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| Roller-Tipped Rocker Arms - Iron Duke? (Page 1/2) |
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82-T/A [At Work]
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SEP 26, 08:15 AM
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Hey guys...
I wanted to ask. Anyone know if the CompCams roller tipped rocker arms that they sell for the V6 Fiero, will fit the Iron Duke? I know a lot of people have done the big swap where they install full roller-rockers and all that. Not really looking for that. But we're going to be swapping out a cyl head on my daughter's Iron Duke, and I figured... if there is a simple roller-fulcrum rocker arm set that I can install (even if I have to buy one for the V6), I would totally do it just to further reduce the drag on the valve train and improve the sound and friction.
Anyone know? I'm not planning on doing 1.6, but the 1.52:1 if I can.
Thanks!
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lou_dias
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SEP 26, 09:26 AM
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I think V8 ones should fit. I'd look for full roller since I believe newer dukes already came with roller fulcrum rollers... You just have to look at the stud diameter. It may be 3/8" vs 10mm like on the stock V6.
When I upgraded my v6 to full-roller, I used the Crane rocker stud adapters to covert from 10mm to 3/8
Also. I believe the duke uses a higher ratio stock than the v6...[This message has been edited by lou_dias (edited 09-26-2025).]
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Raydar
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SEP 26, 09:32 AM
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Without having measurements to back up my statement, I have heard that Chevy big block rockers are a similar ratio to Duke rockers, and have been used on some Duke (or maybe SD4) builds.
There ought to be a huge aftermarket for those. Or at least there was at one point.
You will still likely have the Metric vs SAE fastener size issue.[This message has been edited by Raydar (edited 09-26-2025).]
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82-T/A [At Work]
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SEP 26, 09:53 AM
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Thanks guys, I found these: https://www.summitracing.co...41506/make/chevrolet
It's basically exactly what I'm looking for, and they look pretty similar to the Iron Duke ones. I'm just looking for quality replacements that are a true-ratio of 1.5:1.
On the 3/8ths vs 10mm thing... is the issue that it's unlikely I can simply install the new rocker arm, and re-use the bolt hardware (with the new pivot bushing)?
Lou, I was able to confirm the stock engine ratio is 1.5. And the ones in the link above are also 1.5. So, no real gains there... and that's ok. Just more looking for less valve clatter. To be clear, it doesn't really have that NOW, but I think it will over time (like they all do). Biggest issue with the Iron Duke really is the valve cover and how it basically acts like a speaker magnifying all the valve train nose within it. I wonder if there's a coating that can go inside? I'm rambling now...
So, do you guys think I'll have to remove the studs in the cyl head and install new studs?
Thank you!!
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Raydar
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SEP 26, 10:09 AM
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| quote | Originally posted by 82-T/A [At Work]:
...I was able to confirm the stock engine ratio is 1.5. And the ones in the link above are also 1.5. |
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Ah, okay. I was thinking the Duke was also 1.7, for some reason. But I'm not even finished with my first coffee, so...
I stand corrected. 
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FieroWannaBe
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SEP 26, 10:10 AM
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82-T/A [At Work]
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SEP 26, 01:43 PM
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Sorry Lou, Raydar! I saw a post on the S-10 forum and it was suggesting it was 1.5, I got that wrong!
| quote | Originally posted by FieroWannaBe:
Stock Duke rockers are 1.7:1, with standard for the time GM ball trunnion.
BBC rockers Generally fit, and screw in studs are available.
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Ok, thank you. This probably makes it a bit more obvious to me. I'm only seeing 1.5:1 stamped and cast roller-fulcrum rockers... so I'd actually end up seeing a loss of power, which is not idea. I'll keep looking.
The one thing that stood out though, you said that screw in studs are available. So ideally I could just unscrew the studs that are in there (they're not pressed in I assume), and install new studs? Do you happy to know if they sell a new set, or do I still have to drill and tap the holes?
I'm kind of hoping for something that would be considered a simple upgrade. I've used the machine shop plenty, but for my daughter's video, I want it to be something that any person can just order some parts, and do it without having to take the cyl head off and take it to a machine shop.
Thanks guys!
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FieroWannaBe
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SEP 26, 02:49 PM
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| quote | Originally posted by 82-T/A [At Work]:
Ok, thank you. This probably makes it a bit more obvious to me. I'm only seeing 1.5:1 stamped and cast roller-fulcrum rockers... so I'd actually end up seeing a loss of power, which is not idea. I'll keep looking.
The one thing that stood out though, you said that screw in studs are available. So ideally I could just unscrew the studs that are in there (they're not pressed in I assume), and install new studs? Do you happy to know if they sell a new set, or do I still have to drill and tap the holes?
I'm kind of hoping for something that would be considered a simple upgrade. I've used the machine shop plenty, but for my daughter's video, I want it to be something that any person can just order some parts, and do it without having to take the cyl head off and take it to a machine shop.
Thanks guys!
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The most friction is from the rocker fulcrum, it's a larger gain to go from the Ball and Cup rocker to a roller Trunnion, than the gain from sliding tip to roller tip. Of course there the roller tip may be gentler on the valve guide, but the Duke, stock, doesn't really have enough lift to be concerned.
https://www.hotrod.com/how-...trp-0703-rocker-arm.
Stock should have Metric Bolts (not studs).
ARP makes metric to 7/16 studs.
https://arp-bolts.com/kits/...tail.php?RecordID=36
or
https://arp-bolts.com/kits/...ail.php?RecordID=322
And you would need adjuster nuts w/locks.
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Dennis LaGrua
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SEP 26, 04:00 PM
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If you are going to change the head why not add a mild cam and some porting to the mix. A while back there was a guy here who claimed that the cam change helped his Duke engine to get over 120 HP but he was also running SBC pistons. ------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "
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82-T/A [At Work]
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SEP 27, 01:54 PM
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Thank you! I bought one of each to see which fits properly. If I figure out which one works best, then I can order the correct rocker arm.
I was totally stressed (well, not really stressed, mildly confused) because I forget that the rocker arms on the L4 are literally bolts, as opposed to the V6 which has a stud already in the head and a nut. I kept thinking the L4 had studs in them already, and that I had to figure out how to remove... all while I literally had a bolt and rocker arm from the cyl head that I took off, sitting here at my desk so I knew what to look for. Seriously, some times I am completely oblivious.
Your chart on the left shows a pretty solid array of different roller rockers... with a 1.7:1 rocker ratio, I'll probably go with something like a 1.75:1 as I don't really want to change it too much.
Do you think I'll need to get a set of aftermarket pushrods too? Or should I be able to use the stock sized (brand new) pushrods?
Thanks!
| quote | Originally posted by Dennis LaGrua:
If you are going to change the head why not add a mild cam and some porting to the mix. A while back there was a guy here who claimed that the cam change helped his Duke engine to get over 120 HP but he was also running SBC pistons.
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Thanks Dennis... my daughter really doesn't want to fiddle with the motor too much. She's looking for really simple upgrades that can be made to an otherwise totally stock engine. When she rebuilt the motor, she went with a brand new roller cam, so it's "blueprinted" at least at this point. She's not looking for too much power, just efficiency improvements and keeping it feeling relatively stock, with just a bit more pep.
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