Tuks head is it fixable ???
Turbo Mini Forums

tuk bought this head local to us, the valve seat on chamber 4 is goosed, but is it fixable ie can new seats be put in and it made good again. there is a discussion on the TMC (our club) forum

i have cut and paste my findings on the strip down of the head. here you are any ideas ? he was also sheering rocker that opens number 4 exhaust (i think) my opinion was as below but i could be wrong, i usually am

it has 30 cc chambers which i measured with a syringe, he is running omega pistons i believe but not sure what cc it is. the piston comes flush with the deck

below is lifted from this thread link

http://www.tynemouthminiclub.co.uk/forum/v...=6493#post_6493

right 30 cc chambers have been cut into the head, the beaks have been removed so i can confirm looking at port size it has been used in conjucntion with flat tops what cc pistons did you have ? the reason i ask is i have 6-7 cc pistons and 28 cc chambers and i am running 8.4:1 low compression engine. this is ok for turbo. for n/a i dont think you want to run anything less than 9.5:1 the car wont have any pull, and more importently you may blow the bottom end shells out over revving, basically you would probably have to ring its neck to get anything from it. (engine rebuildsville tennesse) if you let me know the cc of ure piston tops we could work it out. the head is very old IMHO the chamber shapes have been cut old school but non the less it appears good. I would argue that it has NOT been profesionally done, the eleventh stud has been drilled half way through from the underside ? why thay have stopped is beyond me ? the porting in the head is average to good and finished quite nicely, albeit it could be better.

if the valve seats are the only issue we will get the head skimmed and up the CR a bit (pending on ure pistons )

on another note i have measured the head with a vernier gauge against a stock 12g940 casting i can confirm that there is around 20 thou (just over) taken off the top/bottom of the head and face has been machined too this has made the head thinner and so in my opinion the rocker assembly would sit lower and i reckon what has happend is the push rod has opened the valve as it should, the valve has "topped out" and become solid (hence the springs are bound when its under load) the cam has continued to try and lift the pushrod and the end result is that it has sheered the rocker. Tom can you confirm that it sheered on the pushrod side ?

I will drop the valves and pray that its just blown through the seat if it has we are in business !!

i need the cc for the piston from you, the cam, carb and needle spec and zaust ure using, then we can refer to vizzards, there is a specimen 1330 hot road build in there

dont be dis heartened Tom. Jordie has probably built a great engine for you, this lil mis hap happens to so many when buying heads, especially second hand ones.

i will take pics of the head next to another same spec n/a head that i have, if the head is salvageable i will speak with Benross and see about getting new seats put in a skim and rebuild for you. (again i will need to know ure piston cc)

Richie

Ps did u do the oil drop ?


Tom it depends on ure pistons mate.......Ok i have stripped down the head, I have cleaned up the valves as best i can with what i have. there are a few points of concern (on top of the valve seat issue on number four)

iam only bringing these up so you know the score, not to put down summit you have bought, which people have done to you in the past and been wrong to do this !! if it had not been for the seats it probably would have been worth what you paid

1) GUIDES:- inlet guides 4 + 3 are different from inlets 2 + 1 which would indicate that they have been replaced, best practice imho would be to replace the lot not just two.

2)GUIDES:- exhaust guides 1 + 3 are jamming in particular number 3 was very hard to get the valve out. also exhaust guide 4 had traces of silicone sealant which had been run around the guide under the springs.

3)PUSHROD APPERTURES:- (metal swarf was located in)
inlet 3 + 1 and exhaust 2

4)VALVES:- exhaust valves 1 and 4 are badly pitted and IMHO will need replaced in the near future.



pictures !

here is your head side by side with a full works longman. that head was bought with a 1430 block and full race SC box for 500 quid (that is the right price for a second hand engine imho )

note the chamber shapes.


here is close up of chamber 4

next to longman chamber 4


backside



topside all longman heads have the tops skimmed there is usually rough casting around this bit the rocker posts have also been skimmed
here is ures next to mine



the 11th stud issue ?



poorly seated valves methinks ??? the springs are at different heights this is not the end of the world there are many others like this and it probably does not matter, but IMHO again it is an issue of quality.

