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Old 04-06-2008, 05:37 PM
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346236 bbc cylinder heads?

i have a set of peanut port heads. what can i do to them to get more performance. what size valves can i step up to? can i deck them to 118cc chambers? is it worth all the trouble. how much will it cost?

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Old 04-06-2008, 09:46 PM
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I have these heads. Do you know for sure that they are over 118 cc chambers?
I have found some sources to say they are 113. I never measured mine but I do regret not planing them for more compression. What I did to mine was mild port work, port matched head to intake (which is what has to be done with such a small port), stainless stock small valves with undercut stems, and installed pc type valve seals. I am making a little over 400 hp although the idle is rough as I think it is easy to overcam a small port. I rev to about 5500 and it pulls strong till then. I have .095 inch dome pistons. People say these heads are not worth the time but I think that if you have them use them as I saved a lot of money doing things myself and am making tons of torque, the advantage of the small port.
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Old 04-06-2008, 09:56 PM
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Mortec says they're 120 cc chambers, take them to a GOOD machine shop and see what they say about bigger valves and decking them for compression with the pistons you have or are going to get and the application you intend using them in. But remember the ports will only flow so much, so bigger valves, bigger cam, bigger carb and manifold won't do squat w/o some major port work.

Now if you bring your expectations down to a reasonable level and do a little bowl work and install a decent cam then they will work just fine.
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Old 04-07-2008, 05:49 AM
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heads

any cam suggestions.
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Old 04-07-2008, 07:53 AM
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Peanut ports are not bad heads, they are just bad compared to some other BBC heads. Do the port work yourself, forget about bigger valves, and you should see some decent performance gains. You may want to consider getting them angle milled to bump your compression a little. But for a little more money you should be able to get a set of decent 781's
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Old 04-07-2008, 12:01 PM
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When you angle mill the heads do you also angle mill the intake manifold to match?
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Old 04-07-2008, 10:55 PM
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get the june 2008 issue of Chevy High Performance magazine. the mag is full of head stuff, but in particular turn to page 17 and read Performance Q&A's Alloy per Dollar. a guy writes in for advice with your exact heads. p/n 346236 kevin mc Clelland writes "used on 75-'87 454 engines. These heads have 120cc open combustion chambers, 225ccinlet ports, and 116cc exhaust ports. They came with 2.07/1.72 inch valves.... you have 8:1 cr; ....swapping to earlier large oval ports, they breath much better in the higher rpm range...they also came with 2.07/1.72 valves. they came open or closed chamber. closed being 97-101cc's. swapping these heads on your motor gives you an instan full point in cr to 9:1....if you want to stick to your current cr for 87 octane find some open chamber heads that are 113ccs.
some part numbers are: closed chamber: 3964290, for open chamber: 399241, 3993820, 6272292 and he recommends www.mortec.com to find other possible numbers, buy a set of them and have 1.88 exhaust valves installed and blend both int. and exh. bowls. i only put in half of what he talked about.

also, check this out too, peanut heads are also mentioned in the may 08 Hot Rod story on Godzilla Rat on page 101 says "unlike later peanut port casting, they still have fullsize 1&3/4 x 2 inch intake runners."... they use the 353049 casting (large oval port) and say they are supposed to be 113cc's chambers, but when they cc'd them, they turned out to be 122cc's! makes you wonder when you are out shopping for used heads what you'll really end up with.

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Old 04-08-2008, 06:20 AM
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Quote:
Originally Posted by chevyv8_power
When you angle mill the heads do you also angle mill the intake manifold to match?
If a competent machinist is doing the angle milling, he will adjust the angle of the intake surface on the head, then you can interchange any intake you want.
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Old 04-09-2008, 08:10 PM
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heads

how much hp and torque can i get with these heads.
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Old 04-09-2008, 08:36 PM
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Quote:
the june 2008 issue of Chevy High Performance magazine
I think they got over 600lbs/ft TQ with them (peanut ports) - that said, who cares what the HP would be. IIRC that was under 5000 RPM.
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Old 04-09-2008, 08:45 PM
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heads

i have a set that came off my block i cleaned them up and no visable cracks. about how much to rebuild them?
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Old 04-18-2009, 07:00 PM
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I have a BBC with the head casting number 353049 and when I went to buy pistons, I needed to know the head volume. What I have discovered is that Chevrolet used this casting number through the years 1970 through 1984. What I also discovered was that in the years 1970 - 1973 these heads had a head volume of 113cc, but late in 1973 and through 1984 the combustion chamber was resized to 122cc. Maybe for polution reasons. You need to look at the casting date located under the valve cover area. My casting date was K27 72. The months are designated by the letters A - L with January as A and December as L. The next code 27 was the day of manufacture with the 72 representing the year. I believe this is why some people get confused by the head volume. First you need to decode the date. Although my user name is Januarymopar, because I am a Mopar fan, I do now own a Willys pickup with a big block Chevy engine so I need to do alot of homework so I don't screw this engine up. Hope this helps.
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