I knew when I first purchased the 18V engine for my MGB GT that I should have just installed it and run it for as long as possible. While in some ways this would have made sense, it also would have been a big mistake if an engine issue turned up soon after the install. Pull the engine and transmission and start at step one again.
With this in mind I did what I enjoy doing, ripping mechanical items apart and putting them back together in hopefully better condition than before. Here’s what I have learned and discovered about my newer but still old chunk of MGB iron.
Once out of the truck I removed all of the auxiliary parts that needed to come off to access the internals. Water pump, oil filter, flywheel and back plate, anything that could come off was removed and placed into storage for cleaning and hopefully refurbishment. This is going to be an engine rebuild on a budget… I hope!
After installing the 300 pound chunk of iron on my engine stand the first order of business was removing the oil pan and other than some chunks of Glypol that were floating around nothing looked bad. These were large chunks only and all I could find anywhere so I cleaned everything up and moved on. The oil is a little sludgy but no particles were visibly floating around.
The engine has quite a bit of sludge in it but I think a few oil changes and possibly SeaFoam will take care of that. I wiped down what I could, nothing is permanently affixed.
Removing the oil pump was next. Other than being a little sludgy like the rest of the engine everything looks good. It cleaned up beautifully and measurements show that it’s well within specs. This likely has been replaced at some point in the engines history.
At this point I removed the connecting rod ends to expose the bearings. These look to be in very good condition and the crankshaft looks great as well. These are all original size and the bearings have very little wear so I’m guessing that the lower end was recently overhauled.
The pistons were covered with a little carbon but cleaned up beautifully and show no sign of damage. They are .020 oversize so this work was likely done when the connecting rod bearings were replace. I’m hoping and will be guessing that the main bearings were replaced at this time as well although I’m not opening that area up at the moment. My feeling is that a rebuild of the lower end wasn’t done that long ago, very promising. Cylinder bore honing looks reasonable as well. We should be good to go on this part but it’s always a gamble. I don’t want to rebuild this engine completely at this stage so this is it.
A few days ago I decided it was time to pull off the timing chain cover and inspect this area. In the back of my mind I was thinking of installing the double row timing chain and gears from the 1967 18GB engine that are almost new and after viewing the 18V single chain my mind was set. Lots of wear. This gets you thinking that if they had the engine apart to redo the bearings and cylinder bores why wouldn’t they replace the timing chain. Perhaps this is fairly normal wear and I could just change the tensioner but I’m going to upgrade everything as I have the parts. Switching to a single row timing chain was a cost savings measure only and the double row timing chain changes the camshaft timing to a more favourable range anyway.
If you are this far along in the teardown it makes no sense at all not to remove the camshaft and see what condition it’s in. I was disappointed when I pulled it out. There’s pretty bad pitting on the lobes and as I’m installing new tappets it makes no sense to use this camshaft at the moment as it would quickly destroy the new tappets. I’ll get back to this thought in my next post.
So what’s the history of this 18V MGB block? I really don’t know. It’s certainly in pretty good condition and has been apart before. It definitely lived in a cold climate at some time as a block heater is installed, perhaps the rest of the car rusted away and this was left. From comparing this engine to the known age and mileage of my 1967 18GB engine I’m guessing that this engine has perhaps 35,000 miles since a rebuild so lots of life left. The ugly camshaft?, likely not replaced during the rebuild. I hope I’m right!
I’m presently working out a plan that will be a combination of the best of both engines, partly for performance but also to keep the cost in check. More to come.