C5 Heads Rebuild Question - Vintage Mustang Forums
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post #1 of 7 (permalink) Old 05-14-2019, 03:56 PM Thread Starter
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C5 Heads Rebuild Question

Hey Team VMF

I am selling some C5 heads however I got to thinking. I like the smaller CC on them. I have Performer RPM heads on now: 170CC/60CC with 1.9/1.6 valves.

Is it worth rebuild on them. What is the potential here?


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post #2 of 7 (permalink) Old 05-14-2019, 04:11 PM Thread Starter
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Just googled for specs:

C5AE-B – 1965, 289, Windsor small-block, 1.67/1.45 valves, 49.2cc chamber

Does that chamber size seem right?

Regarding date code: C5AE is plain as day. Found the letter designator "B" on bottom of head near where head bolts go in.

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post #3 of 7 (permalink) Old 05-14-2019, 07:04 PM
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On my backup 289 I have a ported set of C5AE heads sporting 1.94 1.60 valves. I wasn't very impressed with them and it would take a ton of money to get yours to the point mine are. Those heads only have potential, if they don't have the EGR bumps to somebody bent on originality or vintage racing. If you want a smaller CC have the Elelbrocks milled.
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post #4 of 7 (permalink) Old 05-14-2019, 10:14 PM Thread Starter
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Thanks. Just the answer I was looking for
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post #5 of 7 (permalink) Old 05-14-2019, 10:43 PM
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The C5AE heads with proper porting are great for a car that isn't intended to see more than 6k. When someone just hogs them out to make the ports larger, oftentimes despite increased top end, you wind up with lackluster performance throughout the rest of their powerband.

It's possible for someone with a lot more knowledge of port design to get real power out of these; I've heard of guys making 350 horses with C5 and C6 heads.

As usual, it all comes down to the engine combo working together.

You'd have to find someone with a lot of experience to make them right, and frankly, that experience wouldn't come cheap. A set of AFR 165's or TW170s would blow them away, and probably be at about the same pricepoint.

Now, if you happen to "know a guy...", bring a case of beer, hang out in his garage and learn something, then it'd make a lot more sense to put the effort into your early heads. They're noted for having a lot of extra 'meat' and being good for porting. But that presumes that the person doing the porting knows what they're doing. They're worse than E7TE's, right out of the box.
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post #6 of 7 (permalink) Old 05-14-2019, 11:18 PM
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Tongue nonsense

John, the C5AE is a fine cylinderhead. Most of them have about a 54 cc chamber. if you get the bigger valves and do some clean up, 200+ flow @ 28 inches is there without too much trouble. Thats enough for 440 hp at the crank. Is that enough ? Do you need part numbers for valves or seats ? Lots of guys like the 289 heads for the smaller chambers. And they're better than an E7TE, even with nothing done to them. LSG
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post #7 of 7 (permalink) Old 05-17-2019, 01:54 AM
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I ran a set of C5 heads for a while. Bigger valves and a home port job. They ran fairly well
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