opinions on motor situation - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BIGBLU 72 · 10-21-2010, 11:45 AM

Here is my situation. The 400 in my 72 GMC has broke one or more oil rings. From my understanding i can drive this motor for a while but it will get worse. so long story short i need to to rebuild or swap.my options are
1.pull the motor and rebuild it!
2. My uncle has an LS3 BBC (complete motor) with 40k original miles that ran great when we pulled it he told me i can have. so i was thinking swap the 400 from my 68 LWB into the Jimmy and freshen up the BBC and drop it in the 68. Selling the 400 in the Jimmy to fund the swap (plus some goodies for the BBC)

Rebuilding the 400 in the 68 was my winter project to get around 350hp and 410 ftlbs. I think that i could get that out of the BBC cheaper without sacraficing too much MPG as the 68 only gets 9 now.

What yall think would be my best route?

Alex Hayley · 10-21-2010, 11:59 AM

I think rebuilding the 400 would be more fun.

Btw, what indicates that there are some broken oil rings?

BIGBLU 72 · 10-21-2010, 03:12 PM

it has oil in the tail pipe, smokes when on the gas and is using a little bit of oil

C20-67_N_MO · 10-21-2010, 03:45 PM

Quote:

Originally Posted by BIGBLU 72

it has oil in the tail pipe, smokes when on the gas and is using a little bit of oil

I would check your spark-plugs to see how they look.

Just a thought.

cdowns · 10-21-2010, 05:33 PM

Quote:

Originally Posted by BIGBLU 72

it has oil in the tail pipe, smokes when on the gas and is using a little bit of oil

using a PVC system with no baffels in the valve covers can easily cause those symptoms

BIGBLU 72 · 10-21-2010, 05:39 PM

i have baffels in my valve covers.and its only on the side with out the pvc valve!

Liddy71 · 10-21-2010, 05:50 PM

I would check my oil returns in the heads and valves seals maybe bad

Jacfourteen · 10-22-2010, 01:15 AM

x2 on valve seals

BIGBLU 72 · 10-22-2010, 02:31 AM

im definitely goin to look into the valve seals but i just feel like i would have noticed them over time and not all at once??

foxhole · 10-22-2010, 03:17 AM

pop it out and pull the heads, if its decent inside just ridge ream it and hone it quick and throw some berrings and seals and maybe relap the valves quick and toss it back together and put in back in. Less than a hundred in parts for cheep rings berrings and gaskets and if you hussled you could crack it off in 6 hours in and out. or out and in i guess that would be.

Liddy71 · 10-22-2010, 07:45 AM

they are old and worn and brittle

Alex Hayley · 10-22-2010, 11:57 AM

Out of curiosity, are you getting much blow by the rings or just poor oil control?

BIGBLU 72 · 10-22-2010, 01:20 PM

well im not sure what blow by is but i have great oil pressure??? the motor was rebuilt in 02 and has around 60k miles on it?

brad_man_72 · 10-22-2010, 01:25 PM

I love my ls swap.......
my crankshaft came out in 3 pieces. Slightly better motivation than using a little oil.

*Ticker* · 10-22-2010, 07:01 PM

Before you chase anything else, do a leak-down test to determine how significant the issue is and specifically what's happening.

http://www.harborfreight.com/cylinde...ter-94190.html

10-21-2010, 11:45 AM	#1
BIGBLU 72 Registered User Join Date: Dec 2008 Location: Ashland, KY Posts: 700	opinions on motor situation Here is my situation. The 400 in my 72 GMC has broke one or more oil rings. From my understanding i can drive this motor for a while but it will get worse. so long story short i need to to rebuild or swap.my options are 1.pull the motor and rebuild it! 2. My uncle has an LS3 BBC (complete motor) with 40k original miles that ran great when we pulled it he told me i can have. so i was thinking swap the 400 from my 68 LWB into the Jimmy and freshen up the BBC and drop it in the 68. Selling the 400 in the Jimmy to fund the swap (plus some goodies for the BBC) Rebuilding the 400 in the 68 was my winter project to get around 350hp and 410 ftlbs. I think that i could get that out of the BBC cheaper without sacraficing too much MPG as the 68 only gets 9 now. What yall think would be my best route? __________________ 68 C10 LWB 2/4 drop 406/th400/3.73posi 04 Silverado SS LQ9 6.0/4L65e/4.11posi AWD

10-21-2010, 11:59 AM	#2
Alex Hayley Registered User Join Date: Jul 2000 Location: NC Posts: 987	Re: opinions on motor situation I think rebuilding the 400 would be more fun. Btw, what indicates that there are some broken oil rings? Last edited by Alex Hayley; 10-21-2010 at 11:59 AM.

