D your right with that idea,i was measuring the stock manifold today the head runs roughly 28mm ports yet the manifold runs 25 brilliant!
doesnt sound like much but calculate the surface area and it does
If it doesnt work this way i have no choice but fabricate another manifold.....So i started on the exhaust ports marked them out milled then I set my self up and started to die gind the valve pockets in both inlet and exhaust ports and then blending into the new milled ports
In one of the photos you will see how much core shift there was
cheers anthony

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as unfamilia said heater outlet,block welch plug (not cam plug)head welch plug or head gasket at the back of the block is the drip central or to one side,perhaps run some coolant in the water to help trace it

welch plug in the back of the block,probably leaks as the coolant system heats up and expands,pull the motor and replace all your welch plugs because the rest wont be too far behind
cheers anthony

were on the same page :)
The offenhauser is designed like most dual plain or non equal length runners they divide the engine in half one for torque the other for higher rpm hp very streetable,under boost even though the fuel is forced the two middle cylinders will run rich so its best to have equal runners...Im running the original A12 manifold But my spare engine came with a a14 oval port manifold im going to try and use this as it has the volume needed same idea as the offenhauser but runners are equal,i hope im able to work the head and manifold to suit each other....cheers for your help mate appreciate it

Opps got me there yes was 35 intake and 29 exhaust H81 head
working out the surface are of the h89 port 28x35 gave me 769 so if I can increase the size of the roundport to 31mm i have a surface area of 754 at 32mm it's 804,i think my biggest restriction is getting the volume into the motor,as the carby manifolds have no real plenum

I bought the msd form speedpro dandenong vic that way if i have an issue i can take it local but you can also try summit in the states or even rocket industries NSW it was about $630 without the Map sensor there is few to choose from straight vacume N/a or boost to 14 psi and then 30psi these are another $100 but im sure you could use a delco mapsensor without the msd logo for less dollars....You can go to the msd web site download the program for free but its not complete with all the interactive software for the msd unit,put you can still plot and play....
Lpg has a ron of around 102 E85 is 108 both have lower calorific value so your volume/air space is less,but as you say E85 being alcohol runs a lot cooler so the cooling effect takes away heat soak .The good thing with lpg is it wont drop out of atomization but E85 can..
larger 1/4 boys are doing away with intercoolers to avoid pressure drops and restrictions and are running straight up on E85

Have to thank Spikes14a i now have another a12 to help me fabricate parts with and rebuild....The next stage will be to hunt up a Auto for it at some point,but for now its a 4sp.
With everyone jumping straight on to H89 heads ,oval port, larger valves,it sounds great but with the popularity has also caused some stupid prices.......
So I have aH81 head off the engine
bathtub chambers
29mm intake 35mm exhaust
What can be done to this, What do people do to the roundports to get them performing better or it flogging a dead horse.
So please educate me in what works as i was going to drop the valves out and start maching the exhaust ports in the milling machine
Cheers anthony

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your right but helps when calculating/playing with final boost pressures
thanks for your help
cheers anthony

ok so my 120y should be std comp of 9.0-1 this head will drop it further down to 8.5-1 ?
cheers anthony

Hi guys,
I have just started to strip the spare engine A12 the markings on the head say H81 /073 i've been told this is a sweden emission head,The whole motor is from a sunny ute ,small port,intake 35mm exhaust 29mm
"what comp" would this head produce on a stock A12 engine..?
thanks
Anthony

Thanks guys i have now secured another engine
cheers anthony