The Triumph Dolomite Club - Discussion Forum

I got the dizzy reassembled this afternoon.

Started off with assembling the manual advance mechanism



When you assemble this don't forget the plastic spacer that fits to the bottom of the cam assembly. More importantly, you need to ensure that the protruding section of the cam assembly (the bit stamped 12 on mine) lines up with the cut out on the shaft otherwise your timing will be 180 degrees out! You'll know when it's right as you will be able to rotate the cam and see the weights pop out.





I also fitted the new cam retainer



With that all assembled and the springs fitted it can be fitted into the newly bushed body. Mine was quite tight but with a smear of graphogen then some grease it rotates nicely now with absolutely no play.

Don't forget the thin shim washer and the plastic collar on the base of the shaft.



Drive cog fitted with a new pin



Then the spring clips that hold the cap in place



Followed by the new vacuum advance...



...and the base plate, ensuring that the pin engages with the rod on the vacuum advance then the points and condenser.



Dust cover on, rotor arm on and we are done.



Ta Da!!



Then I found that I have a problem with the cap and rotor arm, the rotor arm is hitting one of the terminals on the inside of the cap. It does it on both caps and arms that I have and if I tilt the cap very slightly (maybe 0.5mm) then it stops.

I thought I would see how the Lumenition system fits so I removed the points and fitted the base plate.



Fitted the ignition module



Followed by the magnetic pickup



Then again, the rotor arm and cap.





Tested it and again the rotor arm hits the inside of the cap in the same place. There is a 0.8mm difference in the hight of the rotor arm when the Lumenition system is fitted, I span it up with my electric screwdriver and it's hitting about half way up the terminal.

You can clearly see where it has been hitting with and without the Lumenition pickup installed so it's not the fault of the Lumenition system.





I have checked the run out on the cam spindle and it's about 0.04mm which I think is fine given that there's probably a tiny bit of play in there as well.

I assembled my spare and checked it in that exactly the same thing happens so I must have two poorly manufactured rotor arms and caps.

I'll have to order the club ones then but at least the dizzy is back together!!

So it's on to the next job which is something I have been looking forward to for a long time, bottom end assembly!

EDIT: Just checked my original cap and rotor arm (forgot I had them! ) and it works perfectly, dodgy replacement cap and it is arms then .

Nice one, don't see many taken apart and re-assembled.

Will have to do someday.

Don't forget the thin shim washer and the plastic collar on the base of the shaft.

James467 wrote:

and the felt washer in the top of the spindle which requires periodic lubrication

Paul.

James467 wrote: Then I found that I have a problem with the cap and rotor arm, the rotor arm is hitting one of the terminals on the inside of the cap. It does it on both caps and arms that I have and if I tilt the cap very slightly (maybe 0.5mm) then it stops.

[snip]

I have checked the run out on the cam spindle and it's about 0.04mm which I think is fine given that there's probably a tiny bit of play in there as well.

I assembled my spare and checked it in that exactly the same thing happens so I must have two poorly manufactured rotor arms and caps.

I'll have to order the club ones then but at least the dizzy is back together!!

So it's on to the next job which is something I have been looking forward to for a long time, bottom end assembly!

EDIT: Just checked my original cap and rotor arm (forgot I had them! ) and it works perfectly, dodgy replacement cap and it is arms then .

It can't be a poorly manufactured arm, it'd hit all 4 as would run out in the shaft (eccentric rotation). It could be the new caps but the old cap being fine isn't conclusive for this. It could also be the new bushes, if the spindle isn't centred in the body you'd have this effect and no run out. IIRC you ended up with several distributors? Try the new cap and arm on one you've not overhauled. Ideally you'd measure the run out of the cap locating ridge on the body with a dial gauge fixed on the spindle - not easy!

Thanks Alun, and Paul, I forgot about that.

Alun, I tried one of the others that I have and it's exactly the same if a little worse, hits in the same place as well.

I am getting ready to reassemble the engine, making sure everything is spotlessly clean and the workshop's going to be thoroughly cleaned as well.

Standard engine building stuff really.

The bottom end had been balanced with the flywheel, clutch cover and front pulley. I just weighed the rods and 2,3 and 4 are 693 grams, number 1 is 687 grams. How sensitive is the Sprint engine to this, not having built a Sprint engine before is it advisable for me to shave 6 grams off the caps to make them all equal or is this within tolerance.

Thanks

Brain fade, I forgot to weigh them with the pistons and pins!

I think Mick said they were all weight matched for me so I shouldn't have to do anything.

Incidentally I'm not trying to build a race or fast road engine, just a really well built standard one, the way it should have been done.

BHP predictions, I'd be happy with anything over 135.

Right, I have weighed the pistons and pins and matched them up as close as I can.

Cylinder - Rod Weight (g) - Piston & Pin Weight (g) - Total
1 - 686 - 610 - 1298
2 - 693 - 608 - 1301
3 - 693 - 602 - 1296
4 - 693 - 609 - 1301

Thoughts?

Have you checked the valve spring tensions for evenness?

Sorry, couldn't help it

No I was going to do that when the head has been machined!

Hang on... shut up Mahesh!! Hahahaha

I have procured a head so I will probably machine the old head, sell it and use the money to refurbish the new one.

How do mine differ from yours then James? I'm seeing different figures to you.......

The scales don't lie.... I even checked them with a kilo bag of flour and they were spot on!

Lovely looking car and with that history and condition deserves all the attention it's going to get.

I've just bought one myself. In fact, it's a Sprint I've owned before and always regretted selling.

Very best of luck with your restoration

If you're balancing the con rod properly, you need to weigh both ends.

Thanks and congratulations chamberlainmrkg!! I've just done that with an MG Midget!

The first thing that I would recommend is to join the club to benefit from the fantastic range of parts that we can offer as well as the wealth of advice and the magazine!

Then start a restoration thread with plenty of photos.

Good luck with it and welcome!