Best GM SBC Casting (performance-wise) ?
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 3,438
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From: Raleigh NC
St. Jude Donor '13-'14
Best GM SBC Casting (performance-wise) ?
Instead of going the aftermarket route, I'm interested in using an old set of GM head on my 355. What I'm trying to figure is which head to use?
From what I've read, I should look into 186s, 291s, and 462s in that order. Would you agree with this list and order?
Also, I was planning on running about 10:1 compression, anyone have a problem with pump gas and these iron heads at this ratio?
From what I've read, I should look into 186s, 291s, and 462s in that order. Would you agree with this list and order?
Also, I was planning on running about 10:1 compression, anyone have a problem with pump gas and these iron heads at this ratio?
Team Owner
Joined: Jul 1999
Posts: 65,492
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From: Orange Park Florida
#113 aluminum off a L98,
10.5 comp, true the valves could be larger, if that big a deal, get them enlarged.....
almost as good as any head out there, and better than iron, ...
now this is with a cost/benefit ratio taken into consideration....
150-200 for the complete head set, then another 2-300 for a complete overhaul, which I got new springs for that included....
and a few new valves....
10.5 comp, true the valves could be larger, if that big a deal, get them enlarged.....
almost as good as any head out there, and better than iron, ...
now this is with a cost/benefit ratio taken into consideration....
150-200 for the complete head set, then another 2-300 for a complete overhaul, which I got new springs for that included....
and a few new valves....
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Here you go, More info than you will need. You can port the old heads big time. We used to get close to 600 HP out of the old double hump castings back in the 70's. Look at the intake to exhaust ratio and flow @ .400 numbers to make a wise choice.
http://users.erols.com/srweiss/tablehdc.htm#Chevy
http://users.erols.com/srweiss/tablehdc.htm#Chevy
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 3,438
Likes: 41
From: Raleigh NC
St. Jude Donor '13-'14
Here you go, More info than you will need. You can port the old heads big time. We used to get close to 600 HP out of the old double hump castings back in the 70's. Look at the intake to exhaust ratio and flow @ .400 numbers to make a wise choice.
http://users.erols.com/srweiss/tablehdc.htm#Chevy
http://users.erols.com/srweiss/tablehdc.htm#Chevy
I really wish he did a better job of putting that site together, its a headache to look at and try to figure out what all the numbers are. I'll sift through it though, thank you.Peter
Last edited by LeMans Pete; Apr 5, 2009 at 07:52 PM.
Le Mans Master
Joined: Jun 2005
Posts: 5,447
Likes: 3
From: Syracuse NY
#113 aluminum off a L98,
10.5 comp, true the valves could be larger, if that big a deal, get them enlarged.....
almost as good as any head out there, and better than iron, ...
now this is with a cost/benefit ratio taken into consideration....
150-200 for the complete head set, then another 2-300 for a complete overhaul, which I got new springs for that included....
and a few new valves....
10.5 comp, true the valves could be larger, if that big a deal, get them enlarged.....
almost as good as any head out there, and better than iron, ...
now this is with a cost/benefit ratio taken into consideration....
150-200 for the complete head set, then another 2-300 for a complete overhaul, which I got new springs for that included....
and a few new valves....
I thought he was looking for an old GM head
Le Mans Master
Joined: Jun 2005
Posts: 5,447
Likes: 3
From: Syracuse NY
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Thread Starter
Melting Slicks
Joined: May 2006
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From: Raleigh NC
St. Jude Donor '13-'14
Melting Slicks
Joined: Jul 2005
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From: winter haven florida
St. Jude Donor '12
the double hump 462,461 heads can be ported to flow very well. i had a set of nicely ported 461's on my last 383 and it ran very well. the comp ratio was over 10 and i did get detonation sometimes.
Thread Starter
Melting Slicks
Joined: May 2006
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From: Raleigh NC
St. Jude Donor '13-'14
So which order would you guys rank these? I'm heading to the swap meet this weekend, and in case I get a choice (with condition, valve size and price equal) what is the pecking order here?
492
461/462
113
186
291
492
461/462
113
186
291
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
As far as flow The Chevy Turbo heads are the very best old iron. The part # is 340292 The I/E ratio is 88%. Flow is 201 int 177 ex @ .600 lift. This is as good as any modern aftermarket head with a similar port size. They are rare and were a GM over the counter performance head. If you can find a set buy them.
The 492 is next @ 209/141 @ .600 lift
The 186 and 041 is next @ 188/140 @ .600 lift
In comparison the AFR 195 eliminator flows 286/215 @ .600 lift
See why they make big HP numbers!
