My '90 Trooper (3.4 block, 4.3 TBI, bored intake manifold) has a blown head gasket. I'm thinking of upgrading to 1.6 roller rockers while I have everything apart. Replacing the camshaft is currently not part of the plan.

I've read Sean's Power Tricks article and understand the ~10% gain in HP, but more important to me is torque. Will the 1.6 rockers yield a net increase in torque as well, and if so, how much?

Also, regarding torque-to-yield bolts - are there brands to stay away from? I am assuming that I need to use new bolts when I reinstall the head.

Thanks,

Ed

Howdy....My Trooper is setup about like yours. I used Competion Cams 1.6 roller rockers. I can't comment on before/after, because I put them in during 3.4 transplant. I kept the stock cam also. I am very happy <img border="0" title="" alt="[Smile]" src="images/icons/smile.gif" /> , torque plentiful even at 1500rpm, and cruises 60mph @ 2000rpm easily with 33's. And breathes freely up to 5000rpm.

<small>[ March 08, 2003, 12:21 AM: Message edited by: maxwell417 ]</small>

Ed, the 1.6:1 rockers are a definite improvement, although I think the most pronounced effect is on the mid-to-upper end rather than low-end torque. All I know is that my 3.4 with Donormaro motor, stock cam, 1.6's, Holley, etc, has so much torque and immediate response in 1st gear 4-LO that it's almost unuseable. It just leaps forward like you can't believe. But if you take your foot off the gas it'll crawl like mad in 1st.

The cam found in the Goodwrench HT 3.4 crate motor is known for its superior torque characteristics, and even though you aren't planning it, having the heads off is a good time to do a cam swap if ever.

Check the cam lobes and lifter faces carefully for wear. The lifters should autorotate as you're turning the crank; if they don't, the lifters and likely the cam will need to be replaced anyway.

Here's a good discussion about cams and torque issues at the GMForums site:

http://discussions.gmforums.com/showthread.php?s=34be06697657ca31886e20f5426952cd&threadid=33902

BTW for G.P. be sure to replace both head gaskets, if one decided to blow it's not unlikely that the other one may be next.

Not sure about the Torque-to-Yield bolts, I would think that if you stuck to name-brand aftermarket ones there'd be no problem.

I have the GM 3.4 crate engine and love the torque curve. At Crawloween we were waiting for the group to bunch back up after an obstacle, and I was leading. I was trail lead, so I eased the clutch out and crawled for at least a half-mile, up and down hill, over small obstacles, etc., without ever touching the throttle. My right foot was flat on the floor. Finally Craig E. who was following me, asked what I was doing.

Thanks guys,

I think I'll go with the 1.6 rockers.

I plan to do both heads at the same time since I'm not sure which head has the blown gasket. Besides, I don't want to dig into the motor more times than I need to.

Cam lobes and lifter faces, huh? Great, more things to worry about... I've got about 100,000 miles on this engine (Donormaro), so hopefully there won't be much wear.

Unless the cam and lifters are really bad I won't replace them. I need to save money for my next project - a '91 Trooper LS with a seized motor (V6, of course). <img border="0" title="" alt="[Big Grin]" src="images/icons/grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="images/icons/grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="images/icons/grin.gif" />

Jim, I'm curious (and impressed!) - are you running the stock transfer case?

Yes, I am running the stock transfer case. The Teras are on my list for when I am once more gainfully employed.