375-396 Stocker valve springs?

MAURICE BLENDHEIM · 10-27-2012, 10:01 PM

We have a 401 headed 375hp -396 Stocker engine with tool steel lifters and billet camshaft and 7/16ths. pushrods. We are wondering what are the most current valve springs and pressures that are being used? Where is this combination being run at RPM wise? Thank you in advance for your help.

Alan Roehrich · 10-27-2012, 10:07 PM

About 8200 RPM. Pressure is 250-270 on the seat and 525 or more open. The Comp 26115 is a good spring, if you're using an 1.550" spring and 2.00 installed height. You should really talk to the person you bought your camshaft from.

MAURICE BLENDHEIM · 10-27-2012, 10:29 PM

Thank you Alan... We were just talking about you before I posted this. Spent the day on the dyno and got as far as we could go with what we initially had. We are currently sitting with 210lbs. on the seat. We plan to put .090 under the springs in the morning and see where that will take us. If anything, we were easy on the cam.

Jim Hanig · 10-30-2012, 11:33 PM

8200 rpm for a 396 375, I sure hope tou have deep pockets cause that thing wont last long up there. Jim Hanig SS guy I doubt any 375 is making any power at 7500 let alone 8200. Not to say they wont go there they will will they still making use able power ,I personaly never saw one that does. Jim Hanig

SS Engine Guy · 10-31-2012, 02:47 AM

Why not?

Harry 6674 · 11-02-2012, 10:55 AM

If it's a legal stocker with legal weight rotateing assembly seems like a lot of weight to sling around very often. Now if you want to shave some off the crank with lite pistons and rods then it could live at 8200 but.

MAURICE BLENDHEIM · 11-02-2012, 10:14 PM

Quote:

Originally Posted by Jim Hanig

8200 rpm for a 396 375, I sure hope tou have deep pockets cause that thing wont last long up there. Jim Hanig SS guy I doubt any 375 is making any power at 7500 let alone 8200. Not to say they wont go there they will will they still making use able power ,I personaly never saw one that does. Jim Hanig

Jim... Our pockets are standard length, just resourceful. We are prepared to spin it to 8200 if that's what it takes. Our initial session was positive. With the better spring rate we will have better valve control which should net us better results next weekend. In regards to lasting, how long is long? It's a 375, is there anything else?

SS Engine Guy · 11-03-2012, 03:28 AM

Cast crank/ check each year. Anything that wasn't there the year before when checked toss it. Normally they will last 4 seasons. Make sure proper fillets are ground into the rod journals and the bearings are preped for that. 2 bolt block/ no problem. If not aftermarket block go with the thickest sonic test block and prep it with filler. The old 66' blocks were really thick. ATI or Fluidamper. Some overbalance at powerband range. Good pistons and pins. Carefull attention to detail on balance and general prep. Get someone who knows what they are looking for if using 3/8 rods and get rid of the parting line in order to mag properly. Use the best rod bolts and torque them at least 3 times during machine work and then stretch them to manufactuers spec. At next freshen up any bolts that the freestanding length is .001 or greater than in assembly log, toss them.

8200?....mine go thru the traps at that ,sometimes more and peak hp is up at around 7600 - 7800. (Peak hp is only a number to campare, peak torque is what is hard to accomplish). BBC intake ports are adequate for that number. The exhaust is the choke but with a well designed set of headers they will help that out if they scavenge well. (in the 1500-2000 dollar range for a header that works) Bullet Cams can help with some of the exhaust deficiencys. Get someone who understands the importance of a valve job to do the heads. With the new valve seat rule there is extra flow there too.

I understand the concern over piston/rod weight. Crank is rotating weight not reciprocating. Think of the weight of a 540 to 750 inch engine even with aluminum rods. Unless the rods are cyrogenic deep cycle they will weigh the same or sometimes more than a 7/16 chev. rod. Nitrous cars will usually use a heavier piston deck to be stronger in detonation situations. The biggest concern on the heavy rod/piston deal is the wrist pin on the intake stroke, when the piston stops at TDC and is pulled from a complete stop downward. That is why a good pin is necessary and monitoring them is critical.

You are correct. If you don't absolutely control the valve action with the proper spring you will run into clearance problems and beat the lifter into submission. I would tend to like a little more than not enough from a power and reliablility standpoint.

Alan Roehrich · 11-03-2012, 09:36 AM

We were spinning heavy components higher than that not to many years ago. People think it can't be done now because so many light components are common now.

If you're using really good connecting rods and wrist pins, the 396/375 piston is not that heavy.

If you're using a poured and sleeved 454 block, or better still, a Dart block, the block is no problem.

A good steel 396/427 crank is pretty tough, there is plenty of journal overlap, and if the block isn't moving around, it is not likely to break.

If you're not spinning a 396/375 up pretty tight, you're probably not going to go very fast.

chris ok · 11-03-2012, 12:34 PM

Nice to be back, and reading about Big Block Chevys.
8200 rpm big block is a beatiful song indeed.

10-27-2012, 10:01 PM	#1
MAURICE BLENDHEIM Senior Member Join Date: Jun 2011 Location: Langley (no igloos), British Columbia, Canada Posts: 567 Likes: 306 Liked 278 Times in 86 Posts	375-396 Stocker valve springs? We have a 401 headed 375hp -396 Stocker engine with tool steel lifters and billet camshaft and 7/16ths. pushrods. We are wondering what are the most current valve springs and pressures that are being used? Where is this combination being run at RPM wise? Thank you in advance for your help.

