<VV> Conversion to EFI: Is it really cost effective?

[NicolCS@aol.com]

Your comments are interesting too.  I think both the valves and the dual 
exhaust promote better re-filling of the cylinder (=more power) and do provide 
higher hp even at these lower rpms.  Of course gains are proportionately less 
since the target rpm is lower, but still useful.  Why would bigger valves reduce 
the overall velocity? I believe they would promote more airmass entering the 
cylinder and thus higher runner velocity. 

Your comments about the secondaries and decreased responsiveness with the 95 
hp cam are exactly what I expected too.  Oddly, this 140 has much more 
noticeable response to the secondaries than any 140 I can remember (I've had 20+ over 
the years).  With my totally stock and happy 65 Monza/Corsa 140/3.55, when 
the secondaries come on you can tell but not nearly as much as with the '67 
140/3.08. (Go figure.)  My theory is that the secondaries in the '65 come in well 
below the cam's efficient range where the '67's secondaries come in right 
around where the retarded 889 cam is really happy.  (This is one reason why many 
140s cough when the secondaries open) I don't claim to fully understand why, 
but all who have experienced the car really notice the feeling of power.  I 
think that because it makes more power at lower/normal driving rpms, it just 
"feels" more powerful. There's no question that the secondaries impact is more 
noticeable than a regular 140.  

I'm having fun!  This is making me think. (ooh, pain!)
Craig Nicol
<snip>I think the dual exhausts will have a negligible effect on mileage at 
the rpm's used in an economy run or even for normal driving. 
Nevertheless, I would run them too.

The large 140 valves are another matter. Again, they won't increase 
power at the low rpm's in this example. I never thought of them as 
lowering pumping losses. They might do that. One thing they will do, I 
think, is lower the velocity of the incoming fuel mixture which will 
decrease responsiveness at low rpm's. Of course this only gets bad if 
the secondaries are opened. In other words, if you floor the throttle 
at low rpm's and open the secondaries the mixture velocity will go way 
down and the engine will not respond quickly. I think if I were to 
build an economy run engine, I'd stick with a small valve head for 
better intake velocity.<unsnip>