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440 low cranking pressure on one cylinder #676297 04/20/10 11:20 PM 04/20/10 11:20 PM
Joined: Jan 2008 Posts: 350 CT USA N Nick Mineau OP enthusiast
Nick Mineau OP enthusiast N Joined: Jan 2008 Posts: 350 CT USA	hi guys i have a 440 that i am bulding up the top end for more power. i dicided before pulling the heads t0 do a compression test. i have 170 psi in all cylinders except #3. that one only has 140. i put a tablespoon of gear oil in and still had the same reading. i then pulled the valve cover and loosend the rockers. i put shop air to all the clyinders and there is a lot of air sound in the crankcase from any cylinder. i just want to be shure the rings are good before putting the big power#'s to it. its currently mostly stock engine. plese help me figure out the condition of this thing. was rebult 40,000 miles ago and beat on alot and has had very frequent oil chages thanks nick

Re: 440 low cranking pressure on one cylinder [Re: Nick Mineau] #676298 04/20/10 11:25 PM 04/20/10 11:25 PM
Joined: Jul 2008 Posts: 30,431 Florida STAYcation BeEtLeJuIcE ! The village idiot's idiot
BeEtLeJuIcE ! The village idiot's idiot Joined: Jul 2008 Posts: 30,431 Florida STAYcation	GET some engine fogging oil ... then do the test. If it does the same thing .. sounds like to me you have some leaky valves.

Re: 440 low cranking pressure on one cylinder [Re: BeEtLeJuIcE !] #676299 04/20/10 11:39 PM 04/20/10 11:39 PM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	W the eng in the car I'd pull the pan/heads/intake and ridge ream/rering it w a ~$150 moly ring/bearing kit & do your intended head upgrade and read "breakin secrets" at www.mototuneusa.com (a 5 minute read)or easier/quicker just swap the heads & go & be up & running in no time live every 24 hour block of time like it's your last day on earth

Re: 440 low cranking pressure on one cylinder [Re: RapidRobert] #676300 04/21/10 12:56 AM 04/21/10 12:56 AM
Joined: Jan 2008 Posts: 350 CT USA N Nick Mineau OP enthusiast
Nick Mineau OP enthusiast N Joined: Jan 2008 Posts: 350 CT USA	so whats the best way to figure out if it needs rings. ill try the foging oil tommoro

Re: 440 low cranking pressure on one cylinder [Re: Nick Mineau] #676301 04/21/10 11:09 AM 04/21/10 11:09 AM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	Quote: so whats the best way to figure out if it needs rings. compression test (which you've done) leakdown test, oil consumption and general performance/power. A good rering & it'll last a long time and you'll gain alot of addt'l sealing but as you know it'll take more down time as opposed to a head swap but me I'd do it as it's cheap and you're already opening it up then your set and wont have to go inside it again for a long time. Due to bore taper/out of round/piston land/groove/skirt wear it wont be perfect but it'll be damn good. EDIT your #'s are very good/EVEN & I'd say one cyls valves are leaking slightly skewing the readings so with a bit of thought I'd swap the heads and go Last edited by RapidRobert; 04/21/10 11:18 AM. live every 24 hour block of time like it's your last day on earth

Re: 440 low cranking pressure on one cylinder [Re: Nick Mineau] #676302 04/21/10 04:01 PM 04/21/10 04:01 PM
Joined: Jul 2008 Posts: 30,431 Florida STAYcation BeEtLeJuIcE ! The village idiot's idiot
BeEtLeJuIcE ! The village idiot's idiot Joined: Jul 2008 Posts: 30,431 Florida STAYcation	Quote: so whats the best way to figure out if it needs rings. ill try the foging oil tommoro 170 psi cranking psi ? ...... This motor does NOT need rings

Re: 440 low cranking pressure on one cylinder [Re: BeEtLeJuIcE !] #676303 04/21/10 08:14 PM 04/21/10 08:14 PM
Joined: Jan 2008 Posts: 350 CT USA N Nick Mineau OP enthusiast
Nick Mineau OP enthusiast N Joined: Jan 2008 Posts: 350 CT USA	i tested it with oil again today. all the cylinders went up about 3 psi except the #3 cylinder which went up 13 psi. is this acceptable?

Re: 440 low cranking pressure on one cylinder [Re: Nick Mineau] #676304 04/21/10 08:35 PM 04/21/10 08:35 PM
Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,041 Lincoln Nebraska	Quote: is this acceptable? Yes. W that psi what octane is it requiring? live every 24 hour block of time like it's your last day on earth

Re: 440 low cranking pressure on one cylinder [Re: RapidRobert] #676305 04/21/10 09:21 PM 04/21/10 09:21 PM
Joined: Jan 2008 Posts: 350 CT USA N Nick Mineau OP enthusiast
Nick Mineau OP enthusiast N Joined: Jan 2008 Posts: 350 CT USA	seems fine on 89

Re: 440 low cranking pressure on one cylinder [Re: Nick Mineau] #676306 04/21/10 09:30 PM 04/21/10 09:30 PM
Joined: Jul 2008 Posts: 30,431 Florida STAYcation BeEtLeJuIcE ! The village idiot's idiot
BeEtLeJuIcE ! The village idiot's idiot Joined: Jul 2008 Posts: 30,431 Florida STAYcation	You checked with fogging oil ? I think that if you dial-in the heads ....that things should be fine.

Re: 440 low cranking pressure on one cylinder [Re: BeEtLeJuIcE !] #676307 04/21/10 11:26 PM 04/21/10 11:26 PM
Joined: Jan 2008 Posts: 350 CT USA N Nick Mineau OP enthusiast
Nick Mineau OP enthusiast N Joined: Jan 2008 Posts: 350 CT USA	yea

Re: 440 low cranking pressure on one cylinder [Re: Nick Mineau] #676308 04/21/10 11:31 PM 04/21/10 11:31 PM
Joined: Jul 2008 Posts: 30,431 Florida STAYcation BeEtLeJuIcE ! The village idiot's idiot
BeEtLeJuIcE ! The village idiot's idiot Joined: Jul 2008 Posts: 30,431 Florida STAYcation	I think you have a bad valve (you are freshing the heads right?) ..... If it was bad rings in that one cylinder .. it should have picked-up a bunch more than 13 lbs by fogging it.

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