Posted By: sixty7gtx
need help with my 440 - 07/13/09 08:58 PM
I have 69 dodge charger with a 440 motor. Im doing a compression test. how much compression should a stock 69 440 motor have ?
need help with my 440
Posted By: stumpy
Re: need help with my 440 - 07/13/09 09:02 PM
The thing is not to worry about how much compression but that all the cylinders a close to the same compression. Do the test and let us know what you found. Rememebr all plugs out and carb wide open.
Posted By: sixty7gtx
Re: need help with my 440 - 07/13/09 09:04 PM
Quote:
The thing is not to worry about how much compression but that all the cylinders a close to the same compression. Do the test and let us know what you found. Rememebr all plugs out and carb wide open.
#1 70 #2 81 #5 60 #7 55. I stop after that battery stared to get weak.
Posted By: RapidRobert
Re: need help with my 440 - 07/13/09 09:44 PM
Quote:Your patient needs to be operated on. Might be burned valves/recessed seats from decades of no lead gas but squirt several shots of oil in each hole, spin it to coat it & retest. Little/no change points to the heads but if that is an OE untouched eng I would start making plans to go thru the eng.
#1 70 #2 81 #5 60 #7 55. I
Posted By: HealthServices
Re: need help with my 440 - 07/13/09 10:31 PM
Try again with a strong battery, then like robert says afterwards try again with a couple squirts of oil. But make sure the battery is strong thru out the test.
If it is that worn out the motor should be easy to turn over with the battery.
And it just may need extensive work. But good test results require a good battery and starter.
If it is that worn out the motor should be easy to turn over with the battery.
And it just may need extensive work. But good test results require a good battery and starter.
Posted By: RodStRace
Re: need help with my 440 - 07/13/09 10:42 PM
Did you have all the plugs out?
Any battery that can spin a healthy big block should be able to do a complete compression test.
Any battery that can spin a healthy big block should be able to do a complete compression test.
Posted By: Pyper70
Re: need help with my 440 - 07/14/09 12:14 AM
Should be at least 110....And they should all be within 10% of each other.....so if you are racking 100 on each cylinder and one is lower than 90, you have a problem....Thats how I was taught
Posted By: dave571
Re: need help with my 440 - 07/14/09 03:08 AM
How does the motor run?
If it ran strong, and the comp all comes out even as low as 80, its' probably OK.
Reality is, a comrpession test looks for varience, not a total number. The test is properly used for evaluating whether a motor can be tuned properly, NOT to find if it burns oil, or if it's due for a rebuild(although it may iondicate that if a varience does exist) If there is no problem with the running condition of the motor, a comp test will tell you very little.
As for performing the test, I will add that it should be done as close to warmed up as possible, but this is very difficult with headers, or even hp manifolds.
The numbers posted only show an incomplete test done with a dead battery.
If it ran strong, and the comp all comes out even as low as 80, its' probably OK.
Reality is, a comrpession test looks for varience, not a total number. The test is properly used for evaluating whether a motor can be tuned properly, NOT to find if it burns oil, or if it's due for a rebuild(although it may iondicate that if a varience does exist) If there is no problem with the running condition of the motor, a comp test will tell you very little.
As for performing the test, I will add that it should be done as close to warmed up as possible, but this is very difficult with headers, or even hp manifolds.
The numbers posted only show an incomplete test done with a dead battery.
Posted By: Dusted_Ya
Re: need help with my 440 - 07/14/09 03:59 AM
Also the engine should be hot when doing a compression check since it takes a minute for hydraulic lifters to pump up.
Posted By: Mopar Grandpa
Re: need help with my 440 - 07/14/09 11:49 AM
Your compression is pretty low and I would suggest a leak down test. If the cylinders are leaking down, loosing pressure, then it's either your valves or your rings or both. Sounds like it's time for a rebuild.
