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MGB What to replace when engine is out

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drooartz

drooartz

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As mentioned in my other thread, I'm currently swapping in a known decent engine into my '70MGB so that I can get it back on the road. With everything out there are a few things I know I should replace. Here's what I'm thinking:

Clutch (hydraulics are already new)
Throwout bearing
Transmission and engine rubber mounts
Oil cooler and lines

Anything else I should be thinking of? I'm not looking to rebuild this donor motor, just want to be smart if there are easy todo's with it out.
 
Define "decent" - was compression good? How long do you expect to run it?

That said, an easy chore would be to clean up/refresh the carbs. Not a full rebuild, but new gaskets and needle/seat; maybe jets, too. And as long as you're replacing the clutch, might as well pull the flywheel and pop in a new rear main seal. Front as well, especially if it's been sitting a while.

Anything else, and you're getting into machine work.

Oh, and don't forget to check the tappet cover plates and seals; oil pan gasket, too.
 
I'm going to use the carbs and distributor from my old engine -- both were rebuilt a few years ago (carbs by Hap, distributor by Jeff).

Engine compression was okay, nothing to write home about but fine. Car had been sitting for a couple years but was a daily driver before that even with the rust. My goal is to get 2-3 years out of it, so maybe 5k miles reasonably given the other cars in the fleet.

Seals make sense.
 
Mickey Richaud said:
Define "decent" - was compression good? How long do you expect to run it?

That said, an easy chore would be to clean up/refresh the carbs. Not a full rebuild, but new gaskets and needle/seat; maybe jets, too. And as long as you're replacing the clutch, might as well pull the flywheel and pop in a new rear main seal. Front as well, especially if it's been sitting a while.

Anything else, and you're getting into machine work.

Oh, and don't forget to check the tappet cover plates and seals; oil pan gasket, too.
Click to expand...

I had considered putting a new rear main seal in my engine while it is out and on the stand (even ordered 2 since I expected to screw one up trying to do it), but the instructions in the manual started talking about taking bearing journals apart and such, so I opted not to go that far since it had not been leaking last time it ran. There was NO oil at all between the flywheel and engine backplate so my feeling was don't fix what isn't broken. I did put a new oil pan gasket on since I had to pull the pan to straighten a dent in it, plus I wanted to inspect the innards of the crankcase while I had the chance. I did remove and clean the oil pump pickup screen while in there since it had some solidifed goop at the very bottom. Replacing those little cork blocks at the main bearings as part of the new pan seal was a pain (well technically getting the old ones OUT was the pain).

When replacing the clutch don't forget about that little bronze journal that goes in the hole on the flywheel. Good idea on the tappet covers - I think I ordered those but if not I will. Much easier to do while its sitting on the engine stand. Also since its almost impossible to get to any other time, I'd replace the rubber plug with the metal disc in the center that covers an opening in the engine backplate. Mine fell out in peices and it took me quite a while to even figure out what it was and where it these odd metal parts floating around in the bell housing came from.
 
I have owned my own shop, run several more.
Rule of thumb (ignored by "expert" mechanics to their sorrow), change as little as possible at first.
Swap parts over, especially if they worked, because if it doesn't work with a rebuilt distributor, alternator, starter, carburettor, and who knows what else...it's a LONG process sorting out what doesn't work right/
Then, after it's running, if you need, swap out one bit at a time.
 
New front and rear seal, side cover seals, clean out toms knob, replace the rubber clutch hose (super easy with engine out no so fun with it in) and I'd change the water pump as they are cheap and easy to do with the engine out. Great time to do an engine bay degrease and detail.
 
I might investigate a header and maybe a slightly hotter cam
 
JP, There has been a misconception about the MGB exhaust manifold needing upgrading. Because it was designed so well there is very little to no advantage of replacing it with something else, actually a waste of money. Cleaning it up, ceramic coating it can help with heat transfer if needed, but it's already the best exhaust system one can get for the 1800 MGB series engines. The original designers hit the nail on the head for exhaust extraction. :encouragement: JMHO, PJ
 
PAUL161 said:
JP, There has been a misconception about the MGB exhaust manifold needing upgrading. Because it was designed so well there is very little to no advantage of replacing it with something else, actually a waste of money. Cleaning it up, ceramic coating it can help with heat transfer if needed, but it's already the best exhaust system one can get for the 1800 MGB series engines. The original designers hit the nail on the head for exhaust extraction. :encouragement: JMHO, PJ
Click to expand...

I tend to agree (unless you are talking about the very late ones that had to be redesigned to accomodate the cat can). I had to replace one years ago because it cracked, and I went with a header because finding a replacement original was hard. I did not discern any improvement with the header. The non-catalytic exhaust is designed more like a header than a straight manifold anyway. If I ever get my current car reassembled I'll be running the factory 1970 exhaust into one of those stainless Falcon pipe/muffler setups.
 
Thanks for the thoughts. I won't be getting into the internals of this engine, it's a temporary swap and is running, so not going to mess. External seals make sense, maybe the water pump as well. TOC makes a good point about sticking to known parts -- I'll be keeping many of the external bits from my old engine, as they all have miles on them and are known functional.

Hoping to get some parts ordered this week so I can get at it.
 
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