X1/9 1500 Head

Road-race engines and ancillaries - general discussion
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PhilipModro
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X1/9 1500 Head

Post by PhilipModro » Tue Jan 21, 2014 5:43 pm

Hi Guy and everyone,
First post on the forum so I thought I'd begin with a cylinder head I picked up from an internet auction site, which I know isn't really a reliable source but I will cut to the chase. I got it so I could get it modified whilst I continue to drive the car, but now as the car is off the road with a blown head gasket due to overheating (3rd time in a year) I am in two minds what to do as I would like to retain a standard head in case I want to switch it back over etc, the problem causing this dilemma follows.
The head I purchased off an internet auction site is in particularly bad condition (it only cost me £30) as there is lots of rust on the valve seats and valve guides, I originally wanted to have the guides changed and have new seats put in with 39mm valves which I hastily purchased given the opportunity but now am aware this may not be the wisest choice to maintain port velocity and therefore drive-ability at town speeds. This is for a hot street engine circa 140 bhp and as reliable as possible (whats your take on this guy?). Just seeking advice on what to do as I intend on fully rebuilding the car as it is riddled with rust etc, this re-build includes the engine, The car is a 1989 gran finale in mica blue with 80k miles on it. I suspect the current head is warped now from its overheating fests and the block may need decking also as part of the rebuild.
thank you
Phil
Last edited by PhilipModro on Thu Jan 23, 2014 3:28 pm, edited 1 time in total.
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PhilipModro
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Re: X1/9 1500 Head

Post by PhilipModro » Tue Jan 21, 2014 5:48 pm

Here is a few pictures of that head.
head1.jpg
head1.jpg (133.18 KiB) Viewed 1612 times
head2.jpg
head2.jpg (118.07 KiB) Viewed 1612 times
head3.jpg
head3.jpg (153.62 KiB) Viewed 1612 times
head4.jpg
head4.jpg (120.89 KiB) Viewed 1612 times
Last edited by PhilipModro on Thu Jan 23, 2014 3:23 pm, edited 1 time in total.
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Guy Croft
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Re: X1/9 1500 Head

Post by Guy Croft » Thu Jan 23, 2014 4:55 pm

1. Beadblastand hot wash
2. All over deburr and inspect incl pressure-test & thread checks..
3. Gasflow
4. New race guides
5. New valve seats & cutting to suit big valves..
6. Reface

a straightforward but slavish ops list I do all the time.

The production pistons however will NOT accept larger valves and the problem of valve-piston proximity is compounded according to how much milled off the head (already or after true-up)...

G
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PhilipModro
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Re: X1/9 1500 Head

Post by PhilipModro » Thu Jan 23, 2014 6:56 pm

Hi Guy,
Thanks for the fast response.
So new pistons would be needed for the bigger valves? I was considering this in the re-build anyway along with new bearing shells etc.
Would you recommend a standard 45 degree seat with maybe a 3 angle cut?
I have access to a flow bench here at uni (I am doing a degree in Motorsport engineering) however I have not used one before and only done minimal gas flowing on motorcycle heads, so I may send it to you for the gas-flowing as I am yet to get to that stage in my degree.
I assume this is all on your price list that's on the site?
Thanks
Phil
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Guy Croft
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Re: X1/9 1500 Head

Post by Guy Croft » Fri Jan 24, 2014 1:45 pm

What you should do is buy the new GC book!!

Maybe your Uni would like a few!!

G
Guy Croft, owner

TomLouwrier
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Re: X1/9 1500 Head

Post by TomLouwrier » Fri Jan 24, 2014 4:16 pm

What you should do is buy the new GC book!!
Getting your degree in motorsport engineering? Without sucking up to Guy, that is the best investment in your education you can make.

regards
Tom
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Guy Croft
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Re: X1/9 1500 Head

Post by Guy Croft » Sun Jan 26, 2014 3:49 pm

Philip

this is what you are up against on the SOHC with its inclined valves. Standard valves on the X19 1500 are 36/33mm.

The bigger the valves, more radical the cam, the more that has been machined off block and head the worse the problem.

The fact that this is a GC domed HC piston is neither here nor there...

G
Attachments
GT_BP285 dry build.JPG
GT_BP285 dry build.JPG (117.33 KiB) Viewed 1570 times
GT_BP285 LATDC.JPG
GT_BP285 LATDC.JPG (545.06 KiB) Viewed 1570 times
GT_BP285 dry build (1).JPG
GT_BP285 dry build (1).JPG (116.66 KiB) Viewed 1570 times
Guy Croft, owner

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