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Discussion Starter #1
I know that the 305s dont have good flow exhaust wise.

what is there i can do to fix this??? i was thinking about a 30 degree back cut on the exhaust side..would that help?

also is there any way i could fit a bigger valve in there? say a 1.55 instead of a 1.50?
 

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Actually on a sbc it's the other way around. The exhaust side is descent, and the intake side needs help. Bigger valve will help, but only if installed correctly with a bowl cut and blend, and a good mulit angle valve job. Step up to a 1.94 intake valve. The exhaust valve, I think I'd leave it alone size wise.Once you have the heads flowed, you can help by your cam selection. If the exhaust shows weak, then use a dual pattern cam with more exhaust duration to help it out. Now if you were going to run a 2 inch or a 2.02 intake valve, then I'd step it up to a 1.6. But here's the thing. Once you have these heads rebuilt, and all the maching work done, you'll have more money into them than a set of Vortecs would cost you already modified for high lift cams. That's the main reason they're so popular, plus even with all the machine work to the older heads, the Vortecs will out perform them still. I know you're trying to do this on a strick budget, but i don't think in your budget plan you have enough money left over to really work on the 305 heads much. having my heads rebuilt with new bornze guides, and larger valves installed with a competition valve job and bowl blending, along with decking to true the heads, I have $800 just in machine work in them.
 

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Discussion Starter #3
Actually on a sbc it's the other way around. The exhaust side is descent, and the intake side needs help. Bigger valve will help, but only if installed correctly with a bowl cut and blend, and a good mulit angle valve job. Step up to a 1.94 intake valve. The exhaust valve, I think I'd leave it alone size wise.Once you have the heads flowed, you can help by your cam selection. If the exhaust shows weak, then use a dual pattern cam with more exhaust duration to help it out. Now if you were going to run a 2 inch or a 2.02 intake valve, then I'd step it up to a 1.6. But here's the thing. Once you have these heads rebuilt, and all the maching work done, you'll have more money into them than a set of Vortecs would cost you already modified for high lift cams. That's the main reason they're so popular, plus even with all the machine work to the older heads, the Vortecs will out perform them still. I know you're trying to do this on a strick budget, but i don't think in your budget plan you have enough money left over to really work on the 305 heads much. having my heads rebuilt with new bornze guides, and larger valves installed with a competition valve job and bowl blending, along with decking to true the heads, I have $800 just in machine work in them.
Hmm....ok well ill just leave them alone then.


Ive been thinking about my next build already and i was wondering if these heads would be a good setup for a insane 307 build?

http://cgi.ebay.com/ebaymotors/SBC-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
 

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Hmm....ok well ill just leave them alone then.


Ive been thinking about my next build already and i was wondering if these heads would be a good setup for a insane 307 build?

http://cgi.ebay.com/ebaymotors/SBC-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
STAY AWAY from the cheap brands... Many here have had horror storiesusing cheap heads!:yes:


For now, to improve the exhaust flow polish the exhaust valve up real nice. IIRC 305 heads DO suck on the exhaust side.
 

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Discussion Starter #5
STAY AWAY from the cheap brands... Many here have had horror storiesusing cheap heads!:yes:


For now, to improve the exhaust flow polish the exhaust valve up real nice. IIRC 305 heads DO suck on the exhaust side.
iirc?:confused:
 

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Discussion Starter #7
to be truthful i was just going to throw them on as they where

how much hp/ft lbs am i losing by not porting them?
 

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to be truthful i was just going to throw them on as they where

how much hp/ft lbs am i losing by not porting them?
Beats me but I didn't necessarily say porting... Polish the exhaust valve itself... It is less risky than trying to port on your own.:) I doubt you will reach your 300hp goal unless you are willing to do some cheap/free stuff. Little things add up:yes:
 
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