Engine is a L98 350 and the mods so far are Hooker cat back - hedman shorties / y-pipe - cat removed ( cutouts installed in place ) - C.A.I - T.B bypass.

i would love to sort out my heads and cam but realistically i wont be able to go for this until next year. i've read that the 1.6 rockers can give the same gains as a slightly larger cam due to increased lift . that said , do you think this would be an ideal next mod for my engine ?.

I intially thought about improving the intake set up but was worried that i could possibly get to much intake for my mainly stock engine and so decided to wait until the head and cam swap. The rockers seem a good startin point as they are fairly straight forward to fit and could be re-used with my next set of heads any way

 

these were the rockers

Trick Flow Roller Rocker Arms: TFS-31400513 - summitracing.com

or

Proform Extruded Aluminum Roller Rocker Arms: PRO-66915 - summitracing.com

 

you can get pulleys or afpr if you want alittle easier then roller rockers.

 

I installed a set of Crane's "Gold Race" 1.6 rockers on my L98 about 2 weeks ago. Since I was no longer using them on my 4th gen LT1, I figured it would be a quick easy way to pick up some HP on my IROC.

In order to save on the down time, I used my old LT1 valve covers since I wanted to paint them before hand. The only difference between the LT1 covers and the L98 is that the LT1's are "notched" on the passenger side to make room for the alternator. Other than that, the L98/LT1 covers are the same.

I have no issues with clearance at all.

After finally being able to test drive the car, the power increase provided by the 1.6 rocker's was immediately apparent. For starters, the car seems to run a lot smoother. Not just driving around town, but at idle as well. Don't exactly know the reason for this, but it was definetely an unexpected bonus. On top of that, it pulls a lot harder then it did before, especially from 3500+. It was definetely worth the 2 hours I spent installing them...

I put the car on the dyno the next day and with nothing more than those rockers and a full exhaust upgrade (not even a full 3" exhaust at that and I'm still running a cat)), I put 212hp and 290 at the wheels. All else is 100% stock (minus the replacment air filters)

I'd say 1.6 roller rockers are a relatively cheap and affordable mod for some quick and easy HP. A definite "seat of the pants" improvment for sure.

..
..


Somebody also mentioned a set of under-drive pullies. They too are a cheap and afforadable way of increasing HP but be careful they won't effect your alternator's charging capabilities. If you run a big stereo like I do, get March's "Power and Amp series" pullies.

Under-drive pullies are particulerly effective on TPI motors and you should notice a difference right away...

 

how was the install? i guess u dont need to take the manifold off at all lol but how do u set the pushrod/lifter tightness for the new rockers?

 

It would be rather difficult for me to explain the exact procedure of installing a new set of rocker arms because I'm not terribly good at explaining things without being able to speak to you in person. (Plus, if something goes wrong with your install, you'd blame me for it)

Suffice to say, your best bet would be to pick up a Chilton's 82-92 Camaro/Firebird manuel from your local parts store and go from there. They only cost about $10 and they're just about the best "tool" you coud ever buy. A Chilton's manuel will explain to you the proper procedure for this install far better than I can over an internet forum.

That's what I did and the end results speak for themselves. The car's been running like a champ!

Just remember that when you re-connect the battery, your ECM will have to "re-learn" everything all over again. When you start the car, don't panic if the motor wants to stall out and has an eratic idle. Just hold the throttle down for a minute or two at about 2500-3000rpm and take the car out for a spin after that. Everything should run fine by then.

Now that I've learned how to install rockers myself, I won't need a Chilton's book to do this upgrade ever again.

It's always a satisfying feeling to learn something knew. Even more satisfying, is knowing you just saved yourself a bunch of money by doing the work yourself.

Sorry, that's probably not the answer you were expecting, but it's for your own good. Trust me.

A manual for your specific model car is your best choice to get accurate, easy to follow instructions....

 

1.6 rockers it is then. i have heard a few people talking about the underslung pulleys. who makes them ??

 

91greenbird exccuss my ignorance but what is " afpr" ???

 

March/Jet/BBK/ASP and numerous other companies make pullies for our cars. However, as I mentioned earlier, if you drive an automatic, or you spend lots of time in Stop & Go traffic, have a big stereo, or all of the above, go with March's "Power & Amp" series pullies.

You won't have to worry about your alternator not charging properly which is a fairly common problem with most under-drive pully kits. Some of the negative effects of a inneficiant charging system are dimming of both the interior lighting (gauges etc. etc) aswell as your headlights.

The March kit may not free up as much HP as a 3 piece kit, but you wont kill your battery or have any ill effects on your lighting..

One of our sponsors is ThunderRacing and they carry the full line of March pullies including the power& Amp series. Check them out...



It stands for "Adjustable Fuel Pressure Regulator" and I'd say you probably don't need one at this stage of the game. Wait until you have a cam or an upgraded intake before you buy an AFPR, otherwise your just throwing away your money...

 

nice one lt1fun. thanks

 

Keep in mind that a good aftermarket set of 1.5 rockers will yield some improvement too. The stock stamped 1.5s flex a TON under high RPMs.

 

...and also keep in mind that OE heads have press in studs instead of screw in. If ya spend a lot of time at higher RPMs, ya gotta keep that in mind.

....but I doubt 1.6 rr's would be a problem.

LT1FUN, looking at the pic you posted, I see a brake line touching the header primary. That can't be a good thing!!!

 

thanks man. i have a couple of books actually on camaros and just havent looked over them yet. i wanted to do rockers for awhile now. i recently replaced the tpi gaskets and that was a longer process thani thought it would be, but fun nonetheless. i know what u mean about the computer wantin to relearn everything. lol

what do u consider high rpms? my tpi is done at 4200, but the trans shifts at 5. once i install the lt1 intake, it will see 5k more frequently.

