engine mystery? PZ suffix? what combination do I have...

[DarkHelmet]

Car is a 1978 type-IV. The engine is turning out not original. I'd like to discover what it really came from and if it's bolted to non-year-correct for the engine things. Was this a Metro engine swap or just out of a later post-1980 mini?

Block plate says: 99H791PZ 409049
so this is a (99) 998cc engine. Minimania says 99H/791 is an '74 onward mini with dished pistons. The site also says if it starts with 99H then it's most likely a metro engine. The dizzy mount is a single bolt and that gives it away that it's an A+ block which wasn't produced in a mini until 1980. (Means I most likely have 39hp@4750/52tq@2000)

head casting says: CAM4810 (and no that's not 4180 transposed, it's 4810)
Calver tuning says that CAM4180(gotta by typo) in:1.0625"/26.99 ex:1.00"/25.4 25.5cc 998 Mini - A+ (1980-on) and lead free. Other info states it's aparently a standard unleaded head with small valves, inferior to 12g202. So an A+ head on A+ block so far. The head has a second casting number behind thermostat housing: 28J9 (not sure that means anything in this)

distributor says: Lucas 41907A
So that's a 59D4 used for the A+ unleaded engine. Minispares says for 1988 lead free.
supposedly times like this -
16º-20ºat 4400rpm
12º-16ºat 3000rpm
6º-10ºat 2000rpm
0º-4ºat 1000rpm

Transmission: DAM2886
Minispares says its a Rod change 'A' plus with 4 bolt bearing retainer and stronger idler housing. Guess-works decoder says that it's a Std. Ratio Rod Change gearbox with Pot Joints,3.44:1 final drive , A Series Gear Ratios (A+ Mainshaft) based on the engine block ID plate. It does have pot joints.

So I have an A+ block with small valve unleaded standard head and a decently strong A+ transmission that was produced from 78 and on. The clutch type is pre-verto type, unknown if that's what the engine came off of. Probably makes no difference. What I do know, is that this is not the '78 engine since many parts shout the 80's at me. What part of the 80's or what car it came from is still a mystery.

All that's done has been coil/point replacement with Pertronix, which makes it run like an oiled sewing machine quite nicely. Given the head is a small valve nothing special head, is an exhaust+intake manifold+jetting even going to do much in the end? I guess what I do have is a strong base to plop some 68mm pistons within and a better freshened up head+cam onto it in a few years.

[MiniDave]

 I guess what I do have is a strong base to plop some 68mm pistons within and a better freshened up head+cam onto it in a few years.

Bingo!

Depending on how you intend to drive it, a 998 might be the ideal engine for you - with the right pistons cam and head they make decent HP and rev well.

A 1275 will make more torque and is good for pulling taller hiway gears, if that's what your main use will be.....but if you're just going to be totting about town a 998 could be a great choice.

[DarkHelmet]

Well, I'm not looking at Colorado Interstate work (75 which means 80), but the local highways frequently hit 65+/- a few and a few hills......might be a bit much at times but going with an electric fan instead of the pump driven one should free up the strain.

[MiniDave]

Adding a small turbo might be the best answer -  recover some of that lost HP and add a bunch of torque at the same time.

I expect a 998 will struggle with those Colorado "hills" otherwise even with an improved cylinder head and cam.

[94touring]

If you're thinking of ditching the pump driven fan and going electric, I can tell from experience that doesn't work.  Unless you have a front mounted radiator.  The stock fan is required for directing air through the radiator, the shroud playing an equally important roll.  I liked how quiet it was without the fan but it was a short lived experiment due to temps rapidly overheating.

A 998 turned 1098 with crank, 80 over high comp pistons, head, and cam will make more power and torque than a stock 1275. 

[MiniDave]

All that helps it breathe no doubt, but still won't replace the fact that there's a lot less air up there in Colorado - replacing that (via forced induction) will do more for the performance and probably cost less too.

Oh and I agree on the electric fan - I tried that with Buzz too and it did not work.

I think they do it on racecars by building a duct from the grill directly to the rad, but I don't think you can do that easily on a street car.