Cylinder head/manifold erosion

Dave, that might be alot to be milled off, but I had that done on a WC head once that was quite eroded and it worked out fine.  

Okay, thanks guys.  I was considering just milling up a 'sleeve/wedge' to put in there for now (rather than yanking the head)... but I'll wait 'till after I've fired it up to decide on my plan of action. I do have another head here of unknown condition- I'll give it a thorough look-over and see if it's in appropriate condition for a swap.

I assume that if they planed 'em, that there was a fair amount of 'meat' in that casting?

On an old F-350 with 390 that had that problem (brought on, I think, by running with a rotten manifold gasket) I considered making a crushable soft copper gasket that was thick enough to fill the gap. I'd take a sheet of copper and after heating it to red and letting it cool (fast or slow, either anneals copper) I'd form ridges around the places for the manifold openings. So it was corrugated, one or more times. The ridges would make complete passes around each opening. Then I'd anneal it again to be sure it was soft after cutting the require passage and bolt holes and squeeze it in place. On that V-8, exhaust manifold RTV or a new gasket would hold until the first time I used more than 1/4 throttle going up a hill loaded, then the chemical gasket would blow out from the pressure of the pipe and muffler. I didn't ever get around to making the copper gasket. Milling head and manifold is the best solution, if there is metal to mill.

Gerald J.

I put one together like that by filling the "pit" with a high quality refractory (furnace) cement. put it together "wet" and never had a problem with it.

Thanks for the suggestion, ML... I went-a-hunting, and found Belzona 1111- I assume that's the product to which you referred.

Here's a couple'a pictures of it... this is a pretty big gap...




Edited by DaveKamp - 19 May 2010 at 12:58am

And for perspective... this is one of the manifold nuts...

Mine looked that bad also. The reason it looks so bad is because the gaskets are awfully thick. You won't need as much fill as you think. I just used the wire feed to speck in a couple of bad pits and then sanded a little. Not 100 percent right but it was what worked at the time. Mine was the same port.

Edited by Nathan (SD) - 19 May 2010 at 2:43am

I'd still plane the manifold. Did you lay a straight edge across the manifold? I bet that would close the gap up some. Then build the head up with weld and plane it smooth. That worked for me.

Did some more workin' on it, pulled the manifold (it was plugged with a wasp nest) and doulble checked timing, sprayed a little oil in the I-ports, cranked it a few times, then a shot of starting fluid, contact, crank, and she fires nicely on all four for about a dozen rotations, so it's a runner... even the oil pressure gauge jumped, so it's a winner for now.

I put a straightedge on the head, and while there IS a little erosion on the manifold, it's only about 0.044 off.  The head, however, is 0.204" out.  I went to set the manifold up in the Bridgeport to skim a bit off, and noticed a hole burned through the center segment of the manifold, and there's other areas that're very thin.  I looked at my other manifold/head combination, and the #1E manifold side is out by about 0.120", but the mating head side is pretty flat.  The 'necks' of the manifold are pretty eroded down, so I think my best move is to boil out this head, verify the port flatness, and buy a new manifold, reassemble it and call it good.  If I had no other reason to pull the head, I'd find an easy fix, but I'd rather do it right, than do it twice... especially with a new manifold going in place.


Edited by DaveKamp - 19 May 2010 at 7:52pm

Thanks for the encouragement, Dave.

I stripped down this other head... it was gunky, and a couple'a valves were lightly stuck... two of the manifold studs (far right side) broke off flush with the head, and this one doesn't have valve rotators, but does have valve seat inserts.  Springs all seem good.  I'll try MIG-welding a nut to the broken studs and see if they'll back out nicely... I'm guessing that the way the others backed out, they probably will... if not, it'll be a visit to the Bridgeport for a date with the punch and a center-drill.

I'm pretty sure this head is from a WC (no rotators, but seat inserts should date it fairly well).  Would a guy normally replace the seats?  The valve faces are rounded a bit, so they'll need grinding... the seats are probably the same way... I don't think a 3-angle would clean 'em up without really boogering the geometry, but otherwise the valves are good.  I've got a valve grinder, but no seat grinder.

Hmmm... well, it's got seat inserts, but after cleaning the valves, they're not wonderful... and there's no rotators, so this one is a little early.

But I did visit Bill Deppe, and came home with a manifold, some gaskets, and a carb kit for an M-S.

After looking some more, I decided that no matter what route I go, this head will have to come off, and if I have it off, it really wouldn't be a big deal to put it under the mill and trim back.... SO...

I Started pulling down the top end, have everything out of the way, ready to lift the head off, and it's adhered down really good.  Double, then triple checked to make sure that I haven't missed any fasteners... yep, all clear... and even with a carefully placed bar, she won't move.  Now, about 70% of the head-studs are still in place... the nuts backed off, and studs stayed in... so I'm sure that's not helping.

Are there any places on the head/block commonly considered acceptable for driving in a wedge to break 'em free?

Already have the rockers off... you mean, bolt to the rocker-shaft's tower studs and apply lift?  Should I unthread the studs and thread bolts in there with a piece of chain?

Hi Guys!

Well, I double-nutted the studs... couldn't get enough grip, so I TRIPLE-NUTTED the studs (for the water-neck), socked 'em down good, and they STILL laughed at me.

I wound up sticking a piece of 1" bar stock in each port, and putting little hydraulic jacks on 'em.  I was really careful about it, finally managed to lift it free.

Since then, I've cleaned it off, milled the manifold face flat (took off a whole lot!), scrubbed it again, dropped, cleaned, lapped, and reinstalled each valve, and then took a pair of vise-grips and more penetrant to the studs... got most of 'em out, then spun/wire brushed 'em clean, reinserted.

Gotta make a new pair'a gaskets for the water neck, and reassemble... tomorrow's a busy day already, so probably figure on lighting it up on Wednesday or so. Here's a few pix:




Yeah, this flycutter is a bit small for making this pass... and I'm slightly out-of-tram. I made this flycutter about ten years ago, and I should make a few more, probably about 4" diameter would be right... but the lines you see constitute less than a thou... probably more due to deflection (spindle and knee) than tram error.



Edited by DaveKamp - 23 May 2010 at 2:42am

Valve grind looks good! You certainly are having fun.......

That manifold is designed to warp at the ends with those few bolts holding it down. And when the manifold ends warp the head gets eroded like the ends of the manifold. A design flaw.

Gerald J.