CHEVY Old Heads! Yeah, I'm talking to you...

[Sweet_Johnny]

Airflow trumps compression. So unless you're talking going to a 76 cc head over a 64, the few cc difference either way in compression will make less power than a better flowing head. A 1.94 valve is about as big as I would go with on a 305 bore. Too big of a valve will start to cause shrouding on about a 1/3 of the valve due to the smaller bore. If it was me, I would go with the 041 64 cc heads with a 1.94 valve.

Thank you! I was hoping you'd make an appearance here. Will the 1.94s actually clear with no modifications? I was under the impression that they'd touch without minor grinding, or at the least be shrouded and not flow as well as the 1.84s. I've got all kinds of info on aftermarket heads but the factory stuff gets murky for me and I thoroughly appreciate your help.

 

[Sweet_Johnny]

If I currently have 65 cc chambers then the 041 can only help flow. If I currently have 55 cc chambers, do the 041 flow enough to make up for the 10 cc increase? THAT'S the root of my questions. Yeah, I've got terrible 305 heads so almost anything is an improvement but dropping compression on a small CU engine is also terrible. According to research the 1.94 valves clear a 305 bore, but without porting or chamber cleanup they flow LESS than the 1.84 valves 416 heads. So how much of an improvement could be expected without taking a die grinder to them?

Again, this is all based on research with numbers that vary. If I was building an engine from scratch it would be very easy to select new parts that work well together and make changes but I'm looking to just bolt on something stock and go. Perusing over a dozen forums for more than 48 total hours in addition to these 4 books hasn't provided the answer since my questions aren't about principles but rather the characteristics of specific heads.

 

[Sweet_Johnny]

The way I see it, the 416 could either raise or lower compression but not a lot so the valves and runners are a gain. But they add cost. Are they worth it?

The 041 could either have the same compression or a drop due to a 10 cc difference. With the difference they're a wash, without it they're a gain. The bigger valves are good until the shrouding factors in, limiting upper rpm. The compression loss is hurts low rpm. Without a compression drop the valves help but only until they're choked. If I grind them they'll hit higher rpm but would they work as well as 416s that don't need ported or cost compression?

The 434 has better runners and keeps the compression right but still can't breathe up top due to the valves, but are free. Are they worth the trouble though since they have 1.72 valves?

It took me a while to phrase it that way but I feel that anyone with knowledge on the heads would've been able to see what I'm after from the jump.

 

[64nailhead]

Not to disagree with anyone, but if your choice is a 10cc chamber volume difference in that little motor, then I’d go with the smaller chamber.

10 cc’s of cylinder volume will make your cam seem another 10 degrees larger.

 

[Sweet_Johnny]

Not to disagree with anyone, but if your choice is a 10cc chamber volume difference in that little motor, then I’d go with the smaller chamber.

10 cc’s of cylinder volume will make your cam seem another 10 degrees larger.

Thanks for the tip! I was wanting to either keep the same volume or go smaller since little CU engines need more compression- from what I've read that's where most people eff up a 305 build. But for a 305 to make power it has to scream, which calls for bigger valves, which led to flow questions, thus the predicament. I know it's not a big power build but I may as well wring it for all its worth, and what's left after it blows can go with my friend's 350 block & other leftover parts.

I'm picking up some 416s tomorrow for $75.

 

[L05edSS]

Hey, being an Old Head ain't a bad thing, but I like wordplay and if it gets clicks, well, WINNING! I like to think of myself as being one to a hefty degree as well. Plus I'm willing to bet that nobody here under 50 knows a thing about these cylinder heads anyway, thus my need for "Old Heads" to chime in. You've been inside a few smallblocks, any pearls of wisdom you could share or thoughts to discuss? All opinions are welcome and appreciated.




I kind of figured I'd be happiest with 54 or 58 cc and 1.84 intakes but it looks like I've got 1.72s. Without cc'ing the things I don't know if they're 54, 58, or 60 cc chambers, or what the intake port volume is since online reports vary. I'm open to using steel shim gaskets or the thicker ones to achieve proper quench or compression. The internet is full of experts with misinformation as well as typos, and I definitely trust you guys more than them. I also lack any knowledge about which has the best designed ports, ramps, runners, chamber entry, and such. For instance, between the 416, 601, and 525 Vortec there are a few differences I care about but each has its place. The 601 has a better chamber and intake runner as cast but with porting the 416 can be better from everything I've seen and read. I'm still learning and have a long way to go, and have forgotten more than I want to admit. I have no "pie in the sky" dreams for this, but would like to make the best of what I've got at hand. That "dream" for the 305 would be an M90 on a custom manifold feeding some 76 cc 882s with Manley valves and possibly a stroker crank. The heads are on the El Camino, I have no blower, and would have to make the manifold for it. Realistically, I can drop any of these heads on fairly quickly and notice a marked improvement over what I have, and don't need to blow much $$ since the engine has had an issue or two already. If it blows up, it blows up- then the 350 gets swapped over.



Naturally aspirated, yes. A small shot would hopefully be fine with 114° lobe separation and can stay in the car for the next engine. I know the cast pistons and other factory bottom end parts wouldn't like it much though. I don't currently have a setup, nor a strong desire to hook one up in the immediate future either.

i think i forgotten more than i've learned. here's what i can say, i've tossed 2 305s from 2 86; monte ss', heads were fine as far as knew (headwise) and those cars came equipped with the L69 only. i never heard of 305 54 cc chambers but don't mean they don't exist (i'll let someone else confirm or deny that). the L69 heads i understand to be the better/ more desirables from that era with 58cc chambers. i understand some camaros got the L69s too... the compression = 9.5 to 1

 

[Sweet_Johnny]

Thank you, sir. Real world experience is always appreciated. I finally came to the conclusion that the 416s were worth at least $75 even if I don't use them, and I'm likely going to. They're a nice improvement over what I'm running, they'll probably perform as good or better than a bigger chamber & bigger valves, and they'll accept 1.94s if that comes up later. With 58-60 cc chambers it shouldn't matter even if I do have 54 cc's now, they'd be an increase if I have 64, and if I decide to grind on them they should respond well according to other forums. I may even skip the kit and just run 'em after checking things out, depends. Some Fel Pro 1094s and Melling pushrods will complete the package.

Bonus is being able to use them on a 350, thanks in part to the intake runners already being about 165 cc. I think they'll make me happy more than once, although they need a bit of work to be better on a 350.