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MG Midget and Sprite Technical - After an engine rebuild

Just reading about re-torqing the head in another thread and got to thinking about mine. Engine was rebuilt (standard spec 1275) and I've got 300 miles on her since. I was going to flush the oil at 500 miles. What else should I do and when? My thoughts so far:

- oil change
- Re-torque the head bolts. Cold? Warm?
- Check the valve clearances
- Top up dash pots
- Check ancillary fittings are tight (manifolds, exhaust flange bracket, alternator, thermostat housing, water pump, oil filter housing, etc)

Words from the wise welcome

Ant
Ant Allen

Ant,
i would spanner check every thing i could reach that was touched during the engine removal, from prop shaft flange bolts to water pipe clips.
Brad (Sprite IV 1380)

Ant.

Oil change 500 up to 1000 miles (if using running in oil).

Re-torque head COLD. That is, back off and re-torque each nut in the tightening sequence.

Valve clearances cold.

Check ign timing and set up carbs. You may have set them rich for the running in period.

Spanner check everything.

Mark.
M T Boldry

> (if using running in oil).

And if I'm not?
Ant Allen

Your engine will never run in.
Brad (Sprite IV 1380)

There's a do's and don't list on peter burgess website, very helpfull.
Alex G Matla

Hmmm. Here we go again.

I have castrol classic 20W50 in there. No modern anti-wear additives, but not specifically a running in oil either.

The dos and don'ts list says I can go to 6000rpm - I won't be doing that particular "do"! It also says check the valve clearances when hot which is the opposite of what Mark's written above.
Ant Allen

as I'm sure you know, the reason for valve clearances is to allow a bit of space for the metal bits to expand into as they heat up. Therefore the clearance is usually logically quoted for a cold engine.
David Smith

Ant,

I can certianly see the advantages of both checking clarance when its hot and cold, you might try doing both, after all how long will it actually take 5-10 minutes? I think the real question you should be conserned with "Is when do you adjust them?"

Im in the camp of adjust when they are cold and check them when they are hot.... But thats me, im sure this topic is as varied as which brand of oil to use

Being that you are useing everday oil....Im wondering if you shouldnt abuse the engine a little more, I guess My fear is using a good motor oil and to little stress will have the oppisite effect your wanting, after all, bedding in rings is a rather violent act in itself if you think about what has to happen inorder for that act to occour.


Prop
Prop

I would have to think that it would be more logical to check them when it is hot to be sure enough clearance is present when really needed. After all, your engine should be spending a lot more time hot than it does cold. ISTR MGB specs for some years specifying the hot setting whilst other years specified cold.

OTOH, it is good to at least HAVE a cold setting so that you can set it up for that first run. Sorta "chicken and egg" issue. Can't start it cuz I haven't set the valve lash, but I can set the valve lash cuz it ain't hot. Next thing you know, somebody is breaking out the acetylene torch to "warm up the engine".
David "taking both sides of the issue" Lieb
David Lieb

My cam grinder only specified hot clearances. .016 and .018, so I set them initially at .020 and warmed up the engine. Then I adjusted them to spec.

Maybe I over simplify things?

I won't comment on break in oils.
Trevor Jessie

Hi Ant

Why are you worried about bursts of higher rpms, what harm do you think it may do? Rings bed quickest at peak torque and bursts of high rpms help too, you will burn less oil if you use my technique and mineral oil, take it gentle and you may well ruin your engine by glazing the bores.I do not notice new cars having to be run in gently. Hot settings are easiest....imagine, you set your tappets cold and one or three rattle, you now have a 'not' cold engine, what do you do? Wait all night to get a cold engine or set 'em as a hot setting? With regard to re-torquing gaskets, if you have a copper gasket you must retorque, it you have a composite gasket I prefer not to retorque. If you do retorque do you know if you have high or low torque studs? I think Prop is giving you good advice.



Peter
peter burgess

Interesting that you say not to retorque. I was about to do mine. It has a composite head gasket and ARP studs. Maybe I should jest leave well enough alone?
Trevor Jessie

Hi Trevor

It is up to you, we have, for the last 25 years not retorqued the composite gaskets (usually Payen), retorquing copper based gaskets is a must. Did you torque to 50lbs ft as you are sporting ARP studs?

Peter
peter burgess

I always re-torque as a matter of course, I feel it's just an insurance that costs nothing but a little time. I use engine oil on the threads and a little ARP anti scuffing paste on the thrust face of the nut or bolt head. I also back off each nut in turn and torque up again to the manufacturers settings (ARP sometimes recommend a different setting, READ the instructions...).

