1972 Demon 340 engine mods

Summit in Warsaw.... that sounds good! LOL

I would go with the durations you list in first cam, the Voodoo hydraulic flat tappet, or one size larger in that type of cam. Your compression ratio is not very high and that is the problem with the solid cams that you list; with the low static compression ratio and the larger cams, the dynamic compression ratio will be very low (in the 6 range), and the low RPM torque will be like a worn out Trabant engine.

That is a BIG problem with a 3 speed manual transmission; if you have low torque at low RPM's, then you will have to rev the engine very high and slip the clutch a LOT to start off. And then when you make the 1-2 or 2-3 upshifts, and you release the clutch and the RPM's drop, the engine may again act like that worn out Trabant until the RPM's increase.

I had a 250* at .050" cam, low compression Opel 1.9L Ascona that I rallied for many years, and it had exactly that problem: it was WORSE than a worn out Trabant engine below 3800 RPM; and the 2-3 gear step was very bad when rallying in hills and mountains. The only thing that saved that engine was that I could rev it to 8000 RPM. But a smaller cam and higher compression would have been much better for rallying. The important thing to have is a large RPM range; your torque needs to be good from 2000 RPM to 5000 or 5500 RPM.

Solid cams hardly ever come in small durations, and when they do, the lift is low and that does not take full advantage of the good heads. The only one that I like for this use may be the ST-2 made by Racer Brown. It is 218* at .050" and .450" lift. The roller types would be better as you can get more lift, like the Howards cam that you list, but the duration is just too long for the compression ratio that you have with the 3 speed manual transmission.

One thing that WOULD help you with a non-roller cam is to change from the stock 1.5 rocker ratio to a 1.6 rocker ratio. This would change the the .450" lift of the Racer Brown or Lunati cams to around .480". This is a very good change to make with the limited cam duration that you need. There are 2-3 good choices for 1.6 rockers IMHO. Your may also want to look into the B3RE geometry correction kit to make sure the rocker geometry is optimized.

Since you are so far away with the shipping delays and costs, one thing I would advise you to do is to pull the heads immediately and make sure what pistons that you have. All my thinking is based upon the later low compression 340 pistons. If your engine has been rebuilt with higher compression pistons, then all of this thinking changes.

Also, be aware that the bearings in these engines are over 40 years old and the bearing surface materials will sometimes flake of. So you may want to get new bearings with this order and be ready to replace them.

I would also get a new oil pump and be ready to replace that. They are not expensive.