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Username Post: Big Block heads - valve/port sizes        (Topic#204866)
Jim.Biron 
"7th Year" Platinum Supporting Member
Posts: 2527
Jim.Biron
Age: 64
Loc: Saugerties, NY
Reg: 04-10-08
12-09-08 05:04 AM - Post#1580812    

Are all the 2.06 valve size oval port heads known as peanut port heads?
I'm wondering about the 336781 heads specifically as they are on an engine I'm looking at.
How do you tell a peanut port vs an larger oval port head when you are looking at it with the intake and valve cover on? ... OR are all oval port heads peanut port heads?
Jim
www.HudsonValleyCruise.com


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 16234
grumpyvette
Age: 66
Loc: FLORIDA USA
Reg: 03-16-01
12-09-08 10:59 AM - Post#1581058    
    In response to Jim.Biron


lower heads are peanut port, the 781 heads are standard oval port heads

336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports

14092360...86-90...oval...OPEN...454 Truck, "peanut" round ports
346236.....75-87...oval...OPEN...454, 120cc chamber, 225/116cc ports


read thru this

http://maliburacing.com/patrick_budd_article.htm
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 12-09-08 01:16 PM. Reason for edit: No reason given.

 
fritz1990 
Dedicated Enthusiast
Posts: 6426
fritz1990
Age: 53
Loc: Kansas
Reg: 02-16-03
12-09-08 11:39 AM - Post#1581090    
    In response to Jim.Biron

The 781's and the 049 casting numbers (last 3 digits) are the best oval port heads that GM made for performance. Nothing wrong with them at all up to around 550-600hp with the larger 2.19-1.88 valves installed and a lil' bowl hoggin' and gakset matching. Lots of people run 'em including me on my 496.

Regards, Jeff
1998 K1500 6.5 Coal burner
1965 C10 with 498 BBC AFR Heads
1964 C10 Ran 348W for 6 years, now SBC.

Corvettes owned: '74 '77 '78 L82 Silver Anniversary, 2002 LS1

Don't have a nervous come together!

http://picasaweb.google.com/fritz199090


 
Jim.Biron 
"7th Year" Platinum Supporting Member
Posts: 2527
Jim.Biron
Age: 64
Loc: Saugerties, NY
Reg: 04-10-08
12-09-08 12:36 PM - Post#1581127    
    In response to grumpyvette

  • grumpyvette Said:

lower heads are peanut port, the 781 heads are standard oval port heads

336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports

14092360...86-90...oval...OPEN...454 Truck, "peanut" round ports





Nice pics for sure. Is there any complete listing of peanut port casting numbers available?
Jim
www.HudsonValleyCruise.com


 
Impala65SS 
Valued Contributor
Posts: 3767
Impala65SS
Loc: Sweden
Reg: 08-23-07
12-10-08 04:42 PM - Post#1582043    
    In response to Jim.Biron

There seem to be very few castings circulating - though in fairly large numbers each! Castings 236 and 360 are the ones I've come across again and again. Chevy's, Mercrusiers, Volvo Penta etc.

Always demand proper pictures of ports and also combustion chambers. The peanuts always look like Grumpy's pic, and the ovals always look like the pic.

If I have to use open chamber, my favorite is 820. A fairly small chamber (higher compression ratio) and the exhaust valve is unshrouded in the fashion that became hip in the mid 90's and was the precursor to "heart shaped combustion chambers".
http://www.youtube.com/watch?v=SXn2QVipK2o&a mp;fea...


 
Jim.Biron 
"7th Year" Platinum Supporting Member
Posts: 2527
Jim.Biron
Age: 64
Loc: Saugerties, NY
Reg: 04-10-08
12-11-08 05:14 AM - Post#1582399    
    In response to Impala65SS

  • Impala65SS Said:
There seem to be very few castings circulating - though in fairly large numbers each! Castings 236 and 360 are the ones I've come across again and again. Chevy's, Mercrusiers, Volvo Penta etc.

Always demand proper pictures of ports and also combustion chambers. The peanuts always look like Grumpy's pic, and the ovals always look like the pic.

If I have to use open chamber, my favorite is 820. A fairly small chamber (higher compression ratio) and the exhaust valve is unshrouded in the fashion that became hip in the mid 90's and was the precursor to "heart shaped combustion chambers".



Any comment on the 781?
Jim
www.HudsonValleyCruise.com


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 16234
grumpyvette
Age: 66
Loc: FLORIDA USA
Reg: 03-16-01
12-11-08 05:31 AM - Post#1582415    
    In response to Jim.Biron


like I posted
read thru this

http://maliburacing.com/patrick_budd_article.htm
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


 
Impala65SS 
Valued Contributor
Posts: 3767
Impala65SS
Loc: Sweden
Reg: 08-23-07
12-12-08 05:00 PM - Post#1583674    
    In response to Jim.Biron

Obviously they are real fine too. I know of examples with 781 (ported, mind you) yielding 680hp.
Personally, I'm a sucker for closed chamber of the semi-open type (063, 802, 215, 290), so any head with smaller volume than the huge open chambers (118-127cc) is a progress in my view - unless you're set on running a blower.

