Thanks for the responses everyone. That is useful info.

I have a set of these carbs being the BS34 models which I believe were fitted to a Yamaha XS1100 from the late 70's perhaps early 80's. What I have come to learn about these carbs is that from the factory on some models they set the two centre carbs a bit richer by fitting slightly fatter jets, say 115 on the outers and 120 on the inners. No doubt because they get less air to cool them and so run them a bit richer to try to keep the temperatures under control.This no doubt varied from manufacturer to manufacturer so any set you consider these issues should be kept in mind.

Thats all well and good on an air cooled engine but not a factor on anything that is watercooled. The needle heights are adjustable and have 5 different settings and so should be set the same on the bench before fitting up to the car.

Has anyone on here used any of the Mikuni bike carbs on a Dato 1200?

The carbs I am looking at are BS34's. These have the rubber diaphragm and round alloy top cover .These carbs are shown in a gallery pic on this site elsewhere and incorrectly labelled flat slide . They are different beasties.
http://datsun1200.com/modules/newbb/v ... mode=0&start=0&menumode=2

Of particular interest is the fuel delivery set up as they are normally gravity fed and don't withstand too much line pressure otherwise they will flood.

Any info or feed back appreciated.
Cheers

Amazing indeed.
The only damage done was to the bearing shell itself. The shell inserted into the block suffered the front flange shearing off. I assume this was because the block web is slightly wider on the rear and once the cap was torqued down the block effectively acted as a wedge and split the front flange off. That bit was sitting in the bottom of the sump. Not a mark on the crank!
Amazing little engines.

Thanks for all of the replies.

Problem is now sorted. To explain. The engine in question was assembled by another bloke and ran a relatively mild cam. We eventually built our own late block with bigger cam, 1400 head etc.

The discussion here has made me aware that the thrust bearing on the crank is the same for both the early and late blocks. Turns out the guy who assembled the old engine put the thrust on the rear main and not the centre main.!!!!!! Hence the excessive end float.

A new set of bearings is in order and the problem will be all sorted. Lesson for young players!

Our old race motor has about 2-3mm endfloat on the crank.

On pulling the cap and checking the thrust faces on both the crank and the bearing shell there is only relatively minor wear.Certainly not enough to account for this level of end float. On checking another crank with the bearing shell it to produces a similar amount of end float.

This engine is an early A12 with distributor up front.

Question: Are there different bearing sets for the mains to accommodate different production years that accounts for this level of end-float?

Our little Datsun Sunny has a Lucas alternator 15AC. The front bearing became loose in the housing. Having a few spare alternators about I used one of these as a basis for preparing a replacement. The slip rings are all new and all external features/connections are the same.

On fitting we now find that the engine won't shut off. I need to either disconnect the coil or pull the cable from the IND terminal on the alternator. This is the way it has been wired up. There are only the two connections.There is a third terminal marked Aux+ but not used.

Iam thinking there is a need for a relay but why would that be when outwardly both the old and the replacement appear to have the same configuration.

Any one with any clues?

dd, Thanks for that.

I looked in the tech wiki under oil pressure switch thinking I might find the info there.Should have looked at the other info on the pump. Cheers.

Can anyone tell me what thread is utilised for the oil light switch on the oil filter housing on the Dato 1200?

Resurecting an old thread again.

Can anyone tell me what the pitch of the thread is for nuts on the replacement ARP studs?

Often is the case that when studs are used to hold down a cylinder head a finer pitch is used for the nuts.

If that is so then what torque figure is applied for the Dato as a finer pitch would result in greater clamping force for the same torque on the nut as compared to the bolt.

Any thoughts?

What ddgonzal says is right.It is the ability to raise the compression without detonation that yields the increase in power.

Generally the engine will run cooler which may be a real benefit.

Methanol has an octane rating of about 108 . As for racing fuel that will depend on who supplies it so you need to check the Octane rating with them. You should also realise that LPG has an octane rating of around 112. A purpose built dedicated gas only engine may be worth investigating.