327 head question
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Instructor
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From: White Bear Lake MN
327 head question
I am rebuilding the 350 engine on my 72' C3 and found the original owner replaced the factory heads with 1966 327 heads. I am replacing the 327 heads with aluminum heads and wondering if there is a market for the '66 heads? They are in very good condition.
Thanks,
Bob
Thanks,
Bob
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There is always a market for double hump heads, post a pic of one of the combustion chambers, that will indicate valve size and whether there is proper valve relief done if they are 2.02" intakes.
Doug
Doug
Dr. Detroit
Joined: Mar 2012
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From: New Braunfels Texas
There sure is a market......just check out e-bay.....there are dozens of 462's on there....
Without screw in studs these will be of the 1.94 variety....still very good....the 2.02's did nothing for flow because GM never opened up the bowl area to make any improvement in flow.....
These are great heads ported.....all double hump castings had the same ports.....with the exception of a few....
These fetch between $300-$500 on ebay....
Peace,
Jebby
Without screw in studs these will be of the 1.94 variety....still very good....the 2.02's did nothing for flow because GM never opened up the bowl area to make any improvement in flow.....
These are great heads ported.....all double hump castings had the same ports.....with the exception of a few....
These fetch between $300-$500 on ebay....
Peace,
Jebby
Thread Starter
Instructor
Joined: Feb 2005
Posts: 209
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From: White Bear Lake MN
There sure is a market......just check out e-bay.....there are dozens of 462's on there....
Without screw in studs these will be of the 1.94 variety....still very good....the 2.02's did nothing for flow because GM never opened up the bowl area to make any improvement in flow.....
These are great heads ported.....all double hump castings had the same ports.....with the exception of a few....
These fetch between $300-$500 on ebay....
Peace,
Jebby
Without screw in studs these will be of the 1.94 variety....still very good....the 2.02's did nothing for flow because GM never opened up the bowl area to make any improvement in flow.....
These are great heads ported.....all double hump castings had the same ports.....with the exception of a few....
These fetch between $300-$500 on ebay....
Peace,
Jebby
Dr. Detroit
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From: New Braunfels Texas
Jebby
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From: Ocean Township NJ
There sure is a market......just check out e-bay.....there are dozens of 462's on there....
Without screw in studs these will be of the 1.94 variety....still very good....the 2.02's did nothing for flow because GM never opened up the bowl area to make any improvement in flow.....
These are great heads ported.....all double hump castings had the same ports.....with the exception of a few....
These fetch between $300-$500 on ebay....
Peace,
Jebby
Without screw in studs these will be of the 1.94 variety....still very good....the 2.02's did nothing for flow because GM never opened up the bowl area to make any improvement in flow.....
These are great heads ported.....all double hump castings had the same ports.....with the exception of a few....
These fetch between $300-$500 on ebay....
Peace,
Jebby
If they are factory 2.02/1.60 heads then the intake valve was unshrouded from the factory.
All double hump heads had (approx) 160 cc intake ports, except the 461 "X" heads which had (approx) 170 cc intake ports.
If one is careful, and the heads have minimal core shift, then the intakes (chambers) can be further unshrouded and the intake ports opened to more than 183 cc. They will flow more than 260 cfm @ .600 valve lift with 2.02/1.60's.
Last edited by 65tripleblack; Nov 17, 2012 at 05:21 PM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
In 1966 no double hump heads had screw in studs from the factory, and they could be 2.02/1.60 valves. Those are Flint (Saginaw) castings and were used on 300 and 350 HP Corvette, as well as full size and others.
If they are factory 2.02/1.60 heads then the intake valve was unshrouded from the factory.
All double hump heads had (approx) 160 cc intake ports, except the 461 "X" heads which had (approx) 170 cc intake ports.
If one is careful, and the heads have minimal core shift, then the intakes (chambers) can be further unshrouded and the intake ports opened to more than 183 cc. They will flow more than 260 cfm @ .600 valve lift with 2.02/1.60's.
If they are factory 2.02/1.60 heads then the intake valve was unshrouded from the factory.
All double hump heads had (approx) 160 cc intake ports, except the 461 "X" heads which had (approx) 170 cc intake ports.
If one is careful, and the heads have minimal core shift, then the intakes (chambers) can be further unshrouded and the intake ports opened to more than 183 cc. They will flow more than 260 cfm @ .600 valve lift with 2.02/1.60's.
The 2.02's were cut a little bigger...but it did almost nothing as the big sharp edge
around the bowl was never blended.
I was aware of the X head...that is why I mentioned almost all.
There is potential for the 462.....mine flow 244@.500.....I did not open the valve
further during the test. A lot of work to get this....
180 + cc is right.....and unshrouding the chamber to the bore scribe is free horsepower!!!!
Triple black.....what heads did have screw in studs....always thought that was part of the L79 package....
Jebby
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Joined: May 2003
Posts: 4,797
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From: Ocean Township NJ
No screw in studs in 66' eh.....did not know that.....
The 2.02's were cut a little bigger...but it did almost nothing as the big sharp edge
around the bowl was never blended.
I was aware of the X head...that is why I mentioned almost all.
There is potential for the 462.....mine flow 244@.500.....I did not open the valve
further during the test. A lot of work to get this....
180 + cc is right.....and unshrouding the chamber to the bore scribe is free horsepower!!!!
