cam bore repairs

[iangoround]

Three questions:
1. What is the clearance supposed to be for the camshaft "bearings"?
2. Would a head that was twisted and whose cam bores are out of alignment cause side-loading on the valves to destroy the guides? I feel like the answer to this is yes but I want someone smarter than me to confirm.
3. Does anyone know of a machine shop with the equipment to either a) align hone cam journals on these heads or b) do that AND install bearing shells?

I have a ported head here that has about 1000 miles on a new valves and guides with a fresh valve job with a whole mess of sloppy valve guides and bent exhaust valves. I know the cam bores are out of whack because the cam doesn't spin very easily when the caps are all torqued. I had a camshaft grenade in it a while ago and there are also some pretty deep gouges in the bores now too. It flows great and I'd hate to scrap it unless it's gonna cost me less to start over with a fresh head...

[4 l-bodies]

I would check tip heights and put some dye on tip and lash adjuster and check contact area. Lash adjuster should be riding near center of tip. Sounds like they could be way off. Are you running a huge camshaft? Re-ground, using stock lash adjusters? Are valves the correct length? Don't have G-head valves in swirl or vice-versa? If tip heights get way off, the lash adjuster can literally walk right off the end of the valve tip, or load them a lot. That sounds like lots of wear/damage for 1000 miles. Do a search for camshaft alignboring. I just recommended a shop that has the proper equipment. PM me if you can't find it. The camshaft should easily spin in oiled journals when torqued up to spec. If camshaft won't turn just by grabbing lobes with finger pressure only, something isn't right. You shouldn't need to bolt a pulley on the camshaft and use it for leverage to turn the camshaft. Another sign of cylinder head warpage, could be how camshaft turns when torqued to engine. Debris or grooves in camshaft journals are probably from beadblast material running through it from improper cleaning.
Todd

[iangoround]

I have it all apart now so I can't measure anything, but the shop told me they ground all the valves to the proper height. The valves were brand new +1mm swirl valves, stock camshaft. I was using PT lifters shimmed to the correct height, but this head has done the same thing before with a stock cam and stock lifters. To spin the cam with the caps torqued to spec requires a wrench on the bolt.

I did have a camshaft blow up in this head and start flaking material off. It was an aftermarket cam that was improperly hardened. That is probably where the bore damage is from, but if the bores were out of alignment I am sure it didn't help matters.

I can't find a shop around here that has the equipment to align-bore a cylinder head. Now that I'm thinking about it I'm not entirely sure if it is worth it. If they head is as twisted as I think it is, the guide and lifter bores are probably fouled up too.

[Vigo]

I would probably torque one cap at a time and see when it stops turning freely. It's possible the caps were mixed up. You may also be able to tell which ones are most loaded by the wear patterns.

Realistically if you are like me and have piles of crap sitting around, if you can mix and match caps off of junk heads onto your good head that leave the cam spinning freely, it will more than likely work. I have seen some fairly nasty cam journals in cylinder heads that had no noticeable symptoms when the engine was running. I have never heard of a single person on this forum or any other say "I had an oil pressure problem and it all came down to excessive camshaft journal clearance".

Of course, if you don't have piles of junk heads around and actually want it to be 'right', try line boring!

[iangoround]

I did do that. It stops spinning when any two caps are torqued down. The caps are all labeled, so they're in the right order. Maybe theyre not the right caps for this head, but if they got switched it happened before I got the head.

I took an old junk camshaft I had laying around and cut some grooves on the bearing journals and put it in the head. It worked a little and I can now spin the cam by hand if I have the gear on, but it still binds.

I'd really like to get it align bored and machined for bearing inserts, if I can find someone who has the will and tools to do it. Unless of course that costs eleventy billion dollars

[4 l-bodies]

Dan @ Import engine (612-377-5745) MPLS, MN has the alignboring and honing equipment to repair. I don't know if he has equipment to put bearing inserts in or not. I do have a swirl head in my stock that has those bearing inserts. First and only time I've seen a 2.2 head repaired with them. If you call him, tell him large Marge sent you .Bonus points if you can tell me what movie that's from.
Todd

[iangoround]

Pee wees big adventure.

