critique this Magnum hop up, swap.

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gregsdart

gregsdart

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I have a plan for putting a 5.9 Magnum motor in my 65 Dart behind a 904 and 3.55 geared rear end. I am looking for any suggestions for making cheap power beyond what I have already planned for. Here is the plan.
I have a used Comp hydraulic roller cam with .480 lift, and 279 duration on both intake and exhaust, with 224 degrees duration @.050 on a 106 Lobe separation. If it will clear, I want to advance it as far as 102 to help it work with the stock 318 converter. It will have long tube headers, 1 5/8 tubes with three inch collectors going into 2 1/2 inch pipes and super turbo mufflers under the trunk area. (The spare tire well has been replaced with a flat sheet of steel.) Induction will be a dual plane air gap intake and 3310 Holley 750. Since I have to change out the valve springs, and want to look inside the motor a bit, a little back yard bowl porting is an option, along with a thinner head gasket if the motor will tolerate the extra compression? I could also back cut the valves if it is worth doing. Any other tricks or tips welcome.
 
Sounds like a torquey little mill! Magnum's sure aren't race heads, but I feel they are a great way to pick up comp and port velocity. Never hurts to do some pocket porting under the valve heads. Keep in mind the magnum exhaust port works much better than an la head,so getting more intake flow will help. Keep it reasonable, and port velocity will stay up. Between the thin gaskets and the magnums, comp might be as high as 9.5:1. Depends how far down your piston is, and how big it's dish.
 
Pistons on a stock 5.9 Magnum,are roughly .050"-060" in the hole . Sounds pretty solid ,overall.....
 
With the narrow LSA and 224 @ .050 I might need to move up in stall speed some, but that might fit some future plans for the car. I am considering setting it up for Sportsman bracketracing, looking to run mid to low twelves, and not having to have anything more than a helmet for safety equipment. The other car is a rush, but not having to suit up for every pass has appeal.
 
FWIW, try Rhoads lifters to decrease the intake duration to better help with the stock torque converter. I have tried this trick with making use of these lifters on the intake lobes only as well as all the lobes. Adjust pushrods to suite. (Length)
 
Definitely clean up the bowls and port match intake/exhaust. The valves don't really have a big ridge so back cut is your call. The guide supports in the bowls are huge and I removed at least a 1/4" on the intakes. Most of the exhaust seats had 90* ridges in the exhaust bowls.
I run a pro products knock off air gap and found a 1" 4 hole spacer works best.
If you run the thin gasket make sure the heads are flat. The gasket bore diameter is 4.180 so you don't really gain much CR over the stock head gasket 4.020 diameter. I had my heads milled .010" and ended up at 9.3:1
Make sure you check P to V clearance. You have no valve reliefs and if you really advance a cam you may have issues.
Stick a chain tensioner in there when you do the cam. I run a Lunati custom hyd roller 234/236@50, 495/475 lift, 108 lsa, 106 icl. I was able to reuse the stock pushrods and MP Magnum springs.
I would definitely put a better converter in. I run a Turbo Action 10" S800 tight converter and love it.
My car was bone stock Magnum 360/300hp crate motor/stock converter/low gear set 904/3.91 ran 12.7
Home ported heads, air gap intake, custom cam, TA converter best so far 11.86
If the track is not busy I can make 8-10 runs at a TNT session, cap the cutouts, and drive it home.
 
Gregsdart,
Your goal of mid 12s is definitely feasible.
I run 99 block, R/T cast heads (all stock), 9.3:1 comp., Mopar crate cam (501/511 lift), knockoff Air Gap, holley 650, 3000 stall, and 3.55 gears. First time out mid 12s without tuning on street tires shifting around 5500. Point is your combo should definitely be in that window with tuning, and I wouldn't fret over the cam you have should be plenty for the expectation. Plus if not fast enough for ya a gear swap would definitely put you into low, low 12s.
 
Thanks guys. This car will be a street Rod for 95 percent of its' use, so I do want to stick with some conservative choices, like
the 3.55 gears , reasonably tight converter and dual plane intake. The good part is it is a 2Dr coupe, and probably around 3,250 lbs with me in it. According to the Wallace hp calculator it will take about 400 dyno hp to go 12.00 given the elevation and weather in MN. If I need to put any $$ into the heads it will get a set of EQs which ought to do it.
 
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I know you remember the MP create engine, 360/380. Stock bottom end with a cam, intake, with a note on the page saying to use 1-3/4 headers and a 750cfm carb. They normally dyno' over 400hp.
 
rumblefish360 said:
I know you remember the MP create engine, 360/380. Stock bottom end with a cam, intake, with a note on the page saying to use 1-3/4 headers and a 750cfm carb. They normally dyno' over 400hp.
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good info. Haven't bought headers yet.
 
