probably another dumb question but...

on grand prixs and other W bodys rockers add hp/tq

what i want to know is whats the best rockers to go with? do i have to change pushrods and springs i have 175000km on my truck is 1.7-1.85 to much for the stock valvetrain?

what can i get away with? also when i do add a cam how big can i go on stock heads with say 1.85's? or 1.7's? max lift?

do all rockers require pushrod change?
harland sharp or comp?
anyone have power gains?
1/4mile?

anyone ever try split ratio?

thanks
jordan

 

I run 1.8 Crane Gold Race rockers on my truck and I have not had a single problem. I shift at 7100 rpm and the motor will usually see 7500 in the burn out, so I'm not just being easy on them. I doubt you would have to change push rod length if all you are doing is adding the rockers. More than likely you will pick up a little power, but I would imagine that it would only be noticable on a dyno, especially if the motor is stock. When adding a cam later, valve springs will probably be the limiting factor. I don't know what the limit is on stock springs but I'm sure someone will chime in. I have heard of running split rockers and have done so on a few occations. Typically the benefits of running split rockers are found on the engine dyno durring testing and can actually teach you about your cam choice (whether it was a good one or not). A senerio where you might look into running a split rocker set up would be if you built a dedicated N/A motor and then decided later on to spray it or add FI. You could add a higher ratio rocker to the exhaust side to help make up for any short comings of the N/A cam. Just my .02.

 

I've always been curious to see a before and after dyno graph of rocker arms. The stock 5.3L heads max out around .450-.475 lift so I don't see there being hardly any gain from rockers.

 

there are some 1.9s available also. they have a dyno graph of them on a 5.3l 1500 pickup with gains of 18hp at the wheels. it could possibly be more on a 6.0l. the question is if 18hp is worth $370.

https://www.zzperformance.com/grand_...=953&catid=104

 

Alot of choices for aftermarket rockers...alot of guys will say that they aren't worth the coin, and to just do a cam swap instead. But if you've got your mind set on the rockers, here's what I think. The Crane rockers seem to be the best as they're adjustable, and you can get the lifter preload dead on. They're also the most expensive and most tedious to intall given their adjustablity. I have Harland Sharp 1.7 rockers in my truck, and so far they have been fine. I had to relief (grind notches in) the heads a little bit on the pushrod side of the rocker, as the clearance seemed very tight and I didn't want any contact and possible broken parts. Besides that, they just bolted right in and fit under the factory valve covers. They were $399 when I got them a few years ago from Texas Speed. SLP also makes a 1.85 rocker that is the same design of the factory rocker, but I haven't really heard any feedback about them, good or bad. Other choices include Yella Terra, which are supposed to be top notch, but also a little pricey IIRC. Summit also offers 1.8 rockers, which are probably another brand of rocker with the Summit name attached to them. I'm sure that there are more options out there, but this is what comes to mind right now.

 

Everything i've read says the stock heads max out around .550 lift....on the 5.3's. Where did you get your info from im curious to see what the truth is now.

 

thanks dudes

i was thinking about doing 1.75 or 1.8's for now and then when i save up some money get a nice head and cam to compliment them

but i was just wondering for now what would be cool and rockers i know are pretty easy to install and 18whp seems pretty good for 400-500 bucks if ya ask me

another question though... why adjustability? whats the benefit? more power? wouldnt you just want to install and forget about it? thats how it is on a Wbody

thanks
jordan

 

Adjustable rockers are required for solid lifter cams and can be used with hydraulic cams for more flexability.

 

Adjustability to get the lifter pre-load perfect, as opposed to just guessing and throwing in a set of 7.4 pushrods because that's what everyone else uses. It allows for a tighter valvetrain with no play. Once their adjusted and tightened down, you can just drive and forget about them. This is especially beneficial after a cam swap. If you're just swapping rockers on the stock cam, then you should be fine throwing some 7.4's in there, or even re-using the stockers (which I don't recommend, but I'm a worry-wart), and driving on your way. Be aware that the stock pushrods are 7.38, and aftermarkets go up in .025 incremements (7.4, 7.425, 7.45, etc.)

 

sounds good
i definetly want to try out a set of rockers before i do heads and cam

thanks guys
jordan