can I use SOS pads and water to get the rust and gunk off? What'd you use

 

I went with $20/head to have them baked and blasted at a machine shop in town.

They came out looking brand new, and I just painted them.

 

Bead blasted (not sand) makes them look brand new.....

 

I cleaned mine with a plastic Visa card.........when I was all done it looked brand spanking new...and was completely aluminum... :lol: :lol:

 

Instead of starting a new topic Ill keep it in here..... whats steps do I take first? Should I 1st have them cleaned 2nd polish them myself 3rd have the exhaust seats hardend? What other things am I missing? What steps do I take them in... Im new to this so any more minor details and tips would be a great help. thanks :cheers:

 

This gets the "laugh of the day award" :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

 

If you want to have the heads re-conditioned, then the same engine machine shop that bakes/bead blasts them can also do an inexpensive valve job on them. Depending on how much you spend, valve guides can be knurled (cheapest) or new bronze guides inserted (and only where there is excessive guide wear), valve stem seals replaced (and/or umbrella seals added for a tad more), valve springs replaced, valves cleaned, 3-angle valve cut performed and the bowls of the intake runner (exhaust runner too?) blended. And there's always the valve replacement. Once you get into the price-range of a thorough valve job ($250-300) then you are approaching the point where you have to decide if you'd not just rather upgrade to good aluminum or cast iron heads. Just depends on pocketbook thickness and how much is needed... :seeya


[Modified by TedH, 3:13 PM 4/5/2002]

 

I machine heads... professionally.... have been for nearly 30 years.

Knurling is a no-no. Reduces the load bearing surface by 50% and doesn't last long.

Hardened seats are a waste of money.... based on a myth started when the anti-unleaded crowd needed fodder for their arguments.

Pitted seats will occur in any seat given the right conditions... whether the seats are hardened or not.
Hardened seats are an easy sell to people who have no experience in head work.

The damage occurs when an engine is driven with a lot of carbon buildup... the stuff flakes off and gets jammed between the valve face and the seat... the surfaces get damaged, and the problem snowballs. It also happens when someone changes an intake and drops crud into the ports., or, if valves are used that do not have sufficient margin (knife-edged) for proper heat dissipation.

PS- I have been sandblasting heads for about 30 years as well... never, ever had a problem with sand as media.
I put bolts/nuts in the valve guides to protect them.

Tom

 

>Hardened seats are a waste of money...

Really, this is something I have never heard, here or in engine rebuild books.
That's a good money saving tip!

:cheers:

 

For 200.00$ I had the springs seats cut for bigger springs. All bronze valve guides, and had then heads decked and tanked. 216.69$

 

Tom, I have used both sand and glass bead to blast heads. I have noticed that sand does seem to be more abrasive than glass bead, especially if it is used on heads that have had some porting and/or bowl polishing done in the past. It seems to my touch that it leaves them with a little rougher finish than if I use beads. Maybe I should try a different grade of sand.

The plugging of the guides is a good tip, especially if you take the heads to a shop that does general blasting. They may not plug the guides....make sure you plug them before dropping them off.

 

RE: Sand vs beads... yes... sand can leave a very rough finish. But as noted, the "grit" (size) of the sand is the determining factor. Because my blasting cabinet/system automatically recycles the sand, it gets re-used repeatedly. As it is used, it breaks down into smaller & smaller particals. As it reaches a small powder, it gets sucked up and blown out the vent by the box evacuation fan (squirrel cage blower from a Xerox copier). As the sand "disappears", I mix fresh sand in with the old to replenish the hopper. The result is, at any one time, the sand is not so harsh that it chews up heads (or blocks), but still provides a good cutting speed. I also have buckets of super fine (used) sand on hand for doing aluminum wheel rims. It's all a matter of technique.

I rebuilt a set of heads for a customer off a Corvair. They are aluminum. They had sat for a long time with a corrosive substance in one of the chambers. He insisted that I NOT sandblast the heads. However... the one chamber was so totally crusty that I could not refinish it without sandblasting it.... so I did. At first, he was upset when I told him I had to blast the one chamber... but when he saw the quality of my work, he agreed that I made the right decision. It all depends on "technique".

RE: The hardened seats... most "modern" engines do not have hardened valve seats. If unleaded fuel were such a risk, then that would not be true. I do the machine work.... I don't just read about it. Because I have been doing it for so long, I have had the opportunity to re-visit heads that I had machined myself, after 200,000 miles. Engines with significant carbon buld-up (primarily due to worn valve seals) have the most severe valve seat/face wear. Those that have had regular service, including valve seals, have the least amount of damage.

Hardened seats are a good thing. I'm not saying they're a Bubba. But based on my "real world" experience as an automotive machinist, hardened seats are not necessary (except in aluminum heads, of course). If it makes you feel better about your engine... then by all means... have them installed. But unleaded fuel does not have the drastic affect on valve face/seat life as predicted.... it's just not true based upon my experience. I read books too... it's a very enjoyable experience. But you can't believe everything you read. The "spin the push rod" method of setting rockers is another perfect example. And- anyone in their right mind would not disassemble a Corvette rear spindle and set the bearing endplay to .008 even though the service manual specifies .001 - .008. Sometimes you have to split from the crowd and think for yourself.

