does anyone know what size chambers the 416 heads off of an 85 ho engine would be. im wanting to put them on a 350 with dished pistons and want to be sure 93 octane gas will be ok.

 

These heads don't work on a 350 as the combustion chambers are too small in diameter. I have the 416 heads and if the 350 combustion chambers are too big for a 305 then it should work the other way too.

 

Wrong answer. 305HO heads are the same as what came on the LG4 engine, a good chance they could be 416s. They workd great on a 350, they just need a little work. They are 58cc stock. When you cut them for bigger valves 1.94 1.50, or 1.94 1.60, they will increase (due to valve deshrouding) to around 62cc. Perfect for a 350. Many people here run the 305 heads on thier 350, myself included.

 

Since when don't 416 or any other 305 head work on a 350? I had a set on my 350, as do many many others here. Don't beleive me? Look up the thread in Sitting Bull's sig. They work. They work well.

They are cast as 58cc.

 

416, or possibly 601, are the heads you will have if those heads are what your car originally came with.

As said above, they actually work great on a 350, they just need some tweaking to get them to perform well. Things like installing slightly larger valves is a necessity on a performance engine, but some other jobs, like port grinding, etc, isnt exactly neccessary, but goes a LONG way.

What these heads have going for them, in short, is this:

A) They were on almost EVERY 305 made in the '80s, so they are EXTREMELY easy to find.

B) They have small combustion chambers, which make for a healthy compression ratio on a properly built 350 without resorting to domed pistons like you have to with most '350 heads'.

c) Stock vs stock, they will outflow almost every 350 head of the same era, like 882, 624, 993, etc... get out the grinder and introduce it to the ports, and you'll be even farther ahead of those 350 heads.

 

thanks for the replys. i wasnt sure if the high outputs were different.

 

I'm just wondering, but does this mean that if one were to put bigger valves on these heads and put them back on a 305, the compression ratio would decrease?

 

Yes it would. Any time you increase the chamber size, yet leave the rest of the engine the same, you will decrease the compression ratio.

 

Any idea on how far it would lower compression on a flat top LG4 (9.5:1) CR stock?

I'm not too serious about it right at the moment, but the thought of putting a Weiand 142 roots blower on my little LG4 has popped into my head more than a few times. I was concerned that 9.5:1 would be way too high for even that blower, though.

 

Without running the actual numbers, I would say around 9:1.

 

Sounds good.

One more question: My friend keeps telling me that using a larger head gasket would lower compression as well. Any truth to that?

Sorry to hijack your thread, hoogabooga.

 

Nate, lets talk on AIM.

 

i got the anwers i needed. keep it going so i can learn more.

 

If you do this you will change the quench of the motor--Just make sure it is with in specs other wise you may do some damage that u wil not be able to tune out

later and

GB

rick

 

Hey guys you don't need to give me crap. I was just saying that I didn't think it would work stock. Of course if you deshroud and totatally alter the combustion chamber that would work. When I had my heads worked for my 305 I was looking at some 350 heads and what ends up happening is the bore and combustion chamber look something like a mushroom.

Anyway, what are the benefits to running a 305 head on a 350? I would think it would be better to pick up some aluminum heads instead of 305 heads if for no other reason than weight. Is there an actual advantage to this 416s on a 350 method, I just don't know about?

 

305 heads will still work on a 350 whether you deshroud the intake valve or not.

Read the thread linked at the end of my sig for the ENTIRE lowdown on why you definitely want 416, 081 or 601 heads for your smallblock :hail:

 

No one is giving you crap. Stock 305 heads work fine on a 350 too, they usually just have smaller size valves. As far as 350 heads on a 305, as long as the valves clear the cylinders, or you run low enough lift, its not a big deal. You will just lose some compression putting the 350 heads on a 305.

 

Right, but unless you want to run forced induction why would you want to lose compression?

 

Not everyone can swing the price of aluminum heads. Go to a junkyard and you can get them (305 take off's) for cheap.

350 heads on a 305 is totally opposite of what the original poster mentioned. What's the point to be proven here? I can think of no reason to put a factory 350 head on a 305.

 

Make it even slower?