Could a bent camshaft cause rapid guide wear? For giggles I moved this cam to another head I know is good and it also bound. Then I tried a different cam and it spun freely. I took that free spinning cam and moved it to the head I just pulled off and it also spun freely.

I measured the runout on the suspect cam on the end journal to be 0.01" which seems crazy big. Ran out of time before I had to come in to work to measure the other journals.


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[Vigo]

Ahh!! Progress!

[iangoround]

Indeed! The question now is do I chalk the destruction up to that bent camshaft and do a valve job on this head again, or do i say screw it and start over with a fresh head?

[Vigo]

So you said another cam had broken in that head. Was that before or after all the guides were redone this time? Because if two cams in a row are messed up i suspect you have something else going on like too much timing belt tension or something like that. So i'm still suspicious but seems to me if a 'good' cam still spins ok you should be able to keep using the head.

[iangoround]

When I got the head back form Tyler originally I ran it for a while and it started smoking. It was parked for a long time at my uncle's shop waiting for him to paint it. When I got it back, two years later I had forgotten about the smoking bit and put the TU R5 camshaft in it. That cam was defective and all of the lobes started to come apart in chunks. I sent it back to Chris and he verified that it was a material issue. At that point I pulled the head because there was material all up in it and I didn't want to run it any more than it all ready had been run on my fresh shortblock.

I dropped the head off at the machine shop and they told me that every single guide was destroyed. They showed me and the wear on them was incredible. So I had them completely go over the head. New guides, new valves. Kept my Comp 942 springs though.

When I got it back, I pulled a stock 89 Turbo I cam out of the junkyard and slapped it in there. When I pulled the cam out of the junkyard head I noticed that it wasn't spinning nicely in the head even without cam caps, but I figured the head was warped because 95% of the time these cars are in the junkyard because the head gasket went and it overheated like crazy.

It ran great for a while until it spit out the #4 intake rocker arm. I'm pretty sure it did that because the shop set the valve tip heights to be correct, but they didn't have the cam or rockers to make sure the rocker arm had enough clearance on the spring retainer.

I put it back together and it ran ok for a little longer until it started smoking like it had bad valve guide seals. I figured they just popped off or something. I drove it once more to work and back and it was running real rough and sounded like a Subaru. Got it home and pulled the valve cover, didn't find anything wrong. Did a leakdown test and cyls 1, 2, and 3 were leaking in to the cooling system. Pulled the head and discovered that the gasket didn't seal very well, and also that all of the exhaust valve guides are worn.

I have a timing belt tensioner tool, so I don't think I'm over tightening the belt. It always rides right in the middle of the cam gear.


I'll take this head down to the shop Monday and have them straightedge the rear valve cover rail. If it's warped it should show there. I have another straight head here ready to go, but it was my first attempt at porting a head and I'm not sure I want to run it.

[4 l-bodies]

So it sounds like you have a combination of things going on here. What head fasteners and head gasket are you using? What lb. torque are you torqueing head to? Tip heights set to stock production height, might not be correct for camshaft that has .070 more lift. I realize you now have stock camshaft installed. Is it possible that you installed your junkyard camshaft that had a OSJ camshaft installed? Snugging up any two cam cap fasteners and having the camshaft seize suggests something is definitely wrong. I would do some measuring of camshaft journals. Maybe set up dial indicator and check runout on camshaft. Sounds like camshaft could also be bent. Do you know what spring height was set to with the 942 springs? Can you measure your total length of both intake and exhaust valves and post findings. I suspect something with your valvetrain geometry is not right.
Another thing to check is when running the R5 camshaft. The bottom of retainer/bottom of keepers come pretty darn close to hitting top of guides when at max lobe lift. If the guides are not set precisely correct, they could make contact. Mine had only like .015 clearance. They could easily eject the keepers if they make contact.
Sorry for all the ?'s, just trying to help.
Todd

[iangoround]

Todd,

The last time I got it back from the shop the I measured the spring heights with the comp 942s at 1.65"

I dropped the head, cam, and all the other parts off at the shop so I can't measure anything now. I recall measuring the cam I was using and the slider cam I had that spun all right and the journal sizes were similar but not the same.