Since the 049 and 781 are plentiful - and of course much better flowing than the old well known bathtub-closed chamber of 206, 390, 702, - I guess they are more often used and therefore more known to produce high figures. But I'm just guessing. The 820 has a theoretically better shape, but in real builds it might not be what I think. It is of course a 40 year old shape tried in a 270hp engine to start with and that's all the figures I have really.

According to the Stan Weiss compiled flow numbers site, the 820 (apparently untouched) beats the 781 with 2.19"/1.88" in the midlift range and equals in the .500" lift range. It seems the 781 with hiperf valves is more likely to yeild top hp numbers at high lifts like .550-.700" than a std pair of 820
Note the 049 with std valves is not so impressive as the 290,063, 820... Perhaps the same pistons were used in the desktop-calculations of output so it's not quite comparable since the smaller chambers will yeild more compression of course.

In addition, at stan weiss you can also see there is a more recent peanut casting - the 156. Note that the peanuts aren't as bad as their reputation says. A legendary racing head service guy in Sweden told me he prepared a pair of 236 that turned out 700hp. Note that the 236 does NOT have enough material to be essentially ported out to an "oval head". The "as cast" 236, 360, 156 shoul have good potential to work excellent on the street up to 5500rpm - with big enough pistons to get some CR...
edit: honestly, they are just plain unsexy in the way I think open chambers are - and alternators on the passenger side
http://www.youtube.com/watch?v=SXn2QVipK2o&a mp;fea...


Edited by Impala65SS on 12-12-08 05:05 PM. Reason for edit: No reason given.

 
262gearhead 
Forum Newbie
Posts: 9

Loc: Wisconsin
Reg: 12-08-08
12-13-08 05:31 AM - Post#1583932    
    In response to Impala65SS

What intake do you use with the peanut port heads? Do you have to worry about the intake port being larger then the port of the head? I was told by Edelbrock that they don't make a intake for my '89 454

 
66cayne 
Frequent Contributor
Posts: 2113

Reg: 08-06-08
12-13-08 06:09 AM - Post#1583946    
    In response to 262gearhead

If you plan to leave the motor stock and just want to try an aluminum manifold use an oval port BBC manifold(i.e. Edelbrock, Holley, Offenhuaser, Chevy, etc.) The size mismatch will likely not effect performsnce because the volumetric efficency of the peanut port head is so high and the oval port manifold will have no problem feeding it. If you plan to modify the engine (i.e., carb, bigger cam, headers, etc.) you should plan on port matching the oval port manifold and your heads. This will help reduce turbulence and enhance flow. A better idea would be to simply replace the small port heads with some stock oval port heads. Regards, Tom aka: 66cayne

 
262gearhead 
Forum Newbie
Posts: 9

Loc: Wisconsin
Reg: 12-08-08
12-13-08 08:57 AM - Post#1584025    
    In response to 66cayne

I'm planning on putting a 274 hydraulic in it. Just not in the budget right now to do heads, plan on doing them in a couple years.

Edited by 262gearhead on 12-13-08 09:06 AM. Reason for edit: No reason given.

 
greg_moreira 
Very Senior Member
Posts: 3264

Reg: 10-06-03
12-13-08 11:20 AM - Post#1584100    
    In response to 262gearhead

The 781 is basically the best factory open chamber oval port head you can get your hands on....along with an 049 as well.

You made a good find. If stock, the valves will be the smaller sizes you quoted. Still no problem though.....even stock its not hard at all to get a set of those heads to move a heavy car in the 12's without having much of a fancy combo at all.

The heads have a ton of room to grow as well if you want to eventually see some 11's or even 10's. Trust me...very doable with those heads.

The only problem with those heads...they are better suited for 454 or larger engines. For a small displacement big chevy like a 396 or so..it becomes increasingly difficult to get any kind of respectable compression. 9.5:1 compression would be plenty to dial up a nice street combo in a 396....but even that amount of compression is harder to attain with the big chambers of those heads on a small motor.

Doable....but a different head is just better suited. For a comparable port with a smaller chamber....a 215 casting oval head would do the trick for the little motors(these are what I got on my little 408 inch big block).

They have basically the same characteristics of the 049 or 781 in terms of what they are capable of and how the can perform....just got a smaller chamber, which can be used in any app really....but really lends itself well to the smaller motors.

 
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