Joined: Thu Nov 17 2011, 08:08PM
Location: mn
Posts: 5
I found a 383 that appears to have very few miles on it. Cylinder walls are smooth and just a hint of lip. The only problem, in my mind, is the dished pistons.
i grew up when 10.5 or 11 CR was considered required for HP. Yep- that old. If I am able to keep the original pistons, what do you recommend for improvement?
I think I have just enough knowledge to get me in trouble.
Will a modern cam and intake/carb make a big difference?
How about milling the heads to raise the compression ratio? How much is practical?
Any suggestions that will help get another 30-40 horsepower over the stock 290 would be greatly appreciated.
First I say Thank You for finding The Site and Thank You for asking what can be done For Power Enhancement Hints.
As time has shown the best all around Compression Ratio is slightly at 9:1 to more than 9.5:1. With this you can use gas from about any place that you want to pay their price and you still have performance.
Using Factory Proven Items as a guide of what after market vendors copy - use the same cam shaft as you all ready have ( NAPA's CS-327 ) and The Heads - Intake Manifold used for all 1972 - 1978 Big Blocks. The Cam Shaft is spec'd to proved the best umph at the engine speeds you most keep the RPM's at and the 1972 - 1978 Intake Manifold and Heads permit the best breathing.
To many it is what can I do to lower the amount of energy that is being consumed vs what you are asking. Easy flowing is better than forcing and pulling.
Some bolt on items that you can use are The Fluid Fan Drive - The Factory Spec'd A/C Water Pump and the Larger Power Steering and Alternator Pulley's.
Some items that look good - but are worse power wise than what you have are the flex fans and the round chrome plated Air cleaner's.
Joined: Tue Oct 11 2005, 01:33AM
Location: Calgary, Alberta
Posts: 5893
Ray, welcome to the DryDock!
The answers to your questions depend upon what you plan to do with the engine, Sunday cruises around town, highway driving or even racing. I assume you are probably not into racing so you are most likely looking for a street cruiser with a bit of flash. In that case I would recommend Maybe a valve job, a carb rebuild, an electronic ignition and HP exhaust manifolds connected to a dual 2.5" exhaust system. With those small changes you'll have a street machine that runs and sounds like American Muscle and will do a pretty fair job at stop lights. Take a look at my web site below and look at the section on engine build to see what I did. My car will jump, but at my age I doubt my heart would handle a down and out drag race.
I found a 383 that appears to have very few miles on it. Cylinder walls are smooth and just a hint of lip. The only problem, in my mind, is the dished pistons.
i grew up when 10.5 or 11 CR was considered required for HP. Yep- that old. If I am able to keep the original pistons, what do you recommend for improvement?
I think I have just enough knowledge to get me in trouble.
Will a modern cam and intake/carb make a big difference?
How about milling the heads to raise the compression ratio? How much is practical?
Any suggestions that will help get another 30-40 horsepower over the stock 290 would be greatly appreciated.
Thanks, Ray
Mopar big blocks are very easy to get a lot of extra power out of. A 335 hp 383 with just a carb/intake/cam/exhaust swap can easily make 450 horsepower. You can bump that little 290 horse 383 2bbl up to a fun to drive 350 hp fairly cheaply. I've done several, and have always been impressed with the results.
1. The dished pistons are fine for all but a very high output engine, since on the 68-69 models they are set a zero deck (flush with the block). They are also a bit more forgiving of the funky fuel we have today than a higher compression piston.
2. The 68 heads already have the big valves, so when you get them rebuilt have them milled .020" to make up for the thickness of the Felpro head gaskets (the nice blue ones almost everybody uses) and that will put the compression around 9.3:1, possibly a bit more depending on the casting and chamber volume.
3. Put in a Comp Cams Extreme Energy or Lunati Voodoo camshaft/lifters/valve springs with an intake duration around 262 (but don't go more than 268 or you'll have to swap rear gears and torque converters) along with a double roller timing set.
4. Add a nice lightweight aluminum intake with a 650 cfm 4bbl carb. (I recommend an Edelbrock Thunder series)
5. Get a set of HP exhaust manifolds and hook them up to 2.5" dual exhausts.
6. Replace the old worn out oil pump and run an extra quart of oil in the pan.
7. Enjoy!!! You will notice a world of difference...
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
Just to add to what Kraut just said, get a DUAL PLANE intake. I`d suggest an Edelbrock DP4B (can be found used for cheap, almost as good as Performer), Performer or Performer RPM, but be careful of hood clearance with the Performer RPM because it`s quite tall.
Since the engine is out of the car already, drop the oil pan and install a windage tray. That will prevent extra windage due to running a quart over on oil, as Kraut suggests. If you get a Mopar windage tray, use a cold chisel and open up the slots in it before installing. As stamped, the Mopar windage tray has drainback problems because the openings are too small. Or get the Milodon #32000 windage tray