rik89gta

Does anybody know of a good quality set of 1.6 roller rocker arms for my 89 with an L98? I believe my cam has .415 on the intake and .430 lift on the exhaust. What would the increase also be with the 1.6 rockers?

Rob Wade

I run summits on mine. Pretty happy so far. Don't quote me, but I believe if you take your lift and divide by 1.5 then multiply that by 1.6 you will have your lift. I'm not 100% on that though.

1991CamaroRslow

iTrader: (3)

your math is correct, divide by 1.5, multiply by 1.6. You'll also add a little duration.

Rob Wade

Thanks, I didn't want to give bad info. If I am right I believe the duration increase is only percentage points. hardly noticeable. I think I remember a pretty lively debate regarding that, on this forum in the past.

1991CamaroRslow

iTrader: (3)

I don't see how it would increase duration but apparently it can. I've been told it increases something like 1 degree for every .1 ratio you add, I guess it's possible but you're definetly not going to notice it.

rik89gta

Cool, according to that formula.... The stock cam will spec out at .442 on the intake and .458 on the exhaust side with the 1.6 rockers. Are my stock valvesprings capable of the added lift? And once again, what is a good set of rockers that will fit?

Rob Wade

Once again .......s u m m i t ........they sell a narrow body (for center bolt heads) 1.6 rocker. Its the summit brand. I think I paid $206.00. Happy with them so far.

Pat Hall

iTrader: (31)

Your stock springs should be okay at that lift provided they're still in good shape. Most stock springs seem to be okay until you reach around .480 lift or higher. I've know guys who still ran the stock springs at .480 lift, but that's about where I draw the line and start considering running a better spring. In fact, I'd say .470 would be my rule of thumb with stock springs.

rik89gta

Doesnt crane or Comp Cams make a narrow roller rocker setup for the centerbolt TPI'S?

Tony89GTA

iTrader: (7)

You will need rockers that are Self-Aligning since your stock heads don't come with guide plates.

Pat Hall

iTrader: (31)

Yeah, Crane Cams has just the style you need. They're the Crane Gold Series, and they're available in the narrow body, self-aligning style specifically for centerbolt heads. The only downside is they run about $300 for a set.

HD4mula

I'm using narrow body Summits on my AFR heads and they clear nicely my aftemarket centerbolt valve covers. I have a set of GMPP self align 1.6 rockers for sale (didn't use because I needed non self align). I heard these are the same as the Crane Gold.

Rob Wade

Yes I think the comp ones are about $360.00. That why I went with the summits. Using the stock cam/springs there isn't a ton of load on them and they perform nicely for $200.00.

Orr89RocZ

iTrader: (20)

yeah the increase in lift is where the hp gains is at. the heads flow abit more air at near .500 lift than at the stock cam's .415/.430. but you might as well upgrade to new springs if your springs are old. they wear out and new ones will freshen that motor up

rik89gta

Did anybody notice a performance gain or change in idle with the 1.6 rockers? And is it possible to swap out the worn stock springs with the heads still on the engine?

Orr89RocZ

iTrader: (20)

my buddies L98 has 1.6 rockers and full aftermarket TPI and it runs 13.6-13.7 on street tires and stock converter with 3.70 gears!. nice running car. 1.6 rockers should be good for a solid 10hp increase. perhaps 15

and yes u can change springs. u'lll need an air compressor and remove the spark plugs. and a spring compressor. look here for the details
https://www.thirdgen.org/forums/sout...+valve+springs

rik89gta

Thanks for the link Orr89!

Drew

iTrader: (58)

Crane Gold race rockers have been around forever and tend to be the most commonly recommended.

Crane builds the same rockers for GM, without the gold anodizing. They're the ones that GM sells in the LT4 hotcam kit.

If you want a solid recommendation, who would you trust more then the company that built your car originally?

rik89gta

Do you know off hand, the part# for these? Summits online catalog has many of there brand rockers for the 5.7 engine. But none say whether they are narrow body or self aligning. Thanks.

Damon

http://store.summitracing.com/partde...5&autoview=sku

quisterio

Ok, so those are the exact same things as the Gold Annodized ones on summit, but different color and cheaper?

Or are those totally different ones.

rik89gta

Thanks Damon, I am just about ready to order these. But would it be recommended that I swap out my original pushrods while I'm at it? If so, does anybody know of the correct size and type of pushrods I should get?

Damon

No, those rockers are not the same as the Crane Gold narrow body S/A rockers. I'm guessing the Summit house brand rockers are probably made for them over in China somewhere. Not to say they aren't decent quality, but they're definitely not the Crane rockers with a different color anodizing.

I'm using the Big Block version of those Summit rockers in a 454 I'm building right now. My first time using them, so I can't say for sure yet if the quality is good. They look like decent pieces but until I have them in a running motor for a while I will withold judgement.

vwdave

I have the Comp Cams Pro Magnums in mine and I love them. Theyre expensive, but they are also steel which I feel is going to be more durable than the aluminums. Also the bearing assembly is much larger than the aluminums.

The problem I had......is they are much wider than stock. If you are using stock valve covers, it hits the center bracing, so you have to trim it.

As for the springs, I would change them while you are there. Comp Cams 981 springs are great IMO. They fit in the stock seat and they are not too stiff, but a mild upgrade over stock. They are also only $65 or something. While you are at it, sdpc2000.com has stock LT4 retainers for pretty cheap. They are a lightweight steel replacement which is great. When you lighten up your valvetrain, you do not need superman strenght springs to prevent valvefloat.

Hope that helps.

D's89IROCZ

I have Just the good old Comp cams magnum 1.52 rockers . ( roller tipped) . 80 % stronger than stock pieces.

Also , for every .1" of lift, you gain a half a degree of timeing ( according to Visard)