences for the 66 for adjusting the rockers? I can see I'm going to get my feet wet real quick with this car! :)

[UNSAFE]

remove the right valve cover and see if by some chance the rockers are adjusted way loose or tight

Ditto but I would do this first !

If the condition of this engine unknown you may have had water intrusion on that side and some valves may be stuck or it may not
even have pushrods and/or rockers in it .

[mjroads]

ok.. I'll check that out. I know it sat out in a grass yard for "about a year" before I bought it so moisture certainly could be possible. Thanks for the great help! I can't wait to get home tonight to see what I can find out

[terribleted]

I have the 61 manual and 64 supplement, will there be any differences for the 66 for adjusting the rockers? I can see I'm going to get my feet wet real quick with this car! :)

The basic valve adjustments are the same.

[UNSAFE]

[mjroads]

Thanks for the video's and other help. I did adjust the valves as described in the manual and video. Then I did a compression check without any plugs, carbs wide open and ignition coil disconnected. There was still no compression on that side. GRR!! I did think of something else I could mention. If the car has sat for a couple hours, it sometimes backfires when I start it and often the rear tires start spinning despite the car being in neutral. Does that help any? To me the valves seem to be moving in unison when I watch them, but in the video I shot it doesn't seem like it as much. Please take a second and watch it to see if it helps any. Thanks so much for your insight! I'm not sure how to attach the video in the message so please click or copy/paste the link. :)

http://youtu.be/aID7p81MNAE

[kawtoy]

I can't see how the car would idle good, or even star with three dead cylinders. Try this real quick if you haven't already. Start the car and get it warmed up for a few minutes. Then turn it off, pull the three suspect plug wires off the plugs (right side you said was bad). Try to start again and see if anything changed. If not then you likely are correct and something is wrong on that side side, likely the head. If the car runs worse or doesn't start then maybe you were just not getting a good reading. Look down into the plug opening and see if you have something like old plug washer or debris that is preventing a good seal.

[terribleted]

I can't see how the car would idle good, or even star with three dead cylinders. .

In fact Corvairs run and drive just fine on 1/2 an engine. I have had more than one customer that have owned and operated their Corvairs for up to a couple years with 1 total dead carb allowing no function on that side of the engine. They just thought the cars were slow and a bit underpowered. They will indeed idle smooth on 3 cylinders. The issue running on 3 are overheating of the side that is working.

One club member I had known a couple years got a chance to drive my car one day and when he got out he said wow it sure is powerful. "What did you do to it to make to make it run like this?", he said. (his car was a 63 102 Automatic, mine a 65 110 automatic) I said nothing it is stock, why? He said, "Mine doesn't run anything like this one it has no where near as much power." We proceeded to his car and I found the right side carb blocked. I reved it a bit and slapped my hand on top of the carb a couple times dislodging what ever was stuck in the carb and his performance nearly doubled. (we rebuilt the carbs a few days later and got even more out of it). He had owned this car for a couple years driving it like many of us do occasionally and to car events and never knew that there was anything wrong.

[UNSAFE]

I watched the video in slow motion and at least a couple of rockers seem to have a bunch of side movement . Both ends for sure .

Let's try to diagnose the problem without guessing or any unneeded parts swapping .

Did you adjust the valves with the engine running ? Or did you do it by the book/video ? Yes or No ?

It is very unlikely that all 3 pistons have holes or that the head is bad enough on all 3 cylinders to cause zero compression .

The first thing that I would do at this point is very carefully recheck your rocker arm/valve adjustment.

If the valves are not fully closing you will have zero compression . You could try loosening all of the rockers on the bad side and see if the compression comes up.

If you have air pressure available you can quickly find the problem by doing a cylinder leak-down test .

In a nutshell - remove the spark plugs - rotate engine until both valves on the cylinder being checked are fully closed. Now put air pressure into the cylinder ( you may have to rig an adaptor or you may be able to use part of the compression tester) - Now with air pressure in the cylinder put your ear near the carb and listen for air leakage - do the same thing at the tailpipe and also remove the oil fill cap and listen there also.

There should be a little leakage but if you hear a lot of air it indicates a problem . Leakage at the exhaust indicates an exhaust valve related problem . At the carb indicates an intake valve and at the fill cap indicates a piston/ring/cylinder problem. You may also listen at either side of the engine in case it is a head gasket problem but if the gaskets were bad enough for zero compression you would like hear it while cranking - it would sound kinda like a spark plug was removed. You must be sure the valves are adjusted correctly before hand or you will get leakage .

My best educated guess is that it is a valve adjustment problem.

[mjroads]

Ok, I did the valve adjustment with the car running like I've seen in so many videos. (cars with compression in their cylinders haha) I will take my book to the car and go through it step by step and watch your video again to not cut corners. I will then try to do a leak test too, I have an air compressor that I can hook up to my compression tester. I REALLY appreciate your help with this, the education is invaluable..

When I loosened the rockers a little they chattered so I assumed they couldn't get much looser so I stopped and tightened enough to get it to run quiet again. So really I didn't change it much at all.

[bbodie52]

There are numerous YouTube videos demonstrating cylinder leak down tests. This URL will display one, but you will see many others listed to the right on YouTube...

https://www.youtube.com/watch?v=GvG22YMOzUI