Not firing on all four!

Post by **fweddy** » Tue Apr 12, 2005 11:01 am

The engine is running roughly so I pulled the cables to the plugs off one at a time.

When removing one and two it interrupts the engine, but when I do three and four it makes no difference, even if I remove both!

We then swapped the plugs on four and one and it seemed that only number two was firing (very lumpy running).

Then I changed all four plugs to another used set I have and it seemed to be running on two or three of them.

All leads have spark to plugs - what's my problem?

We initally thought maybe a leak between three and four (head gasket??) hope not 'cause that's just what I've replaced! Still doesn't make sense to me. Any help?

Post by **simmitc** » Tue Apr 12, 2005 1:13 pm

We initally thought maybe a leak between three and four (head gasket??)

Exactly what I was about to suggest. Best thing is to run a compression check. Could also be valves. Being silly, what about a dead mouse in the inlet manifold to 3 & 4?

Post by **bmcecosse** » Tue Apr 12, 2005 9:49 pm

Sure you got the plug leads in the correct order ? 3421 I state it that way because it emphasises that there are two pulls on the back port then two pulls on the front port - important to remember if running twin carbs !! But yes - a compression check is urgently required. Have you set the valve clearances correctly ?
And maybe not such a daft idea - maybe not a mouse, but maybe a piece of rag left in there ??

Post by **fweddy** » Wed Apr 13, 2005 2:09 am

Sure you got the plug leads in the correct order ? 3421

Yep checked a few times - BTW Haynes manual is wrong

Have you set the valve clearances correctly ?

Checked and rechecked

Could be in the inlet or compression - must check

suggestions for easiest compression check?

Post by **turbominor** » Wed Apr 13, 2005 7:52 am

i always though the firing order was 1342!?

fweddy did anything happen to the engine before it started running badly?

I have had problems with old engines that have been stood where one of the valves has stuck open

Post by **fweddy** » Wed Apr 13, 2005 8:46 am

did anything happen to the engine before it started running badly?

It was running fine till I re-did the timing chain, then it ran roughly, then I had the head reconditioned (kept blowing gaskets), Then it wouldn't start, then discovered it was one tooth out on the timing, corrected that, now in this situation.

Post by **rayofleamington** » Wed Apr 13, 2005 9:15 am

i always though the firing order was 1342!?

It is - however 3421 is the same order

Starting the sequence with #1 is just more sensible as finding compression stroke on #1 cylinder is the normal way to check engine position / rotor arm position etc.. before you fit all the leads etc..
As long as the leads are fitted starting at #1 going round the dizzy anticlockwise and the timing chain is fitted ok, then you either question your sanity or question the new head.

Post by **turbominor** » Wed Apr 13, 2005 11:08 am

It is - however 3421 is the same order

it was early

if firing order is right, timing is close, and the valves all open and close ok. I would do a compression test and report back.

Have you got a compression tester or can you borrow one

From you description you are not firing at all on pots 3 and 4 so that means no spark, no compression or no fuel..

Unless you have a blocked manfold i would ruel out the fueling issue, so assuming you have a spark on all the plugs ( double check you have the firing order correct to the rotation of the distributor) I would go with the lack of compression either down to the head gasket or valve seating/opening problems

Is this the correct head for the engine or is it a 1300 on a 1098?

A series should run with the timing chain one tooth out.. Even think vissard mentions getting more power by alterning timing position.

Post by **fweddy** » Wed Apr 13, 2005 9:36 pm

As long as the leads are fitted starting at #1 going round the dizzy anticlockwise and the timing chain is fitted ok, then you either question your sanity or question the new head.

Thanks Ray! Leads and timing have been checked, so to save questioning sanity I'm going for the dud head option - might have to whip it off again and have a look-see.

have you got a compression tester or can you borrow one

No and don't know, will have to see what I can source

From you description you are not firing at all on pots 3 and 4 so that means no spark, no compression or no fuel..

