90tbi305

Hey guys i would like to now what you guys think about upgrading my stock rockers too- full roller and going 1.6? What do you guys recomend? Thanks

Fast355

iTrader: (2)

Several guys have used them with stock engines and seen some decent SOTP performance increases. With the puny peanut cam they couldn't hurt. I have the ramjet/HT383 cam in my crate 350 TBI and the 1.6:1 rockers from my 305 really helped it breath in the mid-upper rpm range. I know that I am making more power because I needed to increase fuel pressure by 1.5 psi and recalibrate the VE tables because it got VERY lean in the upper rpms where it was fine before.

xjcamaro89

I have a roller rocker question too. i am going to a big swap meet this weekend and i have seen sets of roller rockers there (NIB) with no engine application on the package, so what should I look for in a set of roller rockers for a L05 TBI engine? ie: stud size, nuts, things like that.

crrllmich

Self-aligning, 3/8 stud, and narrowed body if you have centerbolts.

91RockS

Be careful when installing 1.6 rockers on stock heads to check the clearance between the pushrods and the clearance holes in the heads. 1.6's move the pushrod closer to the pivot, thus moving the pushod very close, or possibly touching the clearance holes in the head. It's hit and miss from head to head and valve to valve. Worst case is that the pushod contacts the clearance hole in the head and does not allow the end of the pushrod sit properly in the rocker seat. Not good. To be safe I'd recommend opening up the clearance holes in the head before the install.

I agree with Fast355 that the 1.6's definately help out at the mid and upper rpm's. I also saw the AFR's lean out at higher rpm's, so you either need to increase VE or bump up FP to get full advantage (and be safe).

robertfrank

iTrader: (27)

what would be a "safe" fuel pressure to run? I haven't been able to get into tuning yet due to funds,(given 30 days to move by a bitch landlord) I know I got a good improvement in power with my comp rockers but it does "feel" like it's running out of fuel up top.

xjcamaro89

would we be better off getting 1.5 roller rockers? Or would staying with the stock ratio and going with rollers not really do anything?

91RockS

XJ - IMO, you won't notice any SOTP difference going from stock rockers to 1.5 rollers. You will feel a difference with 1.6 rollers. I don't want to scare you off from going the 1.6 RR route, just sharing a lesson learned. PM me if your interested in a virtually brand new set of 1.6 RR's, self aligning, narrow body for centerbolt heads.

RobertFrank - It's hard to say exactly how much to bump up FP without datalogging. The recommended approach would be to datalog and adjust your VE tables accordingly. The poor man's way would be to bump up fuel pressure, which will add in more fuel everywhere whether its needed of not. As I recall, my BLM's went up about 8% with 1.6 rockers, meaning that the ecm was adding in more fuel. My FP was 12 psi at the time. Using my example: 1.08 = sqrt(new pressure)/sqrt(12) ==> yields a new pressure of 14 psi (a 2 psi bump up). Again, your motor could be completely different. The smell of raw fuel will tell you if you've gone too far.

Fast355

iTrader: (2)

With your other mods, I would go 14-15 psi. An easy way to tell you if you have gone too far is to use the field service mode with the engine running. Take a paper clip, start the engine, short A & B on the ALDL terminals, let it warm up, the service engine soon/ check engine light will go from a steady blinking of 2.5 times a second in open loop, to an alternating on-off when it goes into closed loop. It will flash approximately 1 time a second. If the flashes are short meaning the light is off more than on, you are lean. If they are long meaning the light is on more than off, you are rich. The ideal scenario is having the it to where it is equal to slightly on longer.

Gunny Highway

iTrader: (1)

No need to drop the $$$ on full RR, just get the ones with the roller tips on them. I'm pretty fond of my Comp Magnums. Definately fixed the fall off I had from 3500 - 5500 rpm's.

91RockS

Gunny may be right, but I've always heard just the opposite . . . that the bearings at fulcrum are where the you get the biggest benefit (reduction in friction), not the roller tips. If you look at the contact area and the amount of relative motion beteen the rocker tip and vavle tip, it's nothing compared to the area and motion between the rocker arm and the pivot *****.

Gunny, did you have to modify your centerbolt valve covers with the Comp Magnums?

Fast355

iTrader: (2)

The real difference is in the rocker ratio, followed by the friction reduction. The roller tip rockers hold the same ratio all the way through their travel. The stock stamped ones actually decrease to what I have calculated to be about 1.3:1 at peak lift. My L82 cammed 305 saw .100" of added valve lift when I went from stock stamped 1.5:1s to crane 1.6:1s. Talk about a performance difference.

Then lets talk about friction. The stock rockers rotate on the pivot ball. Even though oil resides between, they still have alot of friction. I know first hand. I started a cool engine with the valve covers off. Running valve adjustment. I knocked on of the oil clips off the rocker. Killed the engine. Went to put the clip back on and burned my finger. The engine itself wasn't even hardly warm. The rocker nuts were scalding.

BMmonteSS

I've run crane "cool nuts" to help pull the heat out of the pivot *****. They're nothing more than big nuts that catch all the spray oil from the pushrod and direct it onto the pivot *****. They act like a big heat sink. I think I've seen some dyno test show a 5-10 hp increase from roller rockers of the same ratio, how much of that was friction and how much was accurate ratio's who knows.

Gunny Highway

iTrader: (1)

Nope.