That's why I had him build my engine!

Texasdoc,
Another trick used on small aircraft engines to find an manifold/intake leak is start the engine and let it idle, using starting fluid....spray in small bursts in specific zones along the intake gaskets. A leak will be verified by a rise of RPM's.
Also, about the black inside the intake runners. I was not able to open the pic, but here is 2 more cents... Remember, you can only get rich indications or heavy black carbon deposits AFTER the fuel mixture is ignited. So, if a black fuel rich "soot" was inside a runner...that means an intake valve would be hanging open after the mixture was ignited and through the exhaust stroke. But if you did a leakdown test by using compressed air at TDC on the compression stroke, you could hear air hissing through the intake opening.
So, that leaves an oil leak as a possibility. If most of the black was on the top of the valve and in the head...suspect would point to a loose guide and/or seal. If it looked equally black on both sides of the intake runner AND the head runner...suspect would point to gasket. That would explain the head being black in the cylinder chambers too.

3rd...I may have missed it and forgive me ahead of time...but if this was a SBF block, if you had a older block, the deck height was different. 9.480" compared to a 9.503", there is specific intakes to go with each block. But that would be more of a problem than just two cylinders. Again, I may have missed that detail.

Hope this helps close the gap. The starting fluid trick nails it pretty quickly, and it's one of the best degreaser too!

On family car engines, this reasoning is good, however it depends on the cam. If there is a lot of overlap on the valve timing, the intake valve opens at the end of the exhaust stroke. Exhaust gasses do enter the intake at idle, which is why the manifold vacuum is low.

My cam is 236 deg intake and 242 deg exhaust at 0.050" lift. Exhaust carbon is all the way into the plenum on a Victor Jr. Single plane intake. I have EFI so there are injectors drilled into the ports. The fuel washes some of it away, as the carbon is heavier before the injectors. If it was a Carburetor, the fuel may wash some of it away. When I pull the throttle body, it wipes off with a rag.

Brent, what do you use to seal the rocker studs where they go into the intake runners? Search shows ARP sealantis junk, Locktite breaks down and leaks, RTV turns hard and can get into the intake. Do you recommend the DOW 732? Permatex #2? Permatex thread sealant? Indian Head shellac? Teflon tape?

Permatex thread sealant.

Well, crap.

Just got news from the machine shop that all the guides are worn. All of them. I need 16 new guides. There is over 5-thousandths play in them. 7 (out of 8) of the intake valves also need replaced - they have visible/palpable wear on the valve stems. All the exhaust valves are ok. they tested the new springs and they are all functioning normally.

I don't know what is up with these heads. I bought them "new" from Jegs. First - multiple spring failure. Now - multiple guide and valve failure. I made sure to line up the pushrod guide plates so the rocker tips were centered over the valve stems. I used a push rod length checker to make sure the pushrods were the right length. The rockers have a small line in the center of the valve tip with the Sharpie trick. Unless there is a side-to-side geometry error with the casting of these heads, I'm not sure how I would get wear on the sides of the valve stems.

I have a email into AFR. They will review my email and call me back in a few days. They are trying to catch up from the holidays.

Grrrrrr....

Looks like I'm not the only AFR owner with premature valve guide wear problems.

http://www.ffcars.com/

http://forums.corral.net/forums/

I'm going to have him replace all the guides and the faulty intake valves. I'll then go thru the whole valvetrain geometry, recheck the pushrod length, recenter the pushrod guides, etc.

I talked to the machinist today for a bit, trying to figure out why this happened. He said it looked like the geometry was ok. I asked if he thought the wrong length pushrods could have done it. His response was that it *could* but on my heads, the valves looked like I had "nailed" the length correctly (his word, not mine). He said again that he would expect to see this much valve guide wear after 50-100k miles - not 500 miles. There is also valve stem wear. The valves are stainless steel - the guides are bronze. There should not be wear on the valve stems unless it was not lubricated correctly when the heads were assembled. He didn't have any other ideas other than a defect in manufacturing.

AFR was supposed to call me back today but didn't. It is costing me $200 in parts and $300 in labor to repair these heads that likely were defective from the factory.

Happened to my first Roush engine. AFR heads and the guides and stems were worn out at 12,000 miles.

