Ok good to have those feedback. Indeed there are various break in procedures out there. One thing for sure is never do infinite idle as break in. I'm planning on replacing all engine seals. I hope the engine won't leak after. Currently I have ordered about more than 950 euros of parts (engine, suspensions, brakes, etc...). Restoring the engine is a risky bet for me since this is my 1st time full engine assembling. But I don't wan't to feel negative about it. I believe this can be done right.

Edited 20 November, 20214 yr by cedreex

From what I understand, hone the cylinder is necessary for the following reasons :

- Create the scratch inside the cylinder for good lubrication between oil and new rings

- Clean the top of the cylinder where the rings never touch so the new rings don't scratch with the old top

 

So I will hone the cylinder but I don't think I'll do an extensive hone though

Edited 20 November, 20214 yr by cedreex

http://www.mototuneusa.com/break_in_secrets.htm

the hone wont remove a worn step at the top of the bore , if you have one its probably time for a rebore to the next size

 

they dont remove much material , it just remakes the cross hatch finish so that the new rings can mate to the bore and work well 

1 minute ago, steveo3002 said:

the hone wont remove a worn step at the top of the bore , if you have one its probably time for a rebore to the next size

 

they dont remove much material , it just remakes the cross hatch finish so that the new rings can mate to the bore and work well 

 

I think the material at the top of the cylinder is normal because rings never touch this space. This means that the material out there are burnt material. So I don't think you should rebore because of that. Maybe the bottom of this top will not fit the new rings because of an eventual clearance of the old rings but that would mean I'll find a clearance measurement when I'll check the old rings clearance (i.e using a gauge horizontally between ring housing and the old ring).

it can be a build up of carbon that would clean off

 

or on extremely worn engines its a step in the metal where the bore is worn where the rings touch and original unworn on the very top....you wont have this at 112k km

3 minutes ago, steveo3002 said:

it can be a build up of carbon that would clean off

 

or on extremely worn engines its a step in the metal where the bore is worn where the rings touch and original unworn on the very top....you wont have this at 112k km

 

Yes by "burnt material" I meant carbon. On the 112K kms I've found less than 0.5mm of worn at the top of the cylinder but still there is some visible carbon out there. Same for the other engine which has 172K kms.

There's one thing I don't understand well about break in procedure. Once you've assembled your engine then you start it for the 1st time but then you'll have to adjust the dizzy timing and the carburetor. The engine may run bad during these adjustments. So I don't know if this 1st start and adjustments have an impact on the whole break in.

in an ideal world the engine would be ready to drive away ...but yes like you say sometimes it will need adjustments

You are not trying to setup smoothest idle and lowest emissions when it first starts again. You are trying to get it running safely (no leaks) with no cutouts, burning fuel and pushing the piston rings against the cylinder walls.

 

The rings will be tight, so you will need a slightly higher idle speed for a while anyway.

theres a mark on the distributor for basic ign timing ...good enough to start and run 

 

guessing the carburettor ran before ?  

 

i think the main thing is no extended idle....so dont let it sit idling for 30mins and so on

 

dvderlm used break in oil , i used cheapo supermarket oil ...maybe thats why he has more success, who knows , maybe my bores are worn i didnt have any specialist measuring equipment

 

if you have an engine machine shop nearby they would likely measure the bores and hone it for you , and have a special tank that they can dip the block in to clean it up like new

 

 

14 hours ago, dvderlm said:

You are not trying to setup smoothest idle and lowest emissions when it first starts again. You are trying to get it running safely (no leaks) with no cutouts, burning fuel and pushing the piston rings against the cylinder walls.

 

The rings will be tight, so you will need a slightly higher idle speed for a while anyway.

