350/255HP Help please

Chipper Chapman · 05-29-2016, 06:03 PM

Can anyone help me out a bit in knowing what my 350/255 stocker motor should be making for power and what rpm range it should be peaking at? I've been beating my head off the wall with this thing for a few years now and just dosen't want to get any better. I'm thinking I may have the wrong cam in it but really don't know where to turn next. Thanks.

Alan Nyhus · 05-29-2016, 08:26 PM

Assuming no obvious issues, a couple of pulls on a dyno can save you lots of time.

What kind of h.p. numbers are you getting when calculating from the E.T.?

Chipper Chapman · 05-29-2016, 08:47 PM

Made 387 @ 5600 on A&J dyno. 100% new engine except for the cam as it was like new and only a couple seasons old. The worn out peice I had before made 384. The slide calculator agrees with this. A little background info, it's got all what's supposed to be great gear, .065 over cp c6 Pistons with total seal advantage ring pack, Manley rods, new heads from reputable shop that flow quite well, pac 1409x springs, bullet cam, short travel lifters etc.eal down is 8-9% cold, we've had it apart again to make sure nothing is going away or getting tight and all is well. It's just not adding up, and it's beginning to make my head hurt lol.

Kevin Panzino · 05-29-2016, 08:55 PM

Are you saying the leakdown is 8 to 9%????

jamie2370 · 05-29-2016, 09:19 PM

Not trying to be ugly but that combo should make north of 430. How "new" are pistons? Most likely the problem is the ring package. Having said that I am not an engine builder nor do I build my own motors but I have been around stock for all my life and fairly up to date with what it takes to make them run.

HP HUNTER · 05-29-2016, 09:28 PM

Quote:

Originally Posted by jamie2370

Not trying to be ugly but that combo should make north of 430. How "new" are pistons? Most likely the problem is the ring package. Having said that I am not an engine builder nor do I build my own motors but I have been around stock for all my life and fairly up to date with what it takes to make them run.

Yes 430 + with much higher peak than 5600 RPM. 119 MPH @ 3350 = 440 HP

Alan Roehrich · 05-29-2016, 09:32 PM

You're down 35HP or more, and your peak is maybe 600RPM or more low.

If you're really leaking close to 10% on an engine that is up to 160 degrees, you're not sealed up.

I seriously doubt that either Total Seal or CP has missed the mark on the rings or pistons, especially if you had them work together. I've used their stuff successfully many times.

Adger Smith · 05-29-2016, 10:16 PM

He said "Cold" Leak. That never has told me anything. I don't race Cold Engines... Could have bad ex seats and when it gets hot they go away..... Just Saying...

Alan Roehrich · 05-29-2016, 10:21 PM

Quote:

Originally Posted by Adger Smith

He said "Cold" Leak. That never has told me anything. I don't race Cold Engines... Could have bad ex seats and when it gets hot they go away..... Just Saying...

Agreed. Cold leak down is useless. Honestly, on these engines, you need to be using a Dwyer gauge, or something, to test blow by on the dyno. Leakdown, even hot, can be misleading. Measuring blow by eliminates all of that.

Jim Hanig · 05-29-2016, 11:40 PM

If its a junkyard block 384 is not that bad,if its leaking more than 6% you got problems, Call Greg at race rings get his ringpack give him the grove dept,and he will fix you up get it honed with a plate . Cam should be in at 103-104 with a three speed.spring pressure around 145 -385 with reg lifters. Bowtie should pick you up 20. good luck.Not all dynos are the same.

05-29-2016, 06:03 PM	#1
Chipper Chapman Member Join Date: Jan 2004 Location: Belmont N.S. Canada Posts: 473 Likes: 246 Liked 163 Times in 71 Posts	350/255HP Help please Can anyone help me out a bit in knowing what my 350/255 stocker motor should be making for power and what rpm range it should be peaking at? I've been beating my head off the wall with this thing for a few years now and just dosen't want to get any better. I'm thinking I may have the wrong cam in it but really don't know where to turn next. Thanks. __________________ Chris Chapman 1969 Chevelle NHRA F-G/SA 1090

05-29-2016, 08:26 PM	#2
Alan Nyhus VIP Member Join Date: Dec 2002 Location: Lower Dakota territory Posts: 1,180 Likes: 1,074 Liked 799 Times in 236 Posts	Re: 350/255HP Help please Assuming no obvious issues, a couple of pulls on a dyno can save you lots of time. What kind of h.p. numbers are you getting when calculating from the E.T.? __________________ "That'll never work....."

05-29-2016, 08:47 PM	#3
Chipper Chapman Member Join Date: Jan 2004 Location: Belmont N.S. Canada Posts: 473 Likes: 246 Liked 163 Times in 71 Posts	Re: 350/255HP Help please Made 387 @ 5600 on A&J dyno. 100% new engine except for the cam as it was like new and only a couple seasons old. The worn out peice I had before made 384. The slide calculator agrees with this. A little background info, it's got all what's supposed to be great gear, .065 over cp c6 Pistons with total seal advantage ring pack, Manley rods, new heads from reputable shop that flow quite well, pac 1409x springs, bullet cam, short travel lifters etc.eal down is 8-9% cold, we've had it apart again to make sure nothing is going away or getting tight and all is well. It's just not adding up, and it's beginning to make my head hurt lol. __________________ Chris Chapman 1969 Chevelle NHRA F-G/SA 1090

05-29-2016, 08:55 PM	#4
Kevin Panzino Senior Member Join Date: Oct 2002 Location: Pittsburgh Posts: 571 Likes: 288 Liked 738 Times in 134 Posts	Re: 350/255HP Help please Are you saying the leakdown is 8 to 9%????

05-29-2016, 09:19 PM	#5
jamie2370 Member Join Date: Dec 2014 Location: Perry, GA Posts: 331 Likes: 11 Liked 239 Times in 90 Posts	Re: 350/255HP Help please Not trying to be ugly but that combo should make north of 430. How "new" are pistons? Most likely the problem is the ring package. Having said that I am not an engine builder nor do I build my own motors but I have been around stock for all my life and fairly up to date with what it takes to make them run.

05-29-2016, 09:32 PM	#7
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,066 Likes: 1,487 Liked 1,630 Times in 378 Posts	Re: 350/255HP Help please You're down 35HP or more, and your peak is maybe 600RPM or more low. If you're really leaking close to 10% on an engine that is up to 160 degrees, you're not sealed up. I seriously doubt that either Total Seal or CP has missed the mark on the rings or pistons, especially if you had them work together. I've used their stuff successfully many times. __________________ Alan Roehrich 212A G/S

05-29-2016, 10:16 PM	#8
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: 350/255HP Help please He said "Cold" Leak. That never has told me anything. I don't race Cold Engines... Could have bad ex seats and when it gets hot they go away..... Just Saying... __________________ Adger Smith (Former SS) Last edited by Adger Smith; 05-29-2016 at 10:17 PM. Reason: sp

05-29-2016, 11:40 PM	#10
Jim Hanig Senior Member Join Date: Aug 2006 Location: Pukwana SD Posts: 858 Likes: 554 Liked 97 Times in 47 Posts	Re: 350/255HP Help please If its a junkyard block 384 is not that bad,if its leaking more than 6% you got problems, Call Greg at race rings get his ringpack give him the grove dept,and he will fix you up get it honed with a plate . Cam should be in at 103-104 with a three speed.spring pressure around 145 -385 with reg lifters. Bowtie should pick you up 20. good luck.Not all dynos are the same.