So we have a 1970 350 that was completely rebuilt still wrapped from machine shop for cheap. We swapped the 305 out for this 350 to run our 86 Z.
Now I want to do more and need a little knowledge/ advice.
Current engine specs
350 bored .030 over flat top silven pistons
elgin cam kit ELGCL274K
which I believe is 1500-4000 rpm, INT lift .390 EXT .410 DUR @ .050 INT 194 EXT 202 Lobe center 108 116.
For just bolt ons would a set of aluminum heads and 1.6 RR add more HP?
The engine has 441 76cc chamber iron heads now, Edelbrock performer dual intake, Holley 625 street demon carb, Summit short headers, 2.5” exhaust all the way back.
I was looking to see if head swap and RR would benefit without having to pull engine?
If so what heads would you recommend?

I appreciates the advice of all you more seasoned engine builders.

 

That's a dupe of the stock cam. The legendary POS 929. If I was the least bit interested in "more HP", and was going to open up the motor to get it, it'd be the first thing that would go.

A "rebuilt" engine with those heads on it will have a compression ratio in the neighborhood of 7.8x. Which is probably partly why you're asking for more HP. I doubt it makes more than about 180 now. Would probably be 160 or so with stock exhaust.

What kind of budget are we working with? Why aluminum heads?

No need to pull the engine in any case if you don't want to.

 

From the cam specs it doesn't look like a lot of RPM will be involved.
Based on that, and from personal experience with a smaller cammed 350, the best bang for the buck will be probably be a set of Vortec heads.
With the low lift involved, the Vortec could be used right out of the box. Stock springs, pressed in studs and all. I did it with great success.
You'd benefit from the higher lift of a 1.6 ratio rocker as well. Even with the increased lift, you're still within the many times confirmed guidelines for maximum lift. You may find yourself having to enlarge the pushrod holes in the heads as the increased ratio will change the pushrod path somewhat and could bind. This would be with self guiding rockers as it was designed.
There are other routes but for an inexpensive upgrade with minimal work, this is a well worn path.
Besides the better flowing heads, you'll also get a needed bump in compression as the Vortec heads are 64cc.

If you want to get more involved you might have to provide more detail on the engine spec. Do you know how far the pistons are down below the deck? Is there a piston part number? Valve notch cc is handy to know. Have you timed the cam on installation so you know the intake centreline is confirmed? Speaking of cams, I couldn't find that part number. Maybe a typo?

And of course there is this^^^

 

The cam # is from the build sheet of machine shop. It’s a Elgin cam kit so I was just looking it up and trying to break out the cam itself from that part number. Pistons are silv-o-lite flat top 4valve relief.
I got this when we bought the engine. I only paid $1200 for engine. Hind sight always 20/20 and should’ve done more before dropping in but am in the learning process and for me it’s like tearing apart 6 or 7 times before it’s right.

 

Yep. Definitely a top of the page cam. It'll be up to you if want to upgrade that but as mentioned, it's pretty weak and the benefit of upgrading the heads won't be realized unless the cam is bumped up with it.



That said, the heads are certainly worth doing regardless. Even if only for the bump in compression.
And as in most hot rodding, tearing it apart 6 or 7 times until it's right is part of the process.
For the record, it's never right.

 

Truer words have never been spoken...

 

Not sure if the OP is still around but there are options besides the tried and true but limited Vortec heads.

There are the AFR Enforcers which although are off shore (as in Chinese) castings, get a pretty decent review.

There are also Summit's house brand of heads. Both in Vortec style and aluminium.

Skipping the Vortec will save the cost of another intake by the way.

As always, there always the buyer beware factor as both of those brands are off shore castings. AFR states theirs are machined in the U.S.
I can't say the same for Summit.

 

I'm running the Flotek 180cc and am pretty happy with them. Had my local shop tear them down and do a once over on them as well.

Small Block Chevy 180cc/64cc | FloTek - Evansville, IN (flotekheads.com)

 

I got some reviews on those too. And like you said, it's worth it to verify that their QA is really QA. If you what I'm saying here...!

 

Oh I know what you're saying. I believe the casting is offshore but assembly and parts are U.S.A. I read somewhere that the castings are from Australia or the other place that can't even make a toaster properly.

 

Yes I was thinking the aluminums that way I wouldn’t have to buy a new intake. Since the one on it is new. How many cc do you stay around 180, 190 then?
What about those edelbrock heads? Anyone have input on them?

 

I went with the 180 to keep the compression up

 

Unless you're gunning for high HP, my best advice is to keep the intake runners small.
FWIW, I've a 175 cc intake on my aftermarket Vortecs. CFM is 255@.550". 357 SBC.
The guy who is designing and grinding my cam has all of my relevant data and projects HP to be 450 at 6200 RPM (as observed on a dyno with open headers and stripped of accessories, etc.).
Anyway, what that says is 1) a small port can get the job done and 2) for a given CFM target, a small port will do a better overall job (of course there are caveats to that).
Edelbrock, Flotek, AFR Enforcers I think is safe to say are all in the same camp.
It wouldn't be difficult to build a spread sheet with the usual suspects and look and the numbers. CC vs CFM. Valve sizes. Chamber cc. Spring package.

 

Gotcha. I’ll look around. Thank you.
Again I appreciate the the help a tips from all. There is 100 ways to skin a cat and info from every angle is great to piece stuff together. Maybe combining 3 or 4 things always works.

 

The "180 cc" has nothing whatsoever to do with compression. That's the intake port volume. Stock intake ports are in the 160 cc neighborhood; aftermarket ones for SBC go up to around 230 or so.

