17 replies to this topic

[tim]

Just finished rebuild on my 1275 A series engine.

It has new cam and bearings and had rebore to +40 thou.

I am left with putting last bits on I will fit the 11 stud cooper's head on it, but was wondering if I should keep it fairly standard tune for running in?

I have Twin 1 1/2 su's to go on it and 1.5 high lift roller rockers.

Should I just put standard rockers and single 1 1/2 su on while running in?

Also read few theories about running in that its not needed or to do at high rpm?

Anyone know best way of doing?

Once ready would like to put on rolling road to see how well performs.

How long(miles driven) after rebuild and running in should I do this?

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[absx2]

The first priority is to get the motor to a stage that after you have primed the oil circuit it will start on the button and run well enough to keep the motor around 2-2500 rpm for 15 minutes to bed the cam and followers in. If you omit this stage the motor is a duffer anyway.

 

I have built a fair few bike engines and three mini motors and a Ford crossflow and each time they have been run in with plenty of revs and short bursts of 3/4 load followed by overrun.  

I was always told to run them in how you want them to go and it has always worked for me.

 

The worst thing you can do is have it ticking over in the garage having adjustments for ever.

Its always best to jump in and drive it on the road so knowing your setup works is a big deal and avoid over fueling and bore wash at all costs so maybe your 1/2" might be a good plan if you know the motor will run well with it.

 

Personally I am not a fan of high lift rockers as they are known to wear cams out quickly and impose extra load on the whole cam train. There are plenty of excellent cams available that do not require the use of high lift rockers and being a new engine build its a great opportunity to do so.

I would guess bedding a can and followers in with high lift rockers will make life hard for them but i`m sure someone more knowledgeable should be able to advise, mabe plenty of valve clearance ? 

[cian]

Just drive it as you normally would but don't let it idle, pick a good route with plenty of hills to work the motor but don't go mad with the right foot

I don't want to muddy the waters but I'm skeptical about the whole cam bedding in, if you revving a fresh bored and built engine at 2k for 15 mins bore wash is a possibility, any engine I've built I keep the revs up for a few mins and took her out a good run and havnt had any problems yet

Just my two cents

[Dusky]

Standard rockers would be better to put less load on the cam.
No problem using a twin carb setup on running in.
I put my mixture on the lean side to rpevent overfuelling, then just drive the car asap ( and thats most of the time around 5-10 seconds after the car starts).
Ignition timing i set witth he strobe by turning the engine over with no plugs in it, I check for oil pressure at the same time.

On the road I keep my revs over 2000. After a few minutes I use a bit more of throttle, then lift my foot off the pedal to let the car 'brake' on the engine ( don' tknow if this expression is used in english too )

I do this a few times , then return to the garage, leave the engine to cool overnight and retighten the head/set tappets again.

[Cooperman]

There is too much nonsense talked about 'running in'.

Just drive sensibly without allowing the engine to 'labour' at low revs and without using full throttle and/or high revs until it has done 300+ miles. Then re-set everything and drive normally.

Fit the twin carbs and high-lift rockers if you wish, but ensure the mixture and timing are reasonably accurate as you don't want to drive it with it too rich or too lean, or with too much advance or retard.

Just drive it 'nicely'.

[59 Speed]

http://www.minimania...edure_guide_988

[Steve220]

I go by the new engine philosophy. Car manufacturers make engines to specific tolerances, as do we. Therefore I take it easy for a few hundred miles without letting it idle too much and then drop the oil at 300 miles and put in fresh.

[Shaggy33]

Well this thread has really worried me. I've had new engine built with Kent cam and just trying to get the damn thing to tick over was a mission, never mind all this 'do not let it idle under 2k'
My car isn't road-worthy at the moment so can't drive it anywhere to run engine in, it's just on the drive or in garage. It's taken me several sessions to get it happily idling but must admit to have the idle set high, but over 2k? Don't think so...?!
I haven't had it running long enough to get hot enough to follow the builders instructions like re-torquing head nuts and checking clearances!

[cal844]

Run it up to temp(follow cam bed in instructions) then once you have it hot, switch it off and retorque the head... Then do the valve clearances,

Note: you may need to adjust the timing or fuelling slightly so it will pull cleanly

Try not to labour the engine within the first 100 miles, then increase load on engine up to 250 miles.

Change oil and filter

250 miles onwards do what you like.... That's what i was passed by a friend who had fitted an engine supplied by a well known mini engine builder

[carbon]

Well this thread has really worried me. I've had new engine built with Kent cam and just trying to get the damn thing to tick over was a mission, never mind all this 'do not let it idle under 2k'
My car isn't road-worthy at the moment so can't drive it anywhere to run engine in, it's just on the drive or in garage. It's taken me several sessions to get it happily idling but must admit to have the idle set high, but over 2k? Don't think so...?!
I haven't had it running long enough to get hot enough to follow the builders instructions like re-torquing head nuts and checking clearances!

I would strongly resist the urge to run a new engine while the car is still static and not roadworthy. As mentioned by others it really needs to be on the road to run in properly under range of speed and load conditions.

 

Running a new cam at idle may give problems later - you really need to have the engine spinning at 2000rpm to ensure the cam lobes and followers are getting a good amount of oil from the crank. The cam lobes and followers are some of the most heavlily loaded parts in the whole engine, even more so if you're running 1.5 ratio rockers.

[Cooperman]

I built a1098 engine for a Sprite historic rally car. It was needed quickly, so after a full competition build I ran it in my workshop for around 40 minutes. Then I re-torqued the head and re-set the valve clearances, put it on my trailer and took it to Peter Baldwin's rolling road.

 

We put it on the rollers and ran it under light load for about 10 minutes, then did the settings and some power runs up to 5500 rpm. It was fine and ran excellently on events for a long time.

 

incorrect mixture and/or ignition timing that damages new engines once they have started and run for a while.Don't get paranoid. It's running with the wrong mixture and/or ignition timing that damages a new engine,

[carbon]

As Cooperman says, getting the timing and mixture right are important.

 

Ignition timing for a fast road 1275 likely to need about 10 degrees static (some will need more than this), running up to max advance of maybe 32-34 degrees by about 3000 crank rpm, this is using 99 octane petrol such as Shell V-Power (max advance will depend a lot on CR and cam profile, and should really be set up properly on rolling road once run in).

 

For mixture I have found a single SU to be much much easier to set up than twins. And in my experience getting a good tickover with a single SU is also a lot easier than twins.

[Shaggy33]

Well just to add to my paranoia I've been struggling to get the right mixture (ticks over fine once a little warm but it's not revving, just sounds like sucking air). Played around with mixture screw following advice from some who refurbed the carb but can't find a sweet spot.
I only wanted to get it running well,enough so I could drive to rolling road for tuning but struggling to achieve this.

I think I'll run it up to temp at 2k rpm or over, re-torque head bolts, check clearances and go,from there

[Cooperman]

When re-torquing the head nuts, slacken each one off by around 1/2 a turn then re-torque. Do this in the correct sequence and with the engine completely cold.

[Shaggy33]

Turning my attention to getting the timing advance sorted as I think this could be part of the reason for poor running as well as carb tuning.
Going to invest in timing gun....yikes!