140 looper jetting

[vi top shatta]

I'm planing on boring a 140 small bore block to about .440 over size (Bore to a big bore). Also shaving my heads between .10 to .20. I'm also going to have my porting done to match the v8 big bore porting. And enlarge my intake. Is their a formula in witch can put me on the safe side of a jet number and then I would fine tune the jet size, or those any one have an safe jet size to start with just from prior experience. Thanks for the help and if any find any flaws in what I'm planning to attempt please do tell me. I'm always open for constructive criticism

[racer]

no formula as port angles also change the jetting. .044 is not the big bore, the big bore is 3.685 and the small bore is 3.50 plus your over bore. I would start up 4 sizes or more.

[vi top shatta]

OK I got what your saying but I was talking to a friend about turning a 3.50 into the 3.685 but he said it is not worth the time and money it is best to find a 3.685 and go from their. But this block is hard for me to find on my island (St.Thomas) in dessent condition. Also I guess I could bore to .030 over instead of .044 over, would that be a better bore. Another think I was wondering about is should I use the lower unit that comes with this engine or should I use the smaller V 4 lower unit. Which would be a better set up. I'm planing to put this engine on an 16' Glastron. Thanks for the previous tip.

[racer]

Done correctly it is worth the effort, the problem is very few are set up to bore it to the bottom at that size as you will no longer have the recess at the bottom. You also need to report the intake as the larger bore changes port timing.