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Discussion Starter · #1 ·
Hello to all, I have a set of 461 heads that came with the 327 I am going to build. I have read numerous times that the spark plug is closer to the piston on these heads and that you have to watch out for piston to plug clearance when using domes pistons. Would I have a problem using these heads with factory style 11:1 pistons. I think these heads originally were installed on a 327/300 because they are 1.94/1.50. If they put 461's on the high horsepower engines from the factory that would answer my question, I just don't know. Thanks in advance
 

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Holeshot, I have a 327 30 over with stock 350 h.p. pistons with those heads and no problems. But I'm not sure thay are 11 to 1 . I did have a 283 60 over with popup pistons 11 to 1 powerpack heads. And had spark plug issues I had to index the plugs to keep the pistons from bending the spark plug tip. I just used two or three gaskets. Here some pictures of my 327 setup. Ron
 

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Discussion Starter · #3 ·
Holeshot, I have a 327 30 over with stock 350 h.p. pistons with those heads and no problems. But I'm not sure thay are 11 to 1 . I did have a 283 60 over with popup pistons 11 to 1 powerpack heads. And had spark plug issues I had to index the plugs to keep the pistons from bending the spark plug tip. I just used two or three gaskets. Here some pictures of my 327 setup. Ron
I'm pretty sure the 350 horse motors had the same pistons as the 365 and 375's, so thats good new, thanks
 

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Factory 350/365/375 hp engines have "11:1" pistons, and there is no problem with spark plug clearance. The factory piston domes are actually not very tall, and are not all that close to the outside diameter of the piston either. 55 carman's photos show them well.

Only when you go to an aftermarket piston with a maximum compression dome, and angle mill the heads, do you have a problem with spark plug clearance.

When we used to build race engines with this style of head, we'd cut a pretty big relief in the piston dome, and index the ground strap on the spark plug to 12 o'clock to keep the piston from hitting the spark plug.

This was done on angle plug heads too but since the plug location in those heads is higher, the relief doesn't need to be nearly as large.

For a streetable engine, no way would you want or need piston domes any bigger than those factory domes.
 

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exhaust seats

Did you have hardened exhaust seats installed? kind of critical for todays gas.:anim_25:
 

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Discussion Starter · #6 ·
Did you have hardened exhaust seats installed? kind of critical for todays gas.:anim_25:
I haven't done anything to the heads yet. My local machinest has been rebuilding these heads for a long time and he said he wouldn't put hardened seats in them. The seats in the heads look great but my neighbor who ran a machine shop for many years said thats because they are flame hardened and that when I cut them for 2.02/1.60 valves they will be soft and the seats won't last. I probably will have hardened seats put on the exhaust.
 

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The flame hardened or induction hardened seats did not appear until the early 70s when unleaded fuel came on the scene. So 461 heads would never have had that.

I have mixed feelings about the hardened valve seats. One school of thought says that you don't need them even for a performance engine unless it's making the big power continuously. In other words, that school of thought says it's only needed for a circle track racing not drag racing, or for a heavy vehicle that hauls a big load (in other words a truck).

On the other hand I lost a head on a 2 barrel 283 (in my 67 Nova), never overheated. The symptoms looked like classic exhaust valve seat recession. I did put another head just like it on the engine and never had another problem, though I didn't put a lot of miles on it before putting a 350 in the car.

So it's a mixed bag for me.
 

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We use to use 461 heads for years circle track only, of couse we only use VP or Sunoco leaded race fuels never changed seats because we used leaded fuels thats for one type of engine, Aluminum head engines they come with hard seats that we use. You may have to find a shop that knows how to do it many of them here screw up and those heads don't have alot of meat to cut new seats in or the shop will crack the seat area in the head, anyways if i was going to run 11.1 comp. i would not use the east coast 93 junk fuel i have here my tank would have VP or Sunoco leaded in it all i do is blast down the highway once in a while anyway or drive around the street some.
 

