There are a few more considerations wrt removing the smog equipment, though passing an emissions test is the most important. If you're going through the effort of a rebuild (which I assumed because you're pulling the engine) and you aren't worried about emissions, now is the time to remove the smog stuff, but there are some issues that you should consider. I have completely rebuilt my 1980 Midget with the following:
- bored .30" over with flat top 9.1:1 compression pistons;
- mild porting of intakes and smoothing/matching of all intake/exhaust ports;
- three-angle valve job and replacement of worn exhaust valve guides;
- mild camshaft and hardened lifters from ARP;
- new main and conrod bearings;
- dual Weber 40 DCOE carbs;
- Try-Y header;
If your Midget is a California or later FED car, the compression ratio is 7.5:1, the intake and exhaust are brutally restrictive, and the air pump robs a lot of power. Besides doing the above mods, there are a few other ways to gain a couple horsepower and better mileage. I also:
- installed an electric fan (removed old clutch fan);
- put on a remote oil filter (using Fram PH8A 1/2 quart filter which increased oil capacity, is a fraction of the cost of a UK filter, is much easier to access, and no oil spews down the block);
- installed a Hayes 16 row oil cooler;
- installed electric fuel pump (removed old diaphragm pump);
- added custom 7/8" exhaust and turbo muffler;
- lightened the flywheel by a few pounds
I think I may have missed a few things, but the whole engine was hot tanked, cleaned and painted with new bearings, seals and gaskets everywhere. It was as easy as rebuilding a lawnmower engine, took less than a couple weeks, and did not cost a great deal - less than $1K using local auto supply places, eBay, Moss, ARP and Redline Weber. If you're not in a hurry, there are great sales before and after Christmas. The expected improvement in power will be something like double, from stock 50HP to a reliable 100HP.
I am working on the body at the moment. I deleted the (what I consider) brutally heavy and ugly rubber bumpers, and am replacing them with a custom design of my own. They'll offer good protection, and will act as a lifting point for a '60s-style quicklift jacking system. I also removed and filled in the side marker lights, front turn signals and rear licence plate mounting holes. I replaced the front turn signals with modern LED units that mimic the round lights from the early '60s. I have lowered front and rear suspension, and installed stiffer springs and sway bar(s). Expect paint to happen some time in the spring. I hope to post some photos and results of this effort in the coming months.
I did this because it was relatively cheap doing things on my own and using local suppliers, and I hated the anemic performance of the '75 and later MGs. My wife got the car from her father, and after 8 years of living with its disappointing performance, we're really looking forward to seeing an improvement in the handling and power.
If all you're looking for is pulling off the air pump, I really don't think I would. I considered all the pros and cons, and decided it was an all or nothing deal in the end. Partial removal of smog stuff leads to more probs than it's worth IMHO, especially getting it tuned properly.
Good luck with your project.