Excessive valve guide wear.

[motorhead153]

Ok so long sorry short, car was running like it had a dead hole, did a compression test and found that #2 was at 65psi, I suspected it had a burnt valve or similar issue, removed cyl head last night and found a burnt exhaust valve in cyl #2. So I then completely disassembled the head and pulled all the valves and also found #1 exhaust valve was also on it's way out. Once I inspected the guides I found #1 And 2 exhaust guides wear serverly worn (more so #2), they are worn so much that the area around the valve seat ( in the combustion chamber ) is hammered from the valve walking around. Also I noticed that the exhaust guides on 3 and 4 are also worn but only slightly. So my question is what would cause the guide the wear so quickly and so badly?

Car Specs: 89 2.5L fully built. Head: fully ported 44mm int 37mm exh valves, F4 Fwd cam, high RPM springs and lifters. head was fully rebuilt last year with new steel guides, valve seats (FWD) and has about 5000-6000km's on it

EDIT: Oh and all the intake valves, seats and guides are in excellent shape.

[GLHS60]

Sorry to hear of your problem. I'm assuming "steel" valve guides is a typo. Did you check the head before installing it? Any chance of a major exhaust restriction?

Thanks
Randy

[motorhead153]

Sorry to hear of your problem. I'm assuming "steel" valve guides is a typo. Did you check the head before installing it? Any chance of a major exhaust restriction?

Thanks
Randy


Haha I guess I mean iron rather than steel. I assembled the head and check all clearances at that time and it all checked out. There's no restrictions with exhaust, ported manifold, .63 turbine housing, 3" sv and full 3" exhaust with low restrction muffler and dumped b4 dr rear tire

[Aries_Turbo]

i nuked a head (missed shift) one time and when my machinist went to fix everything, he noted that my exhaust valve guides were significantly worn as well. he replaced all the guides, and valves and recommended that i get something more flowy on there for a header.

of course i didnt, i just ran less boost and limited my timing retard to prevent excessive heat in the exhaust manifold.

it was a fairly low mile head too. like 20k on it since rebuild.

brian

[bakes]

I have destroyed valve guides do to a aggressive cam which was two fold aggressive lift and too high of egt's at cruse

[Shadow]

These heads are Brutal for guides even in stock form. Best to go with Bronze silicon when replacing them, Very tough, I have yet to wear any out.

[turismolover22]

Where do you get those?

[GLHS60]

New guide quality always concerns me. As usual Shadow is on the right track with bronze guides, or probably bronze liners.

Thanks
Randy

[motorhead153]

Yea I think shadow has the right idea also I considered bronze guides but I chickened out I guess I should have. I'll be going that way with the next head.

[GLHS60]

Check out phosphor bronze guide liners if actual bronze guides are not available.

Thanks
Randy

[Shadow]

My local machine shop sourced them out for me years ago. I would think FWD Performance would carry them, no?

I hear what Randy is saying about quality. Most ppl don't realize that all guides are Not created equil and many do not have the hole on center like it should be. This is where having a good shop with attention to detail pays dividens as installing an off-centered guide is a def No-No, but it happens more than you'd like to know!

[4 l-bodies]

The exhaust guides always need more clearance when using iron guides. Get yourself 4 manganese-bronze guides with stops and you should be good to go. Your machinist should know he can run them tighter than he would with iron guides. Your valve job will last longer just from running less clearance. These guides should live a long happy life. FWD or TU should have what you need. I do have some custom made Mag-bronze guides with a slightly tighter ID, They need to be honed to fit. I had these made up because the custom Manley valves OD were coming in about .0015 smaller than stock. If you can't procure them from FWD or TU I can sell you a set.
Todd

[DevoBuzz]

That's good to know. Steve menegon is building my head with maganese bronze guides.

[motorhead153]

Well it looks that I've gotten lucky! I was digging through my parts shed last night and I grabbed a head that I knew was ported but never really gave it a second look until now. It actually looks like it has a nicely done port job and once I pulled the valves to do some cleaning I discovered that it has bronze guides and back cut stock valves!

[turbovanman²]

My local machine shop sourced them out for me years ago. I would think FWD Performance would carry them, no?

I hear what Randy is saying about quality. Most ppl don't realize that all guides are Not created equil and many do not have the hole on center like it should be. This is where having a good shop with attention to detail pays dividens as installing an off-centered guide is a def No-No, but it happens more than you'd like to know!

Amen.

[4 l-bodies]

FYI the stock guides were gang drilled on our 8V SOHC engines. That is why the ID is not concentric with the OD. All aftermarket guides that I have ever seen are concentric. The guides I had made up were made in USA. I probably have a few sets of std/std guides as well as smaller ID guides in manganese/bronze.
Todd