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We use to use 461 heads for years circle track only, of couse we only use VP or Sunoco leaded race fuels never changed seats because we used leaded fuels thats for one type of engine, Aluminum head engines they come with hard seats that we use. You may have to find a shop that knows how to do it many of them here screw up and those heads don't have alot of meat to cut new seats in or the shop will crack the seat area in the head, anyways if i was going to run 11.1 comp. i would not use the east coast 93 junk fuel i have here my tank would have VP or Sunoco leaded in it all i do is blast down the highway once in a while anyway or drive around the street some.
We still have some circle track classes that still use those old heads and those old heads take alot of work to make power. We can bowl hog and those old heads need to be deshrouded on the intake side of the chamber, If your putting exhaust seats in use a shallow seat which should not get you into water.

Look under the water port on the head gasket side to see if you have an X in that area if so those are a desired head which has a bigger intake runner and we have made the best power on the dyno using the X heads.
 

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With a bowl job and port match, the X version will make about 30 more hp at the higher rpms.

Only the 62-63 engines, 300 hp and higher had them, and they are quite hard to find now. Racers gobbled up the easy to find ones 30+ years ago.
 

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Discussion Starter · #12 ·
Thanks for all the great advice guys, Mike, I would love to have some AFR's, I just don't have $1500 in my budget, the Vortecs are an option though. The only reason I am thinking of using the old heads is I already have them and I can get them redone with big valves for about $500, a little more if I have exhaust seats put in them. Rick L, I thought flame hardened meant that years of use had hardened the seats somewhat, shows what I know. I really cant believe how good the seats look in these heads seeing as they aren't hardened, and the valves have thick margins so I don't there has ever been a valve job done on them. I'm having a really hard time deciding what heads to use, $500 for these, around $800 for modified Vortecs, $1000 for a set of new iron heads, $1100-1200 for aluminum, and then theres those nice AFR's. If I had 375 hp I'd be happy, decisions, decisions, decisions.
 

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Discussion Starter · #13 ·
We still have some circle track classes that still use those old heads and those old heads take alot of work to make power. We can bowl hog and those old heads need to be deshrouded on the intake side of the chamber, If your putting exhaust seats in use a shallow seat which should not get you into water.

Look under the water port on the head gasket side to see if you have an X in that area if so those are a desired head which has a bigger intake runner and we have made the best power on the dyno using the X heads.
They're standard 461 heads, no X, thanks
 

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Its going to be harder to make 375 hp on that 327 with the 461 heads it took chevy using Fuel Injection, high compression and a mechanical cam to do it back in the 60's.

I think your going to be better served by going with the vortecs or better aftermarket heads to get to 375 hp with a pump gas compatible build.
Also you want to use heads with a intake port runner volume of around 180 or less your going to have a engine thats not going to have much bottom end power.

Regards, Robert
 

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If I had them I would use them, they look cooler on a 55-57 than any other head. I do not like the looks of a classic car with center bolt V/Cs, long W/P, serpinetine belt and a bunch of billet.
 

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Discussion Starter · #19 ·
I posted this thread a while back. In that time I've changed engine plans about like I change underwear. I sold those 461 heads to a buddy and bit the bullet on a set of AFR heads, I got them last year when Summit had them on sale, $150.00 Summit bucks when you buy them. That made them look real attractive. They should do pretty good on top of a Dart 400 SHP block, that is unless I change my mind again.:sign0020:
 

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I posted this thread a while back. In that time I've changed engine plans about like I change underwear. I sold those 461 heads to a buddy and bit the bullet on a set of AFR heads, I got them last year when Summit had them on sale, $150.00 Summit bucks when you buy them. That made them look real attractive. They should do pretty good on top of a Dart 400 SHP block, that is unless I change my mind again.:sign0020:

You will certainly now have the full potential to exceed your HP goals... Congrats on the AFR heads. Great choice. :congrats:
 
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