1. Oil pressure mod- is crushing down the rear pressure regulator all that is needed for the 12a? I've read that brings psi up to about 90... Do I have to shim the front up as well? If so how much?
2. Do I need or should I change to a later model oil pump?
3. Flywheel- my engine is from a 1980, I have it's original flywheel plus another from a 1982/83... Any benefit from using the 82/83? If I swap due to lighter weight do I need to use the counterweight for the one I use?
Thanks

 

1. Yep, just do the rear. Doing the front will make pressure even higher, not necessary for a street car.

2. Go for it if you can, but not hugely important. Any 83-85 will work.

3. The counterweight is built into OEM flywheels, so no swapping.

 

OK, thanks for the info. I actually have a later 80's (82/83) model 12A and my 1980. The 1980 has a lot of chrome flake on the housings so I am using the later housings to rebuild it. So I figured if the later model oil pump and flywheel provide some upgrade I would use them on the rebuild.

Also, can any engine building machine shop re-surface our flywheels? What is expected cost for this?

I just placed an order through Atkins for my rebuild kit...

 

Also, can any engine building machine shop re-surface our flywheels? What is expected cost for this?

I just placed an order through Atkins for my rebuild kit...[/QUOTE]


Any shop can resurface the flywheel. I paid $45 a few months to get mine resurfaced.

 

the pump you want had 17.5mm wide rotors, so you should measure yours. use the biggest one, or the best condition one.

 

I weighed the flywheels and one is 34lbs while the other one is 8 lbs lighter at 26 lbs...

 

please keep in mind, 1982 flywheels are completely different from 1983.

if i recall, the breakdown for 12A cars goes something like:

1979-80 - 215mm, something like 30 pounds
1981-82 - 215 mm, lighter than 30, but don't know the approximate weight off-hand
1983-85 - 225 mm, not sure on weight for these either

i believe the '81-'82 units can go on the SA engines with no consequence, but the '83+ will introduce issues.

there are a few posts floating around here, where you can get better info. search flywheel and use either Siraniko or J9fd3s in the criteria ... OR ... you can check Mazdatrix's site.

 

Thanks... The two flywheels look significantly different. The backside on the 80 is really thick vs the other one is thin.

 

the flywheels are thus:

76-82 rotors: which can be ID'd by the F or R stamp in the combustion recess, front or rear

79-80 flywheel, 30# feels like 300, you could keep an ocean liner from floating away.
81-82 flywheel, 23# perfect!

83-85 rotors: these are stamped in the combustion recess, the US rotors are NF and NR, for non turbo Front and non turbo rear. the turbo rotors are TF and TR

83-85 flywheel, 26# it is NOT COMPATIBLE with the 76-82 rotor weights.

 

Thanks for the info, looks like I have an 83 at 26#

 

it is not compatible with the 79-82 rotors

 

Yeah... Thanks for the info!