Thx gents, all great info.
I think mine is fairly similar to yours Jim. I told the builder it was just for fun, and that I wanted a tire spinning street car. It's just a fun Ratrod type T-bird that I cut a hole in the floor for a 4 speed. I fell in love with the idea of a 390 with a longer stroke after reading a bunch of stuff on the interweb. They all say torque is what'll move a heavy car. The builder told me that it was basically a 66, 67 Merc 410. It was bored .030. Has c4ae heads with CJ exhaust valves (stainless steel) and comp springs. I didn't know anything about "shimming" so I asked the builder after I read it on the build specs. He said something like it makes all the valves perform the same (evenly) and will help stop valve float. He used a CJ cam. It idles OK at 650 rpm. The CR is 10.5 and runs fine on 91 octane. I had found an RPM Performer intake. I put a Edel 750 with the appropriate jets and metering rods for our altitude. I also have FPA headers, they are the only ones I could find for a 59 T-bird - they were pricey but really well made. He said it would probably be in the 375 to 400 hp range and torque would be in the 450 range. The car weighs 3800 without me.
What does .050 quench and 7.5 DCR mean? Also, what is desktop dyno? I'm guessing that's software for estimation purposes?
My rearend is a 3.89 one wheel turner. Once I break in the motor and clutch I will see how the wheel spins and hopefully get a limited slip 3.50 to 3.70ish pumpkin. I want to be able to drive it 90 miles to Albuquerque sometimes. I might buy a used trailer and tow it. If I do I'll go with a lower rearend.
I had a hard time setting the timing and I'm still tuning it. The builder told me the timing should be about 10-12 and that it should never go over 38 total. I think I might start a whole new thread on that when I get some warmer outdoor temperatures and can work on it.
thx, Dave J
Dave J,
You need to figure out first what you want your car to do. With a four speed transmission you have to make a choice. When I restored my 57 Fairlane the first thing I did was design it. I wanted drag racing fun AND touring economy and smoothness. That's why I went with a Tremec TKO 600 with a 3.50 Tru-Trac. I cruise at 65mph and 1850 rpm getting 16 mpg and I can't put big enough tires under my car to keep it from spinning when I get on it. My advice to you with a 4 speed is to make a choice. Since I enjoy driving my car and going on trips I'd choose a 3.25 rear gear ratio at the most. But, if you like cruising down the interstate with your engine turning 3000 rpm, go with a lower gear.
Quench: That's the distance between the top of the piston and the bottom of the head with the head gaskets installed. You can go down to .040 at a minimum and .050 at the most to achieve a more complete gas atomization that will enhance the combustion in the cylinder and lower your needed octane level per compression ratio used. In other words it will help minimize spark knock when using lower octane fuels with higher compression engines.
DCR: Dynamic Compression Ratio is the actual compression ratio the engine sees. You need to look this up on the internet to fully understand it but in summary it's the compression ratio with stroke measured after the valves are fully closed on the compression stroke.
On both my 406 and 410 the Quench and DCR were designed into the engine before the cam, pistons or head gaskets were chosen. That's why I can burn 87 octane with a 10.5 CR, .042 Quench , 7.6 DCR 406ci engine and a 9.5 CR, .050 Quench, 7.5 DCR 410 ci engine.
Timing: My 410 ci engine has an initial timing of 14 degrees and a total of 38 degrees. The 406 ci had to be set at 17 degrees initial with a total of 34 degrees. The 406 had to have an ignition system that retarded the timing 5 degrees to enable the use of a stock starter though. You can't start a FE engine at 17 degrees, not very well anyway. I hope this helps.
PS The 406 engine was initially designed to drag race. I built the engine before I got the car from New Mexico. The car ended up being too nice to cut up so I changed the ring and pinion in the 3.50 Tru-Trac I'd previously bought to a 2.75 gear ratio. I also had to change the cam in the engine and turn the vacuum screw back in the Jay Broader transmission so it wouldn't jerk your head off during slow speed shifts. I get 14 mpg with that engine and I cruise at 2150 rpm at 65mph. I had to make a choice with that car because I didn't have a transmission versatile enough for touring and drag racing. I can barely spin a wheel with that car (406).