Triple black.....what heads did have screw in studs....always thought that was part of the L79 package....
Jebby
The 2.02's were cut a little bigger...but it did almost nothing as the big sharp edge
around the bowl was never blended.
I was aware of the X head...that is why I mentioned almost all.
There is potential for the 462.....mine flow 244@.500.....I did not open the valve
further during the test. A lot of work to get this....
180 + cc is right.....and unshrouding the chamber to the bore scribe is free horsepower!!!!
Triple black.....what heads did have screw in studs....always thought that was part of the L79 package....
Jebby
I believe that screw in studs and guide plates started with the 1970 Z28 and LT1, both of which used the 3927186 cylinder head.
Do you have 2.02/1.60 valves in your heads? I ported mine to 185cc and did one little trick to the chambers, despite reading and being told not to do it. It was good for more flow and that's probably why they flow better than 260 @ .600 lift. This is not achievable unless you are working with 2.02" intakes. Exhaust ports flow better than 200 @ .600 lift with 64cc ports.
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Thread Starter
Instructor
Joined: Feb 2005
Posts: 209
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From: White Bear Lake MN
Jebby,
I believe that screw in studs and guide plates started with the 1970 Z28 and LT1, both of which used the 3927186 cylinder head.
Do you have 2.02/1.60 valves in your heads? I ported mine to 185cc and did one little trick to the chambers, despite reading and being told not to do it. It was good for more flow and that's probably why they flow better than 260 @ .600 lift. This is not achievable unless you are working with 2.02" intakes. Exhaust ports flow better than 200 @ .600 lift with 64cc ports.
I believe that screw in studs and guide plates started with the 1970 Z28 and LT1, both of which used the 3927186 cylinder head.
Do you have 2.02/1.60 valves in your heads? I ported mine to 185cc and did one little trick to the chambers, despite reading and being told not to do it. It was good for more flow and that's probably why they flow better than 260 @ .600 lift. This is not achievable unless you are working with 2.02" intakes. Exhaust ports flow better than 200 @ .600 lift with 64cc ports.
Bob
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Jebby,
I believe that screw in studs and guide plates started with the 1970 Z28 and LT1, both of which used the 3927186 cylinder head.
Do you have 2.02/1.60 valves in your heads? I ported mine to 185cc and did one little trick to the chambers, despite reading and being told not to do it. It was good for more flow and that's probably why they flow better than 260 @ .600 lift. This is not achievable unless you are working with 2.02" intakes. Exhaust ports flow better than 200 @ .600 lift with 64cc ports.
I believe that screw in studs and guide plates started with the 1970 Z28 and LT1, both of which used the 3927186 cylinder head.
Do you have 2.02/1.60 valves in your heads? I ported mine to 185cc and did one little trick to the chambers, despite reading and being told not to do it. It was good for more flow and that's probably why they flow better than 260 @ .600 lift. This is not achievable unless you are working with 2.02" intakes. Exhaust ports flow better than 200 @ .600 lift with 64cc ports.
The exhaust seats were a bit pounded....so I opened them to 1.60
The intake I left alone....but the Serdi had a five angle cutter on it and I carefully
blended this in at the bowl....Chamber around intake was bore scribed and pulled back
to unshroud it....gasket matched but left the port rough along runner to help with suspension......
My heads are not the ones that came with the car obviously....but I wanted to keep a "period" look so 2K went into those heads.....
I kick around throwing some Dart platinum's on it but it looks almost stock and runs great.
To our OP.....post them on E-Bay.....you won't break any records but $500 is nothing to sneeze at
Jebby
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From: Mustang OK
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Jebby,
I believe that screw in studs and guide plates started with the 1970 Z28 and LT1, both of which used the 3927186 cylinder head.
Do you have 2.02/1.60 valves in your heads? I ported mine to 185cc and did one little trick to the chambers, despite reading and being told not to do it. It was good for more flow and that's probably why they flow better than 260 @ .600 lift. This is not achievable unless you are working with 2.02" intakes. Exhaust ports flow better than 200 @ .600 lift with 64cc ports.
I believe that screw in studs and guide plates started with the 1970 Z28 and LT1, both of which used the 3927186 cylinder head.
Do you have 2.02/1.60 valves in your heads? I ported mine to 185cc and did one little trick to the chambers, despite reading and being told not to do it. It was good for more flow and that's probably why they flow better than 260 @ .600 lift. This is not achievable unless you are working with 2.02" intakes. Exhaust ports flow better than 200 @ .600 lift with 64cc ports.
NO screw in studs/guideplates (from the factory) until the 1970 model LT1 (370hp) Corvette engine or the Z28 (360hp) engine. ONLY BBs had them before 70.
And, as an additional note, as pointed out above, almost any double hump head can be gently worked and opened up for larger valves which will dramatically improve flow and performance-----------------it's only money!
BUUUUUUUUUUUUT, be DAMN careful when buying an unknown set of heads from an unknown source. The NEWEST double hump head (with NO threaded holes in the ends) was a 68 model. It is moderately common for these heads----------------ESPECIALLY THOSE WHICH HAVE SEEN SEVERE DUTY---------------to have cracks around seats, between seats or near the center ex ports which is the area where the most heat occurs. Personally, I WOULD NOT buy a set without first having my machinist check and magnaflux them.
Tom Parsons
Last edited by DZAUTO; Nov 18, 2012 at 01:40 PM.