MY question is should I or shouldnt I throw on a set of 1.6 ratio rockers on my new setup. the heads and intake will be ported, 28# injectors, and pcmforless tune. my goals for power are around 400-450, would I achive that with 1.5s or do I need 1.6 rockers?? also would I have to change the studs, IE threaded with guide plates?? thanks -TOT

 

Thats a hard call with stock heads. Higher valve lifts produce more power, and stock studs on aluminium LT1 heads are threaded.

 

First, if you plan on 450 hp, you are going to need 32lb injectors. Second, I don't think 1.6 rockers are worth a ton of horsepower, but they definitely always help.

 

Are you talking FWHP or RWHP???

With a good set of heads you might come near the lower end of your HP goals at the rear wheels, but 450RWHP will never happen with that cam and any rockers.

Use the 1.6s, bigger is always better

 

he said hes doing heads too...i dont see why maybe 400 rw(or somewhere around there) might be possible...

 

i would definately throw a set of 1.6 on there- while ur at it u may as well upgrade to a 7/16" stud. From that depending if you go with SA or NSA will determine if you need guideplates- However if u use guideplates u are also going to have to use hardened pushrods.

basically if your looking to make horsepower in that range you're better off upgrading your valvetrain. you'll probably pick up about 15hp with a good set of springs and some 1.6 rr, but you'll have a good rock solid valvetrain.

 

Well from what I understand and info Ive read on here, TGO and Loyds site heads flowing 260cfm with a cam with similar specs to the 306 I should be near 425hp at the engine. am I wrong at figuring the stock heads ported would flow near those numbers? I would def upgrade the springs I thought that was a givin and the rockers would be SA. As far as the injectors are concerned I was going to just use the 28# set I had kickin around. would everyone agree they need to be upgraded to 32#? thanks - TOT

 

You need RRs either way. If buying them just get the 1.6s. With something as big as the 306 (which is tiny) Don't use stock rockers. I nearly lost a motor by doing this.

I broke a rocker tip off and just enough was left to push on the retainer. No Idea how it didn't pop a lock off and drop the valve, but I did kill it pretty quick when I heard the noise.

 

Well I was planning either way on replacing the rockers it was just a question as to wether 1.6s would be to much with the stock bottom end and lightly modded top end. durability is key! I dont need her to break down on the 2006 power tour!!!

 

If buying get 1.6s just make sure your springs are up to it. Even then you are still tiny (56x/576 lift)

 

what springs would you recomend? I was thinking the hotcam springs would be fine.

 

No, not for 1.6s for sure. I have the cc612s and they are bare minimum. You need something that can handle .600 lift. Call up any of the supporting vendors and tell them your cam, they can recommend springs.

There are several that do not require new seats or machining.

Lol, I say the 306 is little, but its much bigger than the hotcam.

 

ok cool Im on the right track now, thanks for the help guys and if your around for the HRPT 2006 look me up!