I was wondering about the thinner head gaskets as well as I'm doing a cam now. I believe the stockers are like .045 vs .028. Wouldn't this have some impact on pushrod preload and what not?
 
The OE head gaskets were .028.
Yes, it would have an impact on preload.
 
gregsdart said:
I have a plan for putting a 5.9 Magnum motor in my 65 Dart behind a 904 and 3.55 geared rear end. I am looking for any suggestions for making cheap power beyond what I have already planned for. Here is the plan.
I have a used Comp hydraulic roller cam with .480 lift, and 279 duration on both intake and exhaust, with 224 degrees duration @.050 on a 106 Lobe separation. If it will clear, I want to advance it as far as 102 to help it work with the stock 318 converter. It will have long tube headers, 1 5/8 tubes with three inch collectors going into 2 1/2 inch pipes and super turbo mufflers under the trunk area. (The spare tire well has been replaced with a flat sheet of steel.) Induction will be a dual plane air gap intake and 3310 Holley 750. Since I have to change out the valve springs, and want to look inside the motor a bit, a little back yard bowl porting is an option, along with a thinner head gasket if the motor will tolerate the extra compression? I could also back cut the valves if it is worth doing. Any other tricks or tips welcome.
Click to expand...
gregsdart said:
I have a plan for putting a 5.9 Magnum motor in my 65 Dart behind a 904 and 3.55 geared rear end. I am looking for any suggestions for making cheap power beyond what I have already planned for. Here is the plan.
I have a used Comp hydraulic roller cam with .480 lift, and 279 duration on both intake and exhaust, with 224 degrees duration @.050 on a 106 Lobe separation. If it will clear, I want to advance it as far as 102 to help it work with the stock 318 converter. It will have long tube headers, 1 5/8 tubes with three inch collectors going into 2 1/2 inch pipes and super turbo mufflers under the trunk area. (The spare tire well has been replaced with a flat sheet of steel.) Induction will be a dual plane air gap intake and 3310 Holley 750. Since I have to change out the valve springs, and want to look inside the motor a bit, a little back yard bowl porting is an option, along with a thinner head gasket if the motor will tolerate the extra compression? I could also back cut the valves if it is worth doing. Any other tricks or tips welcome.
Click to expand...
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Kinda like I have!...390 hp. Magnum Crate engine. Thermo-block is bored .020 over. Magnum R/T Big Valve cylinder heads. Mopar cast Al. valve covers. High strength SS Valves, 2.02" Int., 1.62" Ex. Heavy duty valve springs. Hydraulic Roller Camshaft- 230'/234' Duration @ .050"/0.513" lift. pistons 9:1 C.R. Double Roller timing chain and sprockets. Single plane manifold w/650 Double pumper. 150 hp. shot of NOS. Line lock. 3000 rpm stall. Hughes racing transmission w/B-M floor shift. All MSD ignition. MSD 6AL Control box w/MSD pro-billet distributor. Blaster 2 coil. 8 3/4" rear with 2.73 gears. (had 4.11 but changed them for better cruising). Dyno: 439.5 ft-lbs at 4100 rpm. 409 hp at 5400 rpm. Fun to drive. Makes me
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Dan B. said:
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Kinda like I have!...390 hp. Magnum Crate engine. Thermo-block is bored .020 over. Magnum R/T Big Valve cylinder heads. Mopar cast Al. valve covers. High strength SS Valves, 2.02" Int., 1.62" Ex. Heavy duty valve springs. Hydraulic Roller Camshaft- 230'/234' Duration @ .050"/0.513" lift. pistons 9:1 C.R. Double Roller timing chain and sprockets. Single plane manifold w/650 Double pumper. 150 hp. shot of NOS. Line lock. 3000 rpm stall. Hughes racing transmission w/B-M floor shift. All MSD ignition. MSD 6AL Control box w/MSD pro-billet distributor. Blaster 2 coil. 8 3/4" rear with 2.73 gears. (had 4.11 but changed them for better cruising). Dyno: 439.5 ft-lbs at 4100 rpm. 409 hp at 5400 rpm. Fun to drive. Makes meView attachment 1715007885 View attachment 1715007889 View attachment 1715007895 View attachment 1715007898 View attachment 1715007900 View attachment 1715007901 View attachment 1715007902

View attachment 1715007903
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Dan, that is a beautiful ride you put together!!
 
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