10-21-2010, 03:12 PM	#3
BIGBLU 72 Registered User Join Date: Dec 2008 Location: Ashland, KY Posts: 700	Re: opinions on motor situation it has oil in the tail pipe, smokes when on the gas and is using a little bit of oil __________________ 68 C10 LWB 2/4 drop 406/th400/3.73posi 04 Silverado SS LQ9 6.0/4L65e/4.11posi AWD

10-21-2010, 05:39 PM	#6
BIGBLU 72 Registered User Join Date: Dec 2008 Location: Ashland, KY Posts: 700	Re: opinions on motor situation i have baffels in my valve covers.and its only on the side with out the pvc valve! __________________ 68 C10 LWB 2/4 drop 406/th400/3.73posi 04 Silverado SS LQ9 6.0/4L65e/4.11posi AWD

10-21-2010, 05:50 PM	#7
Liddy71 Registered User Join Date: May 2010 Location: Kenova, WV Posts: 821	Re: opinions on motor situation I would check my oil returns in the heads and valves seals maybe bad

10-22-2010, 01:15 AM	#8
Jacfourteen Big Red - Now its a SWB! Join Date: Jun 2009 Location: Oroville, Ca Posts: 1,624	Re: opinions on motor situation x2 on valve seals __________________ 68 3/4 ton (Project)-350 Small Block, .030 over, 10:1 comp, 3998993 heads, C3BX edelbrock intake, comp cams XE268, Holley 670 SA, long tube headers, dual flow 40's, E-fan, Alum rad, currently under the knife getting shortened and bagged build thread 41 3/4 ton (wife's)-flatbed, fully restored to original 01 Tahoe LT 4WD (my daily driver)-Magnaflow Muffler, Rollin on 22's 02 Ford Mustang Convertable (Wife's Car)-Flowmaster 50, Clear corners, Intake, sittin on 18's

10-22-2010, 02:31 AM	#9
BIGBLU 72 Registered User Join Date: Dec 2008 Location: Ashland, KY Posts: 700	Re: opinions on motor situation im definitely goin to look into the valve seals but i just feel like i would have noticed them over time and not all at once?? __________________ 68 C10 LWB 2/4 drop 406/th400/3.73posi 04 Silverado SS LQ9 6.0/4L65e/4.11posi AWD

10-22-2010, 03:17 AM	#10
foxhole Registered User Join Date: Sep 2010 Location: victoria BC Posts: 226	Re: opinions on motor situation pop it out and pull the heads, if its decent inside just ridge ream it and hone it quick and throw some berrings and seals and maybe relap the valves quick and toss it back together and put in back in. Less than a hundred in parts for cheep rings berrings and gaskets and if you hussled you could crack it off in 6 hours in and out. or out and in i guess that would be.

10-22-2010, 07:45 AM	#11
Liddy71 Registered User Join Date: May 2010 Location: Kenova, WV Posts: 821	Re: opinions on motor situation they are old and worn and brittle

10-22-2010, 11:57 AM	#12
Alex Hayley Registered User Join Date: Jul 2000 Location: NC Posts: 987	Re: opinions on motor situation Out of curiosity, are you getting much blow by the rings or just poor oil control?

10-22-2010, 01:20 PM	#13
BIGBLU 72 Registered User Join Date: Dec 2008 Location: Ashland, KY Posts: 700	Re: opinions on motor situation well im not sure what blow by is but i have great oil pressure??? the motor was rebuilt in 02 and has around 60k miles on it? __________________ 68 C10 LWB 2/4 drop 406/th400/3.73posi 04 Silverado SS LQ9 6.0/4L65e/4.11posi AWD

10-22-2010, 01:25 PM	#14
brad_man_72 the boat guy Join Date: Jul 2007 Location: springfield mo Posts: 2,339	Re: opinions on motor situation I love my ls swap....... my crankshaft came out in 3 pieces. Slightly better motivation than using a little oil. __________________ 67, swb, fleet, tach, throttle, 5.3, 4l60e, 3.73's, fuel cell, 5 lug, p.d.b., 4-6 drop. great little truck 66, stevens drag/ski 18' silouette, 350, 2.02 doublehump heads. comp extreme marine 278 cam, vette 7 fin valve covers, old polished edelbrock intake, velvetdrive, casale v-drive, adj cavitation plate. 28, model a rpu project,

10-22-2010, 07:01 PM	#15
Ticker Account Suspended Join Date: Oct 2009 Location: Sammamish, WA Posts: 2,404	Re: opinions on motor situation Before you chase anything else, do a leak-down test to determine how significant the issue is and specifically what's happening. http://www.harborfreight.com/cylinde...ter-94190.html



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