Worn rings on my 1.3?

[rubachuk]

I have a 1.3SR with 117,000 miles on the clock. About 200 miles ago I fitted twin 40s, Kent AST2 and a ported and flowed cylinder head. I had the head skimmed and vac tested before it was fitted. It was set up on a rolling road with a very good reputation for Sports (although I'm on Dellortos).

I've never been happy with the results, it's never been anything like the standard car I used to have. That one used to show 130 on the clock, this one just about labours it's way to 100. Acceleration isn't great, it isn't much fun.

I've done all the basics (plugs, leads, dizzy, filters, oil).

It seems to breath fairly heavily so I've just done a compression test. Results were:

Cylinder 1 = 172
Cylinder 2 = 175
Cylinder 3 = 182
Cylinder 4 = 175

Fairly even, but seem a bit low for a head which has had a fair bit skimmed off it (before I had midge's taken off it too). These seem a bit low to me for that reason. Any ideas what I should be seeing?

I'd read on here somewhere that if you put a teaspoon of oil in the cylinder before a test it seals up the rings and should prove the rings. Results were:

210
210
214
200

I reckon my rings are all worn. Am I right? What should I be doing next?

I'm convinced there's mouch more performance to come from this spec and I need to find it.

Cheers.

[brainsnova]

did you run it in before booting it.

[rubachuk]

did you run it in before booting it.

To an extent.

200 miles is a bit low actually it probably did about 300 miles before the rolling road without it me giving it death and I took it easy until then. I was really disappointed after the session there, it was hardly better after. I gave it a boot and I've been dissappointed and trying bits since.

I'm using it everyday at the moment for work and its bugging me.

[nova_saloon]

got to run them bits in by the sounds of it plus it done alot of mileage id consider fittin new rings anyways expecailly with the type of modifications you are doing? upgrading one thing always put a strain on something else and wears it out quickly, have you got the webbers serviced and tuned ?

[rubachuk]

I don't think running any further in is going to make all that much difference now, not the amount it needs to. The carbs are Dellortos and were serviced before I bought them and set up on a rolling road.

[Pistol Pete]

Cylinders 1,2 and 4 seem to have a low reading. Maybe it is worn rings and the new mods are showing this up?

[nova_saloon]

new rings i guess

[rubachuk]

Cheers guys.

Is it a tough job? Can I do it with the engine in situ?

[garyc]

would be best with the engine out so you can get the bores honed. How much did you have skimmed off your head as that will retard the cam. What is your ignition timing set at ie what advance at 4000 rpm?

[tom reid]

Do you have a vernier pulley on it?, I'd get one if not.
Cam timing, and as above advance at 4k, RR don't always get it right 1st time.

[rubachuk]

What are the honing attachemnts you can get for drills like, do they do an acceptable job? Cash is tight and paying someone to do it sounds more pricey than doing it myself.

Also I have limited experience working on engines and I've certainly never taken one out. Time is a bit tight, I can't afford for it to be off the road for much over a long weekend at the moment and I think if I had to take the engine out it certainly would be.

As far as advance is concerned I'm not sure. It was set up at well regarded rolling road but I'm not sure what they set it to. I have a "mechanic mate" who wants plumb the vacuum advance into one of the tubes on the manifold. Is this a good idea, I've not read about it before.

[Pistol Pete]

TBH if you have limited experience in stuff like this, DIY = potential epic fail. You may end up doing more damage than good.

[rubachuk]

I may, but I'd never changed the head or anything else until I did it. It was a fairly big deal for me at the time but I did it OK.

I read up as much as I can and make sure I'm fully prepared before I take anything on. The guys on here who talk about taking engines out and putting a new one in in day must have started somewhere!

There are garages to fall back on if it goes a bit wrong, but they cost money I can't really afford to spend.

[Pistol Pete]

I wasnt trying to put you off. If you want to roll your sleeves up and get stuck in, good for you for wanting to learn. Have a read up first, hell even a Haynes might be of some use!!

[mikey14sr]

My old 1.4 used to give similar compression figures (wet-test didn't make a difference on mine due to worn valve guides) and did use a little oil, so yeah, it could well be the rings.

But then again that engine pulled really well from 40 to 90 in top gear in about 10 seconds, and didn't have T40's fitted.

[rubachuk]

I'm going to give this a go. Pete, I appreciate the note of caution but I have more fun working on the oily bits than I do driving it TBH. The Haynes makes it sound perfectly do-able.

Mikey, you got any other ideas as to what my problem might be given the symptoms? One other thing I could say is that nearly everytime I start it, warm or cold, it seems to only fire on three cylinders for 5-ish seconds and then is OK (leads,dizzy, plugs all new). Oil sealing the rings/bores??

[garyc]

before you go changing your rings I'd look at other things first. I was told by an engine builder that compression tests are only a good test of how reproducble the gauge is. If all cylinders are within 10PSI then everthing should be OK, unless it is smoking like a good un.

If the rings were OK before they should be OK now. if you have improved breathing its bound to be something else.

[rubachuk]

I'm not too sure the rings were OK before though. I bought it about 10 months ago and it had supposedly been stood for 7 years. It took a fair bit of work to scrape through an MOT and it ran sh1te even then. I wasn't bothered though, I put it down to the carb but wasn't concerned cause I had plans!! :D

The symptoms seem to suggest this could well be my problem. I'm not concerned that one of the cylinders/rings is at fault, I'm leaning more towards it just being worn across them all. Surely the test with oil in the cylinders proves this?

I've checked and replaced everything I can think of easier than this, if you have any ideas of something else it could be then please let me know. Honestly, I'd love it if someone could come up with something different.

