Saving Old Seagulls

Ok, my trusty Series 90 the efforts to unblock the cooling passage has been unsucessful. SO I am going to take the head off and manually chip away the crud.

Is there anything I should know befre I do. I know about the risk of snapping head bolts thus I am guessing liberal amount of plusgas and reversing the thread every 1/4 or 1/2 turn. Oh and I bet new head bolts are required too.

Anything else?

Heat helps, applied to the block itself.

Don't use a 1/2" drive socket ratchet to undo it, use a shortish 5/16 BSF or a 1/4 Whitworth ring spanner & be gentle.

ta

I'm doing (another) one at the moment. I find it's just as quick to deliberately shear the heads off, then drill-out and re-tap the threads. Last time I did this I replaced the bolts with studs, so that the head could be pulled off in another 20 years time without all this faffing about. I'll probably fit studs again this time.

SAE 140

Another option I like is to drill out all the threads & fit helicoils. You can go either SAE or metric

Then fit brand new stainless bolts. Capscrews look nice, but, can be prone to chewing out the inhex

Rex

i had a partial blockage sugar soap did the trick.

This is a complete blockage

Whipped 3 of the the bolts off last night, the bolts are fairly new and had some kind of sealant in the thread thus little corrosion. Hence they came out very easily. So the question is, how badly was this chap looking after this motor if the head has been off recently I presume he would have cleaned out the cooling system. I was called away by SWMBO before I could get at the 4th bolt.

Translation

SWMBO : she who must be obeyed

SWMNBN : She Who Must Not Be Named

Is it wrong to have both?

How bad is this then on a scale of 1 - 10?



I think there are living organisms is there

I have seen worse, I have one with the piston still welded in.

Ok, having cleaned out the cooling passages I am ready to reassemble but the head it rather tatty and I am not sure it is smooth enough, even with liquid gasket goo, to get good compression. What is the score on skimming the heads on these?

Also I take it that the jacket is supposed to not sit flush with the head as per the image above?

Skim away, can be hard to hold.

Takes longer to set up than do.

Stepped bar fitted in ports bolted through head stock or metal disc and revolving centre to hold cylinder.

Head I used a piece of angle with holes in it bolted to the faceplate.

H-A

P.S. thought you had given up. There are loads of spare heads about if the head is that bad.

I machine a lot of heads & cylinders & have fixtures for both.