Ok. I've been rebuilding a 350 to replace my worn out 305. I'm trying to keep it as cheap as possible so I don't want to go out and buy new heads. I've never put 305 heads on a 350 and was wondering how they would work out on my 350? i've also got a set of 350 heads, but they need rebuilt because they've been sitting around for about 10 years. and they're from a pickup truck and I wasn't sure if they'd have the performance I'm looking for. what do you guys think I should do?

 

All you need to watch is the compression ratio. 350 heads typically have 64cc or larger heads, while your 416 casting LG4 heads are around 58cc. With the typical 4-valve relief, 6cc flat top piston, you'll get around 9.5:1 CR on a 350 with 64cc heads, so you'll need around 12cc dish pistons or more in a 350 with 305 heads to keep the CR below 9.5:1.

If your 305 is "worn out", the heads most likely need some attention. Especially with regard to the valve seals. That is more of a factor than sitting around for 10 years. But, most likely your 416's are a much better choice than 350 truck heads.

If you can swing it, 416's really respond to 1.94" intake valves (a machine shop job), especially when put on a 350.

Sometimes, going cheap can get expensive. So, chose your cut corners carefully.

 

I wanted to go get a pair of 23* trick flow heads...but I don't have the funds for that right now, this engine rebuild was supposed to take place over next fall after the body work is finished...but it's been pushed forward.
So if I keep the 305 heads, what do you recomend I do to the heads and engine to accomodate them?

 

The heads will be useable, but with the stock size valves, expect the engine to run out of breath early in the rpm's. You will spend as much cutting 305 heads for bigger valves and porting to match as you would for aftermarket heads. I did 20 hours of port/polish work on a set of 081/416 305 heads to run on my 327, ran them for a short while, and now am replacing with a set of World Products Sportsman IIs, which only cost $500 lightly used. Since my time is worth something, all the work to get the 305 heads to barely performance status was a total waste. Want some fully ported/polished 305 heads that don't need a valve job? LOL PM me.