Twin cam head

[matevick]

That's great to hear, I was very lucky as Tim had a street head on the shelf.
Will be in Aus about 6-8 days. Only hard part was parting with the $$$$$$$$.
Ken

[matevick]

Hi Guys
Following up on my NEW twin cam head, it has not worked out quite like I expected (more details later) basically received a sprint head (which should have been a bonus but has turned into a nightmare).
Has anyone fitted standard exhaust valves to a SAS head? or, if have set up one as a standard road car (not race) what valves did you use? My mechanic and head builder are unable to make a brand new set of exhaust valve fit. Any advise would be appreciated.
Ken

[1owner69Elan]

I don't know if the information below will be helpful but I supply it in hopes that it might be useful to you:

My SAS ?street ported? head has 1.625? intakes and 1.375" exhaust. As in my earlier post, the result is a tractable street engine (7K redline, 1700cc) with 181hp @6900 and 143 torque @ 5100, ~flat torque 4K-7K, DCOE 40's, 32mm chokes.

This was the head spec as ordered from SAS.

New LM25TF Casting to original dimensions
Cam bore machined into head (No cam bearing required)
Inlet port machined and hand polished to 40mm Weber 1.3 diameter
Inlet Valve seat cut for 1.625 dia valve- (Inlet valve not included)
Exhaust port machined and hand polished 1.25 dia
Exhaust valve seat cut for 1.4 dia valve- (Exhaust valve not included)
Colsibro valve guides fitted finished for 5/16 valve stems
Combustion chamber machined and hand polished @ 4.640 head height
Standard spark plug 14mm
All core plugs fitted
Full pressure test prior to despatch
Head supplied fully machined with valve guides and valve seats cut, cam caps & cam studs
Valve seats are in sintered material suitable for unleaded petrol.

Valve sizes finally used: 1.625? intake and 1.375? exhaust. Dave Vegher, engine builder, was not satisfied with the intake valve seats ? felt they were too small and redid as below.

Some of the subsequent head work done by Dave Vegher:

Bore original seat bores to accept new larger seats;
order & have shipped new larger intake seats (4);
purchase liquid nitrogen;
install new seats;
open intake and exhaust ports to larger dimension per discussion;
install guides(8) & ream & hone to fit new valves;
perform precision valve job;
final blend new seats to port after valve job;
lap valves into seats;
debur spark plug openings in combustion chamber;
measure & set spring heights for equal valve spring settings;
trial fit new cams with dummy springs & be sure all appropriate clearances exist between all new parts ( e.g., new retainers to guide tops, followers to follower bore bottom, new cam to head & follower bore, new cams' ability to turn freely in new head, enough clearance between follower & cam for sufficient lash pad thickness, etc.)

One other comment from Dave that I relayed to SAS with my order:

"I see he (SAS) is going to install the valve guides thus allowing him to perform cutting the seats in relation to the guide bores. Please specify that the internal dimension he sets in the guide for the pilot he is going to use to perform the valve job is not larger than 3.10". This will allow us to fit valves to the new head by carefully honing them to fit the valves we will fit to it. American valves from Manley sometimes vary slightly in dimension and I hone each and every guide to give a proper clearance between guide and valve."

There were some other comments from Dave, if you are interested I can PM you.

[matevick]

Thanks for reply,
You sure have had some work done on your head. We seem to have struck the problem with the valve size on the exhaust, standard valve seems too small but SAS insist it's correct. I'll pass on your reply to my guys. On the details you sent it states exhaust valve to 1.4 did you order it that way? because that seems to be the route of my problems with fitting the standard valve.
Rgds
Ken

[1owner69Elan]

The 1.4? exhaust was the standard specification from SAS and was ordered that way.
Dave had specified 1.375 but was OK with the standard SAS spec. But he did use a 1.375? valve in the end.

[matevick]

Thanks
That's very interesting as 1.4 was not advised on the spes's they sent me before ordering.
Ken