Certainally have spark, I'm figuring on no compression rather than fuel problem at present

Is this the correct head for the engine or is it a 1300 on a 1098?

The original one that just came off it to be planed etc - only difference is larger exhaust valves

It was running with it one tooth out earlier, but after head replaced it wouldn't, then when it was put right it does run but roughly - I'm thinking maybe it would have run one out but with the new issue with the firing it couldn't.

Not sure if I'm going to get to look at this problem before I leave for W Australia on the weekend - might have to report back after the trip.

Post by **bmcecosse** » Wed Apr 13, 2005 9:56 pm

First - I wonder why you think Haynes is wrong ! I doubt it !! Please explain where/how you think it wrong. Now - how did the valve timing get to be one tooth out ? And are you sure it is not now 2 teeth out ?? Simple way to check - get #1 cylinder at TDC with the inlet and exhaust valves just rocking - they should both be open by EXACTLY the same amount if the timing is spot-on. (This is known as equal overlap at TDC - and is fundamental to good running !) You can check this (slightly crudely) with a Vernier caliper - but it's best done with a dial gauge. At least it can be done without taking anything apart - except removing the rocker cover. When Vizard mentions adjusting cam timing - he is referring to tiny amounts of adjustment - and it is done to get this overlap to be exactly equal. When the valve timing was 'corrected' - it will have put the ignition timing out - has this since been re-set properly ? And why has the head now got bigger exhaust valves ? This is unusual - most would fit bigger inlet valves to get more power - the exhaust valve size often has to be a compromise to get the biggest possible inlet in the head!

Post by **fweddy** » Sat Apr 16, 2005 10:51 am

I wonder why you think Haynes is wrong ! I doubt it !!

I don't remember the order Haynes says now but the order is incorrect - different to what is writen on the exhaust manifold and what works! I'd quote it but the book's down in the shed at the mo.

Now - how did the valve timing get to be one tooth out ?

I replaced the timing chain before doing the head.

And are you sure it is not now 2 teeth out ??

yep - its a good show better than it was, and I checked the alignment marks.

get #1 cylinder at TDC with the inlet and exhaust valves just rocking

Are you talking about #1 rocking or #4 when #1 is TDC?

When the valve timing was 'corrected' - it will have put the ignition timing out - has this since been re-set properly ?

Yeah - I have that near enough to correct to get running so it can be fine tuned with a timing light etc.

And why has the head now got bigger exhaust valves ?

Wasn't after more power - just had the head reconditioned, the inlets were good, the exhaust were worn (many past grinds) so we had to use over size valves which I took from a Marina head and ground to have a snug fit. Obviously it's not a "power mod" just getting it up to scratch.

Post by **57traveller** » Sat Apr 16, 2005 11:25 am

Haynes quote 1-3-4-2 firing order, which is correct, on page 13. Whether it's incorrect elswhere in the book - don't know.

Post by **bmcecosse** » Sat Apr 16, 2005 4:01 pm

The equal overlap check can of course be done on any cylinder - I just used #1 as being handy. Both 1 and 4 will be at TDC - 4 will be on it's 'firing' stroke - 1 will be on it' s exhaust/inlet stroke - hence the two valves will be slightly open 'rocking' - and these should be EXACTLY the same amount open at TDC. Any difference here will upset the engine running (ok a few thou won't matter for this mildly tuned engine) and if the timing is out by one tooth the difference will be very obvious (both valves are moving very rapidly at that point - one opening the other closing) - so it's a good quick check. You say it was running ok till you worked on the timing chain - so you have to think that's where the trouble lies !

Post by **fweddy** » Tue May 10, 2005 4:33 am

Well I've returned and am re attempting this mission.

Haynes quote 1-3-4-2 firing order, which is correct, on page 13. Whether it's incorrect elswhere in the book - don't know.

You are right! - try page 82 it says 1-2-4-3 and I think it is like that some where else too.

