OK, stats:
1969 MG Midget (1600 lbs/726kg)
3.7:1 diff ratio, about 22.8" diameter (580mm)
A15 and 60A 5 speed
H89 head port matched to GX intake with two HIF44 SU carbs.
Some bowl blending in the ports
Tubular header, 2 inch (50.8mm) exhaust, I guess.
Target 9.5:1 CR, fresh engine with .01" (.25mm) overbore and balanced

Intended use: I drive this in the mountains and canyons of Southern California. I use third gear a lot. I am a mature fella, and my driving style is mostly Grand Touring, although I sometimes get ornery and toss the little British tart about. But mostly I use an RPM range of 2000 to 4500 while cruising about up in the twisties. So torque is important. I also need power for passing, and passing on these roads needs to be quick. Grab second and floor it!

I have a good used A15 cam core I can send out for regrind, probably to Delta in Washington state. I assume the baseline cam to be the GX for conversation.

Need more info?

Suggestions?

GX came is for 6400 rpm use. If your A15 is a 1979-1980, the stock can makes peak power at 6000 rpm.

I would keep the 6000 rpm cam and rev the engine up.

4.11 or 4.3 gears would make a bigger torque difference than the cam

The cam core have is the one from the shroud port engine. Isn't that different from the regular port A14/A15?

torque and power? Sounds like a need for some boost pressure.

Agreed. Boost is the answer.

The 1981-1982 shrouded port cam makes peak power at 5600 rpm. Since.you don't like to run at that high an rpm, going longer duration won't help.

i never found SU type carbs to have that snap it open acceleration that even cheap CV bike carbs have. A carb for each cylinder would help and cheap to setup.

Peter Zekert has cams galore ready to go almost any grind. As DD stated that cam is the torque and low rpm cam you best use a GX cam it brings the starting sweet spot much earlier in the 2800rpm range in an a15 well it did for my A16 as compared to the usual 4000rpm as it does in the A12gx engine.

What ignition and flywheel do you run?

any pics of the car? I know its not a datsun but Im a sprite and midget perv and yours has a datsun heart in it so qualifies somewhat here.

I think concentrating on the HP peak to the exclusion of the torque curve and the area under it is not what I want to do here. This is a road car with performance intentions which will be used in a variety of ways whether I am doing some relaxed cruising or freeway commuting if I am travelling sideways. Since the purpose is not exclusively drag racing peak HP is not as important as the curve. So winding it tight will happen, just not often witnessed by the authorities.

What I am missing is a dyno chart of the stock GX engine and also of the non-shroud port A15 for reference. Been searching for a while and have not found either one.

That GX cam in an A15 will respond similarly but lower in the RPM band. How the GX cam would respond to the tighter ports of the H89 head is an open question. Would the greater cylinder volume of the A15 and the smaller port volume of the H89 head translate to higher port velocity which might result in increased cylinder filling at off peak RPMs at WOT over the A12GX? How this particular package responds while winding up is really more important than the power peak at the shift point.

NA is the only option, although I agree with the virtues. I don't have time or money to mess with forced induction right now.

What cam is NZ_datto running in his A15? Just for reference. His dyno sheet from the Performance wiki page is nice and flat:
http://homepages.paradise.net.nz/grah ... s/db_images/db_dyno12.jpg

This is the most critical decision I have to make and I need more infos and stuffs and junks.

One example of the many interesting roads in my area:
http://www.pashnit.com/roads/cal/LittleTujungaRd.htm

Datto Master,

I saw your reply after I posted my last.

The A15 is not in yet. The 1275 is old and last time I had the head off (late last month) I saw that the ring lands of pistons 2 & 3 are rather ragged, LOL. Don't stop me from wailing on it but it has hastened my build plans. A little more smoke when cold, hah, but stills pulls that car pretty well. So I am gonna drop a bunch O parts off at the machinist and get this A15 going.

The flywheel I have is stock. Thoughts?

The dizz is also stock 1982 A15 electronic but I was wondering if it can be hooked to a GM HEI-like module. I like to use those with Ford Duraspark and they used them for the MG Lucas dizz as well. I assume the dizz will need to be recurved?

The A15 north America distributor can be used with an actual GM HEI module, but the stock module is already high-energy. People do the swap if the stock module is missing or physically damaged as the HEI modules are inexpensive. The stock modules almost never go bad electrically on a A engine though sometimes do on datsun L engines due to being close to the exhaust manifold.

Nice Midget!

D says the GX can gives a powerband starting at 2800 rpm on a 1600 CC A-engine. The stock A15 cam powerband starts at 2000 rpm. So it depends on what you want. I would think that a cam ground for your desired rpm range and with extra lift compared to stock or GX is what will fill the cylinders the most at rpms below the peak power rpm.