The numbers having to do with compression are the combustion chamber volume. They're generally in the 60 - 75 cc sort of range. 64 is a very common and usually appropriate number.

Those 2 numbers are completely unrelated. In fact, many of the head mfrs offer the same model of head in every possible permutation of port vol & chamber vol that they cast; for example, 180 cc ports w/ 64, 70, or 76 cc chambers, 200 cc ports w all 3 size chambers, etc.

Aluminum heads REQUIRE about a point higher compression than iron, ceteris paribus. To put the numbers you'd be needing to look at into perspective, a set of 64 cc heads on a typical rebuilt .030" over 350 with 6 cc valve-relief flat-top pistons with the usual stock .025" of deck clearance PLUS the added .020" that virtually all "rebuilder" pistons have, you'll come up with 9.2 - 9.3 compression ratio. Ceteris paribus, you'd need 10.2 CR with aluminum heads, more or less, which will require chamber volume around 54 cc. AFAIK there isn't any such thing.

Which is why I asked, why aluminum. Given the handicaps you're starting out with, not the best choice.

A typical "better" choice that will fit your intake would be something more like Dart Iron Eagles, such as these https://newdart.wpenginepowered.com/...-Sheet-H06.pdf in the 64 cc chamber size. Incidentally they make this series of heads in 165, 180, 200, 215, & 230 cc intake ports as-cast, with 64 or 72cc chambers. I'd recommend a Comp XE262 cam & matching lifters along with them. Buy the heads fully assembled, with the upgrade spring package (1.44" OD) included. If you really want roller rockers my suggestion would be Comp 1601.

I've never used Flotek heads. No idea whether they're any good or not. Dart however is a very long-time familiar mfr that I've used many times before over many decades, with good results. Probably not the cheeeeepest, let alone least expensive, but reliable, and they PHYSICALLY ANSWER THE PHONE when you call them. They're up in the Detroit area.

 

Props for the Darts too.

​​With 64 cc chambers, a piston waaaay down (see what I did there) at like .030" and an .026" head gasket will get you close to 10:1.
Something in or around how one of my 350's was built using Vortecs and a flat top Speed-Pro piston measured at .029-.033 below deck.

 

My bad. I got the spec mixed up. It's the CC volume I was thinking about. Mine are 64

 

As for the cam, you owe it to yourself to think long and hard about that.
Whatever heads you decide on, I'll bet you're just not going to be happy with the outcome.
That cam is very limiting.

 

Yes, JUNK. Performer RPM 60739 - valve springs not cut square, pushrods will rub the sides of the intake runners, not at all unlike the offshore ebay heads.
I expected better from MADE IN USA.

 

When did you get your heads?
This looks like another candidate that needs to be disassembled and inspected. Seems that Edelbrock has really taken a downturn. The 60739's I purchased twenty years were pretty good heads IIRC. Should have kept them too but sold them off to finance more car crafting.

A fellow on another forum who worked in R&D at Edelbrock many years ago said that after the new ownership, the development side got stripped of it's budget. Could be like so many other of the big brands that got bought by some equity firm are now selling goods based on the name and not the quality. Witness Comp Cams. I can't get the lowdown on what they manufacture on their own or where they're getting their cores or machined bits from but prior to the buyout, it was labelled as made in the USA and from my personal experiences, always held up.
This is why I went with a well respected niche cam designer/grinder as at least he offered up the straight scoop on where his cam cores are made. Same with the lifters and springs. I've managed to dial in all made in the USA from quality manufacturers. With solid and recent reputations that are still intact.

 

It could actually be going on 20 years now.

 

Certainly wasn't the case at this end. I'm not trying to tip my hat to them but those heads saw service on a couple of engines and then sold to another racer. Not even so much as a set of guides in that time which is something I can't say for the likes of Brodix or RHS. And it was the same guy setting up the valve train on each (yours truly). But, that's not really a fair comparison.
I can't imagine it's gotten better at Edelbrock with the changes that have happened there. Or Comp. Etc.

It pays to do your research I guess. I'm not talking about what you and I did 20 years ago but more so today as the playing field has really changed. Flat tappet lifters are a prime example of buyer beware. There are countless stories of cams going flat and lifters being wiped out yet my cam guy sells hundreds of flat tappet cams and lifters every year and he can't recount a single case of a failure. That really says something. To keep the record straight, he may have mentioned there was one failure but the details of the how and why escapes me. It's a matter of internet record though. Or call and ask him. I don't recall where his cam cores come from as they're various depending on the cam. For flat tappet lifters he's only ever recommended Hylift Johnson out of Michigan although he has covered a few other US manufacturers. Morel comes to mind. And some lifter origins are a mystery altogether. This is SBC stuff by the way just to keep it in context.

With regards to cylinder heads, Eric Weingartner of Weingartner Racing has a decent string of videos he's been releasing. If you follow his stuff, you'll get the goods on where the heads are cast and where they're machined. He also digs into the quality of any given head he's testing or modifying. It's very enlightening. It's from his channel and from the likes of the some of the contributors at Speed Talk (there are more than a few pro engine builders hanging out there) that I've gained an insight into cylinder heads, who sells what castings as their brand and what their quality is like. And who copies who! Even the venerable AFR has taken to providing a "discount" head that starts life in China. You have to hope the QA people are doing a good job on the final product.
If I were in the market for heads like I was for a cam and lifters, I'd have a pretty sizable database to work with.

In all fairness, COVID really messed things up as well. The experienced tradespeople who did the machining at say an Edelbrock or a Comp, are gone. Or at least not as they were. And this doesn't include the countless closures and /or relocations of facilities as that in and of itself provides a lot of grief for the folks in quality control.