Engine questions: - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chevy72pu · 06-05-2011, 10:16 PM

The PO said it was a 327 with 200 miles on it since a rebuild. A peek under the valve cover on the driver side shows a lot of gunk, not a 200 mile head. The numbers on the head are a hi po 327 but the numbers on the block (front and back) say 307. Anyhow, when I drive it long enough to get the engine warm, it starts blowing oil from the valve cover breather on the driver side, pushing it out around the dipstick, and anywhere else it can. There is vaccum at the carb. The pcv works. If I put my hand over the pcv hole in the valve cover there is no suction or pressure. If I put my hand over the breather hole in the other valve cover the pressure pushes my hand away. Compression on all cylinders is approx 125. One mechanic wants to pull the engine for a rebuild, another says pull the heads first. What do you guys think?

dmack91 · 06-05-2011, 10:48 PM

Sounds like ring blow-by, at least on the driver's side. I predict a rebuild in your future.

Sucks when people lie about their stuff. Or maybe his definition of a rebuild is a new manifold, carb, and valve covers.

SSchevimp · 06-06-2011, 02:58 AM

I'd rebuild it just so you know for sure what has been done to the engine

crazy longhorn · 06-06-2011, 03:35 AM

Probably a 461 or 462 casting on the heads......they should run goood on your 307 , with a freshenup on the old motor. I agree, rings.....you should see 150-160 psi on the guage. crazyL

chevy72pu · 06-06-2011, 07:59 AM

Seems we are all thinking the same problem. Just can't decide on the solution. Either have the 307 rebuilt, or go with the 290hp crate 350.

60ratrod · 06-06-2011, 09:07 AM

for plug and play, the crate 350. but for an awesome lil mouse, the 307. the 307 is frowned upon just because of its cid. but those things are pretty killer with a freshening up and a set of vortec heads

geezer#99 · 06-06-2011, 09:30 AM

You say the pvc works correctly. When did you check it. Just after running a bit or when the motor starts pushing oil out the breather.
A new cheap pvc is kinder to your wallet than a motor rebuild any day.
A fresh motor with poor pvc operation will act just like yours.
Save some mulla. Do a little more research. JMHO.

chevy72pu · 04-14-2012, 11:18 PM

Well the old engine turned out to be a 307 that had NOT been rebuilt. Just painted and dressed up. Found a 4 bolt main 350. Bored it over .30, bearings, rods, rings pistons, polished the crank, upgraded the cam, put my hi po heads on it with all new parts. Added my Edelbrock intake and carb. Used the Edelbrock valve covers for now, but thinking I'll change them for some chevy units painted to match the engine, powder coated the ram horns and dropped it in. WOW! What a difference. Power and performance. First road trip was about 60 miles. No leaks, no drips, no errors.

06-05-2011, 10:16 PM	#1
chevy72pu Registered User Join Date: Jan 2009 Location: Sandersville, GA Posts: 298	Engine questions: The PO said it was a 327 with 200 miles on it since a rebuild. A peek under the valve cover on the driver side shows a lot of gunk, not a 200 mile head. The numbers on the head are a hi po 327 but the numbers on the block (front and back) say 307. Anyhow, when I drive it long enough to get the engine warm, it starts blowing oil from the valve cover breather on the driver side, pushing it out around the dipstick, and anywhere else it can. There is vaccum at the carb. The pcv works. If I put my hand over the pcv hole in the valve cover there is no suction or pressure. If I put my hand over the breather hole in the other valve cover the pressure pushes my hand away. Compression on all cylinders is approx 125. One mechanic wants to pull the engine for a rebuild, another says pull the heads first. What do you guys think? Attached Images __________________ How 'Bout them Dawgs! '10 Traverse LTZ 03 Silverado Z71 ext cab 99 Yamaha Grizzly 600 72 C10 350/350 sportside bed. 68 C30 flatbed. 350 4-speed. "I've got a good memory, it's just short!"

06-05-2011, 10:48 PM	#2
dmack91 Registered User Join Date: Jan 2011 Location: Redmond, OR Posts: 755	Re: Engine questions: Sounds like ring blow-by, at least on the driver's side. I predict a rebuild in your future. Sucks when people lie about their stuff. Or maybe his definition of a rebuild is a new manifold, carb, and valve covers. __________________ 68 Chev C20- son has it now 83 K20 - bought from son 70 C20 - in progress

06-06-2011, 02:58 AM	#3
SSchevimp Registered User Join Date: Apr 2011 Location: Hesperia Ca Posts: 52	Re: Engine questions: I'd rebuild it just so you know for sure what has been done to the engine __________________ 70 c10 long bed 57 chevy 2 door wagon 07 tahoe 96 civic commuter

06-06-2011, 03:35 AM	#4
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	Re: Engine questions: Probably a 461 or 462 casting on the heads......they should run goood on your 307 , with a freshenup on the old motor. I agree, rings.....you should see 150-160 psi on the guage. crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

06-06-2011, 07:59 AM	#5
chevy72pu Registered User Join Date: Jan 2009 Location: Sandersville, GA Posts: 298	Re: Engine questions: Seems we are all thinking the same problem. Just can't decide on the solution. Either have the 307 rebuilt, or go with the 290hp crate 350. __________________ How 'Bout them Dawgs! '10 Traverse LTZ 03 Silverado Z71 ext cab 99 Yamaha Grizzly 600 72 C10 350/350 sportside bed. 68 C30 flatbed. 350 4-speed. "I've got a good memory, it's just short!"

06-06-2011, 09:07 AM	#6
60ratrod yes, i do Join Date: Jun 2007 Location: Spokane, wa Posts: 2,734	Re: Engine questions: for plug and play, the crate 350. but for an awesome lil mouse, the 307. the 307 is frowned upon just because of its cid. but those things are pretty killer with a freshening up and a set of vortec heads __________________ ERROR 404....... SNAPPY COMEBACK NOT FOUND _______________________________________________________________________________________________ -60 Chevy C10, dead 350/good th350 combo, sitting on a 76 c10 blazer frame, built from 11 different vehicles "the abomination" -07 gmt900 silverado 1500 lt xcab z71, granite blue -81 suzuki gs650g "shelah"- current project -81 kz1000m1 csr "sarge" -next project (just beautification) -07 kawasaki vulcan classic vn900

06-06-2011, 09:30 AM	#7
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,542	Re: Engine questions: You say the pvc works correctly. When did you check it. Just after running a bit or when the motor starts pushing oil out the breather. A new cheap pvc is kinder to your wallet than a motor rebuild any day. A fresh motor with poor pvc operation will act just like yours. Save some mulla. Do a little more research. JMHO.

04-14-2012, 11:18 PM	#8
chevy72pu Registered User Join Date: Jan 2009 Location: Sandersville, GA Posts: 298	Re: Engine questions: Well the old engine turned out to be a 307 that had NOT been rebuilt. Just painted and dressed up. Found a 4 bolt main 350. Bored it over .30, bearings, rods, rings pistons, polished the crank, upgraded the cam, put my hi po heads on it with all new parts. Added my Edelbrock intake and carb. Used the Edelbrock valve covers for now, but thinking I'll change them for some chevy units painted to match the engine, powder coated the ram horns and dropped it in. WOW! What a difference. Power and performance. First road trip was about 60 miles. No leaks, no drips, no errors. Attached Images __________________ How 'Bout them Dawgs! '10 Traverse LTZ 03 Silverado Z71 ext cab 99 Yamaha Grizzly 600 72 C10 350/350 sportside bed. 68 C30 flatbed. 350 4-speed. "I've got a good memory, it's just short!"



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