Runs rough

[naderwaswrong]

63 with a 66 2 carb engine. I've rebuilt the carbs (not much to that) set timing, etc, pretty much everything you do to tune an engine. When I got to adjusting the valves, I noticed on one side I could not get some of them to clatter or rattle. Could I have a few bad lifters and pushrods? I'm making the assumption the cam is ok. This is the last thing I can think of. And when I says runs rough, I mean mostly not drivable. Thanks.

[Jerry Whitt]

The word "assume" is quite often cut apart to (ass)(u)(me). When possible, test and confirm rather than guess. Suggestions below.

1. Compression test all around. Normal results usually around 120 lbs, and all cylinders about the same
2. Dwell test. This is measurement of the points while in operation. This is the number of degrees of crankshaft rotation the points are closed. (also known as coil saturation time) Usually about 30 degrees.
3. Timing with vacuum advance unit disconnected from vacuum.

After these tests, let us know results. We can then advise further if needed.

[naderwaswrong]

Thanks, I'll look into that. Don't have access to a dwell meter, however. And you are right about assumptions!

[terribleted]

Wow you were unable to get some of the rocker arms to become noisy? I do not see how this is possible...with the engine running at some point they should start to rattle before they fall off. This assumes of course that they are moving normally. If they are not moving normally then you have isolated your troubles.

[66vairguy]

Not saying this is your problem ---- I had someone call me up and say "I can't hear the valves click during adjustment". I went over and the exhaust system was removed. Needless to say the noise of an open exhaust made it impossible to hear the valves.

With dual mufflers you can swing them down out of the way. With a single muffler system you have to get creative.

[Jerry Whitt]

Dwell meters are usually available at most parts stores. Often in a multimeter and usually at a low price. Probably less than $10.00

[naderwaswrong]

All too true, Ted, on the passenger side I could adjust them all out until they clattered. On the drivers side no clatter on #4 and exhaust #6. That is why I thought lifters or push rods but Jerry is right, check the cam first and work my way out. I will come up with a dwell meter somewhere today. I do have a louder not stock exhaust, but could hear ok. More to come, Thanks.

[naderwaswrong]

Ok, here is my data: Compression #1 120, #2 120, #3 130, #4 120, #5 135, #6 150. Timing @ 12 deg. btdc with no vacuum. Dwell @ 32 deg. 800-950 rpm idle. Thanks.
See utube video https://youtu.be/yhG7KyZ139w

This is the best its run.

[Wagon Master]

All too true, Ted, on the passenger side I could adjust them all out until they clattered. On the drivers side no clatter on #4 and exhaust #6. That is why I thought lifters or push rods but Jerry is right, check the cam first and work my way out. I will come up with a dwell meter somewhere today. I do have a louder not stock exhaust, but could hear ok. More to come, Thanks.

So we did a compression check.....how did the camshaft inspection turn out? It is in my opinion IMPOSSIBLE to not be able to back off a rocker arm until it clatters. If this hasn't been done on each and every valve...your adjustment is not complete. Unless of course you have a couple round lobes.

[naderwaswrong]

I would have to agree. I'll get it back on the lift and remove the oil pan. I know I can see the lifters from there. Can the cam be replaced with engine in car?

[66vairguy]

Find and post the distributor number. Some of the 66 distributors require the static timing be set at less than 650 RPM. A fellow in our club had this issue. The static timing looked fine at 800 RPM, then we reduced the engine RPM and the timing dropped to only 4 BTDC. We advanced the static timing and the car ran fine. These rapid timing advance at low RPM distributors were used on emissions control engines.

[bbodie52]

Sat Mar 03, 2018 1:31 pm

I would have to agree. I'll get it back on the lift and remove the oil pan. I know I can see the lifters from there. Can the cam be replaced with engine in car?

Unlike many other engines, the Corvair engine camshaft is not easily changed. The engine must be completely dismantled and the case halves separated to permit changing the cam.

[terribleted]

I would have to agree. I'll get it back on the lift and remove the oil pan. I know I can see the lifters from there. Can the cam be replaced with engine in car?

With the oil pan off and pushrods in place you will be able to see at most the top 1/4" of a few lifters (the ones that are fully pushed outward at this point in engine rotation. You will not be able to see much if any of the rest of them. rotating the crankshaft will allow you to in turn see the top 1/4 of the rest, but, why bother. Not really much to look at. Engine must be totally dismantled to see or replace the camshaft. So, what happens when you loosen the "quiet" rockers? Given your compression numbers the rockers must be moving. Once you loosen a given rocker far enough the rocker arm will start to wobble all over (and make noise) and if loosened farther still will eventually allow the pushrod to fall out of it (I do not recommend loosening a rocker to the point of the pushrod falling with the engine running as it may break stuff). You should be able to loosen the adjustment far enough to see or feel (using your finger touching the top of it) the rocker arm flopping around. At this point it should be making tapping or rattling sounds. How far did you loosen these? If you stopped at some amount like 1 full turn or something similar to what the other rockers took to make them rattle you may simply need to go a bit looser to hear the rattle or tap.

A rounded off cam lobe could cause a lack of tapping when the rocker is loose, however, the rocker arm would not be moving fully and normally (like the other ones that make noise when loose). This would also likely show up as a lack of or low compression in that cylinder. Doubt it is a major cam problem with compression readings like you posted.

[terribleted]

Sounds like a slight valve noise in your video. You sure that one of those quiet ones is not making this noise? Turn the "quiet" ones in a bit and see if any noise gets quieter. I would slowly adjust these rockers in until the engine starts to lug down in rpm and run rougher and perhaps start to misfire slightly (if need be to see if I could discern the noise of loose). This happens because the adjustment get so tight that valve is no longer fully closing and the engine is loosing compression. This is also why you adjust these nuts slowly, since if you do it fast and exceed the point where the valve is holding open, the point where the adjustment is so tight that valve hits the piston is not very far away (this can cause damage). I am betting there is not a lot wrong with your valve train with the only issue being discerning the "quiet point" so an even adjustment can be made.

In you original post you say runs rough and not really drivable. What does this mean?> what does it do? Does it spit and pop and shake a lot (running rough in my book)? Does it stay fairly smooth but just lacks power? Do both sides of the engine heat up evenly (feel the heat under each primary carb once the engine starts to warm up...the temp should be fairly even). If the car runs fairly smoothly but lacks power your issue may well be in the carbs. These cars idle very well and run moderately well but lack power and run a little rough with only 1 carb working.

[naderwaswrong]

I'm going to give the valve adjustment another shot when I get the car back up in the air with the new info I have. Also will work the timing a bit more as suggested. If it is the cam (and I don't think it is) this car is done, it is a project already, and will likely be sold as-is. However I don't give up easily, and will take another look. Although I have rebuilt a few engines over the years, the Corvair is completely new to me, which is why I found it interesting and jumped on the good deal I made for it. Thank you for all your advice and will post again when know more.

[64powerglide]

Watch this before you do anything!!!!!!!!