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| The White Bug (Page 33/46) |
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Will
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MAY 10, 09:07 PM
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At least it was easy to find
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ericjon262
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MAY 10, 10:29 PM
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glad to hear it will be a relatively easy fix! aren't you running aftermarket steel rockers? ------------------
"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
cognita semper
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longjonsilver
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MAY 11, 11:51 AM
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Sorry to hear. At least you found the problem fast! ------------------
Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.
Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.
I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 3800SC, 4-wheel drifts are fun!
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La fiera
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MAY 11, 08:14 PM
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Oh wow! You caught that on time Patrick! Too much POWA!!!
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pmbrunelle
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MAY 11, 08:54 PM
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Yeah, a bit of a pain, but things could be worse. I should be able to fix this without removing the engine from the car.
Here is the history of rocker arms since the engine rebuild:
- Comp Cams Magnum 1.52 ratio roller-tipped rockers, grooved balls. 15W-40 Shell Rotella T4 + 4 oz Redline ZDDP additive. 2042 km until failure.
- Comp Cams Magnum 1.52 ratio roller-tipped rockers, grooved balls. 10W-40 Liqui-Moly MoS2 Anti-Friction. Lifespan about 200 km until failure.
- Melling MRK-407 stock replacement rockers for Fiero, smooth balls. 10W-40 Liqui-Moly MoS2 Anti-Friction. Lifespan about 9945 km until failure.
Stock Fiero 2.8 stamped steel style rockers have been the best so far, but not good enough.
I have the feeling that maybe average RPMs are higher than stock Fiero, and that oil temperature is higher than stock Fiero because of the turbo. So I'm thinking that I might need fancier rockers with needle-bearing trunnions. Once I remove the valve covers and look inside I might have more insights.
| quote | Originally posted by La fiera:
Oh wow! You caught that on time Patrick! Too much POWA!!! |
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I was lucky enough to have the problem at just the right place! My work colleague was driving the car on the autoroute, and when the sound began, we happened to be at an exit, so he pulled off the autoroute.
Once he stopped, I took over the driving, so he wouldn't have the stress of driving someone else's damaged project car. We were close to my home (1.2 km), so I decided to limp home driving calmly at 1500 RPM.
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Will
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MAY 11, 08:58 PM
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What cam and valve springs are you running?
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pmbrunelle
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MAY 11, 09:40 PM
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*****Camshaft*****
Crower F18059 hydraulic flat tappet
Duration @ .050" Lift: Intake / Exhaust 212° / 218°
Lobe Lift: Intake / Exhaust 0.290" / 0.299"
*****Springs*****
Crower 68301X1-12
Seat: 1.700" @ 101 lbs
Nose: 1.200" @ 297 lbs
Coil bind: 1.130"
I'm not sure what the actual spring heights are on the base circle or nose of the lobe on my installation, but these catalog numbers give a rough idea.
Coil bind would increase the rocker arm pivot force dramatically, and while I do vaguely remember checking for that, I don't have any written record of having done so. So the possibility of coil bind might be worth investigating.
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La fiera
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MAY 12, 05:20 PM
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Why don't you invest in a set of fully roller aluminum rockers? You can you any "Narrow Body" "NON self Align" rocker for a Chevy, those are the ones I use. You can easily get an 1/4 inch spacer machined to make raise the valve covers.
Part# SCP1037-1 $23 each at Summit Racing.
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pmbrunelle
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MAY 12, 08:40 PM
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| quote | Originally posted by La fiera:
Why don't you invest in a set of fully roller aluminum rockers? You can you any "Narrow Body" "NON self Align" rocker for a Chevy, those are the ones I use. You can easily get an 1/4 inch spacer machined to make raise the valve covers.
Part# SCP1037-1 $23 each at Summit Racing. |
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Yeah, I'm considering the Scorpion SCP1037 rockers. Is raising the valve covers the only mod needed?
What hits the valve cover? Is it the rocker arm, or the polylock?
Ideally, if I can find a rocker arm that fits under stock valve covers, I would prefer that, but I am ready to raise them if needed.
This guy here has some Scorpion rockers, but one one pair the rockers are almost touching:
https://www.fiero.nl/forum/...314-2-116255.html#p4
I suspect that he's using self-aligning rockers, so the positioning the the rocker arms in the pushrod area isn't as precise as with non-self-aligning rockers and guideplates.
The SCP1037 rockers don't have that almost-rubbing issue, right?[This message has been edited by pmbrunelle (edited 05-12-2022).]
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La fiera
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MAY 12, 10:53 PM
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https://www.summitracing.co...19-12/make/chevrolet
You'll need Chromoly studs to use the aluminum rockers, I can't remember ARP's part number but this is its equivalent.
As far as the raising of the valve cover, I have a neighbor with a CNC plasma cutter that can make the spacers. If you can't get them done let me know and I'll make a batch to get what you need and sell the rest on ebay.
And no, the rockers don't have the robing issue.
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