some fellas with worked heads on
http://www.bmsc.com.au/forums/buy-sell- ... ars-parts/

there was a nice one recently ported by munyard

Sorry to hear about your mother

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Current Garage:

1971 Datsun 1600
2019 Mazda 6 Touring Wagon
2009 Holden SV6 Sedan

Thankyou Hatchman.

Thanks too d, but I've always done my own heads and have wanted to do a good one for a while so I've gotten a start on the first head I did some 15 years ago when I first went efi, I'll probably post some pics of how it progresses, cheers

great to hear, its an i opener thread cause old boosted virtually stock L donks are often overlooked for modern donks

Yep, I think that when efi and decent turbo's started becoming available people had already made the switch to DOHC engines, so the L got left behind or remained in carb-turbo land for the most part, which in most iterations can't compete with multipoint efi setups. Plus they're normally de-compressed to buggery which wouldn't help. I am impressed by how well the old L performs turboed when given the chance with efi, intercooling and decent manifolding, especially as a street motor, they make quite good torque, but because of this and the combustion chamber design they do require some sensitivity in tuning particularly on pump petrol when the compression is raised. I reckon the people that try it and blow a headgasket just give up and go DOHC, which is fair enough.

Some pics of the head I've been fettling with on and off over the years. I am not a porting guru by any means but I always like to try things myself and try to stay conservative. Had it bead blasted then got to spend some quality time with the valve guide bosses, nothing unusual, but I had softened the squish areas in the chamber previously, you can contrast that to the virtually stock chamber head that is currently in the car. Depending on how much volume the bigger valves take up this might drop my compression a little, either way I expect the engine to take more timing as there will be less turbulence, in theory. As a street motor I don't really touch the ports themselves out near the gasket face, I'm relying on the larger valve to help flow at the higher rpm. Low speed and cold running with a cam on E85 are concerns so I don't want to lose too much velocity, plus the inlet port finish will be left reasonably rough. More work to go, of course

As I understand it opening up the chambers is not a good move from what has been experienced with other open chamber turbo setups. The 2v benefit from the eddy swirl effect using the kidney and heart shaped combustion chambers.
Opening them up creates uncontrolled turbulence that only benefits lower rpm running using low quality fuels.

Small kidney shaped chamber with dished pistons will keep the charge suspension towards the centre rather than all over
the place on the cylinder walls of open chamber heads used on L and A series for reduced emissions, oxides and low octane fuels.

The Naps combustion chambers benefit from boost due to their pro swirl design but the kidney shaped chambers can be made to swirl as efficiently when opened up especially for boost.



a modern 2 valver CC


both chambers are biased for the exhaust valve to face the sparkplug
to maximise the swirl characteristics and effect of the inlet valve to
promote better flame front as it moves away from the chamber,
The dished pistons promote the flame front and force distribution pressures.

Yeah im not going to go welding the chambers or looking for a closed chambered head I assume you're talking about turbulent inlet flow upsetting the inlet cycle? I have seen instances where excessive squish turbulence on boosted engines can generate undesireably high flames speeds. Can you explian what problem you have experienced with open chamber boosted engines?

Got the head back after a couple visits to the machine shop. Matching the chamber volumes and general cleaning up took a few hours. Compression ratio will be about the same as the current head, 9.5:1. Valve spring heights are OK, shouldn't need any fancy retainers for the seat pressure I want. Over the next month or so I will mock it up, measure for lash pads, check the rocker ratios etc. Valves are SI stainless 44mm inlet and 36.5mm exhaust on larger seats with manganese bronze guides. In the downtime I made a little jig to reface some old rockers by hand, too.

Haven't seen this thread before.

Very impressed. Nice build. Inspires me to actually build a decent engine for my 180b. Which, in turn, will inspire my wife to throw a few swear words at me!

Would that be a U67 head? Sorry if I've missed which head it is specifically!

Yep just an old U67 head.

Spoke too soon - measured the head and looks like I'll need 30thou of cam tower shims this time (the head is probably on its 3rd reco in its life) - mocked it up and lash pads will be close to 300thou which are just too sloppy in the stock retainer for my liking, so now on the hunt for fancy retainers

I'm using isky retainers with massive lash pads(.340)
http://m.ebay.com/itm/182000464412?_mwBanner=1
Or Sw Motorsport should have retainers locally.

http://www.precisionshims.com.au/products/slotted (Source of lash pads)

I think precision shims have lash pads to around .290-.300 any bigger you will probably have to drop a flat shim in the retainer first then a slotted lash pad to make up the difference.

Or if you don't want to do that you could get bigger lash pads from the USA up to .340 http://www.thezstore.com/page/TZS/PROD/10-2041A

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When the sign says "don't feed the bears", man you better not feed the bears.

Thankyou Nad! Just started looking for some today and I found some of those options too - would you happen to have a picture of that retainer/lash pad combo or dimensions of those retainers? I have been running 'pretty big' lash pads on stock retainers for years now but it would be much nicer to have them supported.

I probably will call SW or Datsport anyway at this stage, no point reinventing the wheel!

Cheers