Metalchipper

Hello,

Well, as I am contemplating what lifters to buy, since I have the heads off….

I disassembled the heads. The valve job with only about 4000 miles does not look good.

BACKGROUND:

In 2019 I pick up some used 862 heads and DIY ported them. Install new Seal Power valve guides, had .020” milled off and a valve job. The shop did a nice seat job [Neway cutter], installed valve height was even. I thought I did a good job honing out the new guilds…. The machinist smirked as he said he had to open them up a bit. A bit too much I thought, but I do not think it mattered much now.

In 2022,it was burning oil, so I took the heads off and half of the valve seals were off the guide and the guides were loose again. So, I took it to a different machine shop, he replaced the guides, this time with the proper clearance and replaced all the exhaust valve because the hardened stem tips were cracking.

I told him to leave the exhaust side narrow because they get hammered out anyway. But the installed height varied .026” but I made it work. Shimmed to .050” from the listed coil bind. With a Cam Motion cam, intake lift .571”, exhaust lift .562”
Pac 1215 springs, installed height 1.760”, pressure 113-293.
Stock rockers and Manten 7/16” push rods.


Now 4,000 miles later. The exhaust valves are pitted, and the guides are loose again. I know “That’s not how you do it,” the pic below shows how I checked it. At about .035” lift, exhaust are .010” loose and the intakes are .009”. The exhaust valves mike out at .3138” and with .0008” taper, the intakes are .313”. Both guild replacements were the cast iron with the internal oil spiral.

NOW WHAT DO I DO? This is where the intelligent tell me what to do!

1. To get replacement GM guides you buy a new head.

2. Rock Auto sells some “Qualcast” that are heat treated. Do not know if they have the death spiral!

3. A. Found some manganese bronze guides that would fit. I have read that these guilds last longer than cast iron------ and that they do not!

B. When installing bronze guides, should you warm up the cylinder head for easer install?

4. I have a set of good old Comp Steel Roller Rockers. The cam was set up not to need them but with heavier springs like PAC 1218 that might be easy on the valve guides.

5. Does anyone know where you can buy a set of Neway cutters for LM7s with out have to buy a large set to cut everything? I have not priced out the separate pieces yet, should have bought some years ago. Used them, when I used to be a mechanic, I guess I am not one now!



SECOND PART OF WHAT AM I DOING WRONG?

Twice now, over the years of fun, when cracking loose the heads bolts the torque feels low. So I checked with the torque wrench and sure enough for 90% of the bolts, it only took about 45 lbs, then the Loctite kicks in and fight me all the way out!

Fel-pro TTY head bolts and Fel-pro heads gaskets.

I use a dab of assembly grease under the head bolts, dumb idea?

Good news, the new black head gaskets look like they just came out of the box. Might save them for an emergency.

Well, I rattled on enough, thanks in advance for your thoughts



That not the way you do it!

Things are cracking

Black ring on exhaust valve is the seat area

I have nothing to say about this

Pit Party

Different exhaust valve

Cut old seal to locate the valve spring locator on the guide

dixiebandit69

Have you been experiencing valve float? What has the life of this engine been like? What brand/ material of valves are these?


So having an internal spiral is bad? I thought that was beneficial. I'm planning to build some heads with SBI cast iron guides that have a spiral, so somebody please tell me I didn't waste my money.

Metalchipper

No valve float. I bought it new, kept clean but beat on it. Had piston slap and oil usage so I OVH -ed it. Stock intakes, Stock exhaust that had the separation. No idea what the new valves are, the machinist got them. I seen the crack but was not too concerned about it, he called and ordered the new exhaust.

Well, the stock ones do not have the spiral. There is less surface area that contacts the valves. My valve springs could be on the weak side as things go, so that can't be it. so I like to blame something.
I am not going to tell you that you wasted your $$$$. I wish I knew why they are not lasting. I would like more information on the Qualcast springs. Tomorrow I will give them a call.
Thanks

02*C5

iTrader: (1)

I personally wouldn’t fight against these heads anymore. 862 heads are a dime a dozen. Get a new set and send them to a reputable shop so they do the job correctly. It seems that you’ve put on two bandaids on these heads and they have let you down. Stop trying to “MAKE IT WORK” and have them done correctly when you have the money to do so. If this isn’t your daily let it sit until you have a good working set of heads. Advice is free mistakes get expensive in this car game thing.

Metalchipper

I think my excessive valve guide wear is because of a faulty valve train set up. Me trying to quiet the noisy lifters. Plan on going back to either a stock set up or with roller rockers.

Metalchipper

I think my excessive valve guide wear is because of a faulty valve train set up. Me trying to quiet the noisy lifters. Plan on going back to either a stock set up or with roller rockers.
Another set of heads would have the same troubles if the valve train is faulty.

02*C5

iTrader: (1)

That’s what I mean by allowing a reputable shop to do it right with a new set of heads. When I had my heads done by advanced induction they asked every single question possible to the point where they asked for a cam profile card. Granted this was a few years ago but I was revving my 243s to 7200 rpm’s with absolutely 0 issues. They set up my heads to work with my cam for performance and longevity.

Metalchipper

Hello, this is a much-needed update:

After my 1st DIY valve job lasted 50 miles, I waited to update.

Recap, inspecting the heads after removal to replace the lifters, it is needing a valve job. After the machine shop, only 4000 miles and one year earlier, put new guides and exhaust valves. Guides were shot. This time I bought Neway seat cutters, put new exhaust guides in and had the machine shop face the valves. I questioned the scoring on the exhaust stems and was told to polish them smooth.
Well. It lasted 50 miles when a valve got stuck in the exhaust guide. The engine died; the valve was still moving some. The piston pushed it up and the lifter might of opening it some. The chrome must of wore off leaving the stainless-steel stem and the cast guides not getting along. Just a small eyebrow on the piston and a cracked guide……It could have been a lot worse!

Wooops


So, I redid the valve job.

Note on the Morels: posted elsewhere today:

“About 3000 miles and 9 months ago......
I put new Morels 7717 in my truck received from WS6 store [great service!]. Quietest lifters I have ever used.
Did not take them apart to clean, just oiled them up good and dropped them in. Did not have any first start up clanking noise. I stuck an exhaust valve in 50 miles which is another story I will add to an older post. Redid the valve job and started it up, the Morels, still quite as a mouse.
Running with Castrol Edge 10W-30 if you want to know.”


This time I put in Manganese Bronze guides for the exhaust. All new valves and sprayed copper gasket on the 50-mile old head gaskets! Because the Manton pushrods were no longer the correct length…..I dug out my old second hand

Comp Pro Magnum roller rocker with the stock length hardened push rods. I lucked out that they gave a good .060” wipe pattern on the valve stem heads.

With new stiffer valve springs, they make a small ticking noise but I guess that is normal.

To set an even installed height I used my diamond lap.



Stem facing device

On the Neway cutters. I think I lost my touch using them, ending up with some low spots on the seats. So, I faced off the old valves on my bench grinder and used some stainless-steel polishing compound. The seats are harder than the valves, so they needed facing to remove the groove worn into them. I used old valve seals to keep the guides clean and a drill to spin them on the stem.


old valve facing 4 lapping


The truck runs great, I bought HPTuners and sent the first scan to my tuner, he has been sending me tunes since 2005! Had been using an Edge product but it quit. Will play around with HPTuners more.

While I am uploading photos, here are some DIY porting shots. This picture was with the old cast exhaust guides.

That’s all folks.