Valve guide issue on new crate motor

B

brad.arcova

Member
Not sure what to do next.
0. ran a compression test when new; all about 180.
1. engine now has 7500 mile, ran compression test and found 1-8: 175, 149, 90, 174, 173,170, 183, 166
2. pulled head and found that #3 exhaust valve wouldn't seal. could see light through the valve seat by shining flash light through exhaust port.
3. with the #3 exhaust valve spring removed, found .020 front to rear motion on valve stem; side to side only about .007. When holding valve in a certain position, it seals by the light test but with the spring reinstalled it won't seal.
4. can't find a spec for this test but #5 exhaust valve motion is only .005 front to rear and .003 side to side and the valve seals, no light.
5. its pretty obvious the #3 exhaust valve guide is worn badly. haven't pull the right side head to check #2 cyl yet.
6. The engine and heads have only 7500 miles on them. They are no-name vortec style, cast iron.
7. The rocker arms are stamped steel self-aligning.
8. The valve springs don't stand up straight; I've read that off-square springs can cause excessive wear but don't know if "standing up straight" is the right test.
9. no lubrication problems, lots of pressure and lots of flow.
10. Engine under warranty; what should I ask for? New heads?
11. If the builder won't honor the warranty how should I fix this? new valve guide liners?
12. What's causing this? How can I keep it from recurring?

Brad :(
 
it sounds like you have a valve clearance or rocker geometry issue that caused the excess wear, if it was my engine the first thing Id do is closely inspect all the valve train components for wear , then take them to a good local machine shop and have them inspected and get a written description of whats required in machine work and a list of replacement parts that will be required to get the heads back into great condition.
and Id be highly suspect of a badly aligned rocker stud or valve guide on the cylinders that were excessively worn in such a short time, I think new heads should cure the issue so ID sure hope they would exchange the cylinder heads,not rebuild yours.
BUT if they won,t warranty the heads /exchange them, not rebuild yours I would sure either go to a different QUALITY machine shop for a rebuild with new valve guides ,valve springs and where required valves, or just buy new aftermarket heads.
 
Pulled the other head and found the same issue with the #2 exhaust valve, excessive play in the valve guide front to rear that won't allow the valve to seat with the spring installed. Easy to seat without the spring installed. Seating tested by shining light into the exhaust port.

Since this is a Blueprint crate motor with new no-name heads, I don't have a lot of confidence that even with a new set of the same no-name heads I won't be going through the same thing in another 7500 miles. I'm sure not going to spend good money fixing cheap heads when I can get a set of Chevy Vortec heads for $620.

If I can get new heads from Blueprint under warranty I'll sell them on Craig's List.

Now that I've got the top end apart, I'll get that set of new Chevy Vortec heads, a Crower roller cam and all the associated parts to put a high quality valve train together. I'm done with cheap no-name parts.

Brad
 
brad.arcova said:
...

Now that I've got the top end apart, I'll get that set of new Chevy Vortec heads, a Crower roller cam and all the associated parts to put a high quality valve train together. I'm done with cheap no-name parts.

Brad
Click to expand...

thats a hard lesson we ALL eventually learn, and its not always obvious,but for most guys the lesson needs to be repeated several times to stick!
but you DO EVENTUALLY LEARN IT , when you actually learn to measure and critically compare part quality rather than just grab the least expensive parts the catalog suggests fit and install them right out of the box. usually its a darn expensive lesson, like when you save $800 on a cheaper rotating assembly only to have to replace the engine when a connecting rod exits the block at 6000rpm, or when you stomp on the brakes and have the brakes fail and you kiss a guard rail and need to replace a fender, a-arms and a spindle, Ive seen those parts failures happen several times


or the way my mentor always stated it,
"its better to have 4-5 top quality performance up grade parts you really took the time to research, that work correctly, than 10-15 parts for the same cost, that you bought simply because they were priced low enough that they seemed to be a bargain, especially once you realize most of them need to be replaced
viewtopic.php?f=34&t=483&p=13049&hilit=u+joints+corvette#p13049

viewtopic.php?f=33&t=3128&p=8340&hilit=u+joints+corvette#p8340
 
brad.arcova said:
Pulled the other head and found the same issue with the #2 exhaust valve, excessive play in the valve guide front to rear that won't allow the valve to seat with the spring installed. Easy to seat without the spring installed. Seating tested by shining light into the exhaust port.

Since this is a Blueprint crate motor with new no-name heads, I don't have a lot of confidence that even with a new set of the same no-name heads I won't be going through the same thing in another 7500 miles. I'm sure not going to spend good money fixing cheap heads when I can get a set of Chevy Vortec heads for $620.

If I can get new heads from Blueprint under warranty I'll sell them on Craig's List.

Now that I've got the top end apart, I'll get that set of new Chevy Vortec heads, a Crower roller cam and all the associated parts to put a high quality valve train together. I'm done with cheap no-name parts.

Brad
Click to expand...

