Author Topic: So was Sanborn right or wrong about my valve damage...? (Read 1574 times)

70_Fastback · « **on:** June, 28, 2009, 04:33:25 PM »

Dis is what I found when I yanked da heads off...

all exhausts and an intake:

intake and exhaust here:

Got the intake pretty good on dis one:

Fast68back · « **Reply #1 on:** June, 28, 2009, 04:35:43 PM »

How deep are they? Can you catch a fingernail on it?

tarafied1 · « **Reply #2 on:** June, 28, 2009, 05:22:35 PM »

well, for sure they got smacked, but are they bent? Do you have a valve spring compresser so you can pull 'em out? The valves are much harder than the pistons, do the pistons have any damage?

70_Fastback · « **Reply #3 on:** June, 28, 2009, 05:35:13 PM »

Quote from: Fast68back on June, 28, 2009, 04:35:43 PM

How deep are they? Can you catch a fingernail on it?

You can catch a nail on them. Some more the others.

70_Fastback · « **Reply #4 on:** June, 28, 2009, 05:36:42 PM »

Quote from: tarafied1 on June, 28, 2009, 05:22:35 PM

well, for sure they got smacked, but are they bent? Do you have a valve spring compresser so you can pull 'em out? The valves are much harder than the pistons, do the pistons have any damage?

yeah, I've got a spring compresser. Just ran out of time today. I'm going to pull them all and stick'em in the valve grinder and spin them to check if they are bent.

blue65coupe · « **Reply #5 on:** June, 28, 2009, 05:39:11 PM »

that sucks

70_Fastback · « **Reply #6 on:** June, 29, 2009, 05:51:44 AM »

Quote from: blue65coupe on June, 28, 2009, 05:39:11 PM

that sucks

Eh, what can you do? Fix'em and move on.

daveSanborn · « **Reply #7 on:** June, 29, 2009, 12:20:06 PM »

Hmmm..... well I'll be damned. For my next bet, I'd like to venture that none of the valves are bent....

70_Fastback · « **Reply #8 on:** June, 29, 2009, 12:45:03 PM »

Quote from: daveSanborn on June, 29, 2009, 12:20:06 PM

Hmmm..... well I'll be damned. For my next bet, I'd like to venture that none of the valves are bent....

ok, I'll poll that one next

Sluggo · « **Reply #9 on:** June, 29, 2009, 02:46:52 PM »

U don't need to chuck them up in the valve grinder. Just take them out and roll them on the kitchen table. You'll know immediately if they are bent.

daveSanborn · « **Reply #10 on:** June, 29, 2009, 02:59:22 PM »

What on each piston caused that nice clean line/witness mark on the valves? Is there some kind of "ridge" on your piston tops? And... is there a corresponding witness mark on each piston?

Sluggo · « **Reply #11 on:** June, 29, 2009, 05:12:32 PM »

Quote from: daveSanborn on June, 29, 2009, 02:59:22 PM

What on each piston caused that nice clean line/witness mark on the valves? Is there some kind of "ridge" on your piston tops? And... is there a corresponding witness mark on each piston?

Yeah! Take a pic of some pistons foo.

I'm guessing he has some domes on the pistons. I'd bet the pistons have nice little mash marks on them.

lethal289 · « **Reply #12 on:** June, 29, 2009, 05:17:43 PM »

those valves are to consistent, i wonder if maybe they were hitting the pistons before the failure.

Sluggo · « **Reply #13 on:** June, 29, 2009, 05:24:10 PM »

Quote from: lethal289 on June, 29, 2009, 05:17:43 PM

those valves are to consistent, i wonder if maybe they were hitting the pistons before the failure.

That's a very good observation. If the gear drive failed and allowed the cam to stop turning there is no way it could have smacked all the intake valves.

Maybe the valves were touching all along and caused the gear failure.
I'm sure the valve lift on the cam was greater on the intakes too.

70_Fastback · « **Reply #14 on:** June, 29, 2009, 05:34:27 PM »

I thought it was odd as well that all of the exhaust valves hit. And the pistons are flat tops w/ valve reliefs

AzPete · « **Reply #15 on:** June, 29, 2009, 05:37:57 PM »

So are the valve reliefs in the right position? This gets more interesting all the time.

lethal289 · « **Reply #16 on:** June, 29, 2009, 05:42:11 PM »

Quote from: Sluggo on June, 29, 2009, 05:12:32 PM

Yeah! Take a pic of some pistons foo.

I'm guessing he has some domes on the pistons. I'd bet the pistons have nice little mash marks on them.

have any pics of the pistons yet jeremy?

70_Fastback · « **Reply #17 on:** June, 29, 2009, 05:49:58 PM »

trying right now. keeps crapping out on me

70_Fastback · « **Reply #18 on:** June, 29, 2009, 05:57:41 PM »

during build:

After:

AzPete · « **Reply #19 on:** June, 29, 2009, 06:00:16 PM »

Looks like things were a bit tight from the beginning.

Fast68back · « **Reply #20 on:** June, 29, 2009, 06:04:27 PM »

What rockers were/are you running? Comparing the pistons to the valve marks, either the rockers are opening the valves to far or the cam is a lot larger than planned.... I think that timing gear mishap probably saved you a bunch of cracked pistons.

lethal289 · « **Reply #21 on:** June, 29, 2009, 06:11:27 PM »

i agree, it looks like those piston/valves were hitting long before the timing gear gave way. I would think that the marks wouldnt be so clean if it was just from a few smacks as the motor was shutting down.

daveSanborn · « **Reply #22 on:** June, 29, 2009, 06:14:16 PM »

Quote

I think that timing gear mishap....

...may have been the result of a larger problem. Like too much valve lift.

Are we looking at both heads, or just one? Does the other head look the same way? That will tell us more.

70_Fastback · « **Reply #23 on:** June, 29, 2009, 06:27:45 PM »

both heads are the same Dave.

it's a 70 block with '68 heads w/ stock valves also.

I think I listed my cam spec earlier in the post. And 1.6 ratio roller rockers.