Is there an engine build book for dummys?

[Clem Z.]

places were mixed ratios work

on single plane 4 barrel intake using higher ratio rockers on intakes 1-7-2-8 help because of their distance from the carb.

[Michael H.]

Re: places were mixed ratios work

I remember the guys in the dyno room constantly messin with those ratios and they said using 1.6 on all the outer corner intakes did change the HP peak location but really didn't increase it as much as they hoped. Every few weeks they started playing with it again but after a day or two, always wound up coming back to 1.5's. I remember after they got some results that they liked, they ordered another cam from Crane that would include the newer numbers instead of using the rocker. There were cams with two intake lobe patterns and some with different exh patterns for different cylinders. The project was finally shelved permanently because the small results that were gained weren't worth the amount of time spent. I hear thet now, years later, some of the Nascar team engine builders are once again playing with different rocker ratios.

[Clem Z.]

Re: places were mixed ratios work

what it allowed you to do was lean out the carb for max HP but not let the end cylinders run too lean.

[Michael H.]

Re: places were mixed ratios work

I can see where that would work. I remember trying to fatten up the two front cyl's more than the rears because they saw the hottest coolant and always showed hotter chamber temps. Back then, we used EGT probes and it seemed like no matter what we did, we could never get things evened out. A change to correct one end would affect something else. It was a never ending episode. I wonder how the major engine builders do it today?

[Clem Z.]

Re: places were mixed ratios work

playing with the rocker ratio would allow you to equal out the EGT reading and it is still done in racing today where you need fuel milage.

[Michael H.]

Re: places were mixed ratios work

Are they still using different timing numbers for different cyl's also?

I'm sure glad I don't mess with all that today. It was incredibly expensive 15 years ago when I stopped so I can imagine what it's like today.

[Clem Z.]

i am sure they do if it works *NM*

[Chuck R.]

Re: Thanks for all the great responses

I'm going to go with the Performance Trends engine program.

I looks to be the most user friendly out there and is quite affordable.

Appreciate the help folks,

Chuck