As for Tappets, again this is just MY opinion. I set them cold, but as Peter rightly states, if you have one or two that are perhaps a little noisy, then you will have to check them when warm. In fairness, I have noticed very little difference in the settings when cold or hot, perhaps a thou... So it really shouldn't be a worry.

Again a note on running-in based on Peters point. I have built MANY engines, and the ones that perform the best are the ones that are 'pushed' early on in their lives. OK, not 8k from initial start up, but some good hard work for short periods for up to 500 miles. I use a Running-In oil by Millers for build and initial period, but I think the key is attention to detail and cleanliness when building your engine.

Make sure the engine is up to temperature before you rev it hard.

Mark.
M T Boldry

I think checking hot or cold is fine; the clearance for the initial cam ramp is important for both. It's checking during the transition between the two that should be avoided, ie. don't check for rapidly warming engine, as the expansion between the block/head/pillars and rods will vary according to different and changing temps.

A
Anthony Cutler

I'm not recomending you do this but as some of you are aware, I have a very lazy (I just don't worry) attitude of these things. I also have an uncontroled heavy right foot so keeping below a certain RPM is tough for me.
My 1330 engine was put together by Alan Anstead, the only thing I had done was the main bearing strapped, ARP head bolts and one of Peters 123 dizzies. None of the components were balanced or lightened.
The first 200 miles were taken fairly easy not going above 4000 rpm (but that turned out to be not above 3500 rpm as my rev counter was under reading), with the occasional blip up to 5000rpm. All with cheapo 20/50 oil. then an oil and filter change before hitting the track at exactly 200 miles on the clock . 100 miles on track with both the over reading rev counter and speedo off the clock. Sunsequently the car has done 500 miles of spirited road driving in addition to another 100 mile trackday, a sprint and an autosolo.
Nothing's gone bang, it barely uses any oil and it is an absolute pleasure.
Will I have proiblems in the future, who knows?
I'm just wondering if sometimes people are a bit over protective about their engines.
Gary Lazarus

Sorry that should be an additional 5000 miles
Gary Lazarus

From my own experience the most important thing is to avoid laboring the engine; revs are not a problem but letting the engine struggle (because you are in the wrong gear on a hill etc) will knacker it.
Toby Anscombe

Peter, the instructions that came with the studs said 40ft-lbs using the supplied lube. There was a time lapse between reading the instructions and torquing them. Using my superb memory I torqued them to 40 ft lbs, then sequenced up to 50 ft-lbs in 2 ft-lb increments. While cleaning up after the engine build I found the instructions. Having realized my mistake I left it alone and hoped for the best. BTW, this is an iron head. I'm at about 500 miles now and so far everything seems OK.
Trevor Jessie

Hi Trevor I think you may have alot of torque if you used the arp grey lube, leave well alone, if you used oil it will be fine.The biggest problem we see with overtorquing an A series or even fitting the extra two cooper S style studs and putting big torque (40 plus lbsft) is that the head gasket gets a little too squished and comes out the side of the head under full power( with a flat sheet of flame and sparks).

Peter
peter burgess

That is what I'm afraid of Peter. The engine is low compression , but It has the Moss SC kit. Currently, I have it running with the biggest pulley I have. After the engine gets a few miles on it I was going to go to a smaller pulley and re-tune. I think I best order another gasket as that was my last one.
Trevor Jessie

Toby,
My understanding on the rev limit during break-in is that it limits the linear speed of the piston rings, which seems a reasonable concept. OTOH, I think that the driving below that limit should be spirited to force the rings firmly against the bores and wear them to match perfectly.
David "if they had only told me that before I broke in my engine..." Lieb
David Lieb

" I think that the driving below that limit should be spirited to force the rings firmly against the bores and wear them to match perfectly."

I'm just finishing my engine rebuild. Good to know that an autocross can only help things.
S.A. Jones

but how mutch torque is to mutch ?
i am no calculus wonder so the lbs amounts don't say to mutch to me

i always use the 68Nm as stated in my Haynes mini manual
Onno Könemann

Onno you will have to run your numbers thur a conversion chart .... you might have a look on your torque wrench, mine has all 3 calabrations, "Normal" units of mesurment, metric, and the Nm/Hg unit of measurement.
Prop

I stumbled onto something the otherday a long these lines..

when you do an 11 stud conversion...you should only torque the 10th stud next to the thermostat to 25 ftlbs and not the 40-60ft. pounds, because it will bust the block along the water passages...Is that true, I havent seen that bit of info before, until just a couple weeks ago, and Im an avid late night A-1275 search net rat.


prop
Prop

Prop, I don't use 'monkey metal' studs (for the reasons why see Carroll Smith's book 'Nuts, Bolts, fasteners and Plumbing'.

