"416" 305 heads on 307, anyone do it?

[andymarkv]

I finished my friends farm truck.....well enough for now! But I'm planning for next year!
http://67-72chevytrucks.com/vboard/s...d.php?t=409864

Currently it has an edelbrock 600 carb/performer intake, recurved HEI and small 206/212 comp cam http://www.summitracing.com/parts/CCA-12-230-2/ on the factory 307 motor. It is better than it was as a stock 2bbl motor, but its still pretty gutless.

I have read where swapping on dirt cheap casting number "416" 305 heads with 58cc chambers and 1.84in/1.50ex valves is a good way to up the compression and help give these small displacement motors more low end.

The motor is in great tight condition. Cranking compression is 120-125pis on every cylinder. Swapping the heads would be an easy weekend job. Plus I'm sure if I look hard enough I can find the heads really cheap!

Has anyone actually done this? I'd like to hear real world feeback on the results. If it is a major seat of the pants improvement, I think it would be worth the effort. But for a small increase, I doubt I would bother.

I am also curious with roughly 9.3:1 if premium 93 pump gas would be required? The truck is only used for farm work, so heavy 2500 pound loads and not that uncommon. I would assume heavy loads would increase the chance of detonation.

Just looking for anyone who has done the swap and what their thoughts were on the results. I have searched the net and found a TON of people talking about it, but no replies as to driving impressions afterwards.

[w3lfd]

I'm actually about to do this exact swap and do some "seat of the pants" testing with just the heads and a cam. I found a low mile set of 416 heads on ebay for 95 bucks shipped. I'll definitely let you know what I find out.

[andymarkv]

Awesome!
Did you ever find any feeback from others that have done the swap? I've found tons of threads talking about the swap, but none after.

[Jacfourteen]

I know that every engine is different, but my 355 has 10:1 compression and I run 91 octane with no pinging. I have even put in 87 accidentally and it didn't have any problems. Most all cars nowadays are running 10:1 or higher and they are ok on low octane fuel (I know they have aluminum heads and are designed to run on it but I'm just saying it isn't uncommon). Good luck and let us know how it turns out.

[qksilver]

have the dist recurved and you shouldn't have a problem plus make sure the carb isn't running lean. But..................

Steve

[brn agn]

I did it. The engine ran much better, but was still not a "super star". I was still running the stock intake manifold, 2 barrel and exhaust manifolds, which I suspect was really holding the engine back. There was no comparison to the 327 that I have in it now.

I also found that I had some lower end issues, which was likely hurting performance.

My advice would be that if your friends want to keep the 307 and the lower end is in good shape, then go for it. If you don't care about the 307, I would consider putting your money into a small block with better characteristics.

[w3lfd]

Here is one of the most helpful threads i have found in my search.
http://www.jalopyjournal.com/forum/s...ad.php?t=45615

I wouldn't look to win any races. One of my primary motivators is to replace the heads that have non-hardened seats so that I don't have to worry about destroying the valve seats by running unleaded fuel.

Also looking to cam it for towing my small camper while retaining somewhat normal fuel consumption.

[w3lfd]

Figured I would update this thread with a link to the results of my build with #416 heads:
http://67-72chevytrucks.com/vboard/s...72#post4335572