Still struggling with running problems at high rev, HELP!

[sirch345]

Finally put the engine back together and took it for a spin this morning on the way to work..... It's fixed! I no longer have the misfire at 6k

I'm not actually sure how I fixed it, all I did was re-lap in the vavles in the front cylinder head, but it worked.

I think either re-lapping the valves cured it (but my valves didn't get knocked when the CCT went, so I can't understand why this is the case)
OR
Stripping it and rebuilding it all carefully cured it... maybe I had a loose connection or something, but I'm pretty careful so I don't think I had missed anything first time round....

Anyway, I hope this helps others with the same problem!

Well done VTRmart, I bet you're well pleased about that excellent news

It's also good too hear the out come of a problem that others have given advice on, as I see quite a lot don't seem to reply which is not only annoying but unhelpful to others who might be trying to find a answer to their problem before posting the same question again

Chris.

[Stratman]

Could the valve timing have been just a little bit out the first time, then when you replaced the head etc the second time, it was perfect. Just one tooth out would have made a difference I believe.

Anyway - great to hear its fixed and without the expense of a replacement engine.

[VTRmart]

I thought vavle timing the likely problem but I checked it about ten times, and so did a senior mechanic, so I'm certain it wasn't that.

I notices John W posted a very similar reply in this thread.....
Hi there,
just read about your problem, ihad this exact same problem last year after a front cct failed, it drove me round the bend,tried everything like you have until i had the valves recut and ground back into head and set the valve clearances.problem gone!!! All ican think is the valves werent seating properly Now 4000 miles without a glitch.

cheers John W

.......so maybe firestroms are really sensitive to valve seating?

Anyway, I'm soooooooo happy it's fixed, I can see me keeping it for a while now.

Thanks to everyone for the advice and support.

[CountryBoy]

This is all great news, glad you've sorted your problems, i on the other hand am still struggling, i've followed all the advice given by all you kind people and have also removed the head and thought i'd found the problem as a wet test showed the front cylinder inlet valves leaking, reground the valves and retested , dry, rebuilt the engine only to find no change what so ever!!!! ahhhhhh!!!!!!!!!!!!!!.

So at the moment its back to the drawing board, one thing you guys might be able to help with is the timing, i followed all the stuff in the book and had numerous trys at it but i'm still not 100% its right (which could ofcourse be the underlying problem).

Can any of you tell me if the (-) marks on the inner edges of the cam wheels are surposed to line up with each other perfectly as well as the FE and FI being inline with the top of the casing, if the middle lines (-) are surposed to line up then i'm still doing something wrong.

[Pete.L]

They should line up pretty close, very close when the chain is new.
As the chain stretches they go further and further out.
You can get around this by either fitting some adjustable sprockets or replacing the chains

Pete.l

[CountryBoy]

Pete,
I replaced the chain as they they were out by quite a bit, with new chain they are better but still not perfect, any thoughts?

[sirch345]

Can any of you tell me if the (-) marks on the inner edges of the cam wheels are surposed to line up with each other perfectly as well as the FE and FI being inline with the top of the casing, if the middle lines (-) are surposed to line up then i'm still doing something wrong.

You've lost me a bit here, the FE and FI being inline with the top of the casing I follow but the (-) marks on the edges of the cam wheels I'm just not with you on that
When I do the timing I just line up the correct mark for the appropriate cylinder, on the flywheel and use the FE and FI marks on the cam wheels only

Chris.

[CountryBoy]

As you look at the cam wheels face on ie. the same as you would to line up FE FI there are two additional marks which look like they may also need to line up , not explaining this very well! , Try this - if you look at each cam wheel individually exhaust first , the FE mark is at 9 o'clock on the cam wheel, if you look at 3 o'clock on the same wheel there is a horizontal line (-), this is repeated on the inlet cam wheel but the FI is at 3 o'clock and the (-) mark is at 9 o'clock.

Make Sense?

My question is should you be able to line up the inner (-) marks to each other as well when in the FT position?

[VTRmart]

Hi Countryboy,

I know exactly what you mean, mine don't quite line up either and that's why I checked and re-checked the cam timing.

Mine are a few degrees out but it's running fine.

I think the problem lies elsewhere (unfortunately)

I'll have a think about this and see if I can come up with a list of the other things I did to mine..... as I was always suspicious that it wasn't cured by reseating the valves.

Hang in there!

[sirch345]

As you look at the cam wheels face on ie. the same as you would to line up FE FI there are two additional marks which look like they may also need to line up , not explaining this very well! , Try this - if you look at each cam wheel individually exhaust first , the FE mark is at 9 o'clock on the cam wheel, if you look at 3 o'clock on the same wheel there is a horizontal line (-), this is repeated on the inlet cam wheel but the FI is at 3 o'clock and the (-) mark is at 9 o'clock.

Make Sense?

My question is should you be able to line up the inner (-) marks to each other as well when in the FT position?

IMO the way you have explained it the (-) marks need to be ignored, but after reading your way of thinking I am wondering exactally which way you are going about setting up the valve timing Perhaps it might be a good idea if you could explain how you are setting the timing for each cylinder then we can see if you are going about it the right way
Like my Dad always says two heads are better than one even if they are sheeps heads

Chris.

[John W]

Hi there,
Country boy you say you have ground in the valves but did you actualy have them recut on a machine to check they were still round?

Cheers John W

[CountryBoy]

VtrMart - I look forward to any thing you can remember that might help

JohnW - Good point mate but the valves are all new

Sirch345 - to set up the front cyclinder timing i did the follwing :
1. Turn the engine until the FT mark lines up with the static timing mark through the hole in the lower side casing (alternator casing).
2. Install the exhaust cam first keeping the tension on the chain as it comes up from below, position the FE in line with the top of the casing.
3. Install the intake cam and position the FI in line with the top of the casing.
4. At this point all the marks line up perfectly including the (-)'s in the middle.
5. Release the CCT, there is then slight movement in the cams ie the chain pulls them round a touch and this is when you notice the middle marks (-) move apart.

Obviously i've left out all the in between bits like remove covers etc but i'm sure you can fill in the gaps in your head.

[CountryBoy]

VtrMart - I look forward to any thing you can remember that might help

JohnW - Good point mate but the valves are all new

Sirch345 - to set up the front cyclinder timing i did the follwing :
1. Turn the engine until the FT mark lines up with the static timing mark through the hole in the lower side casing (alternator casing).
2. Install the exhaust cam first keeping the tension on the chain as it comes up from below, position the FE in line with the top of the casing.
3. Install the intake cam and position the FI in line with the top of the casing.
4. At this point all the marks line up perfectly including the (-)'s in the middle.
5. Release the CCT, there is then slight movement in the cams ie the chain pulls them round a touch and this is when you notice the middle marks (-) move apart.

Obviously i've left out all the in between bits like remove covers etc but i'm sure you can fill in the gaps in your head.

[Frederick48]

Valves do sound like a possible culprit

At the end, "sound" will alwasy stay the same as it used to.

[CountryBoy]

Does FT stand for Front Top or Front Timed?, its a really stupid question but when timing the front cyclinder with all the relevant marks in the write places should the piston be at the top of the stroke or the bottom, i think its top but just wanted to check, sometimes the obvious is staring you in the face!.