If using ARP studs, then the stud by the thermostat housing should be torqued to:

40 ft.lbs with oil

or

30 ft.lbs with ARP moly base lube.

Deborah Evans

Prop,

My last engine, 1420, was made 11 stud and I was told to use the lower torque for the front stud due to it going into a thin area of the block deck IIRC, nothing to do with the stud quality, rather due to the block structure in that area the higher torque will distort the block top deck. The actual fastener supplied was a special bolt for the job and the thread in the block was fitted with a stainless helicoil to aid future removal. IIRC the details on tightening the front stud/bolt are standard knowledge for 11 stud head users and I would expect it to be covered in Vizard.
David Billington

ok
found a converter

68Nm = 50ft-lbs
54Nm = 40ft-lbs

so what do i use?
and how do you torque?

i was always told not to go to to smal increments up because getting the nut moving costs more torque than it is actualy tightening

so i usualy go 40-50-68

if i grease is this diffrent
and what kind of grease should i use?

i know go arp and all is revealed
but that just did not happen this time but it is my lesson for next time.
Onno Könemann

Hi Onno

I was mentioning that the arp paste puts more torque on the nut than 30 weight oil, so 50# with arp lube is an awful lot more like 60# with 30wt oil. The 9 head stud nuts should be 42/50 depending on stud type ( with factory studs) and the front bolt/rear stud, if fitted should be 25lb ft, the same 25#ft should obtain to the front and rear studs if retro fit(quoted torques with 30wt oil).

Your 40-50-68 sounds good, remembering to do each one in a nice, smooth action rather than a sudden jerk. feel for stretch as the torque wrench clicks off, even ARP bolts tend to creep when being torqued.

Deborah, I don't see that the OE 50#ft studs are monkey metal when in good condition? we have had problems with some aftermarket studs and bolts and have even seen ARP con rod bolts fail under high loading in Cosworth Turbo units, but not fail with Cosworth original bolts

Peter
peter burgess

Peter,

I don't have a problem with OEM studs in good condition.

The problem is with fasteners being marketed as OEM when they are not. Indeed this has been ongoing for 10+ years with things like SAE Grade 8 bolts being copied (but made in an inferior way) by elements in Asia and the Far East.

I've lost count of the number of horror stories I've either seen or heard about of failures occurring as the direct result of inferior fasteners, even though said fasteners were sold as OEM by the major aftermarket classic car companies.

To this end I will not purchase or use fasteners from these people.

My preferences are:

1. Fasteners sourced from Rolls Royce Aerospace (if available)
2. Cosworth (where available)
3. ARP
Deborah Evans

i have now got an new set of OEM studs torqued wit no lube to 68Nm

a new payen HG fitted so i won't retorque when hot

it all seems to run just fine in my test drive

thanks for all the advice

the next time i doe some real work on this engine i will replace most crucial studs nut etc with ARP
because i never want to have this hassle again
Onno Könemann

Hi Onno

Sorry to check on you but did you use oil on the threads or were they dry?

Peter
peter burgess

onno is out there, happily driving around....
Alex G Matla

they where dry

and 68Nm is what my haynes said and the do not mention lube of anny kind

i understood that with oil or grease the amount of torque had to be reduced
Onno Könemann

""Monkey Metal""...LOl, thats good, are inferior fastners called ..."squrrliey Nuts"...LOL

So I meant to mention Im using ARP hardware...And My question was about the block breaking if torqued to same spec. as the other head bolts. which is what peter still answered,,,,as backing up what I came across...25ft.lbs.


Prop
Prop

Hi Onno

The figures you quote are for lightly (30w or 20/50) oil, the arp moly paste reduces the torque reading required to obtain the correct 'actual' torque. I shouldn't worry as I bet you had some residual oil on the studs/nuts.

Peter
peter burgess

thanks Peter
i must admit it might have been a bit oily
isn't everything working under a midget hood!

Onno Könemann

Or any old car? LOL

Peter
peter burgess

This thread was discussed between 20/05/2009 and 24/05/2009

MG Midget and Sprite Technical index

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