TheOtherDodge's 408 Buildup

[Scotty]

(by TheOtherDodge)

Here was my 360 based stroker I ran:

525 hp, pump gas 408

Description: This motor buildup will provide a solid 500-550 hp with plenty of low end torque that, when used in a properly geared/converter/weight car, will net high 10’s/low 11’s in “street” trim. It is based on a 360 block, using a cast 4” crank, ported stock heads, and Chevy sized pistons and rods (for light weight and cost reduction). However, due to the introduction of Edelbrock heads, it is recommended to use them instead of stock castings due to cost efficiency. The motor will run on pump gas (93) with 36 degrees of total timing. The part numbers are either from Jegs or Summit. Either one should be able to cross the other’s numbers.

Parts requirements:

360 block

4” cast stroker crank

ARP Head studs 144-4001

ARP Main studs 240-5501

Eagle 6.125 rods CRS6125B3D

JE SRP forged pistons with .927 pin dia (see special assembly requirements)

ATI Harmonic balancer 085-918603E

Hooker Super Comp Headers (part number based on body style)

Childs and Albert file to fit Rings RS-9771-35

Clevite77 Main bearings (double check year of block) 695-MS1266P

Clevite77 Rod bearings (x CB663H

Clevite77 Cam bearing 695-SH875S

Edelbrock Performer RPM Cylinder head 350-60779

Crane Gold Race Rocker arm set 270-69790-1

Crane pushrods 270-69690-16

Comp Cams custom ground solid cam and lifters (call 1-800-999-0853) specs: .549/.549, 252/252 duration @ .050, 112 lsa.

Cloyes timing chain 220-9-3103

Melling high volume oil pump 689-M72HV

Windage tray P45297090

Hardened oil pump drive shaft P3690715

M1 Single plane manifold P4452891

Gasket set P4120692

Holley 4150 Series 950 hp carburetor 510-O-80496-1

1” open spacer 350-8720

Assembly:

Due to the type of motor being built, it is highly recommended that someone with experience assemble this motor. For that reason, step by step assembly instructions will not be given.

Special Assembly requirements:

1. Restrict the oil going to the lifter gallery.

2. On the lower part of each cylinder wall, a notch needs to be made to allow the opposing rod to clear. Attach and properly torque one rod/piston combo (without rings but with rod bearings). Rotate the motor slowly until the rod contacts the opposing cylinder wall. Mark this spot and clearance the cylinder wall using a grinder. Repeat for the remaining 7 cylinders.

3. To use the Chevy sized rods and pistons, the crankshaft rod journals will have to be ground down to 2.100. While doing this, it is possible to offset grind the crank to get a perfect 0 deck. See part 4 below before grinding crankshaft.

4. Before the piston is purchased, several things need to be done. This buildup is requiring a 0 deck to achieve a good quench to reduce the octane requirements of the motor, allowing the use of pump gas (93 octane). Therefore, the compression height of the piston will vary from engine to engine. Based on the rod length and deck height of the block (after the block has been square decked), determine what compression height you will need, taking into consideration that the crankshaft will need to be ground down. Once the theoretical compression height is determined, you will need to go to the JE SRP piston catalog to find a Chevy 350 piston with the approximate compression height you will need. There are numerous off the shelf pistons for a Chevy 350, so using a special stroker piston will not be necessary. If the piston with the approximate compression height is not going to yield exactly a 0 deck, that is ok. When the rod journals of the crankshaft is ground down to 2.100 it can be offset ground a little bit to move the piston up or down in the bore. Also, you can mill the top of the piston down some to help achieve the 0 deck. This may sound complicated, but any experienced machine shop is very familiar with this procedure. Keep in mind, the reasons for using the Chevy sized pistons and rods are to reduce costs and rotating assembly weight. The only extra cost is grinding the crankshaft rod journals down ($50, or $80 to offset grind). This price is absorbed in the savings of the rods and pistons. The rod weight difference between the Chevy and Mopar is 35 grams each and the piston weight difference is about 30 grams each.

5. Make sure whichever cylinder head is used, that it flows at least 280 cfm on the intake side. Although you can achieve this with a ported stock heads, it is economically cheaper and easier to use an aftermarket head such as the Edelbrock head.

6. Port match the intake side of the M-1 intake, square off the carburetor mounting pad and port the plenum, paying particular attention to raising the roof entrance.

Tuning suggestions:

set total timing at 36.

Run a mix of 2 gallons of 100 octane and 8 gallons of 93 octane to start. Gradually reduce the 100 octane to determine what fuel octane is best. Most likely with this motor and the proper quench of .045, you will be able to run 93 octane.

Use Autolite AR51 plugs set at .045 gap. Make sure your ignition system is good.

