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1956 Belair Sedan, Resto-Mod, Many Upgrades
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Discussion Starter · #1 ·
i have a set of heads off my 79' 305 Chevy SB THAT HAS HARDENED VALVE SEATS AND DRILLED/tapped FOR ACCESSORIES.
My engine is a 327...can these heads be used? Would like to be able to, but don't know if it's possible or adviseable. Appreciate feedback...

Rods56
:bowtieb:
 

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Rod.....IMO, it is possible, but not advisable....Unless someone knows different, I believe most 305 heads are going to have a chamber size of 58cc....Plugging the parameters into a compression ratio calculator https://www.uempistons.com/index.ph...e=comp&zenid=e946cad90e00b53c8403c9e777047f76 , I come up with at least 10:1 even with a .028 head gasket and .025 deck height...Too high with cast iron heads and the quench distance that you would have. Not to mention the small valve size.

Personally, I would recommend finding a set of 350 Vortec heads...They have 64cc chambers and flow very well.
 

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the powerpack heads and double humps where 64 cc. if you smooth & polish the combustion chambers you will gain a few CC,s and any rough casting that could become hot spots. add a thick head gasket and you will be ok.
 

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305 heads are going to have 1.72/1.50 int/ex valve sizes which are a little small for a 327 which had stock either 1.92/1.50 or 2.02/1.60 valves. Port efficiency I don't know about. As noted by LW85 comp ratio could be an issue. 305 also had the small bore, 3.736 I think, so with the 4.000 327 bore you would have to aware of piston to head clearance.
 

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I have ran a few 350s in the past with 305 heads. It will run fine if you don't mind putting in high octane fuel. Back when I was doing it, the highest octane at the gas stations was 93 octane. Now all we have here is 91. You could use them for awhile till you get some Vortecs as David suggested. They're awesome for stop light races but at the strip they can't flow that great from mid to big end. If you are asking cause its all you got and don't plan on racing it, I'd say go for it. If you have a Dremel or Roloc attachment on a mini grinder, you could clean up the area around the valves real smooth to eliminate hot spots. It was all I could afford to do back when I was street racing.
 

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Discussion Starter · #6 ·
Going to scrub that thought...my 327 heads are good, just wanted to have the drilled and tapped bosses. Will satisfy myself with it the way it is. Thanks for the most humble opinions...really.

Rods56
 

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Rod....Do you have fuelie or power pack heads?
 

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305 heads are going to have 1.72/1.50 int/ex valve sizes which are a little small for a 327 which had stock either 1.92/1.50 or 2.02/1.60 valves. Port efficiency I don't know about. As noted by LW85 comp ratio could be an issue. 305 also had the small bore, 3.736 I think, so with the 4.000 327 bore you would have to aware of piston to head clearance.
602 -305 heads have 1.84 intakes. Many 250 HP and 210 HP 327,s had the 172 intake power pack heads. there wouldn't be any piston to head clearance problems.
 

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IMHO, putting cast iron 305 heads on a 350 is a recipe for D & D....Detonation and disaster....What head gasket do you plan on using? And what is your deck height?

The only way GM was able to get away with using 58cc heads on the 350 ZZ4 was to use a .051 head gasket and the fact that the heads were aluminum....Still the CR was 10:1 and required 91 octane fuel.
 

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64cc heads would be a better choice. The comp should be a little below 10, even with a thinner gasket.

I can't argue with the OP's concern about wanting screw-in studs, the extra cost is worth it for peace of mind. I gave up on the press-in type many decades ago after several pull out problems.
 
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