Starting engine after top end rebuild

I’ve just rebuilt the top end of my 2.0 type 4 engine, new barrels and pistons, new cylinder heads, pushrods etc and new seals all round. Is there any kind of procedure I should follow for starting it once it’s back in the van? I know that on a full rebuild it’s running it at 2000rpm for 20 min but does that apply to just a top end?

 

The procedure of running it at 2000 rpm for 20 minutes is to break in a new cam shaft. As you don't appear to have changed your cam shaft I don't think that procedure applies. Check the oil level, turn it over by hand with the plugs out to make sure nothing is wrong and all is working as it should. Plugs in and go for it.....in my opinion. Someone more knowledgeable my be on soon to confirm or otherwise.

 

I’m sure I saw a thread where it was suggested to drive it briskly up to about 50mph, let engine slow down without brakes and repeat several (I think 5 ) times.

 

First, I hope you thoroughly cleaned the barrels, really thoroughly.
Second I hope you used nothing heavier than WD40 to then lubricate those barrels and definitely did not swath them in engine oil.
That out of the way...
Visually check the linkage is balanced, I'm assuming you have simply put your carbs back on like you found them? Just make sure they both start to open at the same time. Also assume you haven't messed with the timing.
Start it up, have a quick check for oil leaks then hit the road. Get into third gear and floor it to 50mph, then foot right off as it slows to 30mp. Repeat 3 or 4 times. If you DID wash the barrels with engine oil maybe do that a few more times.
Go home and check the idle balance and mixtures.
You're done - just drive it then change the oil after 100 miles or so.
It's better to use break in oil for all that - it will help the rings bed in.

 

If you haven't changed the cam, forget the break-in stuff. Disconnect the ignition, crank till you've got oil pressure (even that's optional), then fire it up

 

Is asking about “break in “ oil, still an oil question and therefore banned?

 

Its oil for break in, to be changed after a short time, not necessarily any stuff with special labelling. I ploughed through https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

TLDR: motor manufacturers use their recommended good quality oil, not labelled as break in, for break in. Some oils with lots of magic words on the can arent as good as some other high end normal car oils.

 

Thanks for the replies. I’ve actually fitted new carbs to it which was where the whole process grew arms and legs. I’m guessing I can get them running roughly to at least take the van a drive

 

You don't really have any other option do you?

 

And I hope you checked the piston ring end gaps. Do what zed said but I wouldn't bother with running in oil oil if you haven't replaced any bearings or the cam and followers, but how did changing the carbs end up with a top end rebuild?

 

I’ve just done a big trip round Europe in the van so decided to get some dells and a new exhaust, which then led onto new heat exchangers and then when they came off I noticed the cylinder heads looking a bit worse for wear and leaking and just decided to go all in and whip the engine out, rebuild the top end while I had it out

 

Rolling road.

 

Or fit an AFR meter and begin the journey to a tuned up engine.
You are less likely to kill it starting with the usual horrible rich jetting that is often suggested by carburettor vendors, as it is in their interest not to have their customers come back after a short time with a finger pointing at the carburettors.

Make sure the ignition timing is right and the valve clearances are set properly, and you filled it up to the level on the dipstick ...

 

I think it’ll be the rolling road option, I’d be devastated drilling and welding an AFR into a brand new csp exhaust

 

So instead you know it will do the quarter mile in a good time...but it may still not be best tuned for just cruising, that rare state of affairs in a 40mph limit on a flat road ...

 

No. You will know it won't melt a piston if you put your foot down up a long hill. That's really all that matters - you can't tune your main jets for cruising, that's silly.

 

Rolling road is the best way, just to get the carbs sorted, imho. Probably best to re check the rocker bar and any other thing you can get to, after209 or so miles, inst it?

 

I can, I have a main jet just for that purpose..on the 32mm barrel of the progressive.

And fiddling with float level, air correctors and emulsion tubes can alter the slope of the fuel supplied against air flow even on a simpler carburettor.

 

But this thread is about Dells, not your carb. Perhaps your post was advice for yourself.

 

Read the second half of my post .