Cleaning up a head

[Chris Y]

Ok, the situation is: I have 'recovered' an old cylinder head, which had been lying around on the floor of a garage for over a year. It's a race head, complete with valves, springs, cam and followers. Cam is inside a cam carrier.

Now, the bottom face of the head, the valve heads and inside the ports, is coated with a nice layer of surface rust. Not sure about the cam until I open up the carrier.

So, my question is: What's the best way to clean the head up? Long nights with emery paper? And what would be the best way of tackling the valve seats? (3-angle profile)

[Dave Brand]

I wouldn't use emery on a machined surface - wire wool will do the job & won't do as much damage to the surface. I'd also give it a liberal dose of Plus Gas before starting - dunno if it actually loosens the rust, but it keeps the dust down!

[Al Weyman]

I am doing the same at the moment with a couple of F5000 Chevy heads. I bought one of those highspeed B & Q Dremel look alike drills on a stand with a flexi shaft and have been working away with a light grit roll that fits on a little rubber fitting they supply. Seems to be doing the job OK, trying to stay away from the seats and hope to get away with a valve lape with grinding paste, if not I will have to give them a light lick with a cutting stone.

Mine are a bit beyond wire wool but I agree a bit of WD40 helps. Shame people can't store them properly is'nt it?

[ACE Motorsport]

There is a good rust dissolving acid, I will try and find out its name and post it here next week.

[Alex Hodgkinson]

Don't use anything abrasive on valve seats!!!

If it's been laying around unused for a while it's likely that it's warped, so I'd do something about getting it skimmed.

[zefarelly]

I have resorted to blasting heads, never touch grinding paste with valves, just get the seats recut on the serdi, I have cleaned seats with T cut and a gash valve in the past but don't on my race engines.

re storage, I soak the head and newspaper in a mix of engine oil and brake and clutch cleaner ( home made WD40 ) then wrap them and leave !

I'm rigging up a dishwasher at the moment as a parts cleaner with a recirculating degreasant.

[breezeblock]

i have used nitromors for cleaning off all the **** takes it back to shiny and then a pressure washer with truck wash

[graham bahr]

rotary wire bushes in high speed drills are good at cleaning cast iron and aren't abrasive enough to damage valve seats, although i would always lap the valves in afterwards

[graham bahr]

Originally Posted by Alex Hodgkinson

Don't use anything abrasive on valve seats!!!

If it's been laying around unused for a while it's likely that it's warped, so I'd do something about getting it skimmed.

sorry dont agree there, heads do not usually warp unless overheated and cast iron heads rarely even then

[zefarelly]

I agree with Graham there, heads don't warp for no reason (unless they're mitsubishi diesels, but thats another story)

but I never touch valve seats with anything abrasive

I've recently acquired an aluminium head . . .after years of cast iron abuse I'm scared to touch it !!!

[Al Weyman]

You beat me to that Graham, I can't agree a cast iron head will warp from sitting on the shelf.

[Vernon Head]

Ultra sonic cleaning is best for removing carbon deposits and oil sludge, on alloy and cast. No horrible acid soaking in to those porous castings.

[Russ-Turner]

Alot of people might find this a usefull one to keep in the favourites. (yes it does work!)

http://www.bhi.co.uk/hints/rust.htm

[Chris Y]

Thanks for all the tips so far guys - have had a go at the head today with some Plus Gas and wire wool - has done the trick in some places!

However, there's still quite a lot of surface rust in one or two places in the inlet ports. I had a look for some 'rust eaters', but not quite sure of them. Found some of that POR15 "Metal Ready" from Frost. Apparently it removes rust, but it also etch primes the surface, and leaves a Zinc Phosphate coating - which I guess wouldn't be wanted on a head (or would it?). Other than that, what about plain old metal polish - for the ports?

On a related note - the inlet valves are shiny, but the exhaust valves have a beige coating on them. I'm not sure if this is a deposit layer, or could it be a ceramic coating? It's pitted and damaged in a few places.

[Alex Hodgkinson]

Originally Posted by zefarelly

I agree with Graham there, heads don't warp for no reason

I'm afraid they can do. The metal starts to settle down around areas where it's been exposed to the most extreme temperatures whilst running and in other parts due to the casting grain. So you can start to get a bit of twist.

We've had a lot of big-block American heads over the years to sort out which have done this. Doing such things is my dad's work BTW!

He suggests you use a rotary wire brush on your head.

[graham bahr]

sorry Alex i still dont buy that, 25 years in the deep end of the motor and tuneing trade and i've yet to see it, i wonder how many of these heads came off engines out of shape rather than warping whilst sitting around, if anything i've seen it the otherway round with bent crankshafts following bearing seizure relaxing and becoming straight again after being left a few days.

[JohnD]

If cast iron 'relaxes' how come the (cast) iron bridge, built 1779, at Ironbridge is still standing?
John

[Al Weyman]

On a simliar subject, having worked in the window game for many years would you believe that a pane of glass that has been a window for many years actually gets thicker at the bottom. So maybe the same is true with cast iron especially if not laid flat as most people would anyhow. I think Graham cranks comment I could visulise it trying to go back to its former state, it is not like a bridge as that has not be distorted from its original form unlike the distressed crank in this example.

In the vinyl grapics game I am in now we have two different types of vinyl, Cast and Calendered. The cast is well, cast into shape so holds its original shape better the calendered is squeezed out from a blob like you would make pastry, consequently it trys to creep back to its original shape over time hence shrinkage from cheap graphics. Not the same think in either case but it does demonstrate how unusual materials can behave.

[graham bahr]

arrh the old thicker glass syndrome then,


yes technically glass isn't a solid but a super cooled liquid, so it will change shape slightly given nothing but lots and lots of time,

But cast iron or aluminium for that matter definatly are solid and so shouldn't change shape without any outside influencies

[JohnD]

Plastics like vinyl are long chain molecules, so maybe being rolled out into a flat sheet might be expected to stretch those chains, so that they creep back towards the original shape. Not true of aluminium or iron, which in this application are the cast (non-creeping)form anyway.

And 'glass is a liquid'? Er, no, or not as we know it, Jim. See: http://dwb.unl.edu/Teacher/NSF/C01/C...en/florin.html

John

[Alex Hodgkinson]

Well, I have seen it happen, and obviously you've not. Next time we've got one I'll have to take some photos and measurements to post up here.


Ahh yes, cast iron brake disks, a more common example. Surely you've seen many of these that have warped from just sitting around? It's the same phenomena..

[Chris Y]

Originally Posted by Chris Y

However, there's still quite a lot of surface rust in one or two places in the inlet ports. I had a look for some 'rust eaters', but not quite sure of them. Found some of that POR15 "Metal Ready" from Frost. Apparently it removes rust, but it also etch primes the surface, and leaves a Zinc Phosphate coating - which I guess wouldn't be wanted on a head (or would it?). Other than that, what about plain old metal polish - for the ports?

On a related note - the inlet valves are shiny, but the exhaust valves have a beige coating on them. I'm not sure if this is a deposit layer, or could it be a ceramic coating? It's pitted and damaged in a few places.

At the risk of getting back on topic Has anyone any ideas on the above?

[Dave Brand]

Originally Posted by Chris Y

At the risk of getting back on topic Has anyone any ideas on the above?

Sounds like the normal deposit you'd get on an exhaust valve in an engine running on leaded petrol - in fact, you'd get that colour right through to the tailpipe, not the nasty black you get with unleaded!