335 HP 396 290 Head Casting Build & Dyno Test
 

A while back I was looking for a transmission and came across a complete 335 HP 396 Stocker drive train for sale and and bought it. From what I've been told this engine/trans ran 3-5 tenths under the index in D/SA trim, dyno data also came with the engine which I will share as well. My plan is to go through the 290 head castings and see if I can make some improvements then dyno test the engine and finally run it in the car. I tore the heads down and preliminary cleaned them for a flow test, which I will post as the car ran 3-5 under the index. I will be testing the other head as well before any work starts to make sure it's similar in flow to the first head tested.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

I have had 3 sets of 290 heads on s/s. The best set had bottom of exhaust brazed in and made flat. The intake as high as it could before going thru roof. Kept spring rate 300 or better closed. Under 300 I would lose 1 or more MPH.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

In the picture its hard to see but both the intake and exhaust valves are sunk quite a bit, probably to get CCs and piston to valve clearance, which I will check so I can get my heights setup before any work is done. Flow testing was done @ 28 inches, 4.350 bore, SF 600.

Short port:

.100 73
.200 131
.250 154
.300 181
.350 208
.400 232
.460 243

Long port:

.100 73
.200 132
.250 161
.300 185
.350 210
.400 235
.460 257


Exhaust: No pipe


.200 107
.300 131
.400 152
.480 165

One thing to note, when a BBC head is flat milled to the extent this head is, flow is lost, although I understand CCs have to be met some way, it's definitely a juggling act. At this point I will clean the head, then locate the highest (closes to the piston) intake and exhaust valve and check piston to valve clearance then CC the chambers, after this the cylinder head restoration will start with pictures. If anyone has flow data for this type of casting in Stock Eliminator trim casting numbers, please feel free to post along with opinions.

063
215
290

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Chev V8 Big Block Cylnder Head 3964290 Small plug Flow Data - unported
Data Source Int/Ex Valve .100 .200 .300 .400 .500 .600
Chevy 290 Oval Port Iron CHP 01
253.0 / 112.0 cc's, Exhaust = No Pipe 2.065"/1.725" 60/47 122/88 172/113 214/133 244/152 256/161
Chevy 290 Oval Port Iron CHP 02
253.0 / 112.0 cc's, Exhaust = Pipe 2.065"/1.725" 60/47 122/90 172/118 214/138 244/160 256/174
Special thanks to Stan Weiss for supplying data. This is only a small detail of information available on his website. It is worth the time to dig into his stuff at

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Flow test should be done with correct bore size or you could be getting incorrect data.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

I will agree, but I'm just looking to see the gain, I will not buy a bore sleeve and top plate for this small bore project. I've been very impressed with your qualifying, great work!

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Did you pour the intake and exhaust ports for volume?

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Not yet, but I certainly will pour them, when I'am done the intakes will pour less than they do now. I will not be doing any porting, and they were not ported previously.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Mark,
since I'm not well informed about the stocker combinatons...
What year and body does the 335 HP 396 fit?
I found the small cam 1969 335 HP 427 in Dwights class tool section

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

I believe its been factored down to 330 HP with an automatic, 1968 Nova, Camaro, Chevelle SS From GM 350 HP 396 .460/.480 lift. 335 HP 427 is .398 lift I believe.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

OK, Mark...that works.
I was looking for a GM rating of 335..& should have looked at 350 HP specs.
Yes, 335 is the rating for the 1968 350 HP 396 with stick shift.
What I think I saw is all bodies with stick in 1968 for stock are 335. (Base)
I see it has the bigger cam, too.
That Dog might hunt with a stick.
Thanks for the info...
Adger

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

When are you coming to visit?

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

I'm guessing you didn't flow with the manifold on.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

You would be correct, I simply wanted a base line on the heads as they were run. The 396 was a 440 HP engine as run, I know the factory intake easily supports more than that from other builds I've done in the past. I would be interested in knowing what a worked over intake was worth? I'am pretty sure the heads can be very much improved on, we're going to see soon.

https://classracer.com/classforum/sh...ad.php?t=78477

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Here's a better picture of the head before work was started. Notice both valves are sunk quite a bit. I checked all the valve heights, and checked PV clearance, CC the chamber 100.5. So according to my calculations its short on compression.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Seats installed.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Setting height, there's 60 now with a 2.065 valve BBC.............

