I experienced the value of dyno testing my engine today. I have a good friend that is an engine builder who has an engine dyno. The benefits are more than verifying performance. The engine is a sbc 383 clone that I built for my 49 which I am setting up to be able to tow up to 5000#. My friend did the machine work and I did the assembly. Problems encountered and readily solved included minor contact of the valve covers (CCC!) that was hanging up 2 valves (rocker contacting inside surface of the valve cover, very nice looking CCC ribbed aluminum that don't work!) and a minor oil leak on the plug at the back of the camshaft. All this was found and readily fixed. It would have been a pain once in the truck. The measured dyno performance numbers were a little better than the advertised numbers for the 383 HT with a peak torque of 440 ft-lb at 3600 rpm and peak hp of 345 hp at 4600 rpm. The torque curve is very flat not dropping below 400 ft-lb until 4600 rpm. It has the low rpm grunt that I wanted and idles beautifully at 600-650 rpm, in all just what I wanted for my purposes. It was a good day!

 

Sounds really good, and nice to have a friend who has a Dyno!

 

What trans you putting behind that torque monster?

I had that same problem with rockers hitting the inside of valve cover on a motorcycle. It would hold the valve open, no compression. Took me forever to figure it out.

 

I've never incountered that problem - with a Flathead

 

Ross,
I have a built 700R4 with a 3.70 9 inch with trac loc behind it. It did take about a hour to figure it out. We experienced a bit of a lumpy firing during initial warm up (before any pulls). The hand held infared temp gun said that #1 and #7 exhaust were lagging in temperature on warm up. We went thru ignition checks first followed by a compression check (which was low) and actually extracted the #7 exhaust lifter with a magnet thru the hole in the intake manifold after removing the dizzy to check the lifter. After that I wiped down the inside surfaces of the valve cover and noticed a couple of shiny spots. That meant that there was a light contact of the rocker that would delay valve closing. The problem with the ccc is that they most likely pull a mold off a good USA built original valve cover and don't compensate for the shrinkage of the aluminum on cooling (I have not checked the coefficient of thermal expansion for aluminum however iirc copper alloys are of the order of 1/8 " per foot)

 

Was there enough meat in the cover to grind it for clearance? I ended up having to use 3 gaskets (they use thin ones on that bike).

 

I think that there will be. To complete the dyno, we put on a set of stamped steel oem (Vortec heads) covers. I plan to take the die grinder to carve out the spots a bit and take a bit off the upper flange of the covers in the Bridgeport since the valve cover upper flange is basically contacting the aluminum intake. This would allow the covers to move up on the heads a bit and hopefully between both mods I can get the required clearances. If not, the ccc covers are junk (pretty junk but still junk).

 

A quick fix to keep you from spending a bunch of time die grinding the covers is to lay the covers (or gaskets) down on some .032 aluminum sheet (20 ga steel works too) and cut a shim plate. then add another gasket so the stack up is cover, gasket, shim, gasket, head. By doing this you get a quick .070 of clearance and still have a solid seal.

Gary

 

Gary,
Thanks for your reply. I will look at your suggestion as well. Right now I am installing portions of the interior. I have the cab in final paint and the cab rolled up on the firewall on top of a pad on the floor. It makes behind firewall padding, carpet and other behind dash work easier as well as doing the headliner. After that I need to final install and plumb up the chassis to final set the cab on the chassis.