1MeanZ

iTrader: (9)

hey guys i forgot to ask this earlier. i ran a compression test on my motor about a week ago and i had between 155 and 165 psi on all every cylinder. is that good for an 86 LB9?

Guest

Sounds a little worn but not bad. My 86 LB9 was between 175-180 with 125k on it. Consistency between cylinders is even more important given other variables that can affect compression readings.

breathment

hey, with all emissions tubes (AIR) and A\C on, how hard is it to test compression, like getting the hose in the holes, i now the drivers side wouldn't be as hard, but wut about the passenger side, any tips? cause i need to test mine soon, and i was under the car changing the plugs on the passenger side, am i going to have to get that view again?

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series Muffler added to Unkown CatBack, Ported Intake

http://www.geocities.com/david_angel_16

1MeanZ

iTrader: (9)

well crap madmax, that aint what i wanted to hear! LOL my high hole was 165, my low was 155. my buddy has a LB9 and he had 140 on most all his holes. and i know a guy wiht a 70,000 mile LT1 wiht 180psi on all holes. for 125,000 miles, those are some incredible numbers! anyone else got some numbers??

[This message has been edited by 1MeanZ (edited November 28, 2001).]

1MeanZ

iTrader: (9)

nobody??

ViciousZ

iTrader: (1)

When I ran a compression test on my old 305 my numbers were around 175-180 psi, with 105K on the engine. Sorry, that's probably not what you wanted to hear. Breathment, yup, you're gonna get that lovely view again. Compression testing is about the equivalent in difficulty level of changing your sparkies.

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91 Z28
Come see The Vicious...

1MeanZ

iTrader: (9)

well i am pullin my motor this winter. i am gonna run a ball hone thru the cylinders to deglaze them and install new rings on my old pistons. i am also installing all new bearings, freezeplugs, ect. y is my compression so low with only 45,000 original miles? i called the DMV adn it is legit. i bought the car in '97 wiht 32,000 miles on it. not 132,000. did my stock rings just loose their tension because the car has sat so much?

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86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
Adjustable fuel pressure regulator
port and polish intake and heads
lookin to run low 14s maybe squeak out a 13.9 with my stock chip

1MeanZ

iTrader: (9)

ttt

8Mike9

Couple things to think of before you re-ring it.

Could be the compression gauge's accuracy.

Could be valves.

If you suspect rings, then squirt some oil in the cylinders, if the compression increase, you can think rings, otherwise it in the valves.

Lastly, if you decide to re-ring it, you'll need to cut any ring groove off/out of the holes so you don't hammer the new rings, and don't forget to scrape the ring lands too.

My feeling is with 160-165lbs in all the holes, I'd be driving it without any care in the world.

One other thing, you did have the throttle wide open and the engine warm when you tested it?

1MeanZ

iTrader: (9)

well i had the throttle closed and the motor had been driven about 24 hours before. i didnt try teh oil trick, i didnt figure it would make much of a difference. the only reason i am re-ringin it is cuz i am takin the motor completely out to clean and paint stuff up. my dad got a sweat deal on the parts, so we were gonna deglaze the cylinders, and re-ring and re-bearing the motor. i am puttin in a cam and porting the intake and cleanin up the heads anyway so it will be tore down that far, might as well just do it all teh way i guess.