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Intake flow long port now:

.200 153 + 21
.300 214 + 29
.400 250 + 15
.460 262 + 5

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

I hope you guys are appreciating this.
You could spend 4-6K for a set of Stocker heads and not get this much information.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

For us crayon eaters in the class, can you explain the pictures in better detail please?
I understand you want all the valve heads the same height in the chamber so with sunk seats, you're replacing the seats and getting all the heads to sit at the same height...got it. But in the picture where you say you have .060, you're measuring from the deck height and what? I can't see but I'm assuming you're going to the top of the seat you installed?

Once all valves are sitting in the same place in the chamber, the cc's should be closer to start with...am I on the same page or in left field?

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

60 is the degree cut in the seat, that didn't exist before. This is a good part of the low and mid flow pick up.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

OK- the valve job is 30/45/60/75/90 on a BBC production head the valve bowl is too big to get much if any 60 degree angle with a 2.065 valve. In the picture you will see the lap line, below the lap line is the 60 degree angle which is around .180 wide, that 60 degree angle is partially responsible for the low lift flow gains. If you look at the picture before modifications you will see there is very little 60 degree angle below the 45 degree seat. Hope that explains it.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Mark… I am really looking forward to the results. As per our previous discussion it should be interesting. Maurice

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Great, happy to have you involved. More pictures

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Exhaust flow is now:

.200 126 + 19
.300 160 + 29
.400 175 + 23
.480 178 + 13

Exhaust valve is tullipped.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Ready to be cleaned and assembled.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

If you don't mind sharing, how wide is the seat and how wide are the other angles?

Thanks

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

The intake seat is .045 wide, The exhaust is .065 wide, I will have to measure the other angles widths and get back to you.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Hmm, narrower than i thought. I kept exh seat a bit wider to help heat dissipation (.070)
And then I did the same for intake (.070) and the others were kept to whatever it took to put the seat (45) where i wanted it so the 30 and 60 vary from .030 to .07.

Am i on the right track or did i mess up?

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Can you post a picture? I don't think I'am qualified to answer that question, .005 extra width on a seat I wouldn't think would make or break you.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Certainly more qualified than me! I have a bunch of pictures i have to resize then i?ll post but be ready to be not impressed, lol.

Learning a lot following threads like this!

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

This is the combo I use in my Chevelle. I?ve been working it at a few years and have it down to 330 in that body with automatic. I believe it?s 335-340 in Camaro/nova still

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Lots of ways to go fast!

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Ok- so I finished the heads and started looking at the short block. The original plan was to run the reworked heads on the short block as delivered, but I wasn't happy with the short block and have started the rebuild on that. The dyno sheets I received with the engine showed a best of 441 HP I believe, I can post them if anyones interested, which sounds just right considering what the car ran. So what I found when the pan came off was stock GM rods with NHRA legal pistons with a standard ring pack, quite a bit of drag, the block was filled, .009 piston to wall clearance, a GM big truck pan with a crank scraper and a full length windage tray. Compression was way low considering what's allowed, probably 1/2 of a point, and then the offset head dowel pins and the butchered intake that goes along with that. On a good note the engine had an aluminum hub ATI balancer. So maybe we can get a nice performance gain, so I will go though the short block and get it together and run it on the dyno, then track test it in my F/SA Chevelle, and all by the time the air changes this fall.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

The line hone is done, next the block will be decked, then TQ plate honed to .069 over.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

Done and ready to dyno.

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

When does it go on the dyno? Good read!

Re: 335 HP 396 290 Head Casting Build & Dyno Test
 

It's been to the dyno, the results were 486 HP @ 6300 RPM, up from 441 HP when I received the engine. When I went through the engine I tried to use as many of the original parts that came with the engine as possible. Its definitely down on power, and I believe this is due to the cam, I checked the lobe lift before I assembled the engine, which was where it should be, but what I didn't do is check the profile, which I believe does not have the duration it should, the cam and lifters looked good, but I think it knocked the corners of the lobes off, prior to my build. So from here it will get a steel cam with coated tool steel lifters.