Adamirish
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| posted on 11/1/16 at 08:00 PM |
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Valve guide wear
I'm rebuilding my little 1700 Xflow after its strip down, doing the head I have found a small amount of play in a couple of the exhaust valves,
namely cyl 2 and 3. How much play is too much? Everything else within the engine is low mileage and in perfect condition.
There has always been a small puff of smoke on a cold start up which I put down to the stem seals which are the umbrella/floating type. I have a new
set to go in.
I would rather not spend a fortune getting new valve guides/valves if I dont need to but I will if it needs them.(I have spent ALOT as it is) It has
bronze guides if that makes any difference.
Worst case scenario, what am I looking at price wise? I've never had any done before.
Thanks in advance.
MK Indy 1700 Xflow
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CosKev3
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| posted on 12/1/16 at 08:24 AM |
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I think cost will depend on how hard they are to replace in the head,had some done on my Pug 16v head and they were only £9 each and took the engine
shop no time to swap over.
Although he did mention a lot of guides require reaming once fitted to get the clearance correct.
I would guess if you've noticed the difference in clearance from the others they will need replacing,could well be someone reamed them out
slightly too much,if they've been replaced before.
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nick205
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| posted on 12/1/16 at 08:42 AM |
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It would seem obvious to me to get them replaced whilst it's apart.
The worry of not doing it and having to take it apart again would put me off not doing it!
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snapper
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| posted on 12/1/16 at 02:08 PM |
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But a good head, not easy as Crossflow is an old engine
Put new guides in and you want worry again
If you can feel side to side play then they need replacing.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Adamirish
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| posted on 12/1/16 at 02:48 PM |
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Thanks for the input. You all just confirmed what I thought. I've spoken to the company doing it and dropping it off with them tomorrow.
A very light skim, and 8 new bronze guides is costing £160. Providing they don't need to replace any valves I was quite happy with that.
MK Indy 1700 Xflow
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nick205
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| posted on 12/1/16 at 02:52 PM |
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That seems a reasonable cost to me for peace of mind when it's back together.
ETA...from memory the guides need to be pushed out and back in to get the interference fit right.
[Edited on 12/1/16 by nick205]
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Adamirish
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| posted on 12/1/16 at 03:11 PM |
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quote:
Originally posted by nick205
That seems a reasonable cost to me for peace of mind when it's back together.
ETA...from memory the guides need to be pushed out and back in to get the interference fit right.
[Edited on 12/1/16 by nick205]
That's my thoughts too. Considering it has an £80 head gasket, I don't want to take the head off again in a few months time.
I'm not sure how they do it to be honest but they have a very good reputation round these parts so I'm quite happy that they know what
they are doing.
I shall report back with my verdict of them in a couple of days!
MK Indy 1700 Xflow
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rusty nuts
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| posted on 12/1/16 at 07:04 PM |
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X flow heads never had valve guides fitted as standard just a bore through the cast iron , any bronze guides will have been an aftermarket mod .
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minibull
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| posted on 13/1/16 at 12:56 AM |
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Don't know current thinking on this (and I'm still using pre xflows) but it used to be the case that bronze guides needed more lubrication
so it was recommended that valve stem seals were omited when using them,resulting a smokier engine. For this reason it was recommended bronze guides
were competition use only.
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Adamirish
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| posted on 14/1/16 at 05:41 PM |
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Got the head back today and a damn fine job they did of it too.
Turns out the guides were like new, he didn't replace them as there was no point. In his words, they were as good as the day they were fitted.
It turns out the puff of smoke my have been due to the head being not quite flat. Very very slightly not true. So he stripped the head, skimmed and
pressure tested. Fitted new stem seals(I'm a Guinea pig trying some untested ones). Recut the valve seats and polished the valves.
I should have the engine built over the weekend with any luck.
MK Indy 1700 Xflow
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locost7-online.com
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| posted on 14/1/16 at 08:01 PM |
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I love the xflow, I used to build them to all sorts of specs, they really are bullet proof sounds you had a good job done to me, has it been gas
Flowed previously?
Locost Xflow 150bhp injected! Sold :-(
Facebook blog https://www.facebook.com/Johns-Tiger-Avon-Build-814223212056368/
PLEASE NOTE THIS MEMBER IS NOT A TRADER.
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Adamirish
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| posted on 14/1/16 at 10:10 PM |
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quote:
Originally posted by locost7-online.com
I love the xflow, I used to build them to all sorts of specs, they really are bullet proof sounds you had a good job done to me, has it been gas
Flowed previously?
Yes they are great little engines. Hopefully no oil leaks now too!
Yes the head has been ported, polished and gas flowed. Port matched manifolds, Big valves, double springs, steel rocker post etc etc. It's
running a Kent 244 cam.
It's amazing how good the old lump is really. Very very simple yet really strong. Surprisingly light for a cast iron lump too!
MK Indy 1700 Xflow
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rusty nuts
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| posted on 15/1/16 at 07:48 PM |
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The competition sump gasket from Burtons eliminated 95%of oil leaks on mine , well worth fitting
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Adamirish
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| posted on 15/1/16 at 08:05 PM |
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I have fitted a complete cometic gasket set including a cometic head gasket(£80  ) burtons crank and sump seals. I fitted a cometic rocker box
gasket which stopped that leaking a while ago so I have faith in them!
This little engine is getting expensive! To put it into context, I could have bought a couple of good zetecs for the amount I have spent on the
rebuild.
MK Indy 1700 Xflow
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owelly
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| posted on 16/1/16 at 09:00 AM |
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I'm a bit late to this thread so feel free to ignore this.....
Imho, worn exhaust valve guides would rarely cause oil burning. There's no point in the four strokes where there's any suckage (made-up
word) on the back of the valve. The exhaust valve is closed during the air admittance stroke, closed during the compression stroke, and only open
during the exhaust stroke which then has a positive pressure.
http://www.ppcmag.co.uk
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