Last edited by 63mako; Apr 6, 2009 at 11:10 PM.
Thread Starter
Melting Slicks
Joined: May 2006
Posts: 3,438
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From: Raleigh NC
St. Jude Donor '13-'14
The 461, 462 and 291 have no accessory holes.
As far as flow The Chevy Turbo heads are the very best old iron. The part # is 340292 The I/E ratio is 88%. Flow is 201 int 177 ex @ .600 lift. This is as good as any modern aftermarket head with a similar port size. They are rare and were a GM over the counter performance head. If you can find a set buy them.
The 492 is next @ 209/141 @ .600 lift
The 186 and 041 is next @ 188/140 @ .600 lift
In comparison the AFR 195 eliminator flows 286/215 @ .600 lift
See why they make big HP numbers!
As far as flow The Chevy Turbo heads are the very best old iron. The part # is 340292 The I/E ratio is 88%. Flow is 201 int 177 ex @ .600 lift. This is as good as any modern aftermarket head with a similar port size. They are rare and were a GM over the counter performance head. If you can find a set buy them.
The 492 is next @ 209/141 @ .600 lift
The 186 and 041 is next @ 188/140 @ .600 lift
In comparison the AFR 195 eliminator flows 286/215 @ .600 lift
See why they make big HP numbers!
Plus, I cannot comprehend those flows since I won't be anywhere near .600 lift, more like .495/.502.
Thanks for the info Mako, always appreciated.
Peter
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Price out Dart iron heads. Modern chambers and higher flow. I spent a thousand getting 186 and 292 castings all Zouped up back in the 80's only to give them away because I got tired of looking at them on the shelf when I went to aluminum
About 200 cc is the max practical on 355 ci with a Weiand stealth intake. Modern 180 cc at a minimum
The 292 casting were one of the best when ported and using 2.055 / 1.6 valves. They were also angle plugs for superior flame travel
About 200 cc is the max practical on 355 ci with a Weiand stealth intake. Modern 180 cc at a minimum
The 292 casting were one of the best when ported and using 2.055 / 1.6 valves. They were also angle plugs for superior flame travel
Last edited by gkull; Apr 7, 2009 at 08:36 AM.
Le Mans Master
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From: Butler Pa
Pro
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Price out Dart iron heads. Modern chambers and higher flow. I spent a thousand getting 186 and 292 castings all Zouped up back in the 80's only to give them away because I got tired of looking at them on the shelf when I went to aluminum
About 200 cc is the max practical on 355 ci with a Weiand stealth intake. Modern 180 cc at a minimum
The 292 casting were one of the best when ported and using 2.055 / 1.6 valves. They were also angle plugs for superior flame travel
About 200 cc is the max practical on 355 ci with a Weiand stealth intake. Modern 180 cc at a minimum
The 292 casting were one of the best when ported and using 2.055 / 1.6 valves. They were also angle plugs for superior flame travel
I went this route once and will never do it again.. I had an old set of 291's and by the time I was done doing it right (spring pockets opened up, new springs, new valve guides, pocket ported, gasket matched, new valves, new hardened valve seast for unleaded fuel, valve job, screw-in studs, etc.) they cost me more than a better set of aftermarket bolt-on heads. After soaking all that money into them I ended up buying a set of Dart Iron Eagles and by just bolting them on, I knocked almost .7 off my quarter mile times slip (from 11.60's to 10.90's)..
If your going to attempt any porting you need to know what your doing because yu can decrese performance. You also may not want to polish the runners because it will reduce fuel/air atomization and can also cause fuel puddling when ideling. All-in-all I would only install old heads if I were trying to keep it all stock..
Le Mans Master
Joined: Sep 2001
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From: Unreconstructed, South Carolina
FYI ... look inside any OE ironhead vortec 350 truck motor (aka L31 VIN R) circa1996-2000... all have an OE mild roller cam but they're all billet steel ... not cast.
Last edited by jackson; Apr 7, 2009 at 10:03 AM.
Le Mans Master
Joined: Dec 2003
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From: Fremont CA
My list for production iron heads: Vortec 906, 492, 186, and 041 the 291 and others are left off because they have no end holes for accessory mounts. This being said, unless you have "free" machine shop access, the rebuilding of most of these heads will run more than a set of aftermarket cast iron heads and for $150 more you can have Brodix IK, Canfield, or Trickflow aluminum heads which will support future modifications (think LONG TERM! not "next quarterly statement" like American MBA's do.)
Thread Starter
Melting Slicks
Joined: May 2006
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From: Raleigh NC
St. Jude Donor '13-'14
Peter