Leave the carburetor jetting as is, but replace the front 6.5 power valve to a 4.5 and plug the rear. Replace the stock front 35 squirters with 40.

Optimal gearing is a combination that will allow you to cross the traps at 6900-7000 rpms.

Optimal converter stall is 4800-5000

Optimal shift point is 6400

3” exhaust, Dr. Gas X cross over, free flowing mufflers

What to expect:

Relatively low maintenance. Check valve lash periodically. Change oil regularly. Check plugs regularly.

With an average chassis and 3450 lbs, through full 3” exhaust, I ran a best of 11.20@118.89. I only made 25 passes with the motor, so I never did get to find the optimal tuning. Also, this was in moderate air temps (around 82 degrees) and relatively high humidity (around 65%). I believe in cooler air (50degrees), 11.0X were possible. With a small roller cam (.630 lift) 10.8’s was attainable. The motor is also nitrous ready. A well tuned nitrous kit of up to a 200 shot can be used. With a 175 shot, this motor propelled the same car to a 6.51 in the 1/8th. Gear it for nitrous, and you will have a low 10, high 9 second car! This is all with a very streetable 408 small block!

[Scotty]

(submitted by a member...sorry, don't have their info)

My combo consist of :King Demon 1090 INDY intake,W5 heads-flow (I) 332 at .700 (E) 244 at .700.2.08 and 1.60 valves.Erson roller rockers 1.6.Erson roller cam 276-284 @.050 .675 lift with 1.5 108 LC.Weisco pistons 14.23 comp.BME rods 6.250,4in steel crank,PRO GRAM billet caps(4 bolt)MSD billet dist,ATI balancer,727 T/A T-Brake Coan conv 8in.5600 stall,4.56 9in Ford 28x11.5x15 M/T drags.Best time to date with old combo same as above except for M1 large runner Intake.10.06 at 131.314 1/8 mile 6.354 at 106.449 60ft 1.364.New combo have only ran 1/8 mile 6.47 at 104.777 60ft 1.335 with 69% humidity DA at 3850 ft.It seems to like the INDY intake,makes more torque but I hope it don't lack in HP

[moparwannabe]

Originally Posted by Scotty

(by TheOtherDodge)

Here was my 360 based stroker I ran:

525 hp, pump gas 408

Description: This motor buildup will provide a solid 500-550 hp with plenty of low end torque that, when used in a properly geared/converter/weight car, will net high 10’s/low 11’s in “street” trim. It is based on a 360 block, using a cast 4” crank, ported stock heads, and Chevy sized pistons and rods (for light weight and cost reduction). However, due to the introduction of Edelbrock heads, it is recommended to use them instead of stock castings due to cost efficiency. The motor will run on pump gas (93) with 36 degrees of total timing. The part numbers are either from Jegs or Summit. Either one should be able to cross the other’s numbers.

Parts requirements:

360 block

4” cast stroker crank

ARP Head studs 144-4001

ARP Main studs 240-5501

Eagle 6.125 rods CRS6125B3D

JE SRP forged pistons with .927 pin dia (see special assembly requirements)

ATI Harmonic balancer 085-918603E

Hooker Super Comp Headers (part number based on body style)

Childs and Albert file to fit Rings RS-9771-35

Clevite77 Main bearings (double check year of block) 695-MS1266P

Clevite77 Rod bearings (x CB663H

Clevite77 Cam bearing 695-SH875S

Edelbrock Performer RPM Cylinder head 350-60779

Crane Gold Race Rocker arm set 270-69790-1

Crane pushrods 270-69690-16

Comp Cams custom ground solid cam and lifters (call 1-800-999-0853) specs: .549/.549, 252/252 duration @ .050, 112 lsa.

Cloyes timing chain 220-9-3103

Melling high volume oil pump 689-M72HV

Windage tray P45297090

Hardened oil pump drive shaft P3690715

M1 Single plane manifold P4452891

Gasket set P4120692

Holley 4150 Series 950 hp carburetor 510-O-80496-1

1” open spacer 350-8720

Assembly:

Due to the type of motor being built, it is highly recommended that someone with experience assemble this motor. For that reason, step by step assembly instructions will not be given.

Special Assembly requirements:

1. Restrict the oil going to the lifter gallery.

2. On the lower part of each cylinder wall, a notch needs to be made to allow the opposing rod to clear. Attach and properly torque one rod/piston combo (without rings but with rod bearings). Rotate the motor slowly until the rod contacts the opposing cylinder wall. Mark this spot and clearance the cylinder wall using a grinder. Repeat for the remaining 7 cylinders.

