I thought it was interesting that PAC doesn't recommend the titanium retainers on a street car due to the potential to get small bits of titanium throughout the engine.

 

That is VERY interesting! Because, being in Michigan, I live less than 50 miles from PAC. I drove down to their manufacturing plant, and bought my 1905 springs AND titanium retainers directly from @TurboBuick6 , a Tech forum member here. He never said anything about them not being correct together......

 

I'm not sure "correct" is the right term here.
It's more a "street-and-daily-use" durability vs. "absolute lightest for racing use" longevity issue.

 

Or what many don’t want to hear was in the second test, the beehives made the exact same horsepower as the dual springs. Using too much spring may cause other problems. Wear is the biggest one. Given that the LS oil system has flaws. If your system bypass lets dirty oil past. The extra high pressure causes wear faster. Most often seen in cam lobes and lifter rollers or bronze rocker bushings. Low oil pressure can do it too. Sure stock engines fail too. It’s just lately seeing more posts about parts failing more often when dual springs are used. And if proper beehives make just as much power and handle the rpm’s . Why Risk other problems?

 

Is a 25-35 pound spring rate difference the cause of failures? Some engines are running springs way stiffer than the 400# typical of a dual LS spring.

 

Yes, most of the bee hive springs have a spring rate of 340 to 375 lb/in. Duals are 400 to 415lb/in. The extra pressure accelerates the wear. Then if the oil pressure is compromised it can lead to failure. IMHO running more spring pressure then you actually need is just going to accelerate wear and failure.

 

On a std dual Hyd Roller, Ti retainers are fine for a street car. When a Ti retainer isn't recommended is either on a dampered spring, or a solid roller application with aggressive valve trains and high spring forces. On an LS dual, Ti retainers all day long.

 

Mine lasted 50,000 miles, or 3 LS7 head rebuilds!!!! Anyway, Tony only changed 1 or 2 of them....I think 1, and reused the original 14 or 15. My statement is a sad statement, eh Gary? Imagine PAC saying not to run Ti retainers for long term use, when they are more reliable than OEM LS7 heads. At least MY LS7 heads. I guess bottom line is if you're running OEM LS7 heads, there are a lot more things besides retainers to worry about!!

 

Powell Machine claims that the LS7 seats were machined incorrectly and that is the source of the issue.

 

That may be true for some. Not in my case. My LS7 heads were purchased new, and Thomson Automotive did a precision valve job on them. 20,000 miles later, all the guides were shot, and 7 of 8 Ti intakes had lost some of their CrN coating. I sent them to AHP, and they're the ones who found the scrap valvetrain, except for the springs and retainers. AHP did the second build, and I had the concentricity checked on our shops CMM machine. They did a good job. But I knew my heads must have some other kind of machining error, because when I talked to Kohle, he said whoever did them originally did a pretty good job! So, NO SMOKING GUN. There are a LOT of other machining operations on a cylinder head besides seat to guide concentricity. Anyway, 30,000 miles later, 1 guide had at least .015"-.020" slop, and you could rock the stem tip back and forth at least an 1/8 of an inch!!! Third build went to Tony Mamo, and this time I went with YT roller tip rockers. All seems fine in the first 4,000 miles or so, and the wipe pattern is dead nuts after Tony got done with them. Hard to get a wipe pattern with factory rockers. So,....Crossing my fingers....

 

With the high lift cam, I would have thought roller tip rockers would be been sooner. I’ve had my YT’s for the last 12 years.

 

Ive got a super clean set of GM LS7 heads in the shop. I bought them from a guy who was going Mamo top end and I helped him with pushrods and buttoning it all up. His car is a C6Z with 22k on it when he did the top end. The GM heads I’m talking about have 22k on them and all the intake guides are shot. I ran a dial bore gauge down a few and they are out about .010…ten thou. Guide clearance is typically set at about .0015 or a thou and a half. Absolutely pitiful. Car was bone stock at teardown. Oem springs press out at correct settings.

 

It's terrible what has happened to some guys. Buy GMs flagship car at the time, get a few thousand miles out of warranty, BOOM-Youre suddenly out $20,000 for a new engine! What pisses me is GM is still giving Linamar (the company that did the awesome job machining the guide to seat concentricity, or lack thereof!) contracts to build parts for them. They farmed out differential fluid fills to them a few years back for a different vehicle, and diffs started failing-Often. Turns out they put the wrong amount of gear lube in the diffs!! Where is GM's logic here?? Where is the quality control?? If I were calling the shots at GM, Linamar would be off my list of vendors, and on a very different list!!

 

Gotta wonder if part of the problem is that there aren't a lot of true machinists left. For the most parts it's guys who chuck some numbers into a machine and let it go hog wild.

 

You are exactly right. Since Reagan neutered unions by allowing airlines to use replacement workers for air traffic control back in 1981, the skilled tradesmen apprenticeships have virtually disappeared. Until recently, when someone in the federal government actually used logic and common sense to figure out that if they didn't teach younger guys before the old guys retired, we'd be in a Helluva position if we had another big war. Because nobody would know how to manufacture parts! If we're at war with China, I doubt they'd call and ask if we need another 5,000 machine guns to use against them. Some things can't be learned online and in a classroom. I had to take college level classes for 4 years, plus learn the machines hands on for 10 hours a day. Nowadays, somebody drills a hole using a Bridgeport type mill, and theyre suddenly a Toolmaker or machinist. Our company stopped all our apprenticeships in 1984, and just let us existing Tool & Diemakers get old and retire......

 

Very well said Mike. I tell people all the time to choose their machine shop…or mechanic….or painter, or whomever very wisely. There’s a reason things are cheap. My machinist is the most expensive around, which makes my builds more expensive, but the quality speaks for itself. It’s not a secret that you can easily find 40hp with cylinder wall finish. The machine your block gets set into matters a lot, but the individual running it better know how to get it there.

 

Absolutely!! I'll gladly have a Toolmaker with high mechanical skills, which you must have to be a Toolmaker in the first place, machine a part on a good machine over an inexperienced one on a brand new machine, 24/7...

 

Free trade was a good deal for Japan, Mexico, India and China and not such a good deal for the US.

 

Yup. It shouldn't have taken an Einstein to figure that when you're at the top of the worlds economic scene, the only way you can go is down. We've taught the Chinese how to manufacture things 1/10 the cost of what our own manufacturing base can make the product for. It was ALL junk at first, but we kept buying it anyway, and the complaints and reviews only helped them improve things. Its finally gotten to the point that some of their stuff is actually not bad. We've opened the floodgates, then we wonder why there's no water....