quick question OLDS 5A heads
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I can see many errors in there, like the lack of 72 7a heads but it gives you an idea and some casting numbers.
I don't see the allure of these particular 5A heads unless they're free or dirt cheap. Don't even know what they were used on. Rare to find doesn't necessarily mean better. When was the last time you saw an NOS Olds V8 aluminum cam gear with the nylon teeth? Yeah, I thought so. Who wants that?
These 5As are kind of meh to me. Siamese port is Siamese port no matter how deep and you would still need to weld that up if you want to maximize exhaust flows. And you would still need to modify either head here to get it to work well on a 403, and it would help to open up the valve size on these particular 5As as they're just a hair larger than 307 5As. Choice between 5A heads between 80s and 69 would be obvious. Go old school. But "plentiful" 5 heads are virtually the same head. So if you want to do some work on them, do it. And if it's truly just a cruiser, just rebuild them as is. I know of no one that puts a 403 in anything and simply leave it as a "cruiser". So I'm calling BS on that! 🙂
These 5As are kind of meh to me. Siamese port is Siamese port no matter how deep and you would still need to weld that up if you want to maximize exhaust flows. And you would still need to modify either head here to get it to work well on a 403, and it would help to open up the valve size on these particular 5As as they're just a hair larger than 307 5As. Choice between 5A heads between 80s and 69 would be obvious. Go old school. But "plentiful" 5 heads are virtually the same head. So if you want to do some work on them, do it. And if it's truly just a cruiser, just rebuild them as is. I know of no one that puts a 403 in anything and simply leave it as a "cruiser". So I'm calling BS on that! 🙂
No i mean your pic the tip of the A is 1/8 inch taller then the 5.I believe you mean this which is clearly different in size, THose heads I posted have the same size 5 and A
My pic they are both exactly the same size.
Here is a 79 3A HO head
Hmmmm. The 5 and the A look like the same size to me. Maybe the shadowing makes it look bigger, but I'm not seeing it. I'm wondering what the "A" designator would mean. i.e. was it supposed to be used for irrigation engine, or was it designated for something, or just an "extra" run of 5 heads and needed a new mold, or manufactured elsewhere...I dunno. It doesn't really matter. The 5A seems to be functionally the exact same as a 5 head. Just wondering out loud.
Nice to discuss and all, but all this doesn't cure cancer, so in the end, you pick up and use the heads, or you do not.
Nice to discuss and all, but all this doesn't cure cancer, so in the end, you pick up and use the heads, or you do not.
Those 5A heads should be just as good as any other early head. Cutlassefi got 210/170 flow numbers on 7a early heads with 2"/1.625" valves with just the bowls opened. Those early heads would require minor welding on the divider, I used high temp epoxy. The 307 5A have a shitty exhaust port and divider is a mile into the exhaust port. They were fine for my truck application but no doubt flow worse, especially on the intake side vs 4A heads. These 5A untouched will match the 4A on the intake side and add 30 cfm on the exhaust side. With the bowls opened and 2/1.625 valves, 20 and 50 cfm over 4A heads. With a 2.07 intake and some blending, even more.
Exactly. So the 5A don't mean it's special. Doesn't mean it's a bad platform, it's a decent head as is. For a "cruiser", just rebuild them, make them fit a 403, bolt them on and go. No need to port them or do bowl work on them unless you just want to so you can say you did. They should flow well enough for the street as is.
Man, is there a huge fight anytime someone mentions "Olds heads" or what? 
They only reason im looking for a different head is to bump up the compression a hair
8.5 in anything NA is unacceptable!!!!!!!!!
8.5 in anything NA is unacceptable!!!!!!!!!
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