RAMM
Well-Known Member
Just a quick thread concerning a recent build and dyno session of a 408.
This particular 408 is slated for a Dodge P-U and all of the components were selected by the customer who is a savvy and patient dude. Like many times before this project started with the heads. Therefore a decent job was performed on the stock J heads before the 408 concept had been born. The heads were not ported and were just treated to a really good recondition job. The block is an ordinary LA360 that is .030", line honed, and decked.
Please keep in mind this has been a long term project and I no longer remember every little detail. It is a true blue pump gas ,daily driver, 408 with vacuum brakes and enough TQ to fry the tires at will.
Comp:Can't remember ran it through Eagles calc over a year ago: Cranking comp after dyno was 180-185psi
Cam : Used Mopar Mechanical P.S. .528" cam and lifters
Pistons: Wiseco forged flattops
Rods: SpeedMaster H beam--floating with no pin bushing (steel on steel)
Heads: J's recond'd 2.02/1.60"
Rockers : old 273's
Pushrods: 3/8" custom shortened
Intake : Holley Street Dominator
Carb: 750 QFT Dbl Pumper
Fuel: 94 Petro Can
Besides an embarrassing oil leak at the back of the intake the engine lit off and went without a hitch. We made it all the way through a 20 minute cam break in cycle and made 1 pull to 4500 rpm before any oil leak showed itself. Why did we breakin the cam for 20 minutes if it was a used cam and lifters? Because the customer had all of the lifters (15) except for one that was marked for their prospective position. I had to source a single solid lifter and we had to do a whole break in procedure to ensure that one lifter didn't kill a lobe .
All in all the engine ran great and held on in the upper rpm's a little better than I expected which I attribute to the solid cam. Total timing was perfect @ 32-33 total. The idle was 13-14" @ 900-950 rpm and after 16 tests it was clear that this engine was a solid 430HP/480 tq specimen. It started easily, shut off instantly and repeated within a few HP no matter what we tried-and we tried all manner of spacers.
Trying to be brief here-sorry for the rush. Nice engine-perfect for a truck IMO. J.Rob
P.S. I've included an oil pressure read out to show what a normal OP trend looks like.
Sorry for the sideways photos
This particular 408 is slated for a Dodge P-U and all of the components were selected by the customer who is a savvy and patient dude. Like many times before this project started with the heads. Therefore a decent job was performed on the stock J heads before the 408 concept had been born. The heads were not ported and were just treated to a really good recondition job. The block is an ordinary LA360 that is .030", line honed, and decked.
Please keep in mind this has been a long term project and I no longer remember every little detail. It is a true blue pump gas ,daily driver, 408 with vacuum brakes and enough TQ to fry the tires at will.
Comp:Can't remember ran it through Eagles calc over a year ago: Cranking comp after dyno was 180-185psi
Cam : Used Mopar Mechanical P.S. .528" cam and lifters
Pistons: Wiseco forged flattops
Rods: SpeedMaster H beam--floating with no pin bushing (steel on steel)
Heads: J's recond'd 2.02/1.60"
Rockers : old 273's
Pushrods: 3/8" custom shortened
Intake : Holley Street Dominator
Carb: 750 QFT Dbl Pumper
Fuel: 94 Petro Can
Besides an embarrassing oil leak at the back of the intake the engine lit off and went without a hitch. We made it all the way through a 20 minute cam break in cycle and made 1 pull to 4500 rpm before any oil leak showed itself. Why did we breakin the cam for 20 minutes if it was a used cam and lifters? Because the customer had all of the lifters (15) except for one that was marked for their prospective position. I had to source a single solid lifter and we had to do a whole break in procedure to ensure that one lifter didn't kill a lobe .
All in all the engine ran great and held on in the upper rpm's a little better than I expected which I attribute to the solid cam. Total timing was perfect @ 32-33 total. The idle was 13-14" @ 900-950 rpm and after 16 tests it was clear that this engine was a solid 430HP/480 tq specimen. It started easily, shut off instantly and repeated within a few HP no matter what we tried-and we tried all manner of spacers.
Trying to be brief here-sorry for the rush. Nice engine-perfect for a truck IMO. J.Rob
P.S. I've included an oil pressure read out to show what a normal OP trend looks like.
Sorry for the sideways photos
