cleaning piston heads?

[rrubel]

Ok, got the left-side head off (MAN, those cast iron heads are HEAVY!!). The pistons look like they've got baked-on oil residue (or who-knows-what -- could be RTV for all I know) and I'd like to know the best way to get it off without scratching anything, ruining a ring, or otherwise damaging anything.

Thanks...
[RICHR]

 

[Ken]

You can scrape the heavy crud off with a putty knife or something similar Rich, then use a cleaner on the rest if it bothers you. It shouldn't hurt as long as there's not too much, and there is no damage to the piston otherwise.

 

[JonM]

You may want to use a shop vac once you scrape the pistons...just a thought.

 

[rrubel]

Thanks, guys... It's not like there's a LOT of stuff on there, but the thought of putting something back together DIRTY just rubs me the wrong way. While things are apart, I'm trying to clean everything as much as possible. My poor timing cover is almost a lost cause, but I'm hoping that some sanding and spray paint will take care of it (can't powdercoat because it's got a new seal I don't want to replace).
[RICHR]

 

[tnovot]

piston cleaning

Cleaning the piston tops while installed in the cylinder is not the best way but you probably don't want to hear the alternative.
Do one piston at a time with it at or near the top of the bore. Tape over or otherwise cover the bolt holes and coolant holes in the block.
When doing a piston at the top of the cylinder, a slow speed drill with a wire brush can be a big help.
If you do the pistons while not at the top of the bore, scrape the top of the piston with a scraper which does not have a sharp corner and be careful not to gouge the soft piston or slide off the edge of the piston into the cylinder wall. Maybe make a small protective barrier for the cylilnder out of some aluminum or even a soda or soup can.
When done, use the strongest vac (household or shop) that you can get your hands on to remove as much debris as possible.
Bump the starter or otherwise rotate the engine so that the piston travels downward. You want the rings to move away from the small particles which will be stuck to the cylinder wall.
Use a lint free cloth with trans fluid to wipe the cylinder wall. Do this several times and use a “white glove test” before bringing the piston back up.
Depending on the results of the cleaning, you might want to use a rag with solvent to remove additional carbon.
I don't know if you removed the heads to take them to a shop for rework and new seals but if that was not the purpose, it would be a good idea to do it anyway.
Putting the heads back on with #1 at TDC will simplify ignition retiming.
There's probably more to watch for but I can't think of anything right now. There's plenty of good folks out there who can add helpful info.
Good luck.
Terry

 

[rrubel]

Again, thanks. More good info. I need to clean the cyl walls anyway because lots of crud fell down there while removing the heads. I blasted stuff out with an air can (book suggested a compressed air hose but that I don't have...).

The heads are being replaced by aftermarket aluminum ones... anyone want to buy a pair of cast heads? If I didn't emphasize it enough, those things are HEAVY. I think a pair of AL ones are 40 lbs; these feel like 40 EACH.
[RICHR]

 

[8388]

An old trick I've used in the past prior to removing the heads was to get a spray bottle filled with water and spray into the throttle blades while lightly reving the engine. It won't remove all of the carbon, but you'd be surprised how well it works.

 

[rrubel]

Heh... just a LITTLE too late for that now .
[RICHR]

 

[Ken]

If I didn't emphasize it enough, those things are HEAVY. I think a pair of AL ones are 40 lbs; these feel like 40 EACH.

You got me going Rich, so I tried to look it up.

The funny thing is that although the Specs book doesn't differentiate between the cast iron alloy head and the weight of the aluminum version, it lists the dry weight of a totally dressed engine (dry) in 1985 (with cast iron alloy heads) to be 519.9 lbs. for an automatic equipped vehicle, and 564.2 lbs. for the manaully equipped Corvette. Yet in 1987, with the aluminum heads, the dry weight of a totally dressed engine weighed 541.2 lbs. for the automatic and 592.2 lbs. for the manual transmission!

Why on earth does the aluminum headed version of the engine weigh more than the cast iron alloy headed version?? :confused

It's a mystery to me.

_ken

By the way, it does list the weight of the aluminum heads to be 22 lbs. each.

 

[rrubel]

Ya, I knew when we sent Sothpaw's LT1 heads to be ported, the package with both and packing materials was 45 lbs...

Wonder what else changed between 85 and 87 to make that engine heavier. More emissions crap?

Oh, I think you have your year wrong. 86 lists man/auto dry weights, but 85 only lists one weight - about 580 lbs, no transmission listed. 87 did get a heavier camshaft and pistons, but a lighter crank. Maybe the roller lifters add a bit more, too.

<short pause for research>

Ok. Cast iron heads, complete with valves, springs, and seats, but no rocker arms. 42 lbs each, including coating of oil and crud.

