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Modifying 305 heads?

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Old 12-04-2009, 10:54 PM
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Modifying 305 heads?

I've been searching around, but I can't exactly find what I'm looking for. I know that going 350 is the "way," but I want to see what I can do with my 305. It has hooker 2055s on it also.

I have a 1986 Iroc-Z with the crummy "peanut" cam, and I live in California. I know for one thing that a cam will make a huge difference, but whatever I do I'd like to keep legal, with e.o. numbers etc. I found a mild cam with the c.a.r.b number which probably would make a good difference.

Anyway, from what I've found, beyond the cam, there isn't a whole lot more to do with a 305 without serious work, other than heads. I found Trickflow 175 heads which are legal, but they also run around $1,000. So, what can be done with the stock heads and stay legal? I'm not looking to get 300 horses out of this thing, but I'm just curious if maybe I could get say 240 or maybe 250?

I'm also curious because the block, pistons, etc. only have around 60K on the whole thing. Thanks.

Last edited by tpi305; 12-05-2009 at 05:10 AM. Reason: I mean "175" heads, not "195." Sorry
Old 12-05-2009, 05:54 AM
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Re: Modifying 305 heads?

port your factory heads, install umbrella valve seals and new valve springs then call her a day .

that with adittion to a decent camshaft, headers and exhaust could easily net you 250 hp
Old 12-05-2009, 02:55 PM
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Re: Modifying 305 heads?

Ok thanks! How much do you think it'll all cost? I'm just weighing my options.
Old 12-05-2009, 03:11 PM
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Re: Modifying 305 heads?


Just modify your heads and install a cam with matching vavle springs.
I know of a few places that can do that job. For me to modify my head to 1.94 in/1.6ex and port and polish head with new seals with valve spring they charge me $450 for the pair but they provide everything
Old 12-05-2009, 03:22 PM
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Re: Modifying 305 heads?

Wow that's pretty good! Better than 1K for new ones. I'm sure you get more out of them, but for bang for your buck value, that sounds excellent. Thanks!
Old 12-05-2009, 09:52 PM
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Re: Modifying 305 heads?

Oh and when I do the cam, lifters would be smart, right? The bottom end only has around 60K, but the heads and valvetrain have 122K, so I don't know aboif the lifters were replaced or if they're originals.
Old 12-05-2009, 10:01 PM
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Re: Modifying 305 heads?

If you have a flat tappet cam, you want to replace the lifters as well. not so much of an issue if you have rollers.
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