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Expert
Posts: 2264
  
Location: McComb, Mississippi | I have decided to completely rebuild the 413 in my Imperial and looking for small ways to increae horsepower. So far I have decided to use a close to stock spec cam, electronic ignition, edelbrock 1407 with spacer, port and polish the heads, and a windage tray. I also plan on using synthetic oil. Is there anything else that can increase horsepower? I'm not looking to add headers. I'm just looking for little things to help. What kind of increase can I expect with the plan that I have? |
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Expert
Posts: 1497
Location: Fairfax, Minnesota | Rodger, you are up to bat.... |
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Expert 5K+
Posts: 8443
Location: Perth Australia | Never enough
No matter what you do to it, you will always think "now if I just do this or do that, I will get a bit more" 
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Expert
Posts: 2002
Location: Branson, MO | If your car does NOT have A/C, you can use an A/C waterpump that has a smaller impeller and will save some power. We did this when we were drag racing. Electric fans instead of the standard engine powered fan will save some more. Dual exhausts with an "X" pipe helps with low restriction mufflers. Low restriction air cleaner, block off the crossover heat passage in the intake manifold that warms the carb and eliminate the heat riser. Engine warm-up will suffer with the latter but works fine in the summer. Your HP gain will probably not be all that much - maybe 25HP to 35HP but every little helps and might give better fuel economy to boot! Be sure to advance your timing the most you can with little or no "pinging". If you want to take advantage of advancing your cam with respect to the crank, you can do that with an offset bushing while the engine is torn down but I wouldn't go more than 1.5 to 2 degrees. The advance gives quicker acceleration and retarding the cam WRT the crank gives more top end. The cam is "automatically" retarded as the timing chain stretches. And speaking of timing chain, use the double row roller chain instead of the wide flat one - they are interchangeable.
"It's delightful, it's delovely, it's DeSoto"
Edited by Viper Guy 2016-01-19 7:13 PM
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Location: North Australia | I'm no expert but to answer your question, if you look for small ways to increase power, you will get small increases! 
I rebuilt my 1960 Imperial engine similar to your specs above. Plenty of room for improvement if you match port the in and ex manifolds. When I did mine I found a number of passages with more than 1/8 inch steps on the mating faces. I used a rebuilt standard Carter carb, Mancini supplied standard curve distributor, fitted a thermo cooling fan amongst other small improvements and the engine runs real nice. Heads slightly skimmed to get them flat and smooth (with a slight increase in CR) with hardened exhaust valve seats. Careful piston selection is important, be sure you don't get the truck pistons. I also had the rotating assemble balanced, but it was real close anyway, even the new Egge pistons were nearly spot on.
Steve.
Edited by 60 Imp 2016-01-20 8:18 AM
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Elite Veteran
Posts: 1117
Location: STL, MO | 4.15 crank |
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Location: North Australia | Also think about the valley pan cover, you can buy them with the heat crossover blocked. I installed one in my engine and removed the exhaust valve. I did this because the car lives in the tropic north of Australia (cool air = HP) I also installed a new twin stainless steel system from Waldron's. This installation would (probably) be the worst decision I made in regard to performance of my car because of the small tail pipe. 1 3/4" tail pipe, with 2'' from the manifolds to the rear of the mufflers. The system itself is great (it's SS and fit very well), just the same as standard and very well priced when I got it in 2011.
I am thinking about a cool air duct to the air cleaner from the front of the radiator support plenum (more cool air!). This might be a mod I do when I finally get around to fitting the AC. to the car.
Some pics here of the head work I did.
http://www.forwardlook.net/forums/forums/thread-view.asp?tid=31214&...
Edit, sorry the link went to the wrong part of the thread, pics on page 1.
Steve.
Edited by 60 Imp 2016-01-21 7:02 AM
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Expert
Posts: 1506
Location: Colo Spgs | Hola Christian
The "rolling weight" of any Imperial is a bunch.
To Polish the Runner's is not a good thing with any set up if you keep it below 4,000 RPM's ( just as header's and looong spec'd cam's ).
The Match Porting The Intake to The Head and then to The Exhaust Manifold is a "biggie" with any engine.
Using a Thermo Silicon Fan Drive ( NAPA's number is: 271-303 ) is to not consume power. To use any MoPar or GM Cooling Fan made between 1988 to 1980 has it's benefits ( rear
wheel drive vehicles at a pick & pull ). This assembly only was equipped if the vehicle was a factory A/C. If your Imperial has A/C - The Cooling Fan --- is all you need.
The Muffler such as NAPA's 21-400 will have the same Dyno Data as any Dual Exhaust ( only one series of 1963 Imperial had a Dual Exhaust ). Keep the Diameter the same diameter
from The Exhaust to The Muffler. This started with mid 1964 Dodge Truck's and went to car's later.
To have an Warm Up "flapper" on the Right Exhaust Manifold with a "stove pipe" to the Air Cleaner Housing adds HP when the unit is still below the engine operating temperature. The
"stove pipe" part of this is a after 1968 item.
The Engine Oil that is a 10-30W spec is Dyno Proven to be better than any thing thicker.
The A/C Water Pump - A/C Water Pump Pulley and A/C Diameter of Alternator Pulley is as said --- A Good Thing.
For a change in Cam Spec's that MoPar went to and then was copied by other's is the standard unit used in any "standard" powered 1971-1968 440.
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As always the flex fan and any circular Air Cleaner Housing ( non snorkel ) --- sure looks good under the hood - but is not doing anything towards MPG - HP and the like.
Rodger & Gabby
FltSgt@outlook.com
Colo Spgs |
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Expert
Posts: 2264
Location: McComb, Mississippi | Thanks for the responses you guys. This car has factory air so I have the silicone fan and water pump with smaller impeller. I like the idea of the cooler air intake. I'm thinking of a dual exhaust system as well. Lots of good ideas. |
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Expert
Posts: 3031
Location: N.W. Fla. | Id think it would be of bigger help to get that Land Yacht moving to advance the timing chain to get low end grunt, rather than top end power. |
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Looking for extra HP