[RICHR]

 

[Mad-Mic]

Ken i am pretty sure your weights include the tranny bolted to the motor as one unit.

 

[livinez]

Lost of fun eh Rich?!

Got my motor ready to pull and called it a day. How many miles on your bottom end? Might want to rering if you are putting fresh tight heads on. New bearings while you are in there too. Old school thing, doing both. Dont want that tight top end to blow your bottom and vice versa.
Sent my injectors to witchhunter ordered a fresh set of Sumho ESCTA Supra 712's (under $500 at Les Schwab for you West Coast C-4 Owners!)
Will decide tomorrow how much rebuild I do After I pull heads and look at bottom end.
At least rings, rod and main bearing. About $200 for good stuff from PAW's.
Man what a load of crap on these motors! About used up a box of baggies & roll of masking tape marking wires and lines.
Usually scrap all this stuff but want to keep the TPI & ECM right until I learn what isnt necessary.
But the air pump and cat are headed for the trash! Well, might just gut the cat :eek and figure how to redo the whole alt./air pump mess.
I used to use a brake fluid soak overnight (pistons upside in a pan with ring lands under the fluid. Then scrape, 200 grit emery cloth going to 400 sand then polishing the tops to a mirror finish. Never had carbon build on my race bikes pistons , but didnt every teardown any the few cars I did that too.

 

[Ken]

I noticed that Rich - that the 1985 specs did not say whether the trans was part of the weight or not, but 1984 does show the transmissions as part of the total weight, and 1987 shows it as a total combined weight. Mike make a few slips like that occasionally.

Mic, the fact that the transmission is part of the weight package does not explain the big difference in overall weight. I mean, the autos and manuals for 1984-1987 were the same transmissions right, therefore the weights should be about the same.

 

[rrubel]

Those Kumho's are under $400 from Tire Rack... have a set on mine right now.

Can't pull the whole engine - no room in the garage and no hoist for the duration. If the bottom end blows, after the 140k miles it's got on it, then I'll have to get a shop to do it. I'm hoping all the internal bearings are decent. The outgoing cam looked good, except for a couple of marks on two of the lobes that might be some wear.

Mic, nice avatar...

[RICHR]

 

[livinez]

Oh I see

Then Tnovot's suggestion is the way to go. Maybe let some solvent sit in the top ring when its at TDC to soften any loose carbon that fell in, and a vacuum might help too.
I saw the tire Rack price and by the time I paid freight, Wa. St. tax and installation(with new stems) & balancing costs it was better to get Scwabs and their GR8 warranties. Plus free rotation not done by yours truly!

Heres to unskinned knuckles and smooth installation of it! TC

By the way, what cam did you go with?

 

[rrubel]

Livinez, went with the Lingenfelter/Accel 74219 cam and SuperRam, plus Pro Topline 64cc heads. Plus other misc goodies...

I'm still taking things off right now (working on right-side exhaust manifold today) - taking it slow and doing maybe an hour a day max. Too much other stuff to do .

[RICHR]

 

[livinez]

Work has a way of interupting fun

Sounds like you did your homework.
After doing alittle myself I've figured that intakes and heads arent the route for me. too much green to get the 85's TPI flowing.
Besides I have a great 4 bolt carbureted 69' 350 looking for a home.
Sooo, no cam or other other speed goodies. Just clean it up, rings bearings, lap job on valves and drive it til I get bored with ti then get a better base to build on(C3 or better equiped 90's vette)
By the way the motor shows no wear, highly tempted to just throw it together but the ring and bearing job is less than $200 (don't need machining) so will do it for the next guys piece of mind. And have to buy gaskets and seals anyway.
I've got about 14 hrs into the removal and teardown. Plus my parts runner blew up! 89 MPV with 1/4 mil miles ate its self.
Back to trying to get cutlass with aformentioned build 4bolt to get traction in Washington sunshine. We are flooding out here and it looks like you are getting your share too! Good time to build!
Thanks for your help & best of luck with your project! TC

 

[rrubel]

Tried to do my homework... hope it all works! Lots of help from here. Also lots of things making themselves known as I go along (AIR pump dying, for example). I do think I found my oil leak, though...
[RICHR]

 

[livinez]

Might have air pump for you

If I decide to scrape that whole system on reassembly. Don't know if a 85's will work for you though. If I do go that route will need yours for parts to make a idler pulley to replace mine in serpentine belt set up.

 

[rrubel]

Thanks for the offer. I'm *supposed* to be getting a gutted AIR pump for free, so the car will at least look stock; if that falls through I'll let you know.
[RICHR]