Holden 9 port head

There's no reason to not believe it's a dog cyl head as is. had a look on goggle, your only hope is that the Y/T head has intake port blades to help stop that interference between the adjacent ports . but looks like even the later true 12 port heads have a terrible intake port tract

Came across this info which I hope you find interesting . I think Phil had as good a grip on intake flow as Harry Weslake and Mundy No pics of the chamber shape which is a shame

https://primotipo.com/2015/06/26/repco-record-car-and-repco-hi-power-head/

Each successive head design by GM was definitely an improvement in performance & economy.
Simply adding true extractors also made a leap in everything

Great link thanks, I wonder if the car or at least one of the the heads survived. Grey motors sure are few and far between these days!

Interference between the adjacent ports on a 9 port Red is not an big issue unless you're pulling very high revs and running a crazy cam. The paired cylinders never have both inlet valves open for long enough for inter-cylinder influence to be an issue.

reading the blurb says the car is seen at many car meets and 103 heads were made . so I guess there must be some around ?

I guess you would have heard of WADE cams ? an Aussie outfit,. there was a cam grinder in NZ that supposedly had Wade masters . possibly Franklins ? Any way, I kknew George did a lot of work on the old grey engines, I thought he had designed his own cylinder head for it . but he may have collaborated with Phil and Co ? . take note of the long intake manifolds ! . here they sort of knew enough about wave pulse tuning to try to over come the 2 valves one port scenario

http://www.motormarques.com/editorial/item/196-george-wade-1913-1997

The jury is still out as to weather the Blue/Black 12 port was a significant improvement over the 6. Excluding aftermarket castings there is good proof that (when modified) the 9 port can flow better at high rpm whereas the 12 port has the fatter torque curve.

With modern software based systems for choosing cam profiles the classic wade grinds for the Holden 6 are considered somewhat dated, I'll be looking at custom profile to suit the components, the fuel and the engine usage. I'll probibly use Auckland Cam's for the final choice, Henery has a lot of experience with Holden 6's.

I'm still not sure why you consider the siamesed ports to be an issue on a straight 6 with 153624? (See #3).

Forgot to say I've peen pouring over motormarques.com, thanks for the link.

Agrees

I'm still not sure why you consider the siamesed ports to be an issue on a straight 6 with 153624?

Adds from what i have read re porting well when it comes to port dimensions and diametric reality is the ONLY head i have ever ported in that respect is a lotus twin cam 4 cylinder

" I'm still not sure why you consider the siamesed ports to be an issue "

Well, I suppose if your dealing with a low cost street eng . it's not, . in fact it make the product cheaper to make . but as you start demanding more HP / cc then it all starts to fall apart ( having siamesed ports that is ) No eng design would have S/P 's today, and I can't think of any performance orientated eng since the 1920's . but the old GM / Holden / Ford &c engines were never designed for grunt, just made to keep on ticking on, so for these type of engines, it probably is best to stick with something that keeps the engine in one piece

"" With modern software based systems for choosing cam profiles the classic wade grinds for the Holden 6 are considered somewhat dated, I'll be looking at custom profile to suit the components, the fuel and the engine usage. I'll probably use Auckland Cam's for the final choice, Henry has a lot of experience with Holden 6's ""

When it comes to cams, computer design is about trying to hold the 3rd derivative of lift ( jerk ) to minimums, for long cam lobe follower life . with the much lower zinc levels in newer oils, really makes life tough for push rod cams with increased accel rates . I doubt if Henry has a CNC cam grinder, nor a CAD cam program. what most grinders do is reverse engineer a lobe from another manufacturer . which is pretty easy to do . The CNC bit will be very useful for these people to get enough reference points on their copy to give to a CNC machinist to make a master pattern very quickly, as the CNC machine will merely join the dots

Custom cam ? . your the customer and he has a listed cam, that's as far as it goes . yes there are better profiles these days, but keep in mind the metallurgy these fellas were dealing with 40 > 50 years ago

All i'm saying at the end of it is don't OVER cam the engine, you will gain very little and lose a lot ( Henry will put you right ). hopefully you will make more power than that silly fella with a 13b and 9" diff

Stop reading comics

Aye?

, valve seat throat should be 39.6 mm venturi bowl no more than 40.5 mm ( this is the area by the valve guide boss , which really should be pencil thin ) after that 37,5 mm for at least 3 " and then slowly increasing to the port face ( a guess is maybe 38 > 39 mm ) the-lada-dude (78 78 positive feedback) 5:54 pm, Sun 12 Aug #50

Repeats.

re porting well when it comes to port dimensions and diametric reality is the ONLY head i have ever ported in that respect is a lotus twin cam 4 cylinder

Quote
snoopy221 (432 432 positive feedback) 7:36 pm, Tue 14 Aug #8

[ 711M-6015-B-A block bored to 1800 with forged pistons]