Building a 383 Mopar is very similar to doing a 440 with a couple of notable exceptions. In a short stroke motor the piston moves less distance for the same amount of crankshaft rotation in degrees. In the 383 which has a 3.38" stroke it means the piston doesn't get out of the way of the valves quick enough. If a flat top piston such as stock type or the TRW style forged replacements is used and the heads are cc'd or even planed then the valve to piston clearances are too close for even a MP 509" cam and minor flycutting must be done. That is no big deal to shops used to doing it but many folks live in an area where the machine shop, while good, is just not set up for this type of work. (Remember not everybody lives in downtown LA) In that case it is probably wise to invest in a set that already have flycuts in them. While it is virtually impossible to overcam a 440 when it comes to duration the 383 is very sensitive to it and so duration must be kept on the conservative side. If you use the general guidlines given for small blocks you won't get in too much trouble. The MP 509" does work fairly well in these engines although I am sure it is not the ultimate but it is much much too mild for a serious 440. The 383 will make serious HP but will do it at a higher RPM than the 440. That is because the 440 and the 383 use the same heads and similar intakes and so are capable of passing exactly the same amount of air. (Same heads, carb and intake = same amount of air) For a 383 to pump the same amount of air as a 440 it would have to turn 115% higher.
IE A 440 at 6000 rpm pumps 763 cfm
A 383 turns 6888 rpm to pump 763 cfm
Recently we built an original 64 383 for car collector Glen Cole. He wanted a hot street engine for his 64 Plymouth Sport Fury and it had to be a 383. (I don't know why, I just do what I'm asked) To make a 383 perform well you have to take advantage of everything possible and leave no stone unturned but if you get too rambunctious you will destroy the streetability. We still have to do a serious strip flog on the set-up but it has now seen quite a few street miles. A recent pass down the quarter with no burnout, closed headers, leaving from an idle and letting the trans shift itself gave some timeslips well into the 13s. Our goal is to get it to turn a 12 anything in street trim and I think it is well within reach. If this subject interests you E-mail me and I will post more.
HEADS DONE AS PER "OLD RELIABLE "BOOK DETAILS
TIMING GEARS LINED UP AND READY TO GO
LOOKING LIKE A RIPE TOMATO THE 383 AWAITS ITS NEW HOME
NOTHING LEAVES THE SHOP WITHOUT BEING FILLED WITH OIL AND PRIMED
I believe the money that this has saved us over the years far outweighs the cost of the oil and the time to prime it. I have seen several engines and a couple of very expensive ones that were fired with no oil in them and ruined because of an over enthusiastic crew and often a surplus of "WOBBLY POP" I determined many years ago to eliminate this possibility from the equasion so we fill and prime every engine and if I don't fire it I don't warranty it. Now at the end of a 35 year plus career I am happy that that was the right decision.