Team Camaro Tech banner

1 - 10 of 10 Posts

·
Registered
Joined
·
76 Posts
Discussion Starter #1
Rebuilding 3782461 heads for flat top pistoned 327.
Cam I believe is Edel performer 204/214 [email protected], .420/.442 lift at valve.
intent is responsive performance in manual trans,.355 rear ratio Nova.
Would not expect to run over 5500 rpm.
The question: It was recommended I have hardend exhuast seats installed and need to replace exhaust valves either way, is it worth it to go from the 1.5 to 1.6 exhaust valve size? No cost difference per the machine shop guy. Will I gain/lose much of anything?
Any other recommends for this rebuild?
Thanks
 

·
Registered
Joined
·
477 Posts
How long do you expect to keep these heads? I "needed" them too in my 186's but drove them anyway for 7yrs but I just wasnt going to sink money in those heads. Id say no to all of it but I dont know the condition of your heads now. If its your #'s matching car then Id go for it. youd have to do some porting to take advantage and by the time you were done installing larger valves and porting you could have paid a big chunk on a newer set of heads. If they work good I say drive'm and save for some newer technology.
 

·
Banned
Joined
·
21,341 Posts
They won't do any better unless you plunge-cut unshroud both valves after installing the 2.02"/1.60" valves like GM did the stock, big valve heads!

And then, I would also do a quick bowl-blend and dingle-berry casting flash port clean up too at the same time and then you will be doing the old heads some good, imho..

pdq67

pdq67
 

·
Registered
Joined
·
7,796 Posts
No cost difference ? Maybe for the valve itself but, I'd bet he'll charge you more for the machine work. My engine builder doesn't like to install bigger valves, as it increases the chance of the head cracking, between the valves. Also if you are not going to twist it past 5500 RPM's, you really won't benefit, in the bigger valves. As already stated, they will need porting, to help your gains. You really are better off buying some NEW Pro-Action heads (or other) then to stick much money in the old 461's.
 

·
Registered
Joined
·
2,664 Posts
With that cam and a 327 don't bother unless the heads have had so many valve jobs that the stock valves are sunk. I may be a neighbor. Have been looking for property in the valley. I have to get out of this greatest concentration of idiots on the face of the earth.
 

·
Registered
Joined
·
2,920 Posts
Joe,

There are many things to consider when selecting cylinder heads. Here is what I would do if I were you.

http://cgi.ebay.com/ebaymotors/SBC-...190087300797QQihZ009QQitemZ190087300797QQrdZ1

You will be very, very happy with these heads on your 327, considering your gearing, mild camshaft selection and the rpm range you will be operating at.
I ran a set on a 355 12:1 solid long duration cam, M21 68 Camaro and it pulled very hard, would lift the tires in second gear with street tires (if they weren't spinning long enough to hook). I'm certain that motor was limited by these heads, but they will work very well for your combo. Don't expect those results on your more streetable build though and no these aren't my old heads, mine aren't for sale, they are sitting in the garage on a shelf right now. May that motor rest in peace!

Here's why I think they'll work for you. The old 461 462 casting like yours have a very small intake port volume of 156cc and the I/E relationship of your heads is only 67% with full exhaust, 64% with open headers (yes flows less with open exhaust). A little background on this Intake/Exhaust relationship. If an intake flows 200cfm @.400 lift and the exhaust flows 150cfm @ the same lift you end up with 75% I/E flow numbers. The minimum you like to see on a performance engine is 75%, 80 is better, but much over 80% without really studying the flow numbers you have to question is the exhaust really that efficient or is it hiding a overly weak intake port flow? So the exhaust flow is critical, for this reason if you stick with your heads I would certainly put the larger 1.60 exhaust valves in them. Most good machinists I know stress the exhaust flow is the more critical of the two between I and E. You don't need anything larger than your 1.94 intakes on your heads and as pdq67 already pointed out the 2.02 will flow worse unless you have the combustion chambers cutback to unshroud the intake valve when going up to 2.02. Either way all those heads need is the 1.60 exhaust, a good bowl blending and I would not sink the money into new hardened seats. The other thing to keep in mind when selecting the heads is the balance between intake port flow versus velocity. A very large intake port will flow a lot of air, and give you good peak horsepower numbers, but the port velocity will be so low at low rpms that the engine will produce no low or mid range torque, something that the 327 is already lacking due to the shorter stroke. So I would give up port volume to increase the velocity so it flows better at low rpm. The 170 cc intake port on the World S/R head is certainly not too large for the 327 and will still provide pretty good velocity. The 156 cc is just too small in my opinion for you. The World S/R head will flow 205cfm on the intake @.400 and 156cfm on the exhaust at the same lift and that amounts to 76% I/E ratio, pretty touch to beat for the bucks. The head also has many other advantages over the stock head, despite the fact it is designed to be a Stock Replacement. It is stronger, has better intake ports, screw in studs, guide plates, raised valve cover gasket rail to keep the oil in the head when you take the covers off and is a thicker casting. It also has accessory holes on the front of the head that the early head may not have had.

I know there are some who will jump in hear and tell you a $1500 set of 195 AFR aluminum heads are the hot ticket, but you simply don't need those on the build you're working with. Keep in mind that the World S/R head chambers come in various sizes, the 67cc would be the closest to keeping your compression ratio close to what you have, your current heads are 64cc unless they've been milled down, and 66cc if you went to 2.02 valves and unshrouded the chamber walls. The 76cc head may kill you compression, I'd keep them at least 67cc, the 58cc may be too much. You can play around with various thickness of head gaskets also which can make a few tenths of a point difference depending which way you go.

You can also go with 1.6 rockers on the exhaust to open the valve further, which will benefit you more than having additional duration would and will further increase your I/E ratio. Just make sure the pushrod holes in the head are clearanced for the larger ratio or they may bind, if they aren't you can drill them out yourself, the cast iron is quite soft and easily drilled, I've done this myself many times.

Good luck with you build which ever way you go.

Dave
 

·
Banned
Joined
·
21,341 Posts
Ditto Dave!!

I got those for my nephew for the .040" over 327 that I gave him.

Only problem is that at 67 cc's, they are just a tad down from the about 10 to 1 CR. I like to see b/c it calculate's to be like 9.45 to 1 using Fel-pro's #1094, .015" thick shims.. Sucker should still run like a "scalded-dog" w/ the good old CC 268HE and Crane?Cam Dynamics 272/272 Energizer tho!! Imho...

Cut them down to 62 cc's AND you will be right at 10 to 1!! Just about dead-nuts FINE!!!!

pdq67
 

·
Registered
Joined
·
2,920 Posts
Yeah Paul I agree he's going to want to be around 10:1 static. I'd probably shave the heads down some for the same reason and run a thin head gasket. I'm assuming he's +.030 so that helps bump it up a another .13. Any little thing helps when you're trying not to tear into the bottom end and keep your comp up. With the Worlds at 76% I/E he can run a single pattern cam, doesn't really need the 1.6 on the exhaust, but it may help. Agree as long as you're this far into it I'd consider a little stronger cam and make it really run, like you suggested!

Would make a really neat little street motor especially with the 4 speed behind it and the shorter stroke.
 
1 - 10 of 10 Posts
Top