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Old 04-25-2013, 11:14 AM   #151
AndrewNance
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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.


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Originally Posted by JohnMc View Post
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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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....
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.

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Did you check for valve spring coil bind when installing the hi perf cam?,
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.
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Old 04-25-2013, 02:15 PM   #152
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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.

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Old 04-25-2013, 02:29 PM   #153
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Don't overlook the oil feed if you shim the rocker posts.
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Old 04-25-2013, 02:34 PM   #154
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Don't overlook the oil feed if you shim the rocker posts.
Good call
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Old 04-25-2013, 02:40 PM   #155
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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.

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

Last edited by smokeyfan1000; 04-25-2013 at 05:17 PM..
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Old 04-25-2013, 03:04 PM   #156
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Don't overlook the oil feed if you shim the rocker posts.
What do I need to look for?
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Old 04-25-2013, 03:19 PM   #157
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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.
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Old 04-25-2013, 03:38 PM   #158
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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.
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Old 04-25-2013, 05:22 PM   #159
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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.
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...........
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Old 04-25-2013, 06:03 PM   #160
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Originally Posted by smokeyfan1000 View Post
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...........
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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Old 04-25-2013, 06:04 PM   #161
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Check the valve guide height. High lift cams require cutting down the valve guides and re machining for the seal. The retainer could be hitting the guide/seal. Use an extra rocker shaft spring in place of the valve spring to check clearances. Put that cylinder to TDC, pressurize the combustion chamber and remove the spring with one of these tools


If the retainers hit the seal/guide you'll need to cut down the guides or get longer valves and springs. Either way, the head has to come off. FYI, the Isky double springs require cutting the seat pocket in the head for the larger diameter spring

Rocker shims are used for correcting geometry. At ½ lift the rocker should be perpendicular to the valve.
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Old 04-25-2013, 06:07 PM   #162
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Quote:
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What do I need to look for?
There's something slightly odd about the adjusters on your rockers, normally they have thread still sticking out of the locknut. Are you running the correct valve clearance?
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Old 04-25-2013, 06:26 PM   #163
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Quote:
Originally Posted by hiperfauto View Post
Check the valve guide height. High lift cams require cutting down the valve guides and re machining for the seal. The retainer could be hitting the guide/seal. Use an extra rocker shaft spring in place of the valve spring to check clearances. Put that cylinder to TDC, pressurize the combustion chamber and remove the spring with one of these tools


If the retainers hit the seal/guide you'll need to cut down the guides or get longer valves and springs. Either way, the head has to come off. FYI, the Isky double springs require cutting the seat pocket in the head for the larger diameter spring

Rocker shims are used for correcting geometry. At ½ lift the rocker should be perpendicular to the valve.
I'm just planning to let a machine shop do all of the head work. Do they just need to be machined down the difference in the lift between the two cams?

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There's something slightly odd about the adjusters on your rockers, normally they have thread still sticking out of the locknut. Are you running the correct valve clearance?
.014" as per the cam card.
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Old 04-25-2013, 07:14 PM   #164
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I usually have the guide machined down so there is just enough remaining for the seal. That way there's no chance of interference.
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Old 04-25-2013, 07:24 PM   #165
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Right. Hence my presence on this forum and several others. I need a place to research and inquire when I'm stumped.
It's cheaper to do research beforehand.
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Old 04-25-2013, 07:26 PM   #166
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I suppose the machinist could do that for me. They also put a generic guide seal on them when I had it done. Maybe they could've been taller than the ones available for B18/B20s . I'll just pick up some more guides and seals and go ahead and have my spare head worked up with the Isky springs and retainers. If I go ahead and have them mill it down to E head specs what will I need to do to compensate for that? Is there any amount of clean-up I can do to the exhaust ports myself? At this point I'm not looking to send it off for a full port job.
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Old 04-25-2013, 07:26 PM   #167
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I'm just planning to let a machine shop do all of the head work. Do they just need to be machined down the difference in the lift between the two cams?



.014" as per the cam card.
How deep were the valve seats ground?

I'm thinking the seats may be in need of replacing.
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Old 04-25-2013, 07:28 PM   #168
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It's cheaper to do research beforehand.
I did but the number of articles written about B20F engines with Schneider 274 cams is not very high. This is my first go at this. What did your sig say? "Experience comes from bad judgment" or something of the like.
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Old 04-25-2013, 07:30 PM   #169
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How deep were the valve seats ground?

I'm thinking the seats may be in need of replacing.
That was all done when I first had the machine work done.
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Old 04-25-2013, 09:37 PM   #170
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That was all done when I first had the machine work done.
Cool, at least the valve heads are not sunk into a 1/8" too deep seat.
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Old 04-25-2013, 09:47 PM   #171
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I did but the number of articles written about B20F engines with Schneider 274 cams is not very high. This is my first go at this. What did your sig say? "Experience comes from bad judgment" or something of the like.
You need to read & learn the *basics*. You coulda asked me.......... I just hope you haven't ruined the cam. (that's "ruint" in SC)

While I might not own a 380 hp turboed Volvo, I do have experience with cams, springs, etc from other cars I've owned.

I had a .500 lift, 320 duration cam in my Chevelle, and have installed countless hi lift cams in Harleys too.

Experience coming from bad judgement is quite the expensive way to learn about engines.. But it works if you have enough $$.......

And yes I've done it a few times. Didn't take me long to study up on things afterwards though.
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Old 04-27-2013, 04:32 AM   #172
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Hi Andrew,

Did you have to change the length of the pushrods? When i did my engine i had to measure and get bespoke pushrods made. Also 0.014 does seem quite tight so might be worth checking. i'd need to check my emails but i think kg trimning recommend 0.5mm on their cams.

Apology for not having capital i's,somehing going weird with my wife's ipad.

Last edited by mitch1971; 04-27-2013 at 04:55 AM..
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Old 04-27-2013, 07:06 AM   #173
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It'll be worth checking out when I pull the head off. I compared them to the stock ones and the combination was the same length as stock. I think the lifters are shorter and the pushrods longer, or maybe it was the other way around. Either way they were the same length as stock.
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Old 05-22-2013, 10:15 AM   #174
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I need to update so I feel like I'm doing something. Right now I'm just waiting on the machine shop. They said they didn't have the right size cutter to cut the spring seats for double valve springs so I had to borrow one from a local air-cooled guy.

Just boring stuff really...

Took the head apart:




Ground my valves:


Just shaved a little off of the exhaust ports:


Tried to make a better radius on the roof of the port:


I just need to polish it up a little more when it comes back then it's ready to go. This time I'll check for coil bind
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Old 05-22-2013, 01:08 PM   #175
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*Don't polish the intake ports mirror smooth*. A sandblasted type finish is better for intake ports.

It has to do with turbulence/tumbling of air/fuel mixture to keep the fuel suspended in the air flow.

Mirror smooth intake ports makes the fuel want to puddle/make little rivers , on the port walls/floor. Bad JuJu there.

You can however polish the *exhaust ports* mirror smooth if you wish. Since all you're trying to do is rid engine of spent combustion.

Last edited by smokeyfan1000; 05-22-2013 at 01:14 PM..
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