307 performance head suggestions

[chevyc1068]

I'm looking at spicing up my engine a bit. I've heard that the 307 heads won't allow you to do that very much, if this is not right correct me. So anybody got any ideas for good 307 performance heads. I'm on a very tight budget so try to advise me to some cheap heads that still perform very good. Or advise me towards some old ones that I could pickup rebuilt or something like that.

Any information on 1968 307 heads would be appreciated to, so I can compare them to something. Chamber sizes, compression, valve lift accepted.

Would double humps fit and are they good performers?

[PanelDeland]

I'm not sure you will get the performance from a 307 that you would like.If you already have an aftermarket manifold,headers and maybe a mild cam,then heads might make a difference.Most smallblocks are a bit weak in the heads but if you don't get the air/fuel mix in and out thru the intake/exhaust then heads wont make much difference.If I were try for performance from a 307 I would adress these areas first since they can be used on a 350 later.
Also IIRC some of the smaller engines are restricted to smaller valves because the cylinder is smaller in diameter and the larger valves get shrouded and give little if any performance gain.Good luck with it and lets us know what you decide and how it works.

[chevyc1068]

I plan on putting on a Holley Street Dominator manifold with a Holley 600CFM vac secondaries carb on it. Along with Hooker Comp Headers, true dual exhaust with glass packs. So I don't think that getting the air in and out will be much of a problem, except getting in the heads and out of the heads.

Anybody else want to take a stab at advising some heads?

[stepside454]

I think your best bet would be either a set of 305 H.O. heads or better yet, Vortec heads. With Vortec heads, you also need to use self aligning rockers, vortec style intake & valve covers. but for small displacement engines, they are hard to beat.
If it were mine, Id use a Performer intake. & a 500 CFM carb. since Im assuming your not planning on a camshaft swap, the stock cam is good to about 4800 RPMs....500 cfm is more than plenty....or better yet, a good working Q-jet

[crazy longhorn]

I would go Vortec heads, with a Performer, or perf eps (square flange). I think you will do fine with a 600 cfm Elc choke Edelbrock carb. after that , one of my all time favorites on the cam for a small cube chev , is a Crane energizer 272(.454 lift across, 216 dur @ .050, & ground 110 lobe sep angles).It will idle almost smooth in yout 305/307/327. The cam lifter kit is available for around 120 bones. As far as valve size, the 3 7/8" bore will handle the 1.94/1.50 valves just fine....we ran fuelies on 283's & 307's (back in the day). your late Vortecs will give the same valve size, with MORE kick than the old fuelies (out of the box). I do agree that a good set of 1 5/8" tube headers , with dual exhaust /h pipe/perf mufflers will be a good addition. I would go 2 1/4 " from the headers to the muffs, run an H or x pipe.....from there you can run 2" out of the muffs, to keep the velocity up. While we are doin "cheap", I would toss in a set of Dyno max superturbo's. Dont let nobody tell you that that 307 wont "boogie".....back in the 60's, the bucks down guys were stroking 283's, & racing them on the strip! If that 307 is set up properly, your buds will swear its 327 best of luck, L

[stepside454]

yep I agree on the exhaust, stay smallish, Th eX or H pipe is a good idea on a smaller engine especially. & I agree on the Dynomax Turbos

[Sweet72]

I think your '68 307 heads have 75cc chambers. Stock vortecs have 64cc chambers so your compression would make a little jump. You can get the heads and intake here ready to go... http://www.sdpc2000.com/catalog/2172...mer-Intake.htm
If you go with vortecs you have to get a vortec style intake and center bolt valve covers.

[stepside454]

its worth it

[roj2323]

for the small amount of money it would cost you to build a 350 why bother with the 307 if your going to do anything other than add minor performance parts. what i mean by this is unless your going to restrict your mods to headers, intake and maybe eliminating some acessories it's really not worth spending major money on a small bore motor. if you really plan what your going to do and shop around you can build a 350 or even a 400 sbc for under $500 minus the carb and headers. currently i am doing this myself with a .030 over 350 i got for free out of a junk truck because it spun a berring. here's a little list of what i've spent:

82 block with good heads :free
-berrings
mains $36
rods $24
cam berrings $36

cam $150 aprox new got for free actuly
lifters $110 aprox new got for free actuly
complete gasket set $25 new at swap meet "should have bought more"
rings $75
oil pan $34 (11 shipping) online new unpainted not from ebay
one peice pan gasket $27
intake edelbrock 5001 $45 (15 shipping) with free valve covers lucky ebay purchase
sub total $487

polishing crank not allways needed but in my case $45

my cost minus freebies $272 =)

i learned a long time ago to never pay full price for anything, there is allways a deal to be had all you have to do in look in the right place. whether you look online at a swap meet or ask your friends you'll find what your looking for in less time than you might think.

good luck and i hope this helps,
ondrew

[stepside454]

If your 350 had a spun bearing...how are you going to get by without having the crank turned ?

[roj2323]

i did thus the added cost.
i wrote: "polishing crank not allways needed but in my case $45"
ondrew

[stepside454]

so you spun a bearing & only need to have the crank polished ?

[crazy longhorn]

What about resize on the big ends on any spun rods? Hope you didnt have a spun main......its cheaper to toss the block.... L

[roj2323]

It wasn't a main. "1-2 rods" I had the crank cut 10 under. To be precise it was close to spinning a bearing. The bearings had signs of lack of oil and they were starting to turn copper in color. The engine had a few minutes without oil because I as well as my pop didn’t check it first. It had been sitting awhile and the pan apparently leaked. Lesson learned but either way it was free so I can't complain. After I get done selling the truck that was around it, it will truly be a free engine anyway.

[stepside454]

ahh OK, you failed to mention the cost of having the crank machined