335 HP 396 290 Head Casting Build & Dyno Test

[HP HUNTER]

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.

[Jeff Stout]

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.

[HP HUNTER]

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

[Tim H]

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

[Glenn Briglio]

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

[HP HUNTER]

Originally Posted by Glenn Briglio

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

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!

[Dwight Southerland]

Did you pour the intake and exhaust ports for volume?

[HP HUNTER]

Originally Posted by Dwight Southerland

Did you pour the intake and exhaust ports for volume?

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.

[Adger Smith]

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

[HP HUNTER]

Originally Posted by Adger Smith

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

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.