Projects Long Flatty 6

hey all
I can see there are a large selection of parts availible for the short block mopar flatty 6's, but does any one know if there is parts for the 250ci long motor? Looking for twin intakes and exhaust. Are they out there or am I gonna have to make em?????


Jimmy

 

I have two dual carb/dual exhaust setups for the big 6, they were a factory option in trucks. Both mine were removed back in the '60's because nobody knew how to tune them!

 

an option thats awesome any chance of a pic?

 

Rare in the US, Australia who knows, but probably non existent.

Most guys build their own. You can have cams reground, lifters refaced, shim the valve springs with washers. Weld an extra outlet on the exhaust, in other words split the manifold for duals. The latest thing is to make a square plate that bolts on under the carb and weld the new outlet to that.

It is also possible to weld 2 extra flanges to the intake and make a triple manifold. For street use, just use the 2 end carbs. Or, use an adapter to put a Weber progressive 2 throat on the stock manifold.

If you are real ambitious it is possible to make headers and intake manifolds out of steel tubing and flat flanges.

Another possibility is to get the crankshaft and rods from a 265, they have a 4 3/4 stroke, the longest stroke crankshaft that will fit without hitting anything.

In your case you have the Powerflite automatic. This means some of the hot rod tricks will not apply.

For your car I would suggest the following. Do a straight rebuild of the engine. Use modern low tension piston rings to reduce friction. Have an exhaust system made with pipes 1/2" larger in diameter than stock. Or, split the manifold and run duals. The first is easier, the second sounds cooler. Both make about the same power.

Add a progressive Weber carb to your stock manifold using an adapter.

If you can find someone to regrind your cam have that done. Do a 3 angle valve job and shim the springs .060.

Have the head planed down. You can take off up to .080 for higher compression. Check the specs on Aussie built engines, the Canadian made ones had higher compression after 1956. A later model head may give you higher compression.

When you get done have someone who knows what he is doing, tune up the carb and ignition for optimum performance.

One last thing. Get the engine running first if possible and do a compression test. A new engine has 110 to 120 PSI. 90 or more is good, especially if it is even across all cylinders. If compression is low on one or more cylinders you may need to rebuild the engine.

In any case DO NOT try to hop it up until you tear it down, inspect all parts, and at least replace the rings and bearings.

There are lots of old engines that would run for years if cared for and babied, that will blow sky high in a few weeks if you try to hop them up. Have seen this happen more than once.

To recap: Get it running and try it out. If the engine is in poor shape or you need more power, time to rebuild. While you are at it there are a few simple tricks (cam, compression, carburetor and exhaust) that will give you from 25% to 40% more HP.

The old flathead is not difficult or expensive to rebuild. Give it a chance and it will return a fine performance and decent fuel economy and run for years.