I didnt see any posts about this. Would putting in 1.6 ratio roller rockers on a stock tpi 350 free any power that I would notice. I am just looking to gain some hp and tq . I dont want to do anything that will shorten the life of my engine or modify it much from stock. Would I be better off spend the $250 on something else.

 

I think they're worth about 15 hP tops. Not a bad payback for the money.

 

250$ on roller rockers? use summit's brand, i used their on another build some years ago and they were $170 shipped..

 

1.6s should be common place on a abc valve lift is very important.
BTW I do have a set of Lt4 rockers in the classifieds.

 

doesn't just change the lift, it changes the ramp too, so the power comes on a bit faster.

 

be sure and get the steel ones not the aluminum ones unless your car is strictly a race car. ( i hear they break after 10k miles or so ) i used comp cams pro magnum 1.6's and i felt a difference especially in the higher rpms. and they were around 190 bucks.

 

The trend is away from Aluminum to Chro-mo they are stronger, lighter, and more rigid.

 

How much and what ratio. This has been really good info are the lt4 aluminun could you sent some info about them thank you

 

That change is small..... the power is more noticable in the upper rpms.

If aluminum roller rockers break after 10,000 miles EVERY 96 corvette w/6spd along with the Lt4 SS and Birds would be on the side of the road! Aluminum roller rockers have been used for ever its just the steel rockers have less deflection at high rpm barely noticable unless your motor runs above 6000 rpm for any amount of time.

 

Agreed!

 

So aluminum will be ok. Upper rpms is where I really want to get the power. Love the launch off the line. I hate the way the power levels out over 3k rpms. Whats the ratio on the factory rockers. would I need to program the computer to run these

 

stock is 1.5 and no you dont need a tune for 1.6 roller rockers.

 

Another option is Roller-Tip rockers. They come in 1.6:1 ratios. You get the benefit of the roller tip not grinding away at the top of the valve (or the valve grinding away at the rocker), the increased ratio, and less cash spent - they run about $100 and up a set, some brand names get as expensive as full roller rockers, but I've used the Summit brand ($100) with no issues at all. Not sure I'd run them on a monster race motor, but for a stock replacement they are great and allows you to see the difference without a large cash layout.

http://www.summitracing.com/search/P...?Ns=Rank%7cAsc

 

I'd say if you didn't know which were installed in the engine, and you drove it 10 times, 5 times with each rocker, at best you'd be able to tell correctly which ones were in the engine maybe 50% of the time.

It just doesn't make that much difference.

 

I see in summit they have "Summit" roller rockers for $169 that is a better price then the $230 for the Harland Sharp

 

His '91 is a speed density car. The VE will be off with the slightly higher lift, and the ever so slightly earlier/later open/closing points.

Also, one can assume the AFR under PE mode will be slightly off.

So suggesting that he doesn't need to tune is wrong.

-- Joe

 

I used the summit a couple years ago and they seemed ok. I've used a lot of different brands over the years, and the only ones I had bearing problems with were the steel CAT ones. But they did replace the defective rockers under the lifetime warranty.

I'm using procomp 1.6's on my 412 right now.

Oddly enough, all the cheap rockers seem to be fine, it's the polylocks that come with cheap rockers that will get you when you are not looking. I've had cheap polylocks back off before, and when it does it's a nightmare.

-- Joe

 

so where would i get it tuned at and whats a good price for a tune?

 

Do the " Summit " brand have the polylocks? If they do do I just call Summit and ask for a set without polylocks?

 

It's a TPI ;
changing the rockers ratio is not going to change the fact that the intake can't breath over 4500 rpm

 

yup. they can only flow so much. now they might pick up a little more power earlier on. but peak flow #'s are peak flow #'s.

Aluminum ones break. plain and simple. see them on youtube all the time. the factory rocker arms on corvettes are different. OEM stuff is better than aftermarket especially summit brand, proform, etc. Harland sharp is good and I heard good things about Scorpion's. But I run the comp cams steel magnum rockers on my dodge. I have stockers ont eh camaro still til I upgrade heads.

 

Locally, you would have to ask around. $250-500 for an initial tune is about average. You could always buy the equipment and tune yourself.

-- Joe

 

Are there any 1.6 roller rockers that will fit on a 87 L98 with center bolt Corvette magnesium valve covers with the internal drip tabs?

 

There are narrow body styles that fit but you have to cut the drip tabs off

 

Well, I guess I will keep the drip tabs and pass on the 1.6. Thanks though.