Chevy rockers
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Chevy rockers
In effort to move forward with some performance mods, and sort of learn as I go, I’m considering switching to the higher ratio i6 chevy rockers. I was looking through some of the older posts but I still can’t tell if they will fit my truck, I have the stock efi head.
Is it worth doing or should I just go for a cam? (One of the posts indicated that this was simpler than installing a new cam)
What parts should I ask for?
Will the stock springs work?
All I have for guidance is the Haynes manual and this forum. Can anyone recommend a manual that I should be working with?
Thanks again
Is it worth doing or should I just go for a cam? (One of the posts indicated that this was simpler than installing a new cam)
What parts should I ask for?
Will the stock springs work?
All I have for guidance is the Haynes manual and this forum. Can anyone recommend a manual that I should be working with?
Thanks again
Posting Guru
Joined: Jun 2002
Posts: 1,288
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From: redding U.S.A.
the chevy rockers don't fit the EFI head.
Rockers from a 3.8L ford v6 will fit with very slight modification.
Silver Streak had a thread about them, very informative and even gave a dyno chart. I believe he showed 8hp improvement with the higher lift.
Rockers from a 3.8L ford v6 will fit with very slight modification.
Silver Streak had a thread about them, very informative and even gave a dyno chart. I believe he showed 8hp improvement with the higher lift.
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I just took a look at ss's posts. Interesting. However, I feel that even those slight modifcations are beyond what I'm willing to risk. I'd hoped to see a little better gain as well. Especially in the low end. I suspose I'll just stick to the cam.
Thanks
Thanks
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Joined: Sep 2003
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Originally Posted by coalminer78
How about my 82 carb. engine? I was also think of this mod.
I used Harland Sharp BBC 1.7 ratio roller rockers along with Isky adjustable pushrod guide plates, Comp Cams .080 wall Hi tech 3/8" pushrods with a length of 10.250", Comp Cam 300 springs, stock valves and ARP 7/16" studs in an 84 engine.
I had to do the following to get them to work correctly.
Pedastals were machined down.
Rocker stud holes were enlarged to 7/16"
Isky adjustable push rod guide plates were machined to allow for correct geomoetry.
The rockers had to be machined due to an interference with the pushrod at full lift
For the novice engine builder this may be a difficult task, expensive or both.
I machined the guideplates and the rockers which saved me money. I did manage to snap a few pushrods before I had a handle on what was causing it, that being the interference with the rocker.
Depending on which cam you are using, the 1.7 rr's may be overkill as the 300 head can't flow better than 240 hp unless you work the porting.
Last edited by GHog; Jul 28, 2005 at 04:37 PM.
Postmaster
Joined: May 2002
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From: Broken Arrow, OK
Don't judge the benefit of the 3.8 rockers on my dyno charts. There is a lot more there, I just need to tune it up to find it. The only place the chart shows what's really happening it about 3000-3200 rpm. Below that it's too lean to make good power and above that it's too rich to make good power. There's probably 10-12 ft-lbs and 5 or 6 hp still on the table.
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My decision to stick wiht the stock rockers was based mostly on the idea that the 3.8L rockers needed machined. This is my daily driver and I can't afford to have the engine open much longer than a weekend.
I ordered the Crane H-260-2 today. If it turns out to be too much cam, I'll step down to one of the Crower cams (a little less duration and lift but not too close to stock). Best thing is that I'll have learned something from it.
I ordered the Crane H-260-2 today. If it turns out to be too much cam, I'll step down to one of the Crower cams (a little less duration and lift but not too close to stock). Best thing is that I'll have learned something from it.
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Senior User
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I just wanted to add this as it sounds like I'm trying to say I'm not a novice engine builder in a previous post, I most certainly am a novice when it comes to this stuff.
I built the engine to learn some new things and have fun.
I'm still doing both.
I built the engine to learn some new things and have fun.
I'm still doing both.
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