Datsun engines are internally balanced; the flywheel is not needed to balance it (unlike say a chevy). So you can lighten they flywheel as normal. See Flywheel.

So the datsun conversion may turn out to be a little lighter than the stock british engine/transmission?? Not sure why other MG owners installed heavier coil springs in the front. I can see the reason for better braking capability with the larger engine displacement and more HP. Will have to look into this a little more. Any thoughts on lightening the flywheel?

60-series 5-speed is 70 pounds.

But the A15 is light at 205 pounds. It has a lightweight block casting plus aluminum head, so much lighter than the 1950's tech Austin.

Well checked some MG websites and the car is around 1600lb, the 1275cc engine is around 260lb and the transmission around 45lbs. Cant say for certain on the engine weight. It is all iron however, including the cylinder head. I would expect the A15 is heavier than the British 1275 motor. Also will be using a 60 series 5 speed transmission. It seems comparable to the MG transmission. Other MG owners that did the datsun engine conversion used heavier front coil springs and some did install larger front disk brake calipers. Also someone suggested to lighten the flywheel since the datsun B310 car is heavier than the Midget. I was going to ask this question at a later time to ddgonzal but maybe you can offer some suggestions on doing this. Does the flywheel have to be balanced with the crankshaft if it is lightened? Would a machine shop simply shave off some metal on one side of the flywheel? I haven't done this before. Thanks for any information.

Any idea what the car will weigh with the A15?

Thanks for all the information. I will pass this on to the machine shop to check the springs. He will also be repairing the end play on the crankshaft as well as checking the bearings. The H7240 head is still in the car at a salvage yard and the only way to make any port measurements is if I buy the engine, which I will pass up on. Talking with other MG owners, the only real desirable heads for the A series engine appears to be the H89 or GX. Will post follow up questions as they come up.

I tried to translate the Japan factory service manual (Page 123) for the dual-spring specifications.

Quote:

I should say that I don't have the specs for the GX valve springs. The testing process is listed at Valve springs, but it only shows the regular spring specs.

1. Is there a link on this forum for measuring CC?

CCing

2. Replace crankshaft main bearings? Do the piston rods have bearings and replace them as well?

Inspect. Replace if scored or worn out of spec. Usually they last over 200,000 miles. See Bearings


5. Measured 11mm. So go ahead with swapping out the A12 gears and chain? Should I replace the tensioner?

No need to replace. It's well within the 15mm service limit.


7. Valve_springs...is this the link for checking the springs?

We have no link, the process and specs are in the factory service manual.


8. OK. I would expect to replace valve guides but will use the method described on the link. I did use a straight edge and couldnt see any gaps. It looked real flat. Will get a more accurate straight edge and use the feeler gauge test. Does the rocker assembly require anything?

No. As long as the rockers pivot freely it's OK. If they bind, replace the shaft.


> Do I take the engine block to a machine shop and have them dip it into a solvent tank to clean the inside? Will that harm the cam bearings?

Yes, generally hot-tanking will damage the bearings. Unless the block is unusally dirty, don't have it dip-tanked.


> I know about the H72 head but this one has 4 digits H7240. Does this mean anything?

H72 casting is machined in various version. For USA, it machined for anti-pollution gear with air passage drilled through the exhaust ports. OK head but prone to pinging.

1974: 1.3 liter engine, 75 HP smaller oval port cylinder head
1975: 1.4 liter engine, 80 HP oval port cylinder head
Some H72 are round-port heads (65 hp).

Unknown which one the H7240 is. You can measure the intake port dimensions and let us know.

Much thanks ddgonzal! The following is a continuation of the previous questions....

1. Is there a link on this forum for measuring CC?
2. Replace crankshaft main bearings? Do the piston rods have bearings and replace them as well?
3. OK
4. OK
5. Measured 11mm. So go ahead with swapping out the A12 gears and chain? Should I replace the tensioner?
6. OK
7. http://datsun1200.com/modules/mediawi ... ?title=Valve_springs...is this the link for checking the springs?
8. OK. I would expect to replace valve guides but will use the method described on the link. I did use a straight edge and couldnt see any gaps. It looked real flat. Will get a more accurate straight edge and use the feeler gauge test. Does the rocker assembly require anything?
9. OK
10. OK

Do I take the engine block to a machine shop and have them dip it into a solvent tank to clean the inside? Will that harm the cam bearings?


Also........I have been rummaging salvage yards in the North Texas area and came across a cylinder head from a 1974 B210 car (80 HP engine). I know about the H72 head but this one has 4 digits H7240. Does this mean anything? My intentions are to accumulate hard to get Datsun parts that are worthy in the event I want to take on another project. There aren't many Datsun cars left.

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