Questions about 440 tuning, Cam, and ignition!

I just bought a 73 Cuda from a guy and I am trying to sort some tuning issues out on it and was hoping to get some help / opinions….. The car specs are:

• 71 440
• Stock rods and crank
• TRW Forged Flattops; approx. 10:1 Static Compression ratio
• Out of the box Edelbrock RPM heads (84cc)
• Stock style rocker gear
• Comp XE285HL Cam, comp lifters, Stock Edelbrock Head Springs
• RPM Intake
• 750 Speed Demon Carb
• MP Electronic Ignition
• Doug’s 2” Full Length Headers
• 3” Magnaflow bullet mufflers out the side like a AAR currently, coming a 2 ½ “ X-pipe exhaust system. Current system way too loud.
• 833 4-speed
• 8 ¾” rear 3.91 sure grip
• 275/60-15 rear tires (28” tall)

This is a new engine with very little run time. Once I ditched the vacuum advance hook up and got my total timing to 34 which put my initial at 15, the car starts and takes the gas really good. However the idle quality is very poor. I am pretty sure this is in the baseline carb adjustments. I have not addressed these yet other than a few minor trial adjustments. I do have the following questions.

1. Big Block XE285HL users: How is the idle quality of this cam? I know the comp spec card says ROUGH, but is it too rough for a 446 cube street car? I have to say that it does sound very aggressive for a street car. What RPM should this cam idle? How much vacuum should I have at idle? This would be good to know as I try to dial in this carb.

2. Will I be able to run power brakes with this cam? Brake booster seems starved right now.

3. Valve Springs. The Edelbrock springs have a seat pressure of 115 lbs and an open pressure of 280 lbs. The recommended comp 924-16 has a seat load rating of 112 lbs and an open load of 355 lbs. Coil bind is pretty close at 1.160 for the Edelbrocks vs. 1.175 for the comp springs. Should I change these springs? My gut says yes with the lift rate of this cam. I guess I could lose valve control up high in RPMs? Comments?

4. What is the best plugs and gap to run in this combo?

5. Any suggestions or good how to’s on dialing this carb in? I have never had a 4-corner idle carb. Is there a better carb for my application?

Thanks for any help or comments!

Which TRW pistons do you have? What is the actual deck ht?

Your engine will like a bigger carb.

Carb adjustments are covered pretty good in BG's manuals. Here is the one for Speed Demons.
http://barrygrant.com/fromBarryGrant/Demon%20Instruction%20Manuals/Speed%20Demon%20Manual.pdf
Also look at http://barrygrant.com/demon/default.aspx?page=28
Better download them now as he has gone out of business and I don't know how long his website will be up.

That cams lift (.545) is a bit much for stock rockers and pushrods.

I would run about 18-20 deg initial timing with that much duration. You will need to shorten the advance curve so that you don't have too much total.

A friend has a similar spec Engle cam and he eventually converted his car to standard non-power brakes.

I'd just start w/ the basics. Turn the mixture screws all the way in, then back out 1 1/4. Start the car and crank the idel up to 2500. Set your advance at 36* (w/ those heads you could go to 38*) Then run your idel down to about 900 or so. Turn the screws in/out until you get the best vacuum signal. Go for a romp and adjust from there. That carb should work well enough for what you have. What jets/squirters/PV are in it? I'd think you'd want 76/82 jets, 31 squirters and a 6.5PV to start with.

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I'd just start w/ the basics. Turn the mixture screws all the way in, then back out 1 1/4. Start the car and crank the idel up to 2500. Set your advance at 36* (w/ those heads you could go to 38*) Then run your idel down to about 900 or so. Turn the screws in/out until you get the best vacuum signal. Go for a romp and adjust from there. That carb should work well enough for what you have. What jets/squirters/PV are in it? I'd think you'd want 76/82 jets, 31 squirters and a 6.5PV to start with.

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I agree that would get you close and drivable if you haven't messed much with the idle speed screw. If you have then you probably should look at the first link above and read the part about transfer slots.