Hey Guys,
I picked up a set of 450 casting heads that Mortec says are 60cc heads for a 305.
My 307 engine is currently running an Edelbrock Performer, a Holley 600 cfm vac secondaries, 1-5/8" headers with 2-1/4" exhaust and an unknown cam with a very slight lope and is suprisingly peppy for a little engine.
I did a search on running 305 heads on 307's and it seems to be a good way to boost compression but haven't found anything on these particular heads.
Will they offer any additional gains and what if any inexpensive mods should I do to them before mounting them?
I don't want to spend a lot of money on them as the car is already pretty strong for a 307. But, is there anything I could do myself to help them?

What do you guys recommend. Would it be worth it to swap them?
The car is mainly a cruiser that I drive every chance I can.

Thanks
Dwayne

Unfortunately, 307's will never deliver very much power no matter what you do. The 307's are low torque, low power motors. Your best be would be to find a 327 or 350.

If you already have them, it'd be worth it. I think the 305 heads have 1.84 intake valves, which are an improvement over the 1.72 valves. Plus the increase in CR will help. I don't know if the larger valves will hit the bore (I doubt it) so you might ought to check that out. 305 heads aren't known for flow potential so other than a good valve job any other money spent would likely be better spent elsewhere.

Yeah, I know the little 307 will never be a screamer, but I got the heads for $40 and thought it could'nt hurt to try them.
I've got a 350 in the garage now with a broken crank. I will eventually build it to drop in, but, I'm really in any hurry. The 307 is fine for now. In fact, I would say this one might suprise a stock 350 http://www.chevelles.com/forum/wink.gif

BTW, what would cause the crank to break on a 20k mile rebuilt 350?

Thanx,
Dwayne

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68 SS Chevelle 396/325
69 Corvette 427/390
71 Malibu 307
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"You will keep him in perfect peace whose mind is stayed on you"

I don't know what would cause the crank to break. I've read that they're as good, if not better, than forged cranks to 6500rpm.

A 350 crank shouldn't be hard to come by, and I guess you know your 307 crank in the 350 block would make a 327.

You can run the big valve heads on it if the 66 cc combustion chambers still give you a livable CR. on pump gas. Just use a cam with about .450" lift!!! But really, the medium valve heads are very good, anyway due to the small size of the 307..

In fact a CC 268HE or a Crane little Fireball are very good hydraulic cams for the little engine... Imho.. pdq67