Posted By: scratchnfotraction
Re: need help with my 440 - 07/14/09 12:20 PM
I thinking most were in the 7s for ratio on compression and 80 sounds close to right IMO
cam can raise the the # up by closeing early to build cyl pressure
I wet the cyl after removing all the plugs and chok the carb open wide,charge batt and do all the cyl...only takes a couple turns for each cyl
IMO,sound like I would run it
cam can raise the the # up by closeing early to build cyl pressure
I wet the cyl after removing all the plugs and chok the carb open wide,charge batt and do all the cyl...only takes a couple turns for each cyl
IMO,sound like I would run it
Posted By: sixty7gtx
Re: need help with my 440 - 07/14/09 09:39 PM
Quote:Thanks for all your help . the motor ran fine. I took it apart to paint the motor. i put it all back together started run for about 20mins and air started to go threw were you put the oil in and the air blew off the oil cover. and that it , maybe jumped a tooth on the timing chain????
How does the motor run?
If it ran strong, and the comp all comes out even as low as 80, its' probably OK.
Reality is, a comrpession test looks for varience, not a total number. The test is properly used for evaluating whether a motor can be tuned properly, NOT to find if it burns oil, or if it's due for a rebuild(although it may iondicate that if a varience does exist) If there is no problem with the running condition of the motor, a comp test will tell you very little.
As for performing the test, I will add that it should be done as close to warmed up as possible, but this is very difficult with headers, or even hp manifolds.
The numbers posted only show an incomplete test done with a dead battery.
Posted By: sixty7gtx
Re: need help with my 440 - 07/14/09 09:45 PM
Quote:YES, thanks
Did you have all the plugs out?
Any battery that can spin a healthy big block should be able to do a complete compression test.
Posted By: Mopar Grandpa
Re: need help with my 440 - 07/14/09 09:46 PM
Was the dot in the up position on the crank gear and was the dot down on the cam gear with both dots lined up? The condition you described is not right.
Posted By: Dougsmopars
Re: need help with my 440 - 07/14/09 09:47 PM
also remember to spin motor 3 rotations for a good read. Hit key count to 3 and read your gauge.
Posted By: sixty7gtx
Re: need help with my 440 - 07/14/09 09:48 PM
Quote:let me check and i will get back to you.. thanks joe
Was the dot in the up position on the crank gear and was the dot down on the cam gear with both dots lined up? The condition you described is not right.
Posted By: sixty7gtx
Re: need help with my 440 - 07/14/09 11:12 PM
Quote:Quote:let me check and i will get back to you.. thanks joe
Was the dot in the up position on the crank gear and was the dot down on the cam gear with both dots lined up? The condition you described is not right.
dots are good........
Posted By: Mopar Grandpa
Re: need help with my 440 - 07/15/09 12:46 AM
If you have pressure in the engine that blows your breather off then you have a big problem. A blown head gasket will allow pressure into the engine as well as blow by on the compression rings of the pistons. You really need to do a leak down test and if a cylinder or cylinders is not holding pressure then a head gasket is not sealed or the pressure is blowing by the rings. Based on your compression readings I would suspect the rings are bad. How many miles are on this engine? Was it ever rebuilt? If the intake valves were bad you would get noise back thru the carb and if the exhaust valves were bad then you would have leakage thru the exhaust manifolds but this would not blow the breather off your valve cover. If you are not familiar with a leak down test by all means take it to a professional. 
Posted By: dave571
Re: need help with my 440 - 07/15/09 04:35 AM
Quote:
Thanks for all your help . the motor ran fine. I took it apart to paint the motor. i put it all back together started run for about 20mins and air started to go threw were you put the oil in and the air blew off the oil cover. and that it , maybe jumped a tooth on the timing chain????
Is the pcv valve hooked up(sorry if repeat question)
You should verify that the crankcase is being evactuated properly.
If it is, it would seem the engine is tired, it's just how tired is the question.
As for the leakdown test, it's pointless, and good luck finding a pro who even knows how to do one anymore. They are never done in the trade anymore.
If you've got blow by into the crankcase, you've got a sealing problem in the rings. . The leakdown test may verify it, and it may not, but it doesn't really matter.
You've checked the dot's and they line up, so it's not the tc.
If it's blowing the breather off, it's something youa re going to have to deal with.
On the cheap side, if the taper isn't bad, you may be able to get away with a scratch hone,a nd a rering
