BMC 1.5 oddities, advice appreciated.

[Julian Xavier]

22 minutes ago, Tony Brooks said:

 

Are the senders you have ordered compatible with the gauges? There are two standard US & Euro. If you mix senders and gauges you get readings that are very roughly half or twice what they should be. The two types often use different thread sizes/diameters.

I struggled with that, eventually I did find the specs for resistance and pressure/temp range. Ultimately I just ordered new senders and gages as matched sets. The temperature guage came as a complete kit whereas the Seastar oil temp guage called for a type C sensor (0-80 psi 240-33ohms) so I found the appropriate sender and purchased it separately. It proved difficult for me to find an oil guage sold with a sender.

 

It's a problem I've run into frequently with this motor. Auto parts vendors always want to know vehicle specifics to source parts. Give them specs and measurements... good luck. I've had some luck with parts such as the alternator providing info on vehicles such as the 74 MG MGB that were fitted with the BMC 1.5 Petrol motor.

[Julian Xavier]

Got another opportunity to get down to the boat. I don't suspect the timing chain but I did want to remove and clean the timing chain cover regardless due to the large amount of rust and grime that I just couldn't get to easily. Used an impact gun to get that nut off of the crank pulley mine happened to be 1-5/16" FYI. Here are some images and a video of the timing chain, the tensioner seems like it's got a lighter spring than I expected however being on the slack side I'm not sure it matters. For my motorcycle I usually measure chain wear as the distance pin to pin. I'll have a look in the manual to see if there is a spec but if someone already has the figure or another method for checking I would appreciate the assist. I turned the motor over until the pips lined up, seems close enough to me. Thoughts?

 

https://photos.app.goo.gl/YQymfJM63G8owv336

 

I'm taking the pulleys and the timing chain cover to sand blast them, replace the oil seal and gasket ect. I plan on scraping the rust and old gasket off the motor. All of the bolts are getting replaced, they all seemed pretty tired and corroded.

 

On a different note, does anyone happen to know what the threads/fittings are for the injector pipes? Are they 1/4 bsp or some other designation?

Edited February 16, 2021 by Julian Xavier

[bizzard]

2 hours ago, Julian Xavier said:

Got another opportunity to get down to the boat. I don't suspect the timing chain but I did want to remove and clean the timing chain cover regardless due to the large amount of rust and grime that I just couldn't get to easily. Used an impact gun to get that nut off of the crank pulley mine happened to be 1-5/16" FYI. Here are some images and a video of the timing chain, the tensioner seems like it's got a lighter spring than I expected however being on the slack side I'm not sure it matters. For my motorcycle I usually measure chain wear as the distance pin to pin. I'll have a look in the manual to see if there is a spec but if someone already has the figure or another method for checking I would appreciate the assist. I turned the motor over until the pips lined up, seems close enough to me. Thoughts?

 

https://photos.app.goo.gl/YQymfJM63G8owv336

 

I'm taking the pulleys and the timing chain cover to sand blast them, replace the oil seal and gasket ect. I plan on scraping the rust and old gasket off the motor. All of the bolts are getting replaced, they all seemed pretty tired and corroded.

 

On a different note, does anyone happen to know what the threads/fittings are for the injector pipes? Are they 1/4 bsp or some other designation?

The Reynolds chain tensioner is hydraulic from engine oil pressure when the engine is running, the light spring just keeps the pad against the chain when the engine is not running.

[Julian Xavier]

Thanks, that explains it.

[Tony Brooks]

Take care with the crankshaft pulley. It is also a torsional oscillation damper that means it is in two parts held together by a rubber insert. It's a tuned part so if the characteristics of the rubber is altered it could lead to a broken crankshaft.  A light sandblasting will probably be OK but soaking in degreaser etc. is a definite no-no.

[Tracy D'arth]

If it helps this engine was used in Austin J4 vans and Morris Oxford/ Austin Cambridge cars. Many bits of the MGB engines are similar.

 

I check timing chains by holding them double horizontally against the links and see how much droop there is due to pin and link wear. 

 

Injector unions are UNF threads.

[bizzard]

When refitting the chain case, put all the bolts in and leave them loose, put the pulley and nut on. Turn the engine a revolution by the nut, with one hand firmly against the case to hold it there whilst tightening the bolts ''opposites''. By centralizing the case oil seal on it's pulley track in this way, with a bit of luck you won't have an oil leak. Oil or grease the seal lip or if it's a felt seal, and the track on the pulley before entering the pulley.

Edited February 17, 2021 by bizzard