Sounds good.10 degrees more duration them the GX cam, bit on a 25% larger engine, so it lowers the torque band.
.425 lift at valve compared to GX .476 lift and larger than GX valves should increase the mid range punch


Quote:

Spoke with Delta cams in Oregon and detailed the build and the intended use and was recommended the KC grind (262D, .425 lift at valve). Regrind of my A15 cam. $56USD. Said I could use my stock valve springs.

I just got the engine parts back from the machine shop and started rebuilding today after doing another trial fit into the Midget yesterday. Balanced, ARP rod bolts, pistons to deck clearance checked at .01 so I am on target for 9.3:1 CR. Short block is complete but here is a pix midway.

also tomei now have "street" cams for A-series.
check out their website

Get an aftermarket grind around 220deg @ 0.050" and aim for a valve lift of around .400" on a close lobe separation (105deg). Will be a much more lively & fun motor than with a stock GX cam.

I would go with the GX cam, in my A12 would pull from 2500 and was very good from 3500 to 7200.

As for flywheel use the A12 or one modified per the specs on this site, the modded one is 14 pounds and is what I use on the race car. It's lite enough togivethe motor snap while still keeping the motor tractable.

Tom

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.

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.

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?

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

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.