10-27-2012, 10:07 PM	#2
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,104 Likes: 1,560 Liked 1,784 Times in 407 Posts	Re: 375-396 Stocker valve springs? About 8200 RPM. Pressure is 250-270 on the seat and 525 or more open. The Comp 26115 is a good spring, if you're using an 1.550" spring and 2.00 installed height. You should really talk to the person you bought your camshaft from. __________________ Alan Roehrich 212A G/S

10-27-2012, 10:29 PM	#3
MAURICE BLENDHEIM Senior Member Join Date: Jun 2011 Location: Langley (no igloos), British Columbia, Canada Posts: 567 Likes: 306 Liked 278 Times in 86 Posts	Re: 375-396 Stocker valve springs? Thank you Alan... We were just talking about you before I posted this. Spent the day on the dyno and got as far as we could go with what we initially had. We are currently sitting with 210lbs. on the seat. We plan to put .090 under the springs in the morning and see where that will take us. If anything, we were easy on the cam.

10-30-2012, 11:33 PM	#4
Jim Hanig Senior Member Join Date: Aug 2006 Location: Pukwana SD Posts: 860 Likes: 554 Liked 99 Times in 49 Posts	Re: 375-396 Stocker valve springs? 8200 rpm for a 396 375, I sure hope tou have deep pockets cause that thing wont last long up there. Jim Hanig SS guy I doubt any 375 is making any power at 7500 let alone 8200. Not to say they wont go there they will will they still making use able power ,I personaly never saw one that does. Jim Hanig Last edited by Jim Hanig; 11-02-2012 at 04:50 PM.

10-31-2012, 02:47 AM	#5
SS Engine Guy Member Join Date: Sep 2003 Location: usa Posts: 256 Likes: 1 Liked 1 Time in 1 Post	Re: 375-396 Stocker valve springs? Why not?

11-02-2012, 10:55 AM	#6
Harry 6674 Senior Member Join Date: Dec 2006 Posts: 589 Likes: 0 Liked 0 Times in 0 Posts	Re: 375-396 Stocker valve springs? If it's a legal stocker with legal weight rotateing assembly seems like a lot of weight to sling around very often. Now if you want to shave some off the crank with lite pistons and rods then it could live at 8200 but.

11-03-2012, 03:28 AM	#8
SS Engine Guy Member Join Date: Sep 2003 Location: usa Posts: 256 Likes: 1 Liked 1 Time in 1 Post	Re: 375-396 Stocker valve springs? Cast crank/ check each year. Anything that wasn't there the year before when checked toss it. Normally they will last 4 seasons. Make sure proper fillets are ground into the rod journals and the bearings are preped for that. 2 bolt block/ no problem. If not aftermarket block go with the thickest sonic test block and prep it with filler. The old 66' blocks were really thick. ATI or Fluidamper. Some overbalance at powerband range. Good pistons and pins. Carefull attention to detail on balance and general prep. Get someone who knows what they are looking for if using 3/8 rods and get rid of the parting line in order to mag properly. Use the best rod bolts and torque them at least 3 times during machine work and then stretch them to manufactuers spec. At next freshen up any bolts that the freestanding length is .001 or greater than in assembly log, toss them. 8200?....mine go thru the traps at that ,sometimes more and peak hp is up at around 7600 - 7800. (Peak hp is only a number to campare, peak torque is what is hard to accomplish). BBC intake ports are adequate for that number. The exhaust is the choke but with a well designed set of headers they will help that out if they scavenge well. (in the 1500-2000 dollar range for a header that works) Bullet Cams can help with some of the exhaust deficiencys. Get someone who understands the importance of a valve job to do the heads. With the new valve seat rule there is extra flow there too. I understand the concern over piston/rod weight. Crank is rotating weight not reciprocating. Think of the weight of a 540 to 750 inch engine even with aluminum rods. Unless the rods are cyrogenic deep cycle they will weigh the same or sometimes more than a 7/16 chev. rod. Nitrous cars will usually use a heavier piston deck to be stronger in detonation situations. The biggest concern on the heavy rod/piston deal is the wrist pin on the intake stroke, when the piston stops at TDC and is pulled from a complete stop downward. That is why a good pin is necessary and monitoring them is critical. You are correct. If you don't absolutely control the valve action with the proper spring you will run into clearance problems and beat the lifter into submission. I would tend to like a little more than not enough from a power and reliablility standpoint.

11-03-2012, 09:36 AM	#9
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,104 Likes: 1,560 Liked 1,784 Times in 407 Posts	Re: 375-396 Stocker valve springs? We were spinning heavy components higher than that not to many years ago. People think it can't be done now because so many light components are common now. If you're using really good connecting rods and wrist pins, the 396/375 piston is not that heavy. If you're using a poured and sleeved 454 block, or better still, a Dart block, the block is no problem. A good steel 396/427 crank is pretty tough, there is plenty of journal overlap, and if the block isn't moving around, it is not likely to break. If you're not spinning a 396/375 up pretty tight, you're probably not going to go very fast. __________________ Alan Roehrich 212A G/S

11-03-2012, 12:34 PM	#10
chris ok Senior Member Join Date: Jul 2002 Location: Long Island, New york Posts: 592 Likes: 131 Liked 46 Times in 29 Posts	Re: 375-396 Stocker valve springs? Nice to be back, and reading about Big Block Chevys. 8200 rpm big block is a beatiful song indeed.