Happy New Year! Looking to add a little more response to our 76'. It has a new Crate "Universal" 350. We have a Edelbrock Intake, Quadrajet (rebuilt and works great), and recently ripped out the old manifolds/exhaust for Tight Tuck heads H-Pipe with Magnaflows...sounds great! Additionally it has a Mild Cam...Edelbrock Performance Cam. So, next step for HP has got to be a set of new Heads to get us closer to 350/375HP. Anyone have any before and after testimonials on how much more pedal response making this change gave them? Also, any suggestions? ...Weekend Vehicle, not going on the track but would like a little more kick off the line!

 

Which Edelbrock cam they make a couple.
If its the performer plus its pretty tiny. Kind of like a truck/rv cam
Auto or stick do you know the rear axle ratio? All this will help

But in general the right head will make a huge difference.

 

I'm not sure on the cam...I bought it off my cousin and he replaced everything back in 2007...but it basically sat shortly after the engine replacement until this spring. I believe Rear axle ratio is original and it is an automatic. I know enough to hold a beginner conversation on engines but have no problem replacing cam, as I know some of this has to work together to run well. ...I think rear end is 3.08.

 

If youre sure its an edelbrock cam and idles pretty smoth its probably the performer plus
https://www.jegs.com/i/Edelbrock/350...saAiLOEALw_wcB

If you like the 308 gear their Estreet 170s could be a possibility. 24-2600 converter, cam maybe 10 deg or so larger would work great
Lots of torque decent mpg and good driveability
That could get you low 3xx at the crank. Possibly a little more

 

If we are talking stock heads vs what is out there now...any of them will be better performance wise. If you're going to go down this road I feel that aluminum is the best option over cast iron.

I've had two in my vette Dart SHP. DO NOT buy these heads. They are poorly done, quality control is poor at best, and will cause lots of problems.

I now have AFR 180 heads and the quality difference between them and the Darts is night and day. Very well sorted out with quality components. Have had no issues with them and could have bolted them on right out of the box.

There is a whole lot of meat between those two in the aftermarket aluminum head arena. Just do a search for chevy 350 aluminum heads and you'll see what I mean. Edelbrock, Blueprint, skipwhite etc, etc.
Keep in mind you generally get what you pay for in a head. Important stuff is the intake runner volume (180 is good for a 350 generally speaking) and combustion chamber volume. 64cc is a good place to start would give you about 10:1 CR if the motor has flat top pistons. .Sounds from other specs you've listed that it's likely this is an L-48. In which case it will not have flat top pistons and you'll be around 9.0 ish CR with 64 cc's. and a .015" shim head gasket.

Little hard to spec combustion chamber without knowing what the cam is. Mybe you could check the vacuum at idle, might gives us an idea at least.

Here is a CR calculator that may help you figure your CR and just as important the DCR if the cam specs become known at some point.

https://www.jeepstrokers.com/forum/calculator/

 

If buying Edelbrock heads, the E-Tec are the way to go but they need a Vortec intake.

There are a number of good cheap aftermarket heads. I think Promaxx is one that is decent.

 

I did before and after dynos for my L48.
went from 153rwhp to 276rwhp using Edelbrock Estreet heads(64cc) and torker plus camshaft. I have no complaints with the Estreet heads, I think they are fantastic bang for the buck.
according to edelbrock the Estreet heads and the performer plus cam that you most likely have is good for 315 crank hp and 381 crank torque(so probably 250 hp at the wheels?) There’s room to improve on those numbers with a better cam, as others have mentioned, the performer plus is pretty mild.
If the budget supports, I would consider the edelbrock performer RPM heads though.

 

https://treperformance.com/i-2390029...nter-bolt.html
These are on sale and will boost the compression approx 3/4 of a point on a 350 plus increase flow. Trick Flow has a variety of very good cyl heads, but the small chamber of these are part of their appeal.

 

ok, you need to decide where you are gonna stop. those trick flow heads with the 175 cc intake runners and 56 cc chambers are very nice 350 heads. but if you decide that ain't enough and now you wanna go 383 or 431 those heads are too small. the head and cam have to be correctly sized to match the bore, stroke and piston dome-dish. it would be better to buy a head that is a little too big for your 350 if you think you are gonna keep upgrading.than to have to buy heads twice. and LONG tube headers. no shorties. they are pretty exhaust manifolds...

 

I just have this to say, their are so many choices for heads available. perhaps you could clue us in on budget and if any other mods are being considered.

 

Dart just came out with a revised version of the SHP 180cc head. I like the design even tho it has one mild defect that I've seen on bare or assembled heads. That would be the slight divet by the spark plug holes.

 

Looks like they made some pretty good improvements in the ports. That's good.
One of the major issues I had with dart was the installed height on the valves. It was all over the place and all of them were too high. So even at full lift of .600 it left too much spring uncompressed promoting spring surge and loss of control of the valve. Even max shimmed they were still too high.
Another was the valve guides were loose even new. .004". At the time I didn't know that was unacceptable.
Also the as cast volume for both the intake runners and the combustion chamber were significantly larger than the advertised 180 cc and 64 cc.

I did a lot of porting work in the runners to fix the bumps and valve guide boss' that Dart had left behind impeding flow. Something they seem to have addressed in the new heads.

 

i had 4 iron dart heads on a twinn engined go-fast boat. less than 50 hours since new. one valve guide was so bad the rocker slipped over the side of the valve.

 

Summit/Dart 152123 USA made 72cc. I bought some years ago and are still priced under $700. Made a big difference compared to the crappy 624 stock heads.

 

I would look at Brodix IK 180’s, they flow about 245 for around $1100. Unless you’re going to go through them stay away from the cheap China stuff. E-street is a decent head, but on the expensive side for the flow.

 

I still like vortecs for a street 350, but with screw in studs. There are still a few aftermarket versions I think, that come with perimeter valve cover pattern and screw in studs.

 

The SHP is garbage.......the Pro 1 180cc is a super nice piece and the price reflects it.......
The 180 Dart Pro 1 is a knockout punch for a 350......I have yet to bolt a better head on a 350.....the port is beautiful I and E......the velocity they make is outstanding......
I bolted a set of 200cc Pro 1's on my own 406......torque flat as Kansas......
But......I just built a 357 with the Trick Flow DH 175's on it and the quality was outstanding.....the casting in the ports is some of the nicest I have ever seen.....so I will report on this when the engine is installed and fired.

To the OP......you need more cam.......the old 268H may work very well here but we have no spec on the engine you installed.

Jebby

 

These heads are the replacement spec for a 305...56cc chamber and 1.94 intake valve.

Jebby

 

Yes, I'm aware, and same port as 4.0" bore heads.

 

In my experience with DART Iron Eagle heads, even assembled, you need to tear them down and take to a good engine speed shop to ensure they are set up correctly. I purchased assembled around 2002 and they were worn out by 2010. After a good rebuild/setup in 2018, my IE's are spot on. 72cc chambers but I have Speed Pro flat top hypereutectic and wanted to stay down around 9:1. Heads were lightly decked, moderate bowl blending, new bronze guides, 1 size looser valve seals, hardened exhaust seat inserts cut and 4-angle valve job really brought them to life.

This followed having another speed shop perform an incomplete refresh of the heads with my retro-roller conversion in 2014. Before 2018, I had all sorts of issues and the car started to sit as I didn't have the time and life's complexities got in the way. Now, the combo is VERY streetable and lively (once I fix my ignition heat soak issue - in progress).

My local engine builder in FL had a long list of HP marine customers and went to NASCAR country in 2018-19.