Tom

 

Spend a little money and have the shot peened. I do that at work and they look great.

 

[QUOTE]The "spin the push rod" method of setting rockers is another perfect example. Tom [QUOTE]

Tom
Do you suggest the "rock the rocker" method of valve adjustment?
Thanks
Ed

 

Yes sir.

I have demonstrated the deficiency in the "twisty turny" method at several engine clinics that I have personally presented.. (here in NC, in NY, and NJ) and the verdict is always "guilty".

Lifters all have their own personality. If you get a whole set to exhibit the exact same back pressure for a lifter adjustment, you also must walk on water.

I can't begin to count the number of times I have been called to a twisty-turny disaster... sometimes the valves are even bent.

Rock the rocker rules, but you can't "ape" them... it takes a little tenderness. :)

 

Tom

I find it hard to believe that with todays exacting standards that a company could not produce lifters that behave at least close enough to make it impossible for the human hand to tell the difference between the pressure they exert unloaded. How the hell are they going behave even close with the engine is running? If what you say is true, I'm not saying I could design a lifter myself but I could probably find some and hire them, that could. What gives the lifter is initial pressure or spring?

I might be dead wrong and if so, please explain why lifters can't be produce to a more exacting standard so I can know why.

Thanks

Chris

 

I'm sold on Bake 'n Blast. I've had two motors done; about $50 for block and heads. Nothing else gets the soaked-in oil out of cast iron. Most engine rebuilders have it now.

 

Keep in mind that we are talking about cast iron heads. Aluminum heads still require valve seat inserts don't they? I took apart a 350 with aluminum heads that didn't have any seats installed...and they were worn about 1" into the head...I have no idea how it kept running, but I think it had no more than about 100hp. I've seen some of the strangest things with engines due to people not keeping their perspectives on advice.

Oh, almost forgot...normally when I do heads I just clean them a little bit with some degreaser to provide clean semi-clean surfaces to hold onto, then I take them down to a local machine shop and have them clean it with whatever method they deem reasonable and have them dissassemble and inspect everything, and put it back together ready for an install. But, since we are talking about a corvette, then first a nice acid hot tank, then some bead blasting, then some scraping tool messaging, then some sand paper, then a nice soak in degreaser and blasted with carb cleaner than water and set out in the sun to dry...then paint it real purdy.


[Modified by Rockn-Roll, 7:43 PM 4/8/2002]

 

Okay... I'll try to explain. And this is NOT a flame. I'm just in a hurry.

I have over 30 years of experience actually machining heads & building engines. Not as a backyard mechanic, but as a professional. I owned and operated my own 7 bay shop. Now, that in itself may not mean much... I could still be a "Bubba". But coupled with an excellent track record, it then becomes significant. I don't design valve train parts either... I just work with them.

It's not just the internal spring pressure that determines a lifters dynamic "state" in an engine. It's the internal hydraulic pressure as well.

During the most recent "clinic" I ran, I purposely grabbed 4 lifters from a pile of 16 that I had just removed from a "was running" (SBC) engine.
Two of them could be compressed fully with finger pressure, and two were solid as a rock. This is the problem with "twisty-turny"..
Two of these lifters would exert a backpressure instantly, the other two would compress significantly sooner exhibitiing the same back pressure... which is what the "twisty turny" method relies upon. The end result is two loose lifters, and two over-tight lifters. And this is exactly what I see out in the "real world", not in the books. It becomes even more difficult to trust this method when you cannot actually see what the lifter is doing... way down inside the engine.

My opinions on this are based on 30 years of "hands on" experience, not books, not theories, and no arm chair speculation.
Anyone that wants to challenge me to a dual... I'm ready. I'll pit my experience against the service manual any day.
Doesn't matter what todays technology can produce... the basic lifter design is the same, and the dynamic state is indeterminate by using the twisty turny method.
So... you can believe whatever you want... I'm just reporting the facts as I see them from a service technicians point of view.

mountainmotor.... was that good enough? Or do I need to work on my delivery & tact?

MELVIN: Witness?

Clinic participants: Am I right?

This topic keeps repeating... I need to write a "white paper" so it becomes self evident. :)

Again...not a flame. I write like the techy that I am.

Tom

 

You are making very valid points. May I give you my opinions on this subject.

From my experience, lifters are a very well engineered and constructed product that are made to an exact standard.
As soon as you use that lifter, now you have introduced oil, perhaps additives, maybe some contaminants to that lifter.

At any given point a used lifter will exibit it's own characteristics, which as Tom has stated, makes the "twisty-turny" method not applicable.

If you adjusted the valves and ran the engine for a period of time, and then adjusted the valves again, you could have any given lifter act differently from the prior adjustment.

The point is, once the lifter has been used, each one can act a bit different.

Regarding the initial pressure in a lifter, it is a spring, and not a very strong one. Lifters are a hydraulic device. They function by means of engine oil pressure.

Hope this helps a little.
Barry