Runs like a dog - Compression test results

Hi

Bit of an amateur mechanic as all will become clear.

Bus used to run fine until I had engine out

Was having my bus refurbed and put it on a roller before draining oil...

Then re rolled back,drained oil and removed engine to allow for some structural fixes.

Refitted engine, would not even turn, worked out the issue was too much comprssion in no's 3 & 4....... (live and learn)

Easy fix, took out spark plugs, cranked engine and then mopped up half a litre of oil..............

Refitted plugs and it started amid a massive cloud of smoke...

72 bay, starts first time, smokes no longer as I think I have burned it off.

Has new plugs (put in before engine was refitted) / points, set up correctly, timing done also.

Not much power though when going through gears, any other ideas apart from probably oiled up plugs in 3&4 (not checked yet)

Thanks

 

I take it by 'roller' you mean a big jig that allows you to roll the bus over...if the engine was still in the bus when you inverted it, the only things i can think of that might affect running are the dizzy drive shaft (which should be under tension if the dizzy was still in...if it wasn't it could've moved) and the other being crap in the tank/float chamber...I'm puzzled as to why there was too much compression on 3 & 4 cylinders...did you strip the engine and rebuild it?

 

Have sent you PM.

 

It should have been..... ;D

Thanks for your input

 

Check your plugs again to see if there sooted up and to make sure there all nice and tight.

You could try removing one HT lead at a time off each pot to see if one or two are running a bit lame, at least then you'll know where the problem is and will give you a starting point.

 

If some cylinders were full, I'm surprised you didn't end up with smashed pistons. Lucky escape .

 

Thanks for the tips.

Changed the two plugs that the oil was in (very sooty) and had a look at the other two, (a bit sooty so cleaned)

Ran a bit better, not cracking though.

Not sure the main issue is that it has only done 8 miles over the past 18 months and been started loads of times, probably with choke on and running rich?

In for MOT today, failed, cv joints that I put on 4 years ago as well as a few loose lights.

I'll get it compression tested to see what that shows up.

Once I get it through MOT think I'll juyst try and take it for a good run, get it warm and see what happens.

One further question, timing was done static with a 009 dizzy, 5% ish BTDC #1 cylinder. Is that right?

 

No that's a bit retarded. Do a search and get a timing light.

 

Full advance means that you increase the revs until it stops advancing. 009s are a bit variable so what they are saying is the full advance is more important than the idle advance, if it is 45mm from TDC, I have not checked, make a mark there and use your timing gun to check.

 

When you put the timing light on it is a strobe light that flashes when no 1 cylinder fires, it is pointed at the bottom pulley and "freezes" it so you can see the timing marks.

When you rev the engine the timing marks move (pulley looks like rotating anticlockwise) similarly when dizzy twisted to set timing the same happens. The crankcase split line is taken as a reference so at max advance ie. revving engine lots the pulley will rotate and you need it to rotate to 30 ish degrees from the TDC pulley mark.

A search will tell you exactly how many degrees for the 009 but 45 mm to the right of TDC sounds familiar!

Most lights now let you set the advance on the light itself so actually if the gun is set to desired degrees advance then you just line up TDC mark with crankcase split when revving the engine. It becomes apparent when you do it. Just watch fingers and leads in the fan belt!

 

Read, read, read until you understand, that's why I wasn't very helpful, you need to understand, not be given instructions.

 

... What zed said!

 

Back again

Just done compression test,each pot is at 75 - 80 (psi's).

Had new bores and pistons three years ago and not too many miles since.

Is this too low or should I be happy they are all similar?

Maybe a valve issue??

Thanks again

Ed