Compression test

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61SuperMonza
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Re: Compression test

Post by 61SuperMonza »

First, yes you want to retap or install an insert on cylinder 1. As for the noise and smoke- it sounds like a very loose rocker arm/damaged, and as far as the smoke possible valve guide issue. If you did a valve adjustment and didn't get it right that could be an issue. I say this because I have screwed up a valve adjustment and had to start over. A good rule of thumb is your rockers when adjusted properly should show roughly 2 threads on the rocker arm studs. That is a good starting point.
Norm
First corvair in 1985
Have owned 4 corvairs since
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Bruins_Fan
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Re: Compression test

Post by Bruins_Fan »

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joelsplace
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Re: Compression test

Post by joelsplace »

Sounds on cell phone videos are really hard to decipher. I hear lifter clatter in the background but that knock is something else. It isn't regular enough for a valve issue. Maybe loose converter bolts or broken flex plate? Exhaust hitting the body?
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Walt
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Re: Compression test

Post by Walt »

I have not yet done a valve adjustment that is going to happen soon... Yes I understand it is tough to diagnose from a phone video and one that is so short as well But the exhaust is not hitting the body and I just put a new starter in... Which seems to be working fine so not sure about the flex plate... I think I will continue down my path of finishing the tuneup of setting the timing and syncing the carbs then move on to valve adjustment then just see what I find when I open that up...

61SuperMonza
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Re: Compression test

Post by 61SuperMonza »

Walt, your plan of attack is spot on. Let us know how it works out.
First corvair in 1985
Have owned 4 corvairs since
65 Corsa coupe 180 turbo
66 Monza coupe 110 PG
66 Monza coupe 140 PG
61 Monza club coupe w/ 150 turbo
Anchorage,AK

joelsplace
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Re: Compression test

Post by joelsplace »

A broken flex plate starts out sounding like yours and ends up sounding like a broken crank. It won't bother the starter until it completely fails.
113 Corvairs, 5 Ultravans and counting
Northlake, TX

Walt
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Re: Compression test

Post by Walt »

yes, i will definitely update as i move along, thanks... and that sounds like a major bummer if this is a broken flex plate... how long would it take for complete fail?

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terribleted
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Re: Compression test

Post by terribleted »

Walt wrote:
Sat Oct 24, 2020 8:44 pm
yes, i will definitely update as i move along, thanks... and that sounds like a major bummer if this is a broken flex plate... how long would it take for complete fail?
Start by taking off the front shroud and cover plate access to the convertor to flex plate bolts. make sure the 3 bolts are tight. Just these being loose can make an intermittent knocking racket. If they are loose you may just need to tighten them and that's it. Easy to check all in all.
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joelsplace
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Re: Compression test

Post by joelsplace »

That would be best case if they were loose.
I don't think there is any way to know how long it would last before totally failing if cracked.
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Walt
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Re: Compression test

Post by Walt »

ok thanks, I will definitely check that out!

Walt
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Re: Compression test

Post by Walt »

So just a quick update... I was finally able to get some time to take the valve cover off and see what things looked like and here is what I saw:

As you can see the rockers were pretty loose and a couple weren't very well centered over the valves... So I adjusted this side to 0 lash, put it all back together and good news, bad news... the good news is that the sudden white smoke that had showed up at the exhaust pipe is now gone, but the knocking noise I was hoping to find is still there... I will continue my hunt.

61SuperMonza
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Re: Compression test

Post by 61SuperMonza »

Walt,
Glad you have the smoke issue fixed. You may consider a stethoscope to narrow down the noise. I would also think about dropping the oil pan to get a look at the cam gear. It's a stretch but the cam gear could be failing. I would also check the lifters for proper operation and a bent pushrod or incorrectly installed (side oiling hole at the rocker is correct).
NORM
First corvair in 1985
Have owned 4 corvairs since
65 Corsa coupe 180 turbo
66 Monza coupe 110 PG
66 Monza coupe 140 PG
61 Monza club coupe w/ 150 turbo
Anchorage,AK

Walt
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Joined: Thu Aug 06, 2020 9:41 pm

Re: Compression test

Post by Walt »

Hi, thank you for your reply. I've never used a stethoscope before... any good tips on where to focus it and what each spot means? I will search for a video... cam gear failing sounds like a total rebuild... I know how to check the pusshrods for being straight and the oil hole in the ight place, but what do I do to check proper lifter function? thanks!

61SuperMonza
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Re: Compression test

Post by 61SuperMonza »

As far as the noise is concerned, before you use the automotive stethoscope you should be able to identify a general location. Once that is found use the stethoscope to narrow it down.
If the valves are set to 0 lash and the lifters are pumped up you can feel if there is hydraulic pressure in the lifter (you can bottom out the lifter applying pressure).
The first thing I would do is run the engine with half valve covers or no covers with the floor covered and listen. The stethoscope will help with this if neccessary. If you find a noisy valve check that pushrod and lifter. If the valvetrain is all good then move on to oil pan removal and inspection
I doubt you have a cam gear failure. It's just something to check if the noise isn't in the valvetrain.
Good luck
First corvair in 1985
Have owned 4 corvairs since
65 Corsa coupe 180 turbo
66 Monza coupe 110 PG
66 Monza coupe 140 PG
61 Monza club coupe w/ 150 turbo
Anchorage,AK

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terribleted
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Re: Compression test

Post by terribleted »

Why would you adjust the valves to zero lash? Did you mean zero lash PLUS some amount of preload added? If so how much preload? Your video above looks pretty normal. The rockers with no play at all are currently pushing on their valves, hence spring tension makes them tight. Did you adjust the valves per the shop manual? I prefer to adjust them with the engine running. You loosen a valve until it starts to tap and then after waiting 20-30 secs to see if it stops. If it stops loosen and wait again. Once you have a constant tap you slowly tighten the nut until the tap stops and then turn the nut tighter by at least 3/8 of a turn. some replacement lifters will not like more turn in than this. Stock lifters will take 1/2 turn or more but will generally operate fine at 3/8 of a turn in. If while turning in the rocker nut the engine starts to miss badly, you either turned the nut in too fast or the valve is now adjusted too tight and is holding open. If 3/8 of a turn in make this happen there is an issue like a collapsed lifter perhaps.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

Walt
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Joined: Thu Aug 06, 2020 9:41 pm

Re: Compression test

Post by Walt »

Good morning and thank you both for your replies. Yes I thought about that after I posted it I set it to 0 lash and ultimately turned them just over another half turn. I have seen so many variances on that I know the manual says one full turn but I've seen various videos and forum posts that only do it for half a turn but I didn't want to go that far off from the manual. Thank you for the details on adjusting the valves with the engine running I have just never done that before but perhaps I will enter into that territory soon... Especially if that is how I should be checking it with a stethoscope as well. Thank you both again and have a great day... I will update when I have more info

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