Please, not another engine.....

[jacksoncaddy]

Just got the bus how I like it....and now, the engine appears to have rolled a seven...

Drove fine to Volksworld and back, around 2 hours each way. On Sunday, it felt rough and sluggish, so yesterday morning I popped in to a local Aircooled specialist near my house (SGS Aircooled). Good bloke, has done a bit of work on my bus and I rate his work.

Turns out, it is only firing on two cylinders at tickover. This is weird as it drives and pulls fine, but is lumpy as hell at idle. There is a very teeny tiny weak spark at idle on two cylinders. We tried changing, plugs, Petronix back to points, leads, different distributor, checking for airleaks, checked compression (which was good) and reset the valves.

Still nothing!

The outcome was, the engine could probably do with a rebuild! :x This was a 'rebuilt' engine 700 miles ago! WTF! The valve rockers seem old and kippered though and not new as I was told they were. I think my engine 'rebuild' consisted of new gaskets and very little else.

Any further ideas before I have to have it rebuilt?

 

[timmo24]

OH No! Disaster mate, sorry to hear that after all your hard work too. :roll:
Condenser or coil? have you swapped these out too?

 

[jacksoncaddy]

Yeah dude, tried both of those too....should have added it to the list. All the ignition system is new as well, which is even more ridiculous!

It has started popping now too, must be the unburnt fuel :roll:

Been quoted £750 to rebuilt it with all new parts, new heads etc 1641 with an Engle 110 cam. Probably worth it, but i'd rather spend the money on beer and donuts :?

 

[richbaker78]

what were the reasons given for requireing a rebuild? i dont see how that would relate to the sypmtons. - why you would need a rebuild if its got good compression !!!!also rebuilding the engine wont help your already identified weak spark....look again at your ignition parts....have you checked timing, replaced dizzy cap and rotor? just cos things are new doesnt mean anything...
The popping could indicate either a lean mixture (possible air leak) or timing being out.
What carbs are you running? are you getting fuel at both the non firing cylinders? are the plugs wet?

 

[noddy]

I have to agree with previous post, a goosed engine would not have good compresion, poping could be either valve gaps or timing.

Have you also checked the distributor for wear, if the center shaft on the dissy rocks from side to side it scrap, or up and down by more than a couple of mill, up and down play can be corrected with a shim kit.

What distributor are you runing (take part number of side), is it vac advance or mechanical or both?

 

[jacksoncaddy]

I"ll have to have other look....I would be AMAZED if the engine is toast? Sounds really rough at the moment though! :?

One thing I will say, is I don't see how the valve rockers etc being worn can effect the spark?? I"m no engine tech but still?? :?:

Where's Pete Nice when you need him....

 

[jacksoncaddy]

I have to agree with previous post, a goosed engine would not have good compresion, poping could be either valve gaps or timing.

Have you also checked the distributor for wear, if the center shaft on the dissy rocks from side to side it scrap, or up and down by more than a couple of mill, up and down play can be corrected with a shim kit.

What distributor are you runing (take part number of side), is it vac advance or mechanical or both?

It's a 009 - only done about 700 miles though....

 

[noddy]

Could be your carb is set too lean at tickover, you would hear it popping on over run if its a lean mixture.

What carb/s are you running?

 

[jacksoncaddy]

It does pop a bit if revved. :roll:

Webber ICT 34's. About 300 miles old....

 

[richbaker78]

One thing I will say, is I don't see how the valve rockers etc being worn can effect the spark?? I"m no engine tech but still??

thats my point it wouldnt and even if it did it wouldnt mean an engine rebuild! what was the reason for the rebuild that your expert gave?

the rockers being worn could give popping symptons but it doesnt sound like that was a problem when your expert looked at it anyway?

Given he appears to have given you bad advice i would start again on double checking all the things he has 'checked'

My money is on an air leak to be honest.

I assume you have got a balance pipe runing between the two vacuum ports on the ICTs - if not and you have blocked them off then you will need to run a pipe between them. If there is a pipe check you havent chaffed thru it with your acc cable behind the fan housing causing an airleak.

Check for airleaks again by spraying some carb cleaner around each manifold with engine at idle. if it picks up the you have found your leak. Also stick an airflow meter on the carb if you have one - if not a pipe down the throat of the carb and listen....should be a noticable sucking sound - if not then its sucking from somewhere else - both carbs should also sound the same.

The weak spark..first how did you discover it was weak? are you sure you had them on a good earth when checking?. Double check this is the case. If so i would say is possibly a problem with the dizzy - ie cap, rotor, internals or the dizzy itself.

check you timing and valve clearnaces again too whilst your there.

I assume the two non running cylinders are on opposite banks?

 

[lemonyellow]

hi,had a similar problem on mine,turned out to be bad earth on the gearbox which was only giving 7 volts at sparkplugs so not burning petrol efficiently enough

 

[Araon]

dont you mean 7 volts at coil....

 

[lemonyellow]

dont you mean 7 volts at coil....

yeh that

 

[jacksoncaddy]

Quick update - had it looked at tonight and yes it runs much better, but the timing must have been quite a way out as I stopped on the way home and it wouldn't restart, just trying to turn over slowly. It wasn't strobed, so might not have been timed quite right. I loosened the dizzy and retarded it slightly and it fired straight up. I drove it home and it will stay there until Pete Nice casts his knowledgeable gaze over it next week. We'll get there eventually!

Before fitting the petronix it was sweet as a nut!

At least I know it's not the engine!

 

[aogrady]

And your "specialist" said it probably needed a rebuild - and only been rebuilt 700 miles ago? I for one wouldn't be getting him to do that work if it's only ignition related. I once found a miss fire on mine, seems that the plug gap had closed up, were new plugs, never done it since, reckon the so called "specialist" that also overfilled my oil causing the flywheel seal to go had dropped my spark plug! Lesson - make time to do the service yourself instead of getting someone else to bollocks up your motor - just my 2pence.

Alistair

 

[noddy]

Alister right the kit to service your engine wont come to more than £100, gunson strobe with advance from halfords is about £40, an pulse tacometer (setting tickover speed) second hand from flebay about £10, a set of feeler gauges £3, 2 screw drivers for adjusting card and rockers £10, and a 13mm spanner £4.50.

I recon you should save your self this by the time you have done 3 services and you will get to know your engine so if you get problems going somewhere you will have the kit and the knowledge to try and put it right.

 

[jacksoncaddy]

Totally agree!

Pete is going to sort it all Tuesday. I'll get him to show me how to time etc, I know it's not hard but i've never done it. Gotta start somewhere!

 

[aogrady]

Alister right the kit to service your engine wont come to more than £100, gunson strobe with advance from halfords is about £40, an pulse tacometer (setting tickover speed) second hand from flebay about £10, a set of feeler gauges £3, 2 screw drivers for adjusting card and rockers £10, and a 13mm spanner £4.50.

I recon you should save your self this by the time you have done 3 services and you will get to know your engine so if you get problems going somewhere you will have the kit and the knowledge to try and put it right.

I know, i only got them to do it as we were moving house and i didnt have the time or the space to do it on a busy terrace road with the camper leaning into the kerb!!
I have just done a quick oil change before the Volks world show, and when i am back from holiday in a week or so, will do the rest! The new place has a driveway and garage which was lacking at the old place (a flat)!

Cheers!

Alistair