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Andrew's 122 turbo project

That's bizarre. I've never seen that happen before.

Perhaps that exhaust valve is a bit tight in the guide and seized up when it got hot?
 
I don't know. If I can't turn the motor over by hand today then I guess I'm going to pull the head and make sure everything is alright before replacing it. I wondered if a lifter could have gotten stuck but it seems unlikely between the pressure from the cam and the pressure from the valves. I bought this engine as a core so I never used it before rebuilding. Maybe it had an imperfection that I never knew about. What are the chances that the valve hit my piston being these aren't interference motors? I know it didn't drop the valve.
 
Stuck lifters wouldn't do anything up top, because the lifter wouldn't be moving. Presumably it would massively chew up the lobe and lifter.

Almost has to be sticky valves on the exhaust. Was the head rebuilt? They may simply have been too tight.

If you need some rockers I've got a couple of unused sets kicking around the garage. I could pull a left or right handed one off and pop it in the postal system.
 
Well if you think about it it looks like the issue would have to be on the valve side, that is if something did actually get stuck and this isn't just a failure of the rocker. If the lifter or pushrod got stuck then the valve would just hang open, but if the valve got stuck then there would be pressure on both sides causing that failure....
 
Did you check for valve spring coil bind when installing the hi perf cam?,
 
Well I bolted on another rocker shaft today and all seems well though I still am getting that increased engine noise from about half throttle to 3/4 throttle. I haven't given any more than that at this point. I wondered if it could be a combination of no air filters and a giant hole in my floor that has yet to be covered after installing an 1800 short shifter. Maybe I'm just hearing something that was always there that wasn't audible before? I'm going to get an air filter either way.


JohnMc said:
Stuck lifters wouldn't do anything up top, because the lifter wouldn't be moving. Presumably it would massively chew up the lobe and lifter.

Almost has to be sticky valves on the exhaust. Was the head rebuilt? They may simply have been too tight.

If you need some rockers I've got a couple of unused sets kicking around the garage. I could pull a left or right handed one off and pop it in the postal system.
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Chance said:
Well if you think about it it looks like the issue would have to be on the valve side, that is if something did actually get stuck and this isn't just a failure of the rocker. If the lifter or pushrod got stuck then the valve would just hang open, but if the valve got stuck then there would be pressure on both sides causing that failure....
Click to expand...

Those are good points. The head was rebuilt last summer when I had all of the other machine work done. New guides, seals, springs. Pretty much everything replaced except the valves themselves. I think they just ground them and put them back in. Plus the work was done by a super reputable machine shop that's been around for about 40 years and that has done hundreds of heads for a friend of mine who rebuilds VW engines. I want to think that maybe it was just an imperfection in the rocker shaft. I never ran this motor before rebuilding it.

smokeyfan1000 said:
Did you check for valve spring coil bind when installing the hi perf cam?,
Click to expand...

I didn't change much since the aftermarket cam and the K cam are relatively similar. My cam has 274* duration where the K cam has 277* and my cam has .450" lift where the K cam has .425". So not a whole lot of difference there.
 
Well it appears i'm getting some coil bind. There's about .007" clearance between the coils and I'm sure at 2000+ RPMs they are touching. Going to try shimming the rockers .030" tomorrow. Kinda seems like the diameter of the coils is a little more than it should be.

2u4ume2y.jpg
 
AndrewNance said:
Well it appears i'm getting some coil bind. There's about .007" clearance between the coils and I'm sure at 2000+ RPMs they are touching. Going to try shimming the rockers .030" tomorrow. Kinda seems like the diameter of the coils is a little more than it should be.

2u4ume2y.jpg
Click to expand...

And that's why a good mechanic checks for coil bind when installing a higher lift/longer duration camshaft in any engine, and leaves nothing to chance/luck.

FWIW, it may work fine in one B20 engine and not in another B20 engine.

I've seen a Sifton 440 Avenger cam need no mods and work fine in one 80 ci Shovelhead Harley engine, and not work/clear in another . Even when both engines were same year model.

Production tolerances stack up/vary enough making it needed to check coil bind & spring clearance when using hi lift cams.

When installing hi perf cams *always* check for coil bind & spring travel.........or you're at great risk of fubaring the cam and other engine parts.

I highly suggest you pull the cam and inspect the lobe/s as well as valves.

LINK>http://www.cranecams.com/faqview.php?s_id=21
 
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Smokey gets a cookie!

Shimming up the rocker shafts, however, won't make a difference.

The cam still lifts the lifter, which lifts the pushrod, which rocks the rocker, which depresses the valve, the same amount.

You need different valve springs.
 
Well that's a bummer. I knew I should've just had them put the Isky double valve springs in instead of these. Oh well. I guess I can forget about Carlisle and just get my car more sorted for next year. No biggie. This will give me a chance to go ahead and get my head shaved and rebuilt the right way.
 
AndrewNance said:
Well that's a bummer. I knew I should've just had them put the Isky double valve springs in instead of these. Oh well. I guess I can forget about Carlisle and just get my car more sorted for next year. No biggie. This will give me a chance to go ahead and get my head shaved and rebuilt the right way.
Click to expand...

You might want to read up on valve trains and how they work, and how to properly check for coil bind/spring travel *especially* when using non Volvo cam, springs, and whatever.

It'll save you a lot of money in the long run. One cannot just slap together a engine without *measuring* things. Now you see why good mechanics get paid good money...........;-)
 
smokeyfan1000 said:
You might want to read up on valve trains and how they work, and how to properly check for coil bind/spring travel *especially* when using non Volvo cam, springs, and whatever.

It'll save you a lot of money in the long run. One cannot just slap together a engine without *measuring* things. Now you see why good mechanics get paid good money...........;-)
Click to expand...

Right. Hence my presence on this forum and several others. I need a place to research and inquire when I'm stumped.
 
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