Vs


little things like this should send alarm bells ringing buddy, when ever you look at heads they should be well maintained and looked after its what makes the whole engine work well ? i like the use of washers here YEEEEEHAAAA. fair enough if you put this on though


ok Tom look away here is the seats between inlet 4 and exhaust 4 the bain of ure life !!










here is the odd valve guides.


and final shots with the valves cleaned up, the detritus taken off the face and backside of the head, and the spring sets and locating wedges bagged per stem

Edited by Richie on 24th Apr, 2008.

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MikeRace, Mini13

any comments appreciated

hiya..

that could be fixable but it will be a fairly complicated task

I think combined welding and spray welding could at least restore the shape but the seat would be different densities/material around..
and even of you do it all right ( which is a bit of a task) it would be a bit of a hit and miss affair and it begs the question of you are not better off with a new casting.

unless it is a fairly costly/ brilliantly performing head i would bin it.

just my 2 cts.

EDIT:
stared at it a bit more..

IMHO it is a paperweight. the valves are too big to begin with and there is not enough meat to fit and hold two inserts which is probably best as far as seat quality goes. no way to get a decent bowl shape.

(I have fixed some heads with dual inserts but only because of severe valve seat f*ck ups and it was a nightmare to get a bowl shape back that made some sense)

I like a 33mm intake head as a starter for porting (a bog standard one)


p.s. if you are really adventurous you could pin it .. drill it straight down fit a special taper cast iron plug. never done it.. but you could try it.

see:

http://www.locknstitch.com/Repair%20pdf%20...18%20Repair.pdf

Edited by Sir Yun on 24th Apr, 2008.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

its scrap i am afraid

Edited by BENROSS on 24th Apr, 2008.

i dont have a clue about these things, and ive been told on another forum that its weldable, but the way i look at it, is that a weld would be even weaker than before ? therefore prone to just go the same way.

it would crack mate IT WONT WELD ! my thoughts were putting new valve seats in but it has obviously burnt in too deep.

keep the valves and scrap the casting, get another casting off Fight the fear and get a quote for a porting and the head setup for good CR based on Jordies info
the block spec is
Bore = 72.14mm
Stroke = 81.4mm
Piston vol = 8.4cc
Ring land vol = 0.5cc
BK450 gasket vol = 3.8cc
(cut and paste from the club forum)

Edited by Richie on 24th Apr, 2008.

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MikeRace, Mini13

I have a few heads kicking around if your struggling? You after Period castings?? I have 2 S Heads i think.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

I'd try with first a big OD inlet valve seat, and then a custom made exhaust jobbie. It might work, but you won't know this until you've machine the room for the the inserts.

there is no reason why this cannot be welded, ,it is not a crack but a burn tract, so we know how deep it is, as long as it has not reached the water jacket, [which is 15mm away] which t looks not to have done.

ive mentioned in a thread a year or two back , we succesfully welded a Longman GT 17, this head had the tinyist amount of metal laft between the valves, was actually undercut so was thinner just beneath the seat,
at £700, it was worth a go and worked,

that said its a bit of a rough cut job, but no reason why it wont work well if fixed,

worth a go if it was me.


carl

WWW.FORCE-RACING.CO.UK PLEASE CLICK HERE

i would take a hard look at the rest of the head. the seat height is all over the place.

I have had the odd head where the bowl was undercut, and had a very narrow seat. That made it hard to get a decent seat even when upping the valve size, which as far as i can tell here is not really an option.

would be a shame if you managed to get the burn fixed only to have a mediocre head due to bum valve seats.

on a gt17 it is worth a go..

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

carl i have had a few heads tried and as the steel gets impregnated with oils etc the weld never holds for long

how much are valve seats though ?

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MikeRace, Mini13

Mike can you PM me a price or some sort of deal for the heads ? we are a bit stuck bro i have stuff to trade / cash etc etc

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MikeRace, Mini13

Tom he paid 160 for it bro plus it needs new guides etc, to be fair it 8nt my cash but if it was i would be inclined to skip the casting just in case the weld did fail after all if it does the bits will then be in the block and more damage will be caused.

Edited by Richie on 25th Apr, 2008.

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MikeRace, Mini13

Worth a go at mending it then!

For that money I would shelve it, get another head and rework it. How much is the bottom end of your engine worth. welding and reworking water ways I have seen done, but combustion chambers. And I assume this is going on a turbo. IMHO be safe get another casting.

Own the day