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1800 Rebuild

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Lynn Kirkpatrick

Lynn Kirkpatrick

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I'm getting ready to start a rebuild of a stock MGB motor (#18GK-WE-H 4071). This is the one with a knock while under acceleration, with around 40,000 miles on it. I'll change all the bearings, etc., but I have a few questions.

As I'm reassembling the bearings (assuming the journals are OK, fits OK, etc) should I coat, or wet the bearing surfaces with anything like Castrol or Amsoil or STP or whatever for protection at initial startup?

If I get a cam with more lift and I have the head milled 0.060", will I need different lifters, pushrods, or rocker arms? There is some adjustment on the rockers, but is it enough?

In my Bentley book, talking about milling the head, it says "check the valves at full lift to ensure that the exhaust valves do not foul the top face of the cylinder block." It sounds like the valves won't hit the piston top, but the top edge of the cylinder. (?) How likely is this? If the cylinders are bored out 0.030" will that make a difference?

Is there any benefit of switching to a Weber carb over the twin SU's. I have tuned the SU's on my '68 without a lot of hassle. Is a Weber easier, or give more performance/economy?

And finally, how likely is it that I'll need to replace
timing chain, damper, etc?

Thanks for any advise, I'm trying to get as much as possible on hand so that I'm not stopping and starting, waiting on parts.

Thanks!
 
First, use Clevite Engine Part Cam Guard. It found at your local Napa dealer. This is better than using white grease like I use to.
Why more lift and shaving head? A good performance cam would be great and only a clean up on the head after doing the valves. And yes the edge of the cylinder needs to be relieved to clear the exhast valve. I have specs from a performance manual if you need. I like my SUs. There is an excellent article(on the web I think) about tuning up SUs that says they are just fine for a 1800 motor. And last it is always a good idea to change the timing chain and gears if there is any wear or the chain is too loose. /ubbthreads/images/graemlins/driving.gif
 
My dad told me once when I was young that if I was going to open an engine, I needed to think about anything that could wear - & plan on replacing it! Were it me & I had a good double timing chain, I'd reuse it but definitely replace the tensioner

Webers are junk IMHO - but there are guys who'll say the SU's are junk,,,methinks its just personal preference
 
You never know what you’re in for until you start pulling things apart. When I did mine I replaced all the bearings, oil pump, water pump, cam, timing chain and tensioner basically anything that could wear. The rest was measured and found to be within new spec as the engine only had 46k miles on it. I also had the engine hot tanked, the head magnafluxed, new seats and guides installed and the cylinders lightly honed as that’s all it needed.

When it came time to reassemble all the machined surfaces was wiped down with muratic acid to remove any trace of surface rust and then immediately oiled to prevent its return. Defiantly use some form of makeup grease on the bearing surfaces to help with startup and keep the rust at bay until the engine is started.

If you have a good set of SU's go ahead and keep them. I ended up going with a Weber as it cost less and was new and unmolested.
 
Webers are JUNK?!?!?! Bloody 'ell... Is there a way fer me to swap out all these DCOE's (the Alfa, 2 Lotus' and the MGB) for an SU setup for each? Oh, and I've sent Ferrari a message settin' 'em straight regardin' the V-12's they hung three a side on. I'm sure they'll admit th' error of their ways.

I like Webers: Set 'em an' ferget 'em. Same with SU's, but without the accelerator pumps. You're right, Tony: personal preference. I get slightly less mileage with the Webers, with a LOT more performance... 'course I'm talkin' DCOE's not those poxy DFV thingies. I was never impressed with those.
 
Hey, Doc....check out my '79 MGB's Rover V8 w/Boxer intake & quad HIF-44's:

IMG_1688.jpg
 
Back on topic: If you change the cam, change the lifters as well. As far as the block/valve interference, SpeedSport magazine used to publish a great treatise on head mods and their effects by (of all names) a chap called Clive Trickey. If that's still in print, I'd recommend it. Very likely you will not have a problem, BUT: be safe and do the block mod if you have any doubts. Much easier/cheaper than another teardown for damage control.

Timing chain and tensioner would be on my list of new parts for the same reason stated above.

Pre-lubes, or assembly lubes are a must. The Clevite stuff is good, and there are many others as well. We used to use "white grease" but it will give up it's "carrier" if left to sit for long periods (more than a few months) thus becoming "stiff", so we've changed to a "slurry" (50/50 mix)of regular engine oil and "STP" or an equivalent, with good results. And "PlastiGuage" the bearings to insure tolerances.

That'd be my tuppence worth. HTH.
 
That's BEAUTIFUL Tony!

I durn' near needed to go change me "Depends" viewin' that.

Very nice work, Very Nice.
 
I have the specifications on the block modification if you need it. I can scan and email if you wish.
 
Thanks to you all for the info.

LL - If you please, do you need my email, or is it tucked into Basil's domain here someplace?

Another question, does an exhaust header get me anything, compared to the stock manifold, assuming I change to a flowmaster exhaust? I'm planning on polishing the head, but I'll search for Clive in Speed Sport (Thanks Doc).

Thanks!!
 
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