Hey Guys,
Just playing around with fitting a set of 40mm dellortos. replaced the head but theres something screwy going on...
I'm not getting any response from 3 and 4 cylinders. I take the plug leads off and no change. plenty of petrol and plenty of spark.
Doing a compression test today but i reckon its the valves. I set 1 at TDC then adjust 8 then set 2 at TDC and adjust 7 is this right? anyone know the exact valve clearance?
cheers.

try adjusting cylinder 1 @ TDC then rotate crank 180 degrees and adjust cylinder 3 @ TDC then rotate crank 180 degrees and adjust cylinder 4 @ TDC then rotate crank 180 degrees and adjust cylinder 2 @ TDC. adjust the valve stem clearance by following the firing order.
Does this make sense ?
Also, there are two different valve stem clearances......one for adjusting while engine is hot and one when adjusting while the engine is cold.
As im sure you know..........if the clearance is not enough, the valve will not seal and you will appear to have no or reduced compression.

Also.........just giving your predicament some further thought...........if you are running twin sidedraft carbs, it may be possible that the idle circuit on the carb on cylinder 3 & 4 is blocked or not adjusted correctly.

Benny

Brett, it doesn't sound right to me.

Benny's method is correct, and can be simplified even more. You only need to move the crank twice to adjust the valves:

TDC with distributor pointing at #1 plug:
- valves 1&2 (cylinder #1)
- valve 3 (cylinder #2)
- valve 5 (cylinder #3)

Turn 360 degrees to TDC for #4 plug
- valve 4 (cylinder #2)
- valve 6 (cylinder #3)
- valves 7&8 (cylinder #4)

See the Tech Section article Tune-Up Information for timing marks and clearance.

Are you sure that there is fuel to to back carb? I have had a similar problem and it turned out to be the carb was'nt feeding fuel into the engine because of a blockage. The fuel pump was filling the float chamber but it was'nt going anywhere.

Thanks Heaps guys.
Readjusted the head.. and yes i did have it right. swapped the carbs over and the problem transferred itself to cylinder 1 and 2.
stripped the carb down and found the blockage that was causing the problem... the line to the idle jet!

Now i need to get them tuned properly - its hesitating on acceleration.
Anyone in NZ (wellington) know any good places?

Also... Oh Man so many questions!

1-The assisted Brake vaccuum line - does it matter if it is connected to only one cylinder intake?

2- Vaccuum advance - again do i just tap into the manifold on one cylinder.?

Thanks Heaps!

My brother's bloody good with delorto's.
Sillay engineering, on 4730790.
I'd not run vacuum advance, and lock the dizzy base plate. I once heard of bad things happening if you dont, so I've never run otherwise!!
Sometimes you'll have to tap all 4 ports to get enough vacuum to run the booster. Try it and see....