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| 87 GT cylinder wear maximum (Page 1/1) |
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the_snowman
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OCT 19, 01:46 PM
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I am currently fixing up an 87 GT 2.8L and was wondering where i could find the maximum wear specs for the cylinders?
i pulled it from a junk yard so i don't have an idea how many miles are on it.
if anyone has this information i would be thrilled if you can share.
i am pretty new, this is my first car and first fiero in genaral so any help is more than welcome!
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82-T/A [At Work]
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OCT 19, 03:29 PM
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| quote | Originally posted by the_snowman:
I am currently fixing up an 87 GT 2.8L and was wondering where i could find the maximum wear specs for the cylinders?
i pulled it from a junk yard so i don't have an idea how many miles are on it.
if anyone has this information i would be thrilled if you can share.
i am pretty new, this is my first car and first fiero in genaral so any help is more than welcome! |
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Hi, by cyl wear, do you mean wear on the cyl walls? As in... from the stock bore to the wear along the cyl wall?
You'll need to get a bore gauge (from like harbor freight), a caliper, and measure the bore all up and down the cyl wall. My daughter made a video for measuring cyl bore wear, etc. This should help.
It's for her 4 cyl Fiero, but she does a zoom in of the service manual and it shows the cyl bore size should be (in inches) 3.5036 to 3.5067. I would say that there's really no level of acceptable wear, honestly.
Can I ask what the number will mean to you? Are you looking to rebuild the engine and hoping to re-use as much as possible? In my opinion, depending on the miles... if there's a fairly significant ridge between the top of the cyl wall and where the piston slides up and down... you may want to just have it bored to a larger size. You can generally go with a larger piston bore like a .030 overbore or something. You pick up a couple of horsepower anyway, and the machine shop will bore the engine to the piston size.
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the_snowman
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OCT 19, 04:06 PM
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| quote | Originally posted by 82-T/A [At Work]:
Hi, by cyl wear, do you mean wear on the cyl walls? As in... from the stock bore to the wear along the cyl wall?
You'll need to get a bore gauge (from like harbor freight), a caliper, and measure the bore all up and down the cyl wall. My daughter made a video for measuring cyl bore wear, etc. This should help.
It's for her 4 cyl Fiero, but she does a zoom in of the service manual and it shows the cyl bore size should be (in inches) 3.5036 to 3.5067. I would say that there's really no level of acceptable wear, honestly.
Can I ask what the number will mean to you? Are you looking to rebuild the engine and hoping to re-use as much as possible? In my opinion, depending on the miles... if there's a fairly significant ridge between the top of the cyl wall and where the piston slides up and down... you may want to just have it bored to a larger size. You can generally go with a larger piston bore like a .030 overbore or something. You pick up a couple of horsepower anyway, and the machine shop will bore the engine to the piston size. |
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Hi, thank for for the assistance! "Can I ask what the number will mean to you?" - either i would be looking at getting another block or seeing if i can bore it out a little.
i am trying to do a rebuild using as much of the parts on the engine as possible (especially as a teen).
i do mean the cyl walls as in from the stock bore to the wear along the cyl wall.
Those number are making sense now, it does have a significant amount of wear between the ridge and where the piston moves... so i may see if i can have it bored to a larger size.
i am just trying to use it as a daily driver, no need for speed. (it doesn't hurt to have some though).
if i do get it bored out, depending on how much would i need larger pistons and ect...?
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Vintage-Nut
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OCT 19, 04:54 PM
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If you can find them; Fiero 2.8L Oversize Pistons are 0.50MM / 0.75MM / 1.00MM and 1.50MM
One Source is RockAuto:
https://www.rockauto.com/en...2,engine,piston,5620
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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles[This message has been edited by Vintage-Nut (edited 10-19-2025).]
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IMSA GT
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OCT 19, 06:14 PM
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The factory bore for the 6cyl should be 89mm which equates to 3.50 inches as mentioned above.
Then take Vintage Nut's numbers and you can measure how much it's worn vs. what's the next size available.[This message has been edited by IMSA GT (edited 10-19-2025).]
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82-T/A [At Work]
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OCT 19, 09:12 PM
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It looks like Rock Auto is totally out of replacement pistons. But... I found this on eBay, which sells the pistons with the match set of chrome-moly rings: https://www.ebay.com/itm/274363119580
I'm drawing a blank, but people usually do a .020 overbore, or an .030 overbore, or even a .040 overbore. For the life of me, I don't have the brain capacity at 9:07 on a Sunday to figure out what that equates to in .50 / .75, etc... but if you want to save money on buying a bore scope, and unless the engine was really abused, you'd be fine going with a "30 overbore."
I'd get a shop manual too... but there's a lot of things you can reuse... the crank, rods, main caps, and even the rod and main cap bolts. You'll want to have the heads redone, and also get new head bolts and all new gaskets and head gaskets. Also new bearings of course, but you'll re-use a lot.
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Vintage-Nut
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OCT 19, 10:26 PM
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82-T/A [At Work]
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OCT 20, 07:47 AM
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Thanks VN!
As for crank bearings... unless the crank and rods are worn (as in, you're hearing a knocking or rattling), they'll probably still be STD size. I generally don't like the idea of thicker bearings and grinding down the crank unless you absolutely have to. But you'll have to tell us why you decided to rebuild the engine, to see if there's something wrong with it.
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sleek fiero
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OCT 20, 10:36 AM
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I believe WOT tech has pistons available. He is now a member of Pennocks
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