80 replies to this topic

[Project_1275_GT]

Cylinder head - 12G940 

 

Time to clean and assemble the cylinder head, cleaned off all the surface rust and tidied up in the valve chambers / ports. Tomorrow i will paint it and lap in the valves. Need to drill out the water take off port and tapp the holes. Will be using standard rockers and new double springs. 

 

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[Project_1275_GT]

Cylinder Head - 12G940 

 

Lapped all valves, Cleaned again, Drilled hole for water take off, Stripped and rebuilt rocker set, Checked CC @ 21.4 then painted 

 

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[Project_1275_GT]

Cylinder Head - 12G940 [Complete with T3 and HIF44e]

 

Another cold but productive day, completed the head and found all necessary nuts, bolts and studs to bolt it all together. 

 

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Needed to bolt it all together as the T3 had been taken apart. I have aligned the oil feed and drain and the turbo outlet. Looks to be correct. 

 

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[GraemeC]

Looks tidy. Rockers 4 and 5 look like they'd benefit from some spacer between them and the posts though - just to get them onto the valve tips better.

[Project_1275_GT]

998 + 20 rebuild 

 

Managed to get some work done on the block, fitted the new oil pump, EVO 001 cam and new cam followers [put new cam bearings in previously]. Also put in the new core plugs, new main bearings and installed the crank to check end float. All looks good. Wish id remembered to order the piston insertion tool... Should be here soon so i can then install new pistons and check deck height for CR calculations. 

 

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I did drill and tapp the water way on the block front next to No4 cylinder as this seems to be advised when fitting a 12G940 head to a 998 block. M12 grub screw fitted and locktited in.

 

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Edited by Project_1275_GT, 07 January 2021 - 03:48 PM.

[Project_1275_GT]

Looks tidy. Rockers 4 and 5 look like they'd benefit from some spacer between them and the posts though - just to get them onto the valve tips better.

 

I did look at the alignment of the rockers to valves and was a little concerned. I have only fitted them finger tight at the moment as its all got to be put together with push rods etc. Is it ok to space the rockers without upsetting the push rod alignment and oil way holes? 

[GraemeC]

The pushrod holes usually have plenty of free space (as long as you don't go daft). 

Its fairly common to adjust with spacers to get better alignment. AEG168 and AEG169 are 40thou and 10thou shims available just for this.

[Project_1275_GT]

The pushrod holes usually have plenty of free space (as long as you don't go daft). 

Its fairly common to adjust with spacers to get better alignment. AEG168 and AEG169 are 40thou and 10thou shims available just for this.

 

Thanks for the info. Will space out with feeler gauges and see how it looks. Then order some spacers with the next order of mini spares parts required to finish it all. 

 

Cheers Rob

[Project_1275_GT]

Water pump modified to allow 12G940 head to fit 998 block

 

Cut down the top of the new water pump to allow the fitting of the 12G940 head. Looks like it should all work ok 

 

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[Project_1275_GT]

Cleaned and polished the top face of the pistons. 

 

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[Project_1275_GT]

12G940 chamber polishing 

 

Well i decided after roughly assembling the head last week to get new valves, then new guides and finally thought why not have a go at polishing the chambers to slightly increase CC and get the best finish i can. WHAT WAS I THINKING ... 

 

BEFORE 

 

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HALF WAY 

 

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[Project_1275_GT]

Bit more grinding and polishing 

 

Getting the feel for in now. Going very slowly as this is my first ever chamber work. 

 

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[MiNiKiN]

Nicely done. What die grinders do you use, as I struggled to get my chambers as even as yours?

[Project_1275_GT]

Nicely done. What die grinders do you use, as I struggled to get my chambers as even as yours?

 

Thanks. Will take a picture of what I used

[Project_1275_GT]

More grinding 

 

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After fitting the valves in the new guides the seat alignment on No1 exhaust is not quite centred. Looks like it will be a slow grind in by hand job 

 

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Attached Files

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