 

That's just an optical illusion from the angle that pic was taken. There's actually a 3/4" gap between the two.

Even though I know there's a gap, after reading your post, I thought I'd go out and double check again just to be sure

Nope, they're not hitting...

Thanks for the concern though

 

More or less like running in Auto X events or racing at the track. When the RPM's get up there, those stock rockers/studs start to show their weakness. When I had my new rockers installed, (same as LT1FUN's cept mine are 1.5) I got screw in studs. Added strength and piece of mind

 

Ok guys, back when I had a GTP I installed rockers. 1.6 was stock and I went up to 1.9s. Back then, the deal with them was 1/2 the increase from a cam for about half the cost ( gaskets and chain and oil change, etc).

Is that true for TPi cars as well? I understand the difference going from 1.5-1.6 is less than 1.6-1.9. Fill me in.

 

Well simply throwin more lift to add HP is no different than saying bigger is always better. It may work, but it's certainly not a hard rule to follow all the time.

My rule of thumb is that if I can't explain how a certain mod increases my performance, then i won't do it.

I suppose if you're simply at the bolt-on stage of modifications, then it'll probably add a couple of horses. Airflow on a stock L98 is so bad, anything helps. IMHO, bang for the buck of 1.6's is horrible.

I'd bet lunch that with headers/exhaust already in place, you won't even feel the 1.6 gains.

Without a doubt, I'd go with an AFPR or even a higher stall converter. I got a cheapo B&M holeshot and it might've been the single best mod I've done. A new manifold maybe? I dunno, I just think you'll be disappointed with the rockers.

 

i got my l98 dyno'd and it has headers/exhaust/gutted air box. thing was 12.2-12.5:1 a/f. one run was 11.68. its rich as it is with stock fuel pressure. an AFPR would do nothing but burn more fuel when there already is too much.

i think a converter in an auto L98 or manual trans swap is the best thigns you can do to gain performance.

i'm thinkin of 1.6 rockers...and i hope it gains some. cuz there is still more airflow to be squeezed out of the stock heads. they flow peak in the .450-.500 range and stock cam lift is .415-.430. so they should help gain a few ponies. combine that with some pullies/AC delete to free up some power, and your maximizing that L98, which is my goal for now. lets see how fast a very mild L98 can go

 

sounds like your in the same sort of position as me orr89. the torque converter is already on the cards for this year.

I want to go with simple bolt on mods this year just to see what theold girl will do . reason for the 1.6 rockers is that its a mod that can be swapped over to the new heads when pruchased.

abubaca , you reckon invest in the airflow system first then ?? did look at the as&m runners and then porting the stock intake and plenum to match.

 

i'd recommend a good exhaust system and airbox mod first. advance timing to about 10 degrees

then get the converter and gearing right. with some suspension mods too.

this is where my car sits and it should be deep 13.7s possibly 13.6's at 98 this weekend. has gone 13.79 at 97 in 80 degree heat and humidity.

next up will be LT1 intake and possibly some ac/smog deleting...gutted cat or highflow too. fuel pressure might go with the lt1 intake but i might just tune the chip for more fuel. also would like to do 1.6 rockers...

hoping for 13.4-13.5's with that. we'll see

 

Not true. An adjustable fuel pressure regulator doesn't effect how much fuel you have introduced into the cylinder, only the pressure at which it's injected. The higher the pressure, the better the fuel atomization, the better the burn.

Not to say the AFPR is the cure all hands down obvious answer, but for under $100, the bang for the buck factor is high. 100% ANY FI motor will run best with the proper fuel pressure, that's a given. What are the chances that a modified motor will run best on the stock pressure setting from the factory? TPI's are super sensitive to fuel pressure.

 

i was pretty sure that it adds more fuel...higher presssure coming in usually means more flow out. many ppl have been using it as a tuning aid when adding cams/intakes instead of tuning the chip

 

As for my personal knowledge, I'll say that I could be wrong. ...but from what I've read, it doesn't effect AF ratio.

...and you'd think if it DID effect the ratio, then I can't see how so many people see gains without any additional tuning.

I still think I'm right on this one, but I'm open to anything. Lemme look around a little.

 

Ok, pretty muchevery post had a few constants, and few rather vague ideas.

Without a doubt, the power comes from the atomization of fuel at higher pressures. There IS more fuel due to the higher pressure. The 02 sensor compensates for the additional fuel and leans the mixture, which would essentially now be a little rich.

I'm just gonna sit this one out I guess, but I still think the AFPR is a good idea. I dunno, maybe not.

 

i do agree with you that the higher pressure makes for better atomization and thus better burn. i just thought that it would add more fuel since you've increased the pressure. but it would depend on how much more was added. but in my current state, i dont wanna add anymore fuel to the stock TPI. i wanna take some more out.

so what would be best i assume, is to crank up fuel pressure, but tune the chip/ecm to take some fuel out or not inject as much...so your gettin similar fuel amounts injected as before on stock pressure, but now at a better atomization rate so you should get a better burn and more power that way. also accomplished the goal of leanin it out to make power that way too. so i'm might try that some time and see how it runs

 

Turning up the the fuel pressure adds more fuel. The amount of time the injectors are open is still controlled by the computer.

An injector open for 20ms at 50 psi will put out more fuel than an injector open for 20ms at 43 psi.

An AFPR is good if you are gonna tune. Since you can add FP and reduce the amount of time injectors are open to keep AF in check

 

Get the rockers you will be glad you did, but don't buy those. Get the Comp Cams Pro Magnums.

 

you run the pro magnums the forsale ?? what results did ya get, and any problems ?