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Hi Guys. I Have A Chevy 350 That I Am Rebuilding. I Have A Fresh Set Of 305 Heads That Have Been Reconditioned 1000 Miles Ago. Can Someone Give Me Some Info On If These Will Work On This Sweet 350 With A Mild Cam Edelbrock Intake And A 650 Holley. I Have Heard That They Will But My Compression Ratio Will Be Way Too High. How Can I Make Them Work. If I Can Use Them I Want To So I Can Save Myself A Little Bit Of Money. Thanks Guys
 

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1967 Chevrolet Biscayne 10-71 blown 433 Big Block Chevy, T400 & 12 bolt 3.73 rearend
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There are pistons made specifically for this combination. They are popular with budget circle track racers. Most are cast since they are for claimer engines. Low buck solution.

Barry
 

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Don't put 305 heads on a 350. The ports are tiny and they won't breathe, and unless you have pretty big dishes in the pistons your compression will be about 12:1

If you think about it, the highest factory hp you could ever get in a 305 was 210 and that was optimistic. Your 350 has the capability for 350 hp easy, so why choke it with heads designed for 60% of the power?

Putting 305 heads on a 350 was an old-school backyard trick to raise compression back in the day when all heads sucked, and it wasn't a very good idea then either. It was a way to get more compression and the gas was good enough to do it. If you looked at something like Vortec heads today and compared those ports I think you'll agree that 305 heads are just boat anchors.
 

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86 I believe. Then they went to the 90* center holes in 87, then in 96 started the Vortecs with all holes at 90*

The aftermarket has tons of heads available with either bolt pattern, but they're expensive. Maybe look for some used iron performance heads. New GM Bowtie iron heads can be had for $600 a pair, so they can probably be had for very little used on Ebay. Brodix, Dart, and World all make good iron chevy heads, but they don't flow nearly as well as their numbers suggest. They are really cast as a head meant to be ported so there's a lot of meat in the walls. You can also use some stock 462 or 441 castings and put 2.02" valves in them. while the valves are out do some really mild pocket cleanup just in the casting flash just inside the valve seat.

For the record, you could sell your current intake and buy a used vortec intake. The Vortec heads really are as good as everyone says they are. More flow, smaller ports for better velocity, fast burn chambers... really a marvel of technology. I picked up a set of pocket ported rebuilt Vortecs with Manley stainless valves and aftermarket springs good for .550" lift for $360 plus shipping on Ebay. I got a bowtie aluminum vortec intake as a brand new takeoff from a crate engine for $112, and I sold the old Edelbrock 2101 intake for $75 to a friend. Total investment of under $500 took my build from a 225-hp stocker to a 350-hp engine.

Just throwing that out there.
 

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I'm using 305 heads on my el cheapo 350 and they work fine. Just make sure your using dished pistons and the 350 head gaskets. If your on a tight budget and you know there good heads why buy new ones. Unless of course your looking for a screamer. But for a good daily driver they fine and they have excellant throttle responce and torque.

GMPP cam 212/222 @ .050 435/460 lift
edelbrock street master intake (not the best choice)
600 holley w/ 4 hole spacer
1 5/8 headers

Th350 and 3.08's
 
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