Before you jump off the deep end, why not determine if the valve train geometry was so far off that it's the reason that the valve guides failed. Even quality parts are going to fail quickly when not setup properly. You can't say the heads were the problem until you KNOW what caused them to fail.

viewtopic.php?f=52&t=528&hilit=geometry
viewtopic.php?f=52&t=697&hilit=geometry
viewtopic.php?f=52&t=4957&hilit=geometry


 
Took a lot of measurements and the bottom line is that the valve guides were crooked to begin with and the valves were initially seated with those crooked guides. The rest of the valve train geometry is correct and with the springs installed the valves stand up straight. Over 7500 miles of driving, the geometry has forced the valves to stand up straight and in the process wearing the crooked valve guides heavily so the valves will stand up straight. When the valves are standing up straight though, they won't seat because they were initially seated with with crooked valve guides.

I'm measureing straight and crooked by checking how parallel the valve stems are. With the springs intalled, the stems are parallel. With the springs off, I can move the valves side to side (i.e. front to rear) in the guides until the valves seat. When the valves are seated, the stems aren't parallel. The valves themselves appear to be straight and undamaged. The seats don't have any detectable imperfections. The stems have worn more on one side as they've worn away the valve guide as the springs force them to stand up straight.

The head seating surfaces appear very straight and I don't see any cracks or any other kind of imperfections.

I suppose I could grind the valve seats so that they seat with the valves standing straight up but then I'd still have badly worn valve guides. I could also take the heads to a machine shop and have all the guides redone but that would be a minimum of $200 and not include any other work.

I'd hate to spend that kind of money on cheap heads.

I'll see how my warranty claim goes but if I have to spend my own money, I'll get new GM vortec heads. Does that sound like the smart solution?

Is it common to have new valve guides be crooked and out of parallel?

Brad
 
a lot of guys love those standard 170cc vortec heads, "because they don,t cost a great deal but out flow fuelie heads"
what they forget to mention is all the little changes that are required and how the cost rapidly add up to the point they are not the screaming great value you may think, especially if your looking for big power numbers
there are options.
bye the time you purchase the vortec heads, self guide rockers, better valve springs, get the heads machined , get the matching intake, center bolt valve covers etc. you could just add a small bit more and get far better heads that allow re-use of the standard intakes, valve covers, rockers etc. and heads that far out flow the vortec heads that are designed to maximize torque at only about 4800rpm, vortecs in stock form only flow about 230cfm, while thats a good deal better than the stock SBC heads that seldom flow more than 200 cfm, its pathetic compared to the better aftermarket heads available
before going further, your describing the rocker binding at location (B) not location (A) or (C) correct?

rpo1x.JPG


Always measure the clearances and check valve train geometry, if you find its binding up at some point like valve spring coil bind, or a rocker slot hitting the rocker stud, or a rocker hitting a retainer, etc if, thats the case the push rods or the rocker studs or the guide plates are wrong for the application OR you never had the cast rocker bosses in the heads correctly machined for the screw in studs

studs1.jpg

standard screw in rocker studs to use with or without guide plates require the rocker stud boss be machined for required clearance
studs2.jpg

there ARE screw in rocker studs that can be used WITHOUT machining the bossed but they CAN NOT be used with guide plates and DO frequently result in cracked rocker bosses.

studs3a.jpg

stock cast rocker bosses must be machines to gain clearance for guide plates and screw in studs
millboss1c%20(2).jpg

EACH type of engine and every set of rocker guide plates and studs will effect how far the rocker boss must be machined for clearance but on most sbc engines the boss is machined down about .360, CHECK WITH YOUR MACHINIST AND HAVE THE PARTS AVAILABLE TO MEASURE
READ THRU THESE LINKS CAREFULLY, once again a few hours spent reading links, before proceeding further, can save anyone dealing with similar questions a great deal of time and money


compare a few heads
http://users.erols.com/srweiss/tablehdc.htm

viewtopic.php?f=52&t=333&p=27234&hilit=head+flow+numbers#p27234

viewtopic.php?f=32&t=5521&p=23459&hilit=l98+aluminum+heads#p23459

viewtopic.php?f=44&t=7463&p=25274&hilit=head+flow+numbers#p25274

viewtopic.php?f=52&t=462&p=24466&hilit=head+flow+numbers#p24466

viewtopic.php?f=99&t=6461&p=20464&hilit=head+flow+numbers#p20464

viewtopic.php?f=52&t=5078&p=18935&hilit=head+flow+numbers#p18935

viewtopic.php?f=52&t=2630&p=21649&hilit=valve+guides#p21649

viewtopic.php?f=52&t=984&p=1723&hilit=valve+guides#p1723

http://www.rustpuppy.org/chp/

http://www.airflowresearch.com/articles ... 0/A-P1.htm

http://www.airflowresearch.com/articles ... A27-P1.htm

viewtopic.php?f=44&t=529&p=27299&hilit=machining+vortec#p27299

viewtopic.php?f=44&t=6175&p=19304&hilit=machining+vortec#p19304

viewtopic.php?f=52&t=401&p=6078&hilit=machining+vortec#p6078

viewtopic.php?f=52&t=266&p=321&hilit=machining+vortec#p321
 
Well, I made my warranty case to BluePrint Engines and they sent me a set of replacement heads that just arrived, no cost. Unlike the old pair, these have a GM casting number so I'll put these on and see what happens.

Brad
 
glad to see they stood behind the warrantee!
let us know how things work out, once the replacement cylinder heads are installed
 
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