‘69 RR ignition timing mild cam

[Jeremy Nelson]

The RPM is the one that can cause clearance issues, the others you list are lower and will fit no problem (except I'm not sure about the M1)... Just my opinion but I would definitely stick to a dual-plane for your type of motor and driving. The RPM is an excellent street manifold, if you choose to run that one you may just have to get creative with a drop base air cleaner... Edelbrock's website has all the different dimensions for the different intakes as well

Thank you for this detail, I really appreciate it!

 

[Garys1969RR]

Power and torque are a result of cylinder pressure. The higher the pressure ( When the fuel/air charge burns) then the higher the torque. So you may be losing cylinder pressure past worn piston rings, or leaking valves. Do a compression or leak down test to see if this is happening. If you have good compression, then make sure you have strong and properly timed spark. My son's 383 Super Bee had great compression, but poor performance, and was hard to start. Turned out the Electronic Ignition box was going bad. Made in Taiwan, was old and rusty looking. You probably have points ignition. After checking for compression and strong spark, check for accurate cam timing. I bought a 65 Belvedere with a 451 in it. Poor power, but had 180 PSI compression. Turns out, the cam was 20 degrees retarded! They put the crankshaft keyway straight up, lined up with the cam sprocket timing mark. That's how a chevy cam is timed, but not Mopar! It ran great after I fixed it. Do some investigative work, you will soon find the problem. Good luck!

 

[Garys1969RR]

And I like to set ignition timing at 20 initial, and 38 total. You have to limit the amount of mechanical advance in the distributor to do this. This works well at 5400 feet. May want to go 18 initial at sea level if it pings.

 

[Jeremy Nelson]

And I like to set ignition timing at 20 initial, and 38 total. You have to limit the amount of mechanical advance in the distributor to do this. This works well at 5400 feet. May want to go 18 initial at sea level if it pings.

Thank you very much for this advice. I’m checking compression as soon as I can, and will also do a leak down test. If that all checks out I may need to check the cam for sure. I suspect something really silly is happening here. It just doesn’t add up. Like you said it will be found! Thanks again!

 

[Sweet5ltr]

Folks:
So here’s my claim/questions. The car just doesn’t run like it should. Seems to miss a little and is really sluggish. In my opinion, this rig should scream but it feels sluggish and seems that something is holding it back.

May feel sluggish because unfortunately, it's not going to be on the same level as a modern powertrain many of us have become accustomed to.

These engines are forty years old, they really weren't that great at power production new (remember, GROSS power ratings) with good fuel, but they were great back then because the power was relative to other vehicles of that era. Something as simple as a mechanical fan can detract up to 30-hp. When we look at something like a modern 302 32-valve DOHC V-8 Coyote engine, it's making 435-hp NET. Our 440ci six-pack (supposedly, monsters) had a difficult time making 330-hp NET in 1972.

Fortunately, it really doesn't take much to make a big difference in power. Run a nice, large air-cleaner base and quality filter (Wix / K&N / etc). Clutch-driven fan. Performer RPM intake manifold. 1 3/4-1 7/8" headers, and a free-flowing 2.5" exhaust system with good mufflers: Borla - Dynomax - Magnaflow. Deep sump pan and a new budget nylon windage tray, when it says 7qt. capacity run 5-5.5qt's. Camshaft is probably fine if it doesn't seem too radical, but while you have the intake manifold off I would glance at the lobes for irregular wear patterns. With a factory diameter tire, I would be hard pressed to run anything lower than a 3.73 R&P on a street car.

Be conservative on the timing, there is no reason to run anything higher than 34* on pump gas with iron heads. Something as simple as increasing engine operating temperature from 180* F to 195* F can have a dramatic affect on the engines optimal (required) octane. Let's not even start on inlet air temperatures, many would be very, very surprised if they had an IAT sensor.

 

[Mebsuta]

I have beat up 68 RR, 383 4 spd 3.91. It has factory pattern hp cam, factory pattern pistons, 2.08 1.74 open chamber iron heads, M1 dual plane intake that looks like the stock one, Edelbrock 1405 carb, 4-1 headers, 2.5 exhaust.

I use dum old single point distributor with the heavy spring removed and the light spring in its place. Initial ignition timing is 10 btdc, and I forgot the number on the slots for the mechanical advance, so it's probably 36-40 total. Runs on 93 octane and has 16 inches of manifold vacuum at idle, which is 800 rpm. That's just where it likes to idle, no matter what I do.

It's not sluggish. It goes nicely. A 383 RR is not a fast car by modern standards, but it's still quick enough to annoy everybody and all those farty Mustangs running around, even with oil on the clutch. If you're rolling along in 2nd gear and goose it, it will shove you back and snap your head back.

It does drive like a car though, not a tow truck. Starting from a standstill in 2nd gear is not too exciting. With the hp cam, it makes acceptable low end torque for a street driven car, not spectacular. It won't idle up a hill in gear, but if you concentrate too much on low end, it will drive like a tractor.

 

[Mebsuta]

nm posted twice.