Mixing Rockers 1.7/1.6

[myroc]

Has anyone heard of mixing up your roller rockers 1.6 with 1.7. You would put the 1.7 on the exhaust and the 1.6 on the intake. I heard this make more power then just running a complete set of 1.7 or 1.6.Any info on this would be great.The reason i'm asking is cause i'm going to buy some 1.7RR (all ready have 1.6 rr on the car) and thought i would give this a try.

thanks myroc

 

[shttygtstang]

no it sounds good though ive heard the exhaust side is weak so it would let more out but y wouldnt you do like 17 intake and 172 exhaust 0r higher

 

[nito88stang]

thats typically how its done, 1.7 on the exhaust and 1.6 on the intake to favor the intake side. SBF's arent the best in exhaust side of things

 

[Michael Yount]

For a stock motor, there may some advantage to the suggested approach. But what you've got to look at is the heads and cam you have on the car. If the heads are intake biased w/regard to flow - then helping the exhaust side may improve things. However, a lot of aftermarket cams are already designed to help the exhaust side with more exhaust duration. So to know how mixing the ratios might impact your combo, you really need more to go on than 'somebody said', don't you think? I suppose that's why you posted.

With the 2040 cam (E303) and 1.6 rockers, you have 220/220 duration, .498" lift. The RPM flow numbers I've seen show pretty good intake to exhaust flow ratio - about 77%. If you want to increase rocker ratio, I'd put them on all 16. The heads should like the extra lift on both sides.

As a practical matter however, trial and error/dyno/track is about all that will really tell you how it's working in your case.