Daniel thanks it will be a couple of weeks before I get the A15 out of the wrecked car. I also have an event May 13th so it will be one last hoorah with the A12.

Tom

Quote:

Is the soft rev limiter your foot? Or have you some way of rev limiting the car?

I ask as I am thinking on letting my son drive some motorkhanas in my 1200....and don't want him to blow the motor....

Rod length on A14's and A15s is 133mm centre to centre +/- 0.05mm.

Watch your compression on the smaller a12 chambers. You can actually go for quite a big cam with an a15 and still achieve 0.060" clearance between piston and valves.

I have a simulator which can give very accurate results with all this type of thing. Its very useful in designing engines. When you have a good idea of what you are planning to do, then I'm only too happy to run your specs through it.

Things I'll need to know are bore, piston brand and type, cam specs (or let me figure out the biggest), chamber volume and depth the valves sit above the head/gasket interface. If you give me head flow figures, inlet manifold dimenions, header dimensions as well then I can also give you a rough idea of flywheel HP.

Daniel

Bruce I called Elgin and will be sending him a core. They were asking about how much the head flowed , as if I had a clue , but said provide as much detail as possible. Anybody know the rod length center to center?? I can give him valve sizes , carb size , RPM range and most of the stuff including my desire to have a non interferance fit. This sould make the "pokey" not so Pokey anymore.

Tom

use the lightest flywheel, really makes a noticeable improvement in acceleration light crank pulley will help too. I don't even have double valve springs and the engine is really responsive ( spools quick ) and I never go over 6250 rpm ( soft rev limiter )

I'd go with roller rockers in any case where you have $$ as it reduces valve train friction and makes more power go to the wheels.

the A15 isn't a rev monster, but you won't need to rev it as much. Having a lighter valve train makes downshifting more fun.

Tom,
Contact Elgin Cams ( http://www.elgincams.com/ ) in Redwood City, CA. Tell him about the engine, gearing, etc. and he should be able to grind a cam that will work (make sure you send him a A14/A15 cam core)
Bruce

Thanks for the info , with the A15 it's not likely I will have to buzz the motor to 8000 to keep the car moving forward.
Basiclly I'm lazy , I like to drive the 1200 not work on it so I'll give up horsepower for bullet proof reliablity.

Tom

My cam specs

I run 1.65:1 roller rockers
So its probably abit big for your requirements of non interference

Thanks guys keep the opinions coming

Talking brake HP

OK on the Cam anyone have a rough spec on something more aggressive than the GX but will still allow non interferance fit??

The 100HP is a "goal" regardless the A15 will still have more go than the A12 for sure.

Tom

100 Brake, or at the wheels?
No way in hell are you going to get within a bulls roar of 100 Brake horsepower with a GX cam. They are a prodution grind (Read tame) that is bugger all better that a stock one.
I'd pull the head off the A15 and check out what chamber it has before making any decisions on which one to use.