When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Im baaaaaacccckkk. After enduring a considerable amount of lifes curveballs, I just got thrown another one. In my 50+ years of being around, and working on engines, Ive NEVER seen anything like the guide wear I see on cyl #8 exhaust guide in my LS7. Pressed for time now, but will post a vid later.......
Good morning guys/girls. Tied up yesterday with family. I tried posting a video yesterday on another forum, and had to have a more computer literate member post it for me after I sent it to him via txt. It then posted. Anyway, I sent it to a member here, in case I run into the same wall here. Then I'll ask him if he'll post it. To review, 4 years/35,000 miles ago I sent my heads to AHP because my guides were shot in under 20,000 miles, though they were not worn nearly as badly as this guide is. 7 of the 8 Ti intakes were also losing their coating. I want to say up front that AHP did a fine job. In NO WAY is this on them, unless the hardened PM guides they sold me weren't as hard as they should've been, which I doubt very seriously. As Tool & Die guy, with over 40 years in the trade, even though I'm retired, I still have a few connections. I personally checked their work with an indicator and gage pins, plus I had an inspector use a CMM. Both said the guides were concentric within .001, with most showing between. 0005"-.0008". These heads had a valve job done before they ever went on this engine. Bought the heads at Thomson Automotive, and valve job was also done by Thomson (NOT Thompson!) Automotive, which was sold to LPE in Wixom, MI. They did a good job. Good enough that I was sad when Kohle@AHP said whoever did the original valve job did a pretty good job. Sad, because I was hoping for a red flag. I pretty much knew then that the heads were going to have to come off again in the future, just when was the question. It has now been answered. Wait until you see the video. I've been working on engines for over 50 years, and I've NEVER seen a guide wear this badly. Ever. The Ti retainer on this valve, the pilot that fits down onto the inside diameter of the outer spring? It has a spiral matching the spring hammered into that pilot/boss diameter! You have to figure there was an impact driver effect when the rocker opened and closed the valve, and hammered the spring against the retainer. The fact that I didn't drop the valve says a lot about the strength of the Ferrea valves! This all came to light because I was changing out the valvesprings. #8 exhaust was first, and is the guide in the video. #8 intake was next, and it is in much better shape. The BIG question is this-What to do now? At 70 years old, I have better things to do than R&R cylinder heads every 25,000 miles. I'd guess the guide was junk 10,000 miles before the inspect now at 35,000 miles, hence the 25,000 mile figure. Hell, I may not be above ground in 4 years, who knows??! Finger pointing solves nothing. To move forward is all that matters. I would guess that, using the insanity definition, installing a 3rd set of new guides in just over 50,000 total miles, expecting a different result would be insane. Still, I guess selling the heads would be the best route. For many, they'd be fine. I drive my Corvette. For a guy that puts 2,000-3,000 miles on his car yearly, like many Corvette owners do, having this issue every 10 years is a lot more reasonable than a guy like me, who does 10,000 or more yearly. Please check out the video, which will be posted sometime today, and help point a reasonably economical/reliable path forward. Blaming GM has been beaten to death, and I only want to move forward. Can't change history. Thanks guys
You have 2 choices to "fix" the problem. The issue is the head itself and how the rocker attaches. To keep the stock heads you have now, you can cut the rocker pads off and put some shaft rockers on and that will solve the issue, cost about $3000. Other choice is go aftermarket head. TFS or Brodix gets my vote. I can get you a deal on some new Brodix heads if you go that route. Mind you, you will need to build the new heads, valves/springs/etc. That cost is in the $4000 range w/ Ti intake valves. I think the aftermarket heads is the only way to go. To spend more $$ on stock heads is same as throwing it away. For reference, I just passed on a set of ported stock LS7 heads w/ Crower shaft rockers for $2500. The orig builder had to have over $5000 in them, but that was all he could get.
That sucks that you're going to have to put another set of guides in the car, it seems like no matter what you do, the guides are just going to wear out, doesn't matter if it's an stock or an aftermarket head.
The only examples of an LS7 head that I know of that went 25k miles and still had the guides within spec are a set of AHP Archangel head with the MS90 guides and Ti/moly intake valves, I'm fairly certain that was with stock rockers. I think AZ Dave on CF actually still had his in spec at 20K miles too with Katech stock ported heads with Ti/moly valves.
I do wonder if this issue exists with all the other LS heads, but no one bothers checking because they're not at risk of losing a $15K+ engine. I remember noticing that I could wiggle the valves in my stock LS1 heads when I swapped them out for PRC 225s.
Hello,
This is the short reply,
So this my thinking, tell me if I am wrong. The chrome plating on the after market valves is too thin or soft so after the plating is worn off the stainless steel and cast iron guides gall and wear out out the guides. So the Manganese Bronze guides is necessary to prevent the galling between the stainless steel and iron guides. The OE valves must be a better quality so the chrome does not wear out.
So let me know if this correct or not.
