Re: Please forgive this Newbie.
☼ Best Answerby Spit Builder 2021/01/02 16:15:43
Welcome to our forum
I'll start with a piston choice first, if you want more capacity, the std size piston from a 2.8 cologne v6 (93mm)will fit but will sit about 0.60th under deck height so either a slightly longer rod or offset grind the crank if there's enough meat available then deck the block to get things level.
Valves size we generally go for are from UK(Burton Power) 44.5mm & 38.5mm waisted stem stainless steel. Depending on the cam you use and lift , the valve springs I've always used are from Burton and are single springs code VS9 , never used double springs as they wear down the rockers far quicker for no real benefit. Before the anoraks say I know nothing, I had a pinto throttle jam on flat out (twin 45s) free revving beyond 9500 with no valve bounce at all.
Porting , just clean and remove the valve guide and match to your intake, not the gasket. Do not polish ports, that is bad..
Compression ratio, your running 98 so you can get it up to 11.5 by skimming the head 0.100 - 0.140 th but doing this the spark plugs might just touch the piston so add a washer or mark the plug so the electrode is facing between 9 -3 o'clock position to be safe. Spark timing will be very close to TDC, maybe 2deg before or less.
A single weber might get you there of 48mm with some good low end torque . I built a slapper pinto with a towing cam (std lift but 292deg duration) , a 48mm sidey and the dyno pulled 137bhp @ 6800rpm , had very little porting and std valves . Get an adjustable cam wheel to help dial in more power.
I reckon you will get 150 without a problem