[jimbob-mcgrew]

maybe the rings couldnt deal with the extra compression gained by skimming the head. u can get away with changing the rings and honing the bores with the block still in the car, the head and sump will have to come off, id reccomend doing one piston and bore at a time making sure to keep the order of 2 halves of the crank bearings as u go, and covering the crank/other bores while you hone the bore, to make sure no swarf lands on anything, haynes has an easy do-it-yourself explanation using sandpaper rubbing gently in a criss-cross pattern, might seem alot of work, well... it is to be honest, but its doable without taking it to a garage, hopefully it sorts the prob out :thumb:

[garyc]

first off how much was take off your head?

set the bottom pulley marks and take a picture of the top marks, then post them up.

get a timing gun and check the ignition timing at 4000 rpm.

170-180 sound OK, I think mine were about 120 last time and that is on a rebuilt engine.......

[rubachuk]

first off how much was take off your head?

I'm don't know, I bought it off a guy who ran it on his rally car and I only had the smallest amount possible skimmed before I fitted it. The guy who skimmed it only said it was "well worked". Is there a way of measuring it while in situ? I suppose I could measure from the top of the block to the top of the (edit) head and then measure the standard head I have. If I make an can measure the gasket and allow for that it should tell me.


set the bottom pulley marks and take a picture of the top marks, then post them up.

I'll see if I can find time to do this this afternoon after work.

I'll see what I can do about getting the ignition timing checked, it's not a piece of kit I have

What are your thoughts on the improvement with oil in during the compression test?


Jimbob - cheers

[rubachuk]

Something else I maybe could mention is that about 4 weeks ago I found that the dipstick was out of its hole (blown out??) and small amounts of oil had been spraying out. The breathers aren't blocked, they're smoking away like good un's as I've mentioned.

Might be unrelated though.

[garyc]

you could try measring take off 1.2mm for the HG. They always breath well if they have been driven hard.

[rubachuk]

first off how much was take off your head?

I measured my standard head at 95.9mm and my modded head at 96.1 to the top of the block. So if you're saying 1.2 for the HG then that's 94.9mm, only 1mm off. It looks more, the sticking out bits where the spark plugs come in have been machined a bit so suprised its only 1mm.


set the bottom pulley marks and take a picture of the top marks, then post them up.

http://i306.photobucket.com/albums/nn266/rubachuk/IMGP2447.jpg

http://i306.photobucket.com/albums/nn266/rubachuk/IMGP2448-1.jpg


get a timing gun and check the ignition timing at 4000 rpm.

170-180 sound OK, I think mine were about 120 last time and that is on a rebuilt engine.......

Will get the timing checked on Friday afternoon, what should it be? What should I try getting it set to taking into account the spec?

[garyc]

it wants to be around 30-32 degrees at 4k, but if its a bit more it should be OK. Check its advancing too.

[rubachuk]

The guy who's going to check the timing knows what he's doing, but for my benefit in the meantime, how do you check its advancing? Do you check it at idle and then at 4k?

I thought these were vacuum advance, which is obviously disconnected now. Is there some sort of mechanical advance also?

The guy who's doing it was suprised the vacuum advance was disconnected. He's been talking about plumbing it into one of the tubes of the inlet manifold. I've not heard of it before but is it a good idea?

[mowgli]

The guy who's going to check the timing knows what he's doing, but for my benefit in the meantime, how do you check its advancing? Do you check it at idle and then at 4k?

I thought these were vacuum advance, which is obviously disconnected now. Is there some sort of mechanical advance also?

The guy who's doing it was suprised the vacuum advance was disconnected. He's been talking about plumbing it into one of the tubes of the inlet manifold. I've not heard of it before but is it a good idea?

you have just answered the problem......

if the advance/retard is not connected, it will not rev properly

[Novasport]

Not necessarily, 40's tend to run better without vacuum advance. It is mainly there for economy reasons.

[mowgli]

and if it is still on standard factory settings, it will be as flat as that cat Ade ran over. my adv/retard failed on my old 1.2 & it could hardly pull itself up the road. i massively advanced it & it ran roughly, but would accelerate.

[novaxe235]

your vac advance should be blocked off and i would of thought 32 degrees advance is too much to be safe i would set it to 26 at 4k just my opinon though

[rubachuk]

What's best to do then? Is plumbing the vac advance pipe into the manifold a decent idea, do other people do it? Or, is it better to advance it as recommended (30-32 deg) and leave disconnected?

If I leave disconnected, should it be bunged up or left open?

[novaxe235]

it should be bunged up either that or get the proper dizzy with the right power curve for the job.

[jimbob-mcgrew]

bunged up as in right sized bolt thru it and jubilee clip ?

[rubachuk]

Vac advance bunged up and timing OK set at 4k as advised, mech advance checked and working. It revs much cleaner and has sorted out a flat spot at about 3k. It starts better particulary from warm and generally feels a little bit keener.

But, its still not right. I know it could benefit from a proper rolling road session, but I'm convinced there it still a fundamental problem somewhere that no amount of rolling roading is going to sort out. I really need to nail the problem down beforehand or else I think I'd be throwing (more) money away.

Symptoms are still the same on the whole. Any ideas anyone?

[dj_wudgey]

i think its the rings me matey!! didnt know you were having problems with it though!! it will be something scilly though dude!!

[rubachuk]

Is your SR on the road at the moment? Might be interesting to see what yours is like sometime so I've something to compare it to.

I'd love it to be something silly, but it doesn't help when you don't know what the silly thing is!