1.6 Rockers on my 350 Goodwrench Engine?

[PetieG383]

OK, here's the deal.

I've got a basically stock (under 4k miles) 350/260hp Goodwrench engine in my 80 Malibu. It has an Edelbrock Performer intake, a 600 Holley Vac Sec carb, full length 1 5/8 headers and a 2.5" Pypes exhaust. I'm looking to pull a little more power out of it without tearing into it too much (i.e. install a cam). Can I put a set of 1.6 roller rockers on this engine without much fanfare? It currently has the stock .390/400 lift cam in it (basically the same cam that every stock 350 cam with back in the day), and 8.5 compression.

Has anyone else done this? What kind of HP increase can I expect? I've never run anything bigger then 1.5's on any of my cars in the past. I know it will obviously increase the cam lift, but I'm wondering if it's worth it. I can probably pick up a set of rockers for under $150. I'm just looking to increase the HP a little, maybe make a little more noise. It's just a cool every day driver.

Thanks everyone.

 

[cmonson]

WIth 1.6s your lift would net to .416/.427

What cylinder heads are you running?

If it is for a DD I am not sure if I would bother. I think you would just be wearing out valve guides faster and not notice that much of a difference. There probably isn't that much of an advantage running over .400 lift using stock 350 heads.

Saying that there has been lots of discussions in the past on the topic of different ratio of rockers. Do a search and I am sure you'll dig up many threads.

 

[PetieG383]

I'm not even sure what head they are. I never looked at the castings. I'm sure they're whatever GM drops on there with smaller valves.

 

[rustbucket79]

If the engine uses rail tip rockers without the guide holes for the pushrods, maybe, if the head casting guides the pushrods, NO. (without machining) Since most factory heads don't flow much more over .400 lift anyways, the rocker change is a waste of time. A cam change will improve performance, but is naturally more work for you.

 

[andymiller]

Installing 1.6 rockers on a engine thats not turning rpm's over 5k on a stock engine is not worth it.

Like it was said above. Swap the cam, and it'll be worth more power for the same ammount of money, just more work.

 

[Damon]

Yes, you can physically install them without any problem. They are standard old-style non-self aligning rockers and are easily upgraded.

But expect no miracles in terms of performance. The slight increase in effective duration from the rocker change will help some, as will a little more "area under the curve" from the higher ratio rockers. But if it's worth any more than 10HP and a smidge of torque I'd be surprised.

The heads are -993 castings with 76cc chambers and 1.94/1.50 valves- nothing to write home about. The pistons in the motor are -12cc dished 4-relief cast units like many emissions motors from the 70s. A head swap to Vortecs would probably do more to wake that motor up than a cam change (better flow and higher compression ratio), but if you're not going to dig into the motor then that's off the table.

 

[Lowend]

I've said it before and I'll say it again...
If you think you want higher ratio rockers than you really need more cam
I think 1.6 rockers are a waste of money in about 90% of the applications people use them in

 

[Kamikaze]

One factor I'm surprised no one has mentioned is the possibility of the pushrods rubbing against the head with the ratio increase.

Many a stock type head especially those "Hecho en Mexico" Goodwrench castings may be too tight around the pushrod slot and will require some clearance with a Louis tool to open up the slot.

Like nearly everyone else stated, you would do much better with a better cam.

Either Chevy High Po or Car Craft did a build of a stock Goodwrench 350 and step by step they went doing small changes and gained a ton of torque and horsepower for a street application.

I'll have to see if I can find the series for you and post some of the details.

 

[rustbucket79]

Reread my first post, as stated 1.6 rockers will require machining on most factory heads for the pushrods to clear. (although I wasn't overly clear on what had to be machined)

When you install the 1.6 rockers on a factory guided head, everything looks good because the lifter is on the base circle of the cam and the pushrod is farthest away from the rocker stud. (and that side of the pushrod slot) The problem lies when the lifter is at max lift, with the plunger at the top of the lifter, because as the rocker goes through it's motion the pushrod moves towards the rocker stud and that side of the pushrod slot. For those who don't know, a 1.6 rocker is made that way by moving the pushrod socket closer to the fulcrum point, in this case the rocker stud centerline. What you end up with on an engine using the stock heads and high ratio rockers is the pushrod goes into a bind at maximum lift. You may never experience a problem, then again you could end up with bent pushrods, extreme wear on the pushrod balls and rockers, or even reduced cam and lifter life.

The best home for more rocker ratio is when conventional means can't give you the lift that the engine combination requires. It isn't a slam dunk method to increase performance.

 

[pdq67]

Smaller chambered heads along w/ shim headgaskets and a mild cam will pick her right up!!

And I wouldn't mess w/ the 1.6 ratio rockers if you change cams!!

Run the CR. numbers here!!

http://www.campbellenterprises.com/Race math calculators.htm

pdq67