Maybe. But I can't imagine all the springs were from the same batch. Maybe just the two that broke. I would imagine that they make the springs by the hundreds, if not thousands. One intake and one exhaust spring broke. The rest didn't. ALL 16 guides are worn. Seven out of eight (88%) if the intake valves have damage. None of the exhaust valves are damaged. One of the damaged springs was intake, one exhaust.

Maybe all the springs were over heat treated and made them brittle. Maybe that caused valvetrain problems that ruined all the guides. Why did it only damage intake valves? I don't know - I'm at a loss as to why or how.

Thanks for the input tho.

What brand valves? Ferrea by any chance?

No idea. As you know, when I was having problems with the springs, they said there current spring manufacturer was PAC. But I don't know about MY springs as the heads were manufactured 2 years ago - right about the time they switched spring manufacturers. I haven't talked to them yet about the valves. They didn't call me back.

I had the same problem with a set of aluminum FE heads once. They had Ferrea hollow stem valves.

Brent. ever heard of Moldstar 90 guides?

Boy this whole discussion is hitting home for me. I just replaced valves and guides in my Dart Pro-1 heads. 3000 miles, 1 quart oil per tank of gas. Same wear characteristics as yours. I checked and determined the push rods were too long. Also the roller tips were wearing sideways through the rockers. The lifter centers are 1/8 inch narrower than the valve stem centers. I caught that and the roller tip wear putting it all back together. I was spending to much time adjusting the guide plates. Well, I ditched rockers, studs, and plates and went with Jessel's sportsman shaft system. I think there was a large side load from the angled pushrods that wore everything. I think. Maybe. I hope. I drove the car once last week before the rain started. Every thing sounded good. I've had a lot of problems with these heads related to the pour workmanship of the professional engine builder who is no longer in business.

Finally got the heads back from the machine shop. New intake valves, all new guides, valve job. Working last night to check the push rod length. After about two hours of checking, I came to the conclusion my pushrods were the correct length.

I tried it a couple different ways. Looking for the thinnest stripe, not specifically centered. I also tried setting the pivot points of the roller and trunion parallel to the retainer (90 degrees to the valve) at half lift. All these came out to the same.

The smallest stripe I could get was 0.055 or so. Most online sites say I should be less than that. Is 0.055 a good stripe width for a .600 lift cam? I do have hydraulic lifters but am using checking springs.

A .055" stripe is fine for .600". Sometimes you can only go so far with it, due to the geometrical variables of the rocker arm. Some rocker arms do better than others....

OK, installing the studs (with thread sealant), guides, and rockers. Well, the guide plates keep breaking where the stud bolt goes thru the small ring. I give up! I'm torquing to the required 55 ft-lbs. Why is this hardened steel breaking? First, multiple spring failure - machinist says if they weren't heat treated, they would just get weak and sag. If they were over-heat treated, they would fracture/break. Then the valve guide wear. Still no idea why. I've been paying close attention as I've been putting it back together to make sure the geometry was correct.

Now the steel guide plates are breaking. Makes me wonder if I am not getting enough oil into the heads and everything is overheating, the metal becoming brittle, then breaking. Are these guide plates just a one-use item and need to be replaced once heat cycled?

How does a hydraulic lifter function in respect to oiling? I ran the oil pump with the drill. I see oil coming out of some of the lifters. Pushrods are not installed yet. I didn't run the engine over with a wrench or the starter, just driving the oil pump. Oil didn't come out of all the lifters. If I grab one lifter set (Howard brand link bar), oil come gushing out of the lifter hole. Will a lifter only pass oil if it is in the right place up/down in the bore? Will it only allow oil if a pushrod is installed and "pumping" the lifter as it lifts against the spring?

I'm about to invest in some dynamite for these heads...

I would replace the guide plates of course. I have never seen one crack or break.

The lifter will only pass oil in certain positions. If the oil band on the lifter is not in the path of flow, it will be less likely to pass it up through to the pushrod. Roll the engine over and you should be able to get oil out of all 16.

If things got that hot, you would see a lot of bluing on the parts.

https://www.dropbox.com/s/01ruqaly1l...lates.jpg?dl=0

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