Author Topic: Guessing I need to resurface?? (Read 4174 times)

Brady · « **on:** April 15, 2013, 01:40:16 PM »

Soooo. got my cylinder head bead blasted last week to clean up all the carbon. long story short. they blasted the mating surface w/ glass and it looks like this now. am i right that this is going to need to be resurfaced?

70CB750 · « **Reply #1 on:** April 15, 2013, 01:42:23 PM »

How is the surface quality?

Bankerdanny · « **Reply #2 on:** April 15, 2013, 01:52:51 PM »

You're not the first person to experience this.

I would think that an experienced shop would (a) know not to blast the gasket mating surface or (b) ASK, "is there any place that you don't want blasted?"

Brady · « **Reply #3 on:** April 15, 2013, 02:01:07 PM »

Quote from: Bankerdanny on April 15, 2013, 01:52:51 PM

You're not the first person to experience this.

I would think that an experienced shop would (a) know not to blast the gasket mating surface or (b) ASK, "is there any place that you don't want blasted?"

yeah, they do engine work too. i asked before to make sure as well. he said it wouldn't be an issue....shoulda told him to boil it.

@70cb750 it's smooth still...no where near as prior but smooth. what are you thinking?

iron_worker · « **Reply #4 on:** April 15, 2013, 02:08:22 PM »

I would get it surfaced. The head gasket requires a certain surface finish to seal properly and I think if you had it tested you would see it's way off due to all the tiny "dimples" in the surface now.

It's either that or risk blowing a head gasket down the road.

IW

70CB750 · « **Reply #5 on:** April 15, 2013, 02:10:04 PM »

I would check it for flatness - steel ruler and bright light helps - and use it without resurfacing if it is flat.

The surface would have to be pretty "hilly" to cause a leak by itself.

nancy · « **Reply #6 on:** April 15, 2013, 02:12:41 PM »

Not just the gasket mating that is threatened is it? Wouldn't the valve seats be possibly compromised as well?

iron_worker · « **Reply #7 on:** April 15, 2013, 02:14:54 PM »

Yes, valves will have to be lapped for sure.

IW

RAFster122s · « **Reply #8 on:** April 15, 2013, 02:17:36 PM »

Yes, the valve seats will have to be lapped smooth or valves cut to restore their sealing surface. They screwed up your head, caused a lot more work. Who was the shop, so others can avoid them. Definitely wouldn't give them any more business and would share the experience with others to "help" their business given it appears they are looking to line their pockets with additional service charges.

iron_worker · « **Reply #9 on:** April 15, 2013, 02:24:55 PM »

I watch this series of videos off of youtube:

Mercedes Benz 6-Cylinder Head Resurface

The guy measures the surface finish "Ra" at the end. You can see it needs to be very smooth.

IW

754 · « **Reply #10 on:** April 15, 2013, 02:58:04 PM »

I think the blasting would if anything , improve the head biting into the gasket.. ..

iron_worker · « **Reply #11 on:** April 15, 2013, 03:21:12 PM »

From what I understand that is an old school methodology or way of thinking. Any modern type gaskets require the surface to be as smooth as possible.

IW

754 · « **Reply #12 on:** April 15, 2013, 03:29:13 PM »

Works great for base gaskets.. On big bores it helps..

Brady · « **Reply #13 on:** April 15, 2013, 05:04:20 PM »

hmmm. well what to do.

i was planning to relap valves and seats anyway so no biggie there....i have a lead on a cylinder head w/ springs and valves in really nice shape for about the same it would cost to resurface....i may just do that anyway.

on the bright side i snagged a 650 cam to drop into my 550 today.

what am i out if i try to make this head work? $$ for a new head gasket and time/energy to replace it? what's the consequences of just trying it out? just leaks or low compression yea? not going to blow the engine right?

70CB750 · « **Reply #14 on:** April 15, 2013, 05:19:38 PM »

Do more research on it. Opinions are like aholes, everybody got one

I would like to know more on it too.

thirsty 1 · « **Reply #15 on:** April 15, 2013, 05:22:29 PM »

You say they used glass beads? I wouldn't glass bead the mating surface myself but I wouldn't have a problem putting it together either. Glass beads break and don't take material like sand. They will take material if the nozzle sits in one place for say 10-15 seconds but if they just went over the surface then no biggie. I know I'm new to this board but I use a glass bead machine at work all the time. I'd check the surface for dips and high spots. If its ok then run it. I also use copper coat but that's just me. Rubb it down with a red scotch brite pad and check for trueness. You might be surprised.

thirsty 1 · « **Reply #16 on:** April 15, 2013, 05:26:53 PM »

One thing I would do is run a tap in ALL of the holes. There is bound to be debris left over and putting bolts in holes with left over glass beads will not work. Chase out those threaded holes. Check the thread in my sig. You'll see a complete engine glass beaded.

Brady · « **Reply #17 on:** April 15, 2013, 05:43:20 PM »

Quote from: 70CB750 on April 15, 2013, 05:19:38 PM

Do more research on it. Opinions are like aholes, everybody got one

I would like to know more on it too.

yea i found a lot of threads saying it would need to be resurfaced but nobody that had actually tried a head in this condition and whether it worked or not....i may still just get that other head i have a lead on b/c my valves were so cruddy i was considering getting new ones anyway...i also have one slightly sticking in a guide so the head isn't in the best condition to begin w/.....bike was running prior to disassembly w/ a spun crankrod bearing on #4.....

if i use this thing i'm going to pressure wash the bejesus out of it to make sure it's clean.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #18 on:** April 15, 2013, 06:06:34 PM »

If I used it I would be tempted to use an old style or graphite gasket that would seem to conform more to that surface than a MLS gasket.

750IV · « **Reply #19 on:** April 15, 2013, 07:39:15 PM »

I would run a wet stone over it with WD40 or even water and you will be amazed on how smooth it ends up. The better stones have a smooth and a rough side. Use the smooth side.
750IV

754 · « **Reply #20 on:** April 15, 2013, 07:58:09 PM »

Put a straightedge on it..if its bowed..the blasting is a non issue..

lucky · « **Reply #21 on:** April 16, 2013, 08:38:10 AM »

Quote from: 754 on April 15, 2013, 02:58:04 PM

I think the blasting would if anything , improve the head biting into the gasket.. ..

Exactly. Not a problem.

If the valve seats were blasted I doubt it would even effect that very hardened steel at all.

iron_worker · « **Reply #22 on:** April 16, 2013, 08:59:42 AM »

If you're going to run it as is I would use the old school fiber type head gasket as they were designed to take up some surface imperfections of common machining practices of the day.

Since machining has improved more and more they have gone to more MLS and copper head gaskets which need a very smooth and flat surface but are ultimately stronger if the surfaces are prepared as they should be.

IW

crazypj · « **Reply #23 on:** April 16, 2013, 10:47:28 AM »

I would skim it 0.010", but, I would skim it even if it hadn't been blasted

Slight bump in compression won't hurt anything

Brady · « **Reply #24 on:** April 16, 2013, 11:58:05 AM »

i'm probably just going to snag this other one w/ springs and valves. looks to be in better condition all around than mine.

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Author Topic: Guessing I need to resurface?? (Read 4174 times)