I did try to measure the runout of the junkyard cam installed in the head and it was something like 0.01"

Thanks for the tip about the bottom of the retainers. I remember reading that somewhere, but I don't think the previous shop took it in to account. I'm trying a different guy this time who builds mostly race engines and is more familiar with OHC stuff. He's going to check both of the heads I dropped off yesterday and tell me which one is the best candidate. I bought all new valvetrain parts, and once he tells me one of those heads is good I'll order a NEW cam and drop it off so he can set everything up correctly.

[iangoround]

I just found this interesting tidbit from an engine builder mag. I provided stainless steel +1mm valves, and the shop used OEM cast iron guides. When I dropped it off the other day the machinist noted that all of the old valves were severely galled. I'm sure the valvetrain geometry being wrong didn't help, but I wonder if the cast iron guides played a role too?

Cast iron guides are used mostly by OEMs due to its wear characteristics that result in longevity for high mileage applications. Cast iron is used with chrome valve stem applications as well. Cast iron cannot be used with stainless steel because of its tendency to gall.That’s why high performance applications do not warrant the use of cast guides due to the fact the material can’t handle the high loads associated with higher spring pressures. Under high stress, cast iron guides tend to crack and fracture, which can result in engine failure altogether. Cast iron is inexpensive and works best with daily drivers and high mileage applications.
For any kind of performance application, the choice is manganese bronze. The way to pronounce this correctly is MAN-GA-NESE. I often hear this as magnesium, which is not correct. Manganese bronze is ideal for performance because it is more compatible with titanium and stainless steel.

[4 l-bodies]

Could have been too tight of clearance which caused them to gall. Originally installed with no assembly lube? That is one of the beauties of using Man-bronze guides is you can run clearance slightly tighter than you can with iron guides. That means your valve job will also last longer.
Todd

[iangoround]

I didn't put the valves in, so I'm not sure. Waiting to hear back from the shop now. If either of the heads I dropped off is usable I'll go with man-bronze guides and have them make sure everything is lined up right.

Unfortunately FWD-P is out of their F series cams at the moment, so I'm not sure what I'm going to do about a new cam right now.

[iangoround]

Just heard back from the shop. The head is super warped, so I'm going with head option #2.

Where can I pick up a set of bronze valve guides for it?

[4 l-bodies]

My source for custom spec guides was bought out by SI industries. I have been told by another member that called them that they no longer make custom spec guides, but the catalog they sent me listed manganese-bronze guides as available. You could also try Qualcast.net, maybe even Goodsen. I'm going to call them in the near future to see if they will make a batch of custom made guides. Most machine shops should have contacts for stuff like that. That is a very common item to replace when refurbishing cylinder heads.
I agree with trying another cylinder head. Smart that you know when not to throw good money after bad. OEM cylinder heads in good shape are getting tougher to find.
Todd

[iangoround]

Yeah I saw the listing in the SI catalogue. My machinist orders from them a lot so he will check it out. If they're a no go I'll try the others, or maybe he can just line some iron guides?

There are only three tbi cars in the yard here. I may borrow a straight edge and go harvest the heads off of them for future use.

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[iangoround]

Here's the final verdict. The Tyler head was twisted severely, putting the cam bores WAY out of alignment and just generally messing the whole thing up. So, it's scrap now. Well not scrap I guess. I'm keeping it to be a cool paper weight and use as a template for the next time I get a clean head I want to port.

My machinist took the head that was my first porting attempt and found it to be straight enough to run. The cam spins a little tight for a few degrees, but I can still move it by hand without the cam gear. Did all new stainless +1mm valves, , FWD Crane springs, SI bronze guides, 3 angle valve job, and decked it.

Got it installed on the car last night with new ARP studs, found a dead fuel injector, had to pull all the 52lbers out and replace them with 33lbers because I didnt have a spare 52. Drove it around some last night, then pulled the valve cover off today to re-torque the studs. Only a few were down from spec. So far it seems to be running pretty good. I need to tweak the tune again, but it did just make a 150 mile round trip today without exploding so I've got that going for me which is nice.