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Preformance Engine mods

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Stewart

Stewart

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The engine on my B has been removed from the car for paint and body work and since it's out and its going to be torn down somewhat to change gaskets in an attempt to slow the leaks and check the condition of the engine internals. If everything checks out ok I wouldn't mind spending the bucks now when everything is apart and can be matched together.

What would your suggestions be for engine mods that are reasonable on the wallet and reliable for the street? Carb and manifolds will be replaced and hopefully the ZS will have a long retirement in the garage.

Engine is from a 75 with 46k miles on it.
 
Well definitely check the bearings. If your pulling the head, look to see if the rings are in good shape or if there is any wear in the bores. Personally, I'm a fan of SU's, either HS4's or HiF's. They look right and are well matched to your engine. Set them up with a K&N filters. Also the early CB header flows nicely.

I hope to have a set of rebuilt SU's to sell shortly.
 
Twin SUs and / or porting the head will give the most impressive results but are both a little pricey (several hundred each). A hotter cam such as a Piper 270 would give a little more HP in the upper RPMs.
 
I have most of the engine torn down and as soon as I can find some 3/8th fine 4.5" bolts so I can put it on and engine stand then finish the rest. So far everything looks great except for the cam and lifters. 3 of the lifters were badly galled and the cam shows some wear. So it's looking like a cam replacement will happen as well.

It's scary when you start digging into thing and you start finding all kinds of little problems. Lots of loose bolts.

Also when it comes time to paint the block what is the correct color. Interior seems to be red/maroon and there are traces of red/maroon on the outside and black as well.
 
I would suggest How To Power Tune MGB 4-Cylinder Engines from Speedpro. It gives guidlines to several levels of tune and what to expect from each.
 
As mentioned earlier in this tread mods to the head will give the most rewarding results. If the engine is apart re-do the head with new guides (bronze), valves and springs. You may also want to replace the springs with the earlier version twin springs (to reduce valve float) but this implies changing the caps and bottoms also.

Make sure to have a very good 3 angles valve job done by a reputable machine shop. Just that will give you a lot more horses.

You may also want to skim the head a bit to increase compression.

One thing for sure on a 75 engine huge power gains are obtained with the pre-74 manifolds and twin SU’s.
 
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