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#1 |
![]() Join Date: Jun 2006
Location: Sparks, NV
Posts: 2,852
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So... shortly after I bought my latest 90' Z in June I bought a new compression tester kit at Harbor Freight. I already had one an old one, a Sun Equipment brand, but I wanted one with a check valve and pressure relief. I always had good luck with the Harbor Freight stuff so I got one of their better kits.
I tested the compression on the new Z shortly after I got it and found the readings around 150lbs but steady across all cylinders. While not happy about the readings I was not surprised as the car has 180k miles and I'm at almost 5000ft altitude. LGAFF suggested I do some intake de-carbonizing and possibly it should pick up some compression. So to start I did 2 rounds of Sea Foam spray directly into the intake. Thought it felt better afterwards. Today I decided to run another compression test and see what if anything happened. Last time with the new tester I had trouble getting the fitting seated in the #8 cylinder. So I decided to start with #8 and use my old tester that has a slimmer hose. Ran the test and was shocked to get a reading of 195! Hmmm... ![]() The old Sun tester has always been accurate. So I got on the Harbor Freight web site and checked the reviews for the compression tester. Guess what, numerous complaints about the testers running 20 - 40 lbs low. One guy even rebuilt his snow mobile engine only to find out the tester was wrong. So tomorrow the tester goes back to Harbor Freight, I'll stop a Summit Racing down the street and pick a new one with the features I want. And... most importantly I'm jazzed that my 180k mile Z has surprisingly good compression. 195 corrected for altitude puts it in the 210 to 215 range at sea level. ![]() As for Harbor Freight, still good for hand tools, some specialty tools and supplies. Probably not so good for the more sophisticated stuff. If you can call a compression tester sophisticated... lesson learned. H ![]()
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90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold. |
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#2 |
![]() Join Date: May 2009
Location: Sparks, Nevada
Posts: 41
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Hans, i might buy a Harbor freight item if i will use it a fee times. But usually if critical measurement is needed i would use a better quality tool.
Sent from my SAMSUNG-SM-G930A using ZR-1 Net Registry mobile app |
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#3 |
Join Date: Jan 2017
Location: US
Posts: 233
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#4 |
![]() Join Date: Mar 2007
Location: Crystal Lake, IL
Posts: 7,194
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Sweet!
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LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359 |
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#5 |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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HATE IT WHEN THAT HAPPENS!
Compression test a few months ago, 1-3-5-7-2-4-220 psi+/- 6=180, 8=165 😲 WTH! Auto Zone compression testor seal went bad! Bought what I hope now is a good one. Thing is, i was looking for a blown head gasket - and my heart sank when i thought I'd found one. Cant imagine how happy I was to discover a bad seal on the compression test gauge. Turned out to be something simple insread!
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Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry Last edited by Paul Workman; 07-23-2017 at 09:06 PM. |
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#6 |
![]() Join Date: Jun 2006
Location: Sparks, NV
Posts: 2,852
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Confirmed! Got the new compression gauge, it confirmed the higher 190-195 readings of the old Sun gauge I had. Looks like this engine is pretty solid for 180k miles
![]() On a side note, I took the Harbor Freight gauge back and since I didn't have the receipt (CRS on my part) they exchanged for a new one. Well, the new one is bad too. Exactly the same as the first one. Oh well, I'm sure they'll exchange it for something else I can use... H ![]()
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90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold. Last edited by Ccmano; 07-25-2017 at 03:04 PM. |
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#7 | |
![]() ![]() Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,493
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__________________
Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry |
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#8 | |
![]() Join Date: Jul 2007
Location: Bartlett, IL
Posts: 7,153
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At least we know the gauges are consistent.lol Sent from my iPhone using ZR-1 Net Registry
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1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978 |
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#9 | |
![]() Join Date: Jun 2006
Location: Sparks, NV
Posts: 2,852
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H ![]()
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90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold. |
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#10 |
![]() Join Date: Jun 2006
Location: Sparks, NV
Posts: 2,852
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To be fair, in general I am not displeased with the things I have gotten a Harbor Freight. Everything has done its job satisfactorally. Certainly not top quality tools but for people who do just occasional work, a good alternative. This is really the first time I can think of that I have had this kind of problem. If I were a professional technician it would be a different story. Like I said lesson learned....
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90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold. |
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