The longer version is here https://ls1tech.com/forums/generatio...-part-two.html
An alternative solution could be to put a nicely ported LS3 head on the car.. You will give up a little power but if this just a cruiser then you won't notice. I wouldn't do it, but based on what you have said in here, it is a viable option to get back to driving the car reliably without worrying about the guide wear issue.
That being said, HPR has new longer guides that they designed specifically to combat this. If you want to stick with OEM LS7 heads, i would highly consider them. I think you'd be okay for a very long time with those.
You have 2 choices to "fix" the problem. The issue is the head itself and how the rocker attaches. To keep the stock heads you have now, you can cut the rocker pads off and put some shaft rockers on and that will solve the issue, cost about $3000. Other choice is go aftermarket head. TFS or Brodix gets my vote. I can get you a deal on some new Brodix heads if you go that route. Mind you, you will need to build the new heads, valves/springs/etc. That cost is in the $4000 range w/ Ti intake valves. I think the aftermarket heads is the only way to go. To spend more $$ on stock heads is same as throwing it away. For reference, I just passed on a set of ported stock LS7 heads w/ Crower shaft rockers for $2500. The orig builder had to have over $5000 in them, but that was all he could get.
Thanks, Bob. Appreciate it. Just trying to help others realize there is more wrong with these than just eccentric guide to seat dims. I'm done with OEM heads. Aftermarket may be better, and if they aren't, doubt they could be much worse. Never heard of heads needing 3 sets of guides in 50,000 miles. Unbelievable. I'm 70 years old. I still run the car up to redline maybe every 2 weeks to a month. Obviously, I'm not a 25 year old beating Hell out of my car at every stoplight. Most of my driving is top down, 60-75mph (1,800-2,400rpm). This, is pig manure, and stinks worse. Yes, I've smelled pig manure. Would rather smell it for a week straight than run this scrap again.....
Hello,
This is the short reply,
So this my thinking, tell me if I am wrong. The chrome plating on the after market valves is too thin or soft so after the plating is worn off the stainless steel and cast iron guides gall and wear out out the guides. So the Manganese Bronze guides is necessary to prevent the galling between the stainless steel and iron guides. The OE valves must be a better quality so the chrome does not wear out.
So let me know if this correct or not.
The longer version is here https://ls1tech.com/forums/generatio...-part-two.html
Hope that helps
I am not aware of any hard chrome plating on the Ferrea valves I have (F-2042P?). Hardened stainless is pretty damn hard, and mighty tough.
Hello,
This is the short reply,
So this my thinking, tell me if I am wrong. The chrome plating on the after market valves is too thin or soft so after the plating is worn off the stainless steel and cast iron guides gall and wear out out the guides. So the Manganese Bronze guides is necessary to prevent the galling between the stainless steel and iron guides. The OE valves must be a better quality so the chrome does not wear out.
So let me know if this correct or not.
The longer version is here https://ls1tech.com/forums/generatio...-part-two.html
Hope that helps
I was running AHP's hardened PM guides. I was told they were harder than the GM guides. I will say that my original GM intake guides weren't worn this badly even with the CrN coated Ti valves losing their coatings@22,000 miles. Which admittedly is less than the 35,000 miles seen here.......
Did your head shop actually replace the valve guides with longer ones or just replacements? If they did the job right then the solution is as simple and as difficult as figuring out why you have no lubrication, too much heat, or God knows what else.
I was running AHP's hardened PM guides. I was told they were harder than the GM guides. I will say that my original GM intake guides weren't worn this badly even with the CrN coated Ti valves losing their coatings@22,000 miles. Which admittedly is less than the 35,000 miles seen here.......
Hello Grinder11,
Just a side note, we are the same age. I am a retired auto mechcanic, 1/2 part of a machinist, and trying to retired from my hand engraving self employment enterprise.
Valve guides can be generally classified into two groups: cast iron and manganese bronze, which covers a wide range of applications.
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.
Cast iron guides are great for OEM street engines but can become damaged or even crack and fail when used in high horsepower performance or racing engines. Kelford Cams have developed a series of high-performance valve guides for popular engines including Ford, Toyota, Nissan, Toyota, Subaru, Mitsubishi & Honda. Excellent for setting up your cylinder heads to make reliable power.
Manganese bronze guides offer many benefits over cast iron; higher strength, more load capacity, low friction, improved heat transfer rate and good corrosion resistance.
Manganese bronze is compatible with all valve stem materials. If you’re upgrading your valves and they are stainless steel, manganese bronze guides are required. Cast iron guides are incompatible with stainless steel, these parts can gall/stick and seize.
My thoughts:
I also read that modern gasilone is dryer than the old stuff and does not lub as well. And.., we all know that the PVC system in LS motors keep the intake side well oil saturated!
Hope this makes sence,
Only time when you are too old to learn, is when you are room temperature.
Last edited by Metalchipper; 06-11-2024 at 06:46 PM.
06-08-2024, 12:07 PM
LS7 guide wear after "fix"..... 
I'm sure there was also some noise during engine operation indicating something was wrong. 
iron guides? 