 

Thank you. Now I understand better the 1st engine start vs break in. Still I hesitate again about changing or not the piston rings if mine are still usable (i.e if the clearance measurements of the old rings are fine). There's clearly a break in difference between new piston rings and old ones. Moreover I may use the new rings later if I want but in the other side I have the opportunity to change the ring myself when assembling the engine so why should I wait later and disassemble the engine again and risking to have to use oversized ones.

my oil control rings were stuck with carbon thats what made me replace them , you could also free them off by soaking in chemicals , mark all the parts so they go back in the same place

One thing I'm afraid of is what if my engine take time to start at 1st. I mean is there some caution or impact against the break in if I need several crank in order to start the engine for the 1st time. Of course I will make sure my carb is sufficiently loaded in fuel before cranking but there always can be some reasons for engine not starting quickly. I know cranking the engine is something less than 200rpm but maybe several crank is not good for the new rings. From what I understand I should make sure the engine starts quickly for the 1st time with some high enough idle and avoid rich mixture. For this reason I think I should not touch my carb but use it as it was uninstalled and only restore or adjust the carb after break in is done.

Edited 21 November, 20214 yr by cedreex

Because if I'm not wrong I've understand that the goal is to preserve the cylinder hone job before starting doing the break in.

Edited 21 November, 20214 yr by cedreex

It's the first hour of use that matters say that Mototune article.

 

I'm sure even a couple of minutes of gentle running while you fiddle/adjust won't harm the hone pattern much and a carb will need richness from choke with cold engine. 

(Autochoke fast idle speed on a Pierburg will be fine).

 

You may even want to crank a couple of times without plugs to help the oil get circulated. A friend with an RX7 directs a fan heater at the sump for 20mins before first restart when he rebuilds because the rotary engine seals are worth looking after. 

 

An engine is an air pump, so the ring condition matters for efficiency. Me, I'd do the job once. Otherwise you have to like buying cylinder head bolts and head gaskets. 

 

Beware: You may snap a worn ring when removing it from piston.

But it is the perfect width and sharpness to scrape the ring land grooves with.

Make sure to use a piston compressor to squeeze the rings for refitting.

 

snapped a new ring when fitting mine too 😞

Thanks for these useful informations, I appreciate. I absolutely agree with @dvderlm on doing things once and avoiding buying the some parts twice.

 

I'm relieved that the break in can be much less than a thousand of kms as they did years ago. The soon I can drive the car normally the soon I can take it to the French MOT. They will rev the engine quite high during polution control so I'm a bit afraid. Since I have no car, this is gonna be my daily and it's quite hard to have to wait.

 

The MH carb is indeed a pierburg 2E3 with autochoke (which is working but not sure if its throttle clearance is ok). The carb was working but maybe running a little rich and I was planning on disassembling it to clean any eventual dirt inside. I'd prefer cleaning the carb before the break in if possible. Otherwise I'll run with it.

 

I have to clean all the engine part first and engine parts won't arrive soon. I've tried to remove some part like piston rings and valve seal using non specific tools or even by hand. But I've soon realized that even if it can be done without specific tools, it was quite hard to do. So I've bought the 3 tools below to help me. I've already tried the tool for the ring (don't know its English name). They're not the best quality tools out there but they really ease my job. I have a lot of work to do on this car (renewing everything) and the car I'm working on is outside. The weather gets cold and I'll have to find courage to achieve this.

 

Edited 21 November, 20214 yr by cedreex

you should have taken a fresh test before taking the car apart , then you have a year to finish it and tune it up 

53 minutes ago, steveo3002 said:

you should have taken a fresh test before taking the car apart , then you have a year to finish it and tune it up 

 

I only did a compression test on both engines before disassembling them. One engine had 30psi on 3rd cylinder and 150psi on the 3 others. The other engine has low and inconsistent values (something like 60 to 150psi). Then I checked their head for leaking valve using water (could have used fuel/gasoline also). The 1st had a bent exhaust valve on 3rd cylinder and the other had no leaking valve (at least a very little amount of water was leaking). Obviously these engine are not in their best condition.

 

Unfortunatly I don't have a year to finish the car. I hope I can finish it before the end of the year. Maybe that's impossible maybe not. I don't know, I'll try and see. Anyway it won't be the end of the world if I fail to finish it. I'll find a car and try again next year.

Edited 22 November, 20214 yr by cedreex

check for valve guide wear , that would be the first thing that wears in my opinion , and dont use budget valve stem seals