getting old iron heads to flow?

[Knanthrup]

Hey guys. It\'s winter and so I\'m just tinkering in the garage when I get a chance. The other day I realized that I have an set of old iron heads that came on my crate engine. They\'re cast #33417369 and I really don\'t know much about them other than that they\'re 76cc ports and came on the block (#10066036) which is supposedly a 79-85 GM goodwrench engine, it has 4 bolt mains. But then when I look up the heads, it says they\'re from a 90+ GM goodwrench crate engine, so maybe the block is newer than I thought or maybe they just changed heads somewhere.



Anyways, I\'m really not doing anything with them and I\'ve got a grinder out there. I\'ve been thinking that maybe just for fun I would try doing my own port job and try to widen out the runners to get some flow going. Maybe a little more machine work like screw in studs and whatnot and then toss them on the engine to see if I make more power than I am currently. I figure it might be a fun experience and possibly end up with some nice gains, plus I don\'t need the heads so if I screw up it\'s no loss. Anyways, I don\'t know much about head work but is it possible to make these old iron things flow pretty good with some porting? I figure as long as it\'s got a good chunk of iron to work with it seems like it would have as much potential as any.



My other choice would be to keep the #369 heads for backup and try to work with the #376450 heads that I have on it now. The #450 heads are from smaller sized SBC like 305 and below, but the shop that sold them to me said they could make good power. They\'re 64cc and have 2.02/1.60 valves with a back grind, plus a few small machine extras but no porting. Obviously these are high compression heads, do you guys think I have more potential or getting power out of these or the other heads? I\'ve had a lot of people frown on these because they came off a 305 and below smallblock, whereas the #369\'s came off a 350 crate.



And don\'t worry, if I do decide to I will try to read up on self-port jobs, I know there\'s some good write-ups out there. Suggestions? Comments? I\'d really appreciate input from thosewho are experienced.



p.s. i have absolutely zero money to spend, so don\'t tell me to switch to vortecs or ditch iron for aluminum. in good time it will happen but im working with what ive got for now http://www.s10v8.com/images/smilies/icon_smile.gif



thanks guys! http://www.s10v8.com/images/smilies/icon_razz.gif

[Knanthrup]

By the way, I found some more info on my engine parts here. With the 64cc heads I have now, my compression is about 9.1:1, if I go back to the 76cc it will drop to 8.5:1.



Also, the #369 heads I want to port are using 1.94/1.50 valves. My #450\'s have been upgraded to 2.02/1.76.. so i don\'t know which to use now. It seems if I had enough meat to port on the #450\'s that with the larger valves and higher compression that I could make more power. I\'m so confused!



Oh and I actually found the exact specs on my engine the way it came. Here\'s a link... this is the exact engine I had received, all the part #\'s match. I am using a much larger cam and the #450 heads right now though..

www.paceparts.com/index.asp?PageAction=VIEWPROD&ProdID=24755 (http://www.paceparts.com/index.asp?PageAction=VIEWPROD&ProdID=24755)

[MARKYMARK]

my suggestion is to port the 76cc heads, watch out on the exhaust ports don\'t try to make them go straight through, because you will .wright into the waterjacket.take your time then go to ebay and buy some speedpro .150 or .230 raised pistons $135. that will increase your hp bigtime

[Knanthrup]

thanks for the advice, i will certainly consider this.



anyone else?

[ChevyKiD_69]

i heard that 6 out of 8 will go into the water jacket.

[Knanthrup]

On 2004-12-28 05:01, ChevyKiD_69 wrote:

i heard that 6 out of 8 will go into the water jacket.



I think you\'re hearing this from the wrong source. Porting doesn\'t so much involve removing material from the heads, it\'s smoothing the material inside and removing burrs and flaws, as well as polishing the exaust side (not intake). If you\'re cutting into the water jacket then you\'re not doing it right.

[fastw23s]

Be Careful, the biggest mistake made by rookies is to remove too much material. Bigger is not better.



The bowl is where you\'ll find the biggest improvement on a stock head. Never take it past the valve seat. Generally the ports will respond best to a gasket match that you flow into the runner, remember air is easily upset, and any type of sharp edge or abrupt change in direction will cost you power.



Honestly, do not expect major gains, but you should see some improvement. Although, if you put the larger chamber heads on without adding comp., you will not see any difference, no matter how well you do.

[ChevyKiD_69]

that is what i heard. so i dont know how true it was.