I'm looking for data on a set of old school 76cc iron heads...liek the 882s, or 441's...etc. I have data for stock ones, but I need some after heavy porting. Also, with both 1.94/1.50 and 2.02/1.60 valves would be helpful.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
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btt before bed

 

Jester,

Jus' pushin' it back to the top - all I could offer would be a guess. SOMEONE must have some real numbers. BOX!? GhoSST!? Are you guys out there? Glenn!? Somebody who's had good heads?

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Later,
Vader
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"Make Me Bad"
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Oops!

Been travelin' guys. Sorry it took so long to answer.

As for those "smog" heads - the 76cc variety.

This may sound cruel - but unless you're on a REALLY tight budget....well, they make good boat anchors.

But, if you must keep them.....and porting is your new hobby......

Concentrate on the short-side radius, blending as you move toward the bowl. It's bowl cleanup that will produce the bigger numbers.....and with the short-side radius, combined with a port match to a Fel-Pro #1205 gasket.....

Look for 210 cfm on the intake side (which is a helluva lot better than stock), and about 160 cfm on the exhaust side. Speaking of exhaust side.....

Polish the entire runner from bowl to gasket - but do not jack with the exhaust port opening - you'll risk reversion problems, especially with a big cam.

Look up Standard Abrasives' web site for how to port sbc heads.

One last thing....those old castings have a HUGE obstruction in the form of a guide boss - and it has sharp edges on two sides. I don't even want to discuss the heat riser setup. ("Perfecto Rocky - what else can we screw up ?") This is what a fly on the wall of GM's engineering-powertrain dept. would have heard in 1972.

Having said that, I'd recommend slow, careful work. And porting cast iron is work. It does pay off - those smog heads will improve greatly, using a dual pattern cam will help a lot too.


BOR

 

Thanks for the push up top guys.

The data I have for 882 heads (which is what I have) sez 204 intake, I think 160 exaust as cast, untouched. from looking at these heads..I'd guess some porting could do ALOT of good, lots of rough, easily portable edges. I'd hope for alot more than 210 after I was done , but i'd still like to see some numbers.

I have ported heads before though...and would spent a great deal of time on these before I used them Also, I'm always on a really tight budget

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
Jesters's Page of Sick Pleasure
Florida Thirdgenners Message Board
ICON Motorsports

 

anyone?