Rocker arm ratio

**killface** · 03-20-2015

Hey! I'm thinking of trying 1.6 ratio rockers on my Chevy C2500 350. It's got the stock TBI heads with new valve springs that can handle the lift. I have an Edelbrock can and they say to use only stock 1.5 ratio rockers. Any one tried this? And what was the outcome? Thanks!

**DOCBAWRENCHTURNER** · 03-20-2015

is it the Edelbrock fuel injection rated cam? If so they are probably just trying to keep the cam's lift within a range that can be handles by a stock TBI PCM

**killface** · 03-20-2015

Yeah, it's the 3702.

**jim_in_dorris** · 03-20-2015

One thing to consider is that with the increase in ratio, the geometry will change and your push rods may rub on the holes where they come through the head causing premature failure. It is common to enlarge those hole to make sure your push rods do not touch. The stock TBI PCM doesn't care about your lift, however it will run better with tuning. That cam even with the 1.6 ratio lifters will not be a problem. However if you have the stock 193 heads, some folks like a single pattern cam for better performance.

**steveo** · 03-20-2015

the difference between 1.5 and 1.6 on a smaller cam is really not much.

unless you're upgrading to full roller already or have them laying around, i wouldn't waste your money and time.

i went from 1.6 back to 1.5 on a mid-sized cam and ve barely even changed, the butt dyno didn't even feel it.

**killface** · 03-20-2015

I was just going to change the intake side so it would act more like a single pattern cam as far as lift is concerned. But if it really won't make a noticeable difference, then I might leave it alone. Probably not, I'll most likely mess with it, because as good as my truck runs, I cannot leave it alone, it's like a treasure hunt for horse power. Thanks!

**Fast355** · 03-21-2015

Originally Posted by steveo

the difference between 1.5 and 1.6 on a smaller cam is really not much.

unless you're upgrading to full roller already or have them laying around, i wouldn't waste your money and time.

i went from 1.6 back to 1.5 on a mid-sized cam and ve barely even changed, the butt dyno didn't even feel it.

On the otherhand, I have put them on several different engines, noticed small changes in the VE, but have also seen gains of 10-20 HP depending on the setup. I will only use 1.6 or 1.7 full roller rockers on stuff I build. I put them on a TBI engine that was running a stock LT4 cam and stock heads and felt noticeable gains.