3. To use the Chevy sized rods and pistons, the crankshaft rod journals will have to be ground down to 2.100. While doing this, it is possible to offset grind the crank to get a perfect 0 deck. See part 4 below before grinding crankshaft.

4. Before the piston is purchased, several things need to be done. This buildup is requiring a 0 deck to achieve a good quench to reduce the octane requirements of the motor, allowing the use of pump gas (93 octane). Therefore, the compression height of the piston will vary from engine to engine. Based on the rod length and deck height of the block (after the block has been square decked), determine what compression height you will need, taking into consideration that the crankshaft will need to be ground down. Once the theoretical compression height is determined, you will need to go to the JE SRP piston catalog to find a Chevy 350 piston with the approximate compression height you will need. There are numerous off the shelf pistons for a Chevy 350, so using a special stroker piston will not be necessary. If the piston with the approximate compression height is not going to yield exactly a 0 deck, that is ok. When the rod journals of the crankshaft is ground down to 2.100 it can be offset ground a little bit to move the piston up or down in the bore. Also, you can mill the top of the piston down some to help achieve the 0 deck. This may sound complicated, but any experienced machine shop is very familiar with this procedure. Keep in mind, the reasons for using the Chevy sized pistons and rods are to reduce costs and rotating assembly weight. The only extra cost is grinding the crankshaft rod journals down ($50, or $80 to offset grind). This price is absorbed in the savings of the rods and pistons. The rod weight difference between the Chevy and Mopar is 35 grams each and the piston weight difference is about 30 grams each.

5. Make sure whichever cylinder head is used, that it flows at least 280 cfm on the intake side. Although you can achieve this with a ported stock heads, it is economically cheaper and easier to use an aftermarket head such as the Edelbrock head.

6. Port match the intake side of the M-1 intake, square off the carburetor mounting pad and port the plenum, paying particular attention to raising the roof entrance.

Tuning suggestions:

set total timing at 36.

Run a mix of 2 gallons of 100 octane and 8 gallons of 93 octane to start. Gradually reduce the 100 octane to determine what fuel octane is best. Most likely with this motor and the proper quench of .045, you will be able to run 93 octane.

Use Autolite AR51 plugs set at .045 gap. Make sure your ignition system is good.

Leave the carburetor jetting as is, but replace the front 6.5 power valve to a 4.5 and plug the rear. Replace the stock front 35 squirters with 40.

Optimal gearing is a combination that will allow you to cross the traps at 6900-7000 rpms.

Optimal converter stall is 4800-5000

Optimal shift point is 6400

3” exhaust, Dr. Gas X cross over, free flowing mufflers

What to expect:

Relatively low maintenance. Check valve lash periodically. Change oil regularly. Check plugs regularly.

With an average chassis and 3450 lbs, through full 3” exhaust, I ran a best of 11.20@118.89. I only made 25 passes with the motor, so I never did get to find the optimal tuning. Also, this was in moderate air temps (around 82 degrees) and relatively high humidity (around 65%). I believe in cooler air (50degrees), 11.0X were possible. With a small roller cam (.630 lift) 10.8’s was attainable. The motor is also nitrous ready. A well tuned nitrous kit of up to a 200 shot can be used. With a 175 shot, this motor propelled the same car to a 6.51 in the 1/8th. Gear it for nitrous, and you will have a low 10, high 9 second car! This is all with a very streetable 408 small block!

What would a combination like this cost to build? Just a ballpark figure.

[Scotty]

You'd have to pm TheOtherDodge to find out. I don't know what he spent on it. Sorry.

[TheOtherDodge]

The idea of that buildup was to keep the cost down, but still make a high quality motor. I figured about $4500 from carb to headers, but maybe a little cheaper if you can find used parts like a carb, intake, headers, etc.

[GMachineDartGT]

4500, I wish. Between my heads, porting, and valvesprings I'm for 1800 so far. Add in 750 for cam/lifters (roller), 750 for pistons, 400 for rods, 300 for crank, 250 for rings brgs , oil pump, 200 pan, 500 carb, 200 for a balancer, 200 for an intake, 350 for rockers, 200 for pushrods. Add in machine work, and you can blow through 4500 in no time flat.

[mikesduster]

i have a few questions.....

what if you wanted to run better heads like W-2/W-5,INDY,BRODIX,etc.??

what if you ran a bigger cam like a .MP.590/MP.620???

do you really think a motor making 500-550 HP and a shot of 175-200 NOS will survive with a CAST 4" crank??

how much comp. did you have and with how much CCof your heads??

[red440]

Theotherdodge,

quick question, what size nos shot did you use ? and how offten did you spray it ? ( the 408 ) thanks a lot..............Red

[mikesduster]

ANYONE???....ANYONE???