Both 1 and 4 will be at TDC - 4 will be on it's 'firing' stroke - 1 will be on it' s exhaust/inlet stroke - hence the two valves will be slightly open 'rocking'

That makes sense now

You say it was running ok till you worked on the timing chain - so you have to think that's where the trouble lies !

No I don't believe so - having replaced the timing chain I'd say has affected my timing some what (as it would have been adjusted at some stage to allow for the streched chain) now that its tight it would be slightly out. I've played with the timing since and think I have it plenty close enough to get going better. Remembering that the head has also been worked on I'm guessing that is where my trouble is some how.

Since returning and running it to see what's happening, its runnign rough still and if I take the lead off plug on it affects the engine. Off number two makes no difference (makes is run a bit quicker if I just hold the lead just off??) Number three makes no difference. Number four affects it abit.

If I take 2 and three off together no difference, if I also take 4 off it ticks roughly on no. 1 only. If I take all except 4 off it can barely run.

Correct me if I'm wrong but this tells me that now I'm not firing on 2 or 3 and am weak on 4. note that this has changed since my first post (then was not firing on 3 & 4 or 2 only)

Can you make sense of this? Seems the mouse in the inlet has shifted.

Post by **57traveller** » Tue May 10, 2005 9:14 am

fweddy wrote:You are right! - try page 82 it says 1-2-4-3 and I think it is like that some where else too.

Strange that fweddy, my Haynes - an original print run though - states 1-3-4-2 on page 82 (ignition section).

Might be a south of the equator thing?

e.g. (alleged) water down the plughole type phenomenon.

Post by **fweddy** » Tue May 10, 2005 10:29 am

Strange that fweddy, my Haynes - an original print run though - states 1-3-4-2 on page 82 (ignition section).

hmm - mine is not the hard cover with the trav on the front but the blue soft back with the engine on it. Copyrighted 1971
The section is "Sparkplugs and leads" in the "Ignition System" chapter

Post by **bmcecosse** » Tue May 10, 2005 11:06 pm

Have you simply tried a new set of plugs ?? The fact that #2 runs better with the lead held just away from the plug suggests a fouled up plug.
Also - the dizzy runs anti-clock (well it does in the Northern hemisphere !) so just check the 1342 leads take account of the anti-clock rotation.

Post by **fweddy** » Wed May 11, 2005 9:19 am

Have you simply tried a new set of plugs ??

Had new plugs in it - I have also tried other plugs

the dizzy runs anti-clock (well it does in the Northern hemisphere !) so just check the 1342 leads take account of the anti-clock rotation.

yeah it certainally is going anti clockwise even in the southern hemisphere - and the 1-3-4-2 is correct.

I have an update now tho. I contacted the local mechanic (did his apprenticeship in BMC stuff and is very helpful) He had a few ideas that I had already tried. In the end I humbly got towed into his garage and he's looking at it. As of midday he had adjusted the carb (runing too rich) and he has been able to check the compression - it was down and he's managed to improve that. He has put it down to the vacum advance in the dizzi, he says the unit is faulty, so I've pulled two other dizzis from my collection of valuable junk (do you see why I have 5 morries?). He's make up a good dizzi from the three and see how we go.

If that is the problem does it not seem that its probably coincidental timing with the other work I was doing or does any one see a link?

Post by **bmcecosse** » Wed May 11, 2005 9:01 pm

Don't understand how the mechanic managed to improve the compressions - unless it was needing the valve clearances set ? The vacuum units don't last after 10 years or so - usually they just affect the economy, although they can also make the engine a bit 'flat'. Well done on the 'Morrie' !!!!!!!! At least I am not alone !

Post by **rayofleamington** » Thu May 12, 2005 12:15 pm

Don't understand how the mechanic managed to improve the

I've heard of redex - ring decoking stuff being used which (if the rings are gummed up in the pistons) could make a small improvement although I really doubt it.