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choosing the right heads
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gg68camaro
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PostPosted: Mon Aug 04, 2003 11:11 pm    Post subject: choosing the right heads Reply with quote

This is a great site! I have a question regarding choosing the right heads for my car.

I have a 355 small block chevy with old fuelie heads. I have about 10 to 10.5 to 1 compression, possibly higher because I'm not sure if the heads were milled. They are 461 castings and looked up the combustion chamber size which is 62cc. My cranking cylinder pressure is around 200psi.

I have a crane roller cam 630lift and 252/260 duration at .050. The RPM range is 3500 to 7200. Running a powerglide with 4000rpm stall and a 4.56 gear.

I believe these heads are holding me back but I am not sure which size head, brand, intake runner size to choose. Any recomendations? Please respond with personal experiences and results so I know what to expect.

My car currently runs 12.50 @111mph
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Hanz
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2003 Dodge Ram

PostPosted: Tue Aug 05, 2003 6:01 am    Post subject: Reply with quote

For a quick answer, either Dart Iron Eagle 200cc or Pro 1 if you want aluminum. It will be a nice increase, but can't really predict numbers.

I believe 461's are 58cc, and less if they have been milled which is likely. 462's are 64cc. If you buy a 64cc head you probably want to have them milled to keep your compression ratio up.

You can also maybe find a deal on used heads (ebay?) that have nice components and some port work. Just shop wisely.

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techinspector1
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PostPosted: Wed Aug 06, 2003 8:43 pm    Post subject: Reply with quote

You know fellas, the neat thing about this forum is the fact that if a question is asked that I don't know the answer to, then I feel compelled to research it as much to increase my knowledge as to answer the question. Here's what I found out: The 3782461 head was used on (depending on the source) A. '64 to '66 327 B. '61 to '70 302/307/327/350. It has 2.02/1.60 valves, 64 cc chamber, 161 cc intake port volume and 62 cc exhaust port volume. The 3782461x was used on '60 to '63 283/327, uses 1.94/1.50 valves, 172 cc intake volume and 62 cc exhaust volume. What really frustrates me is that I looked for 2 hours trying to find cfm flow on these heads and came up empty. Jack Merkel (Merkel Racing Engines) says the 461 might be the best head Chevy ever produced, but that there are better heads out there in the aftermarket today. A pretty good comparison of different heads can be seen at (http://www.topher.net/~bearman/gmheadcomp.html) Take particular notice of the Airflow Research 190 and 210 heads. If big numbers mean anything, then these are the DADDY heads. A guy might have to stroke his 350 out to a 383 to take full advantage of these. Richard.
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Hanz
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PostPosted: Wed Aug 06, 2003 11:29 pm    Post subject: Reply with quote

Richard, with all due respect, I can tell you that some of that casting info is wrong.

461 heads are a completely closed chamber, like a bathtub, and only came on 327's, never 350's, 283, or 302. They also never came with 2.02/1.60's. 461 and 461X have the same chamber size, I believe 58, but definately not larger. The 461X were made in Canada, and supposedly had slightly better ports, therefore bring their weight in gold to certain stock car classes that demand no portwork.

462's are similar, still what some call a closed chamber, but with a radiused relief on the spark plug edge. This allowed some unshrouding for larger valves (2.02/1.60). This chamber shape is 64cc, and are what other HP heads were designed after for many years, including Bow-Tie heads. Other similar casting numbers from 70 and on include 186 and 292, both which have accesory bolt holes in the ends. The 462's and these others could have optional 2.02/1.60 valves.
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techinspector1
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PostPosted: Thu Aug 07, 2003 12:40 am    Post subject: Reply with quote

Hanz, since I have no direct experience with these heads, I yield to your expertise. I will list the sites where I got the info:
www.chevytalk.com/tech/engine/SBC_Heads.html
www.topher.net/~bearman/gmheadcomp.html
www.jimsperformance.com/headchart.html
www.thedirtforum.com/castings.htm
www.nastyz28.com/sbchevy/sbch.html
Richard.

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Hanz
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PostPosted: Thu Aug 07, 2003 6:13 am    Post subject: Reply with quote

See, I can look at those charts and find they are full of errors, that I can prove. I am looking at the Dirt Forum site. You can not use the same casting for bolt hole/non bolt hole heads, since bolt hole heads have extra casting bosses on the end, for the brackets to bolt to. And since head mounted brackets started in either 69 or 70, you can't have the same casting number cover pre69 and post 70. It's ridiculous that he has 441's from 67-79, because besides the issue I just covered, there was a major change in about 76 when they went to thin castings to shave 12 lbs off a pair. These are indentified on all SB heads, the outside profile by the exhaust side, where the edged dips in between every head bolt hole, where as earlier heavy casting heads only dip in at the dipstick tube.

