Running in top end overhaul

[crankedup]

My 1928 Vauxhall (2.7cc six cylinder) is being treated to a top end overhaul. Valve guide seals are being introduced along with new piston rings and valve grinding. Should I run the engine in following usual rules? I also tow my vintage caravan with the Vauxhall, the caravan weighs about 750kg, should I restrain from using the Vauxhall for towing for a period of time after the engine work I have had done?
Thanks, any comment/advise appreciated.

[lowdrag]

Not an expert on prewar cars, but I wouldn't have thought so. Running in is usually for pistons and bores, not a top end overhaul. I'd refrain from towing and use the car a bit first though, just in case.

[itiejim]

Presumably the bores are being honed when you replace the rings? They really need to be otherwise you'll never get the rings to seal properly.

Assuming this is the case, you really need to give the engine some load from the very outset in order to seat the rings. Running on a very light throttle or low load will just glaze the bores.

[davepen]

crankedup said:

is being treated...new piston rings.

Rings don't sound like Top End. Do you mean piston rings or valve seat inserts?
Have the main bearings or big ends been dismantled, or was the block removed from the crankcase? (Period pictures in the Alvis 12/50 Handbook show this method.)

Consider what running in is; using the engine so that any (slight) mismatch in the sizes of any moving surfaces have time to bed down. While doing so that any excess heat generated doesn't give rise to a distortion and seize the movement, especially on white metal bearings, and finally any swarf created is removed PDQ - by changing the oil.

You say "being treated" - assuming that some one else is doing the work, does your engine builder give any advice - we got very detailed instructions after the (full) rebuild of an A7.

Also I assume the Vauxhall have a detachable head? Various theories available on head torque-ing techniques with modern asbestos free gaskets, basically might want to revisit the torque after a few (hundred) miles.

[davepoth]

Rings are I think the reason you need to run an engine in anyway.

[crankedup]

davepen said:

Rings don't sound like Top End. Do you mean piston rings or valve seat inserts?
Have the main bearings or big ends been dismantled, or was the block removed from the crankcase? (Period pictures in the Alvis 12/50 Handbook show this method.)

Consider what running in is; using the engine so that any (slight) mismatch in the sizes of any moving surfaces have time to bed down. While doing so that any excess heat generated doesn't give rise to a distortion and seize the movement, especially on white metal bearings, and finally any swarf created is removed PDQ - by changing the oil.

You say "being treated" - assuming that some one else is doing the work, does your engine builder give any advice - we got very detailed instructions after the (full) rebuild of an A7.

Also I assume the Vauxhall have a detachable head? Various theories available on head torque-ing techniques with modern asbestos free gaskets, basically might want to revisit the torque after a few (hundred) miles.

Thanks to all with responses, all the bearings are in good condition (white metal)pistons are good as well as all the other stuff. The rings were found to be weak and a few had seized onto the piston groove. The garage made a point of advising me that they will be honing the bores. A serious lack of use most likely cause. Valve stem seals are being inserted, although this engine was never designed for them, handbook tells me 1000 miles to a gallon of oil is fine. No need to let oil run through like that and I know others with same engine have installed stem seals with benefits to oil consumption. I shall take the advise offered here to not tow for a few hundred miles and torque up the head after that period. I was fortunate to be able to purchase a full top end gasket set from the Vauxhall club, all new with no asbestos. The stem seals are of a 'foam' type material but I think the garage are going to use a better solution of material. After all the work I may be selling the Vauxhall as I am considering a R.R. 20hp saloon. See how things develop.