I did the B20 conversion , bored out my B18, changed to 2L needles, 1967 carbs, 2 into 1 exhaust, D cam polished the ports, balanced the engine, big valve head stainless guides.

what I did was pulled a distributor from about a 74 140 with about the same engine. It came with the black box which gave me electronic ignition. it had a vacuum advance on the side of it. that car had an auto transmission.

somehow I took the distributor apart and flipped the vacuum advance over and made it go the other way so it added to the advance rather than retarding the timing as it was originally intended. I did not change the springs. the springs advance it part way and the vacuum advances it further.

i can say it's been like that 20 years, never gave me an issue , no pinking, and it seems about right. I can drive it like an old lady. I can drop the clutch and then step on the gas , I can start in 3rd, or race it up and it pulls just fine. I think having all the parts balanced made a world of difference. I polished the ports too. I never had any sophisticated equipment but I somehow got there just by trial and error. I was happy to get rid of the points. It's been a problem free solution so far.

I dont know how I got onto the idea of flipping the advance mechanism over but I think I had the distributor apart and realized it could be put together differently and it seemed to work. Maybe I got lucky. I hid the electronic box, no one really seems to notice it's not the right distributor, it looks similar but it's an aluminum distributor. I did not change the coil.

i think I used the crank and head from that 1974 engine and the con rods and pistons from a 122. AS I recall it was a heavier crank but I wanted the lighter rods, less reciprocating force.

once back together I did loose the cam. I was out in the middle of nowhere with the valves making a real racket. adjusting did not help. I pulled out the two pushrods and drove it home om 3 cylinders with one spark plug removed. It sounded funny but ran surprisingly well .. those loose lifters simply flipped up towards the top of the head and stayed there. It saved me a 200 mile tow and it survived that.


after a new D cam and lifters I still had valve float, then I added some shims under the new but OEM style single valve springs, most of the valve float issues seemed to go away then. all I did was put pieces of paper in the springs and made sure they were not coil bound. I always thought that could be dome more scientifically.

I ground down the rocker shaft on my lathe, and fitted all new bushings to my old rockers, and I made some some bronze thrust washers for either side each of the rockers. that went ok.. I couldn't really afford new rockers and they went a bit dish shaped so I think I adjusted them with a dial indicator to measure how much they rocked rather than trying to measure the clearance. hard to use a feeler gauge because the rocker is dish shaped. they are case hardened and I think I polished them a bit but I think they sunk in a little afterwards.


I changed the rear end gears to that of a 123 and added overdrive. No limited slip diff. it works well now, the trans is a bit noisy but it shifts fine. I chose not to lighten the flywheel. I put a cutout in the exhaust with a spring and a 1" ball so if I had enough back pressure it would open, that worked, kind of, but it rattled a bit when it was at equilibrium.. so I blocked that off and ever since I'm running the OEM "peashooter exhaust". It would surely make even more power with a 2" exhaust but it's fun anyway. the thign actually has a lot of power. I tried not to change the look of things more than necessary, so it's a bit of a sleeper. It idles pretty nice, a bit of a lump but nothing obvious. most people can look at it and not even realize it actually does have quite a bit of power and a few mods. Volvo people note the big valve head and a few minor things. I think my main issue now is after watching that "drive it like you hate it" video I really do want to , so Ill take it out for a really hard and very fun drive once or twice a year you know , because it's cheaper than therapy ;-) I try to refrain from driving it much. I keep reasoning that I need more time to work on it if I'm going to do that very often.

it lives in a tent not a garage, I'm getting a bit of rust and I go some fenders that are a little better. I've been chasing rust and replacing rust holes with metal since I bought it back in 1985 and I don't see any end to that.

123 haven't been helpful at all. I've asked for the stock curve settings and they won't give it to me. "See the chart" is what I get and although that's helpful to a certain degree, it would be nice of them to simply give all Bluetooth users the files for the old curves--I paid enough for the damn thing over the switchable and USB version.

Have you any suggestions on the MAP curve? I'll try what you suggest on the centrifugal.