Many of these charts if you look, are cut/pasted on each others site, down to the comments. I have an AERA casting number book I will look at when I get to the shop, that is much more the 'Bible.' Hanz

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gg68camaro
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PostPosted: Thu Aug 07, 2003 11:36 am    Post subject: Reply with quote

Here's some other info on my heads.

They were originally a 1.94/1.50 valve size that I had opened to 2.02/1.60. They do not have any accessory holes in them and the flow numbers that I found on these heads were 218 intake 147 exhaust.

I enjoy reading your responses, but I still need advice on if a head change is worth the investment. My choice so far is the AFR 210 head.

I also use nitrous on this car once in a while, 125 to 150 shot if that makes any difference. Thanks for the info. George
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techinspector1
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PostPosted: Thu Aug 07, 2003 1:30 pm    Post subject: Reply with quote

I'll write down your combination and take it with me to the next Team Firebird race and ask the racers what their experience is. That's the best I can do for you, because like I said, I have no direct experience with these heads. Richard.
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Hanz
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PostPosted: Thu Aug 07, 2003 2:01 pm    Post subject: Reply with quote

I don't think you'll go wrong regardless of which aluminum aftermarket head you decide on. Are you getting ported heads? Are your 461's ported?

As to if its 'worth the investment,' that is an opinion that you will have to make depending on your cash and what you will be happy gaining. So say the heads and gaskets cost you $1500 (unported,) what would you expect from them? Just to pull a blind number out of a hat, would 3-4 tenths make it worth it to you? I'm sure that 5-6 would, but can we get that...?

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gg68camaro
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PostPosted: Thu Aug 07, 2003 7:43 pm    Post subject: Reply with quote

O.K Here's a little more info without writing a book. I am thinking about changing the heads because I have hit a road block.

I did a cam change recently because I'm trying to match my parts the best I can to go as fast as I can. The cam that I pulled out was somewhere in the range of .660 lift, which is what a machine shop measured it to be. I couldn't track down the cam numbers to a manufacturer to get to real numbers. I was breaking valve springs and thought the cam was to big. I went to a crane .630 lift with less duration to try and pick up some bottom end.

After the cam change, I went to the track and didn't pick up any time. The only variables to the runs were about 25degrees in outside air temp and I stepped up the front bowl jets from 72 to 76. Being very frustrated after returning from the track, I pulled out my headers and reduced the header size to 1 3/4 tubes. I used to have big tube 2 inch headers with the aluminum adapter plate. {These headers are for sale if anyones interested}. I am also running a powerglide for a tranny. I am trying to go into the 11's on motor. What do you think? GG
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Hanz
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PostPosted: Thu Aug 07, 2003 8:34 pm    Post subject: Reply with quote

You didn't say if the 461's were ported at all, or even blended when the 2.02's were installed.

If they are ported, I'm not sure if bolting on another set of heads will gain you 6 tenths.

If the 461's were not ported, then a ported set of (any good brand) aluminum heads would really help...maybe to that 6 tenths degree...but...your compression is a little low for a drag car, don't ya think? And if you go from 58 to 64cc, it will drop even more...I would inquire about having them milled, drasticly, to bump it up. Or inquire about the new (Dart) cast 48cc heads...Or Unless you feel like changing pistons...

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Blown65
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PostPosted: Thu Aug 07, 2003 11:25 pm    Post subject: Reply with quote

The cam you are using is way to large for you application. You should go back to the cam guys and ask them for a better one.
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gg68camaro
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PostPosted: Fri Aug 08, 2003 9:20 pm    Post subject: Reply with quote

I have no clue if the heads are ported or not. My mistake was bringing the heads to a local shop. Since it appeared I had stock 1.94/1.5 valves in the heads, I felt why not put in the 2.02's. [waist of money]
I am really guessing at compression also, basing it on the 62cc combustion chamber and flat top pistons. I figure about 10.25 to 10.5 to 1.

I also had crane cams pick out the camshaft based on my combination of parts.

I drive this car for the most part on the street and occasionally on the track. Of course I have expectations on what the car should run, and what I've been told it should run, I just can't figure it out. Am I asking for too much. GG

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PostPosted: Sat Aug 09, 2003 12:22 am    Post subject: Reply with quote

I've never done this, but it might work for you. Start networking with every gearhead you know. Let them know you'd like to "rent" a set of heads from someone who has them lying around, not being used. Explain that you're not sure that new heads would cure your problem, but you want to find out by renting a set of heads for a couple of weeks. Go to the meetings of all the car clubs and let all the members know and ask them if they will tell their buddies of your needs. Stop by all the auto parts places in town and put out the word.Right now, you're dead in the water until you get your mitts on some heads to try. Visit speed shops in your area and go to the local drags, talk to people. This way, maybe you could try several different manufacturers for very little out-of-pocket, just some "rent" money, gaskets and your labor. If you find a set that cures your ills, offer to buy them.
Richard.

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PostPosted: Sat Aug 09, 2003 12:25 am    Post subject: Reply with quote

Too Funny Mr. Green
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