Help troubleshooting 440 carb/ignition problem (long)

[1gtx]

Problem:

Looking for help in nailing down carb/ignition problems in a HP 440.

Problems -
1. Engine compartment seems hotter than it should be. Heat soak on shutdown is not awful (about 3/4 by gage), but it can take 30-60 minutes to be able to touch anything on the engine
2. I can't seem to get rid of the pinging, especially on WOT
3. Converter performance is disappointing (sort of like, why bother
4. My Firestone SS20 tires are in no immediate danger of of getting shorter :-)

Standing info -
Idle 800 rpm, cooling system pressure tested (holds 15.5# vac forever, vacuum 14.5# at idle, 182* at idle (90* weather), 202* at 2500 rpm in the same conditions, initial at 10* BTDC (stock), air flow through radiator, etc. is substantial

Impressions -
- Seems to like 15-20* initial though will ping like crazy under moderate accel (even worse at WOT). no starting problems even in heat
- Backing off initial to 5* will cause temp gage to go from 1/4 to 1/2 fast.
- At 10* initial, full advance will be around 44*!
- Rejetting carb to match a 1411 (lean version of 1407) will increase pinging for moderate or more throttle tip in
- Plugs are ok, look a little on the lean side for 1411 jetting, a little on the rich side for 1407 jetting
- At higher initial advance the car seems more responsive

Questions -
- I know there's too much mechanical advance in the distrib. I was thinking an initial of around 20-24 with a total in the 36* area + vacuum on top (~52* total) would be about right for this combination. Am I right?
- The MP distribs only have about 18* mechanical advance in the carb, right?
- Does anyone have a copy of the old Opar Muscle article (Apr 98) detailing recurving a distrib for heavy automatic cars?
- Does anyone have a similiar setup with the edlebrock carb? What are you using for jetting?
- Since there has been extensive work done to the engine is the high heat ouput normal?
- Has anyone had any luck with a similar combo with the MP 177K converter? Or am I expecting too much?

Basic Description -

Car: '73 RR/GTX 440, 4150#
Engine: ~9.3:1 compression, .030" over, lightweight rotating assy (-20%), Ross flat top pistons, Manley H beam HD rods, HP oil pump, forged crank, race balance (.25 gram), Hughes 1923 can (219/223 @50) ~.515/.538 lift, 1.6 adj alum. rockers, 452 heads (new) with my own pocket porting and gasket matching, SS stock (nail) valves, blocked cross over, edelbrock performer RPM manifold, stock vac controled dual air horn air cleaner w/heat riser and K&N cleaner
Transmission: B&M kit, extensive custom mods, part throttle kickdown, MP 177K converter, slap stick
Cooling system: newly recored 4 row 28" brass radiator, HD MP plate trans cooler w/hard lines, 180* hi flow thermostat, 7 blade 20" deep cut fan, HD thermal fan clutch, full shroud w/blade half in/out, A/C pump, stock pulley, 16# stock cap w/overflow bottle
Fuel system: 3/8" hard line, stock filter (new) with vapor seperator, stock (new) fuel pump (5.5#), 92 octane gas (76), Edelbrock 750 carb (1407) with electric choke and stock delay control
Exhaust system: 2.5" mandel bent pipes with crossover tube, cast HP manifolds, hemi mufflers, stock resonators w/flamethrower tips
Electrical: Stock electronic dist (w/about 30*! of mech adv and large spring removed--all in by 2800), MP chrome box, 7.5 mm spiral wires, 65 amp alt, 850 amp battery,
Other: 9.25" rear axle 3.23:1 w/sure grip, power brakes front: 11.75" reinforced rotors Rear: 11"x3" finned HD rear drums, power everything, A/C with sanko(?) compressor (ok for 6K+ rpm) + more, more, and more :-)

Sorry for the length, but I'm getting frustrated. Any help would be appreciated. Thanks.

- Mark

[amxauto-x]

Check out this web site and call Don. He is south of Portland;

http://www.4secondsflat.com/

[skankweirdall]

My initial question would be if you actually can see what the total advance is? In other words is the dampner degreed or is the total timing marked so you can read it with a timing light? Have you tried another timing light?

Secondly, how did you arrive at that compression figure? Do you know the exact cc's of the combustion chambers? Did you just figure it from spec's or is it an accurate, measured spec? You left out a lot of spec's here like piston deck height, combustion chamber cc's, head gasket thickness etc.

Thirdly, have you tried running some high octane race gas like 110 just to see if it improves?

Fourth, what are you using for spark plugs? Have you tried colder ones?

Fifth, is it any better if you fatten up the carb some (not at idle)?

You shouldn't need more than about 38 degrees total advance all in by about 2500 should be fine. Disconnect the vacuum advance, I don't think it's needed and may just be causing some problems at cruise rpm. I would also fatten the carb and get some colder plugs, preferably at least 2 steps colder, 3 or 4 if you can. If that doesn't help try some race gas in it just for a quick confirmation.

[1gtx]

Thanks for your response. I couple of clarifications.

- The 9.3 compression is accurate within + or - .1. Accurate measurements were taken, The variation is just my way of not getting too wrapped up in the fine print.
- Total advance is on the balancer as well as checking with multiple lights.
- TDC and the timing marks were confirned (within 1/2*)
- The cam was degreed three times just to be sure (no stackup adjustment required)
- I don't have a clue where to find race gas (though it can't be that difficult). I just not sure that it's worth the effort. I'm pretty sure that it would be fine runnin on it.
- Spark plugs could be a weakness. I'm currently using the old standbys: Champions RJ12YCs
- I can try changing the jets and rods again. I hesitate because a quick plug reading indicates that I've gone to the rich side already
- For the results I posted the vacuum advance was disconnected and plugged (still is in fact).
- The 10* initial and 43* total was with the stock components. Retarding the timing down to 5* (to get a total of 38) really jumps the water temp (see orginal post)

You might be onto something with the plugs. I haven't been able to come up with any guidelines for when to change them other than to try that if the carb and ignition are right.

Any recommendation on the specific plugs if I'm starting with the 12YCs?

Thanks.

-Mark

[skankweirdall]

I've never had any luck with the 12's in my BB. I've always tried to find an equivelant to a J9Y and use an MSD. Although the chrome box will work, it won't keep the plugs clean at that heat range. You do need to do something about that advance, I've always locked my distributors (just a quick tack weld does the trick). There are other ways of doing it but none cheaper or easier and I've never had a problem starting it hot. Idle and low rpm driveability should improve a bunch as well.

[6 packin]

You should never ping on 93 octane gas, with around 9.3:1. I bet the engine is way lean, has to be. No explanation for it pinging. Should be able to run 40 deg total, not that much more than 36-38 deg would be benifitial. That would explain, your overheating problem to! Ditch that voodoo tuning eddy for a Holley carb of some kind. If the coinage allows, get a speed demon from Cuda66! You need a good dial back timing light to check total timing at around 3000 rpm's.

[skankweirdall]

Oh yeah, you'll find you can run it richer with the MSD which should also help bring the combustion chamber temp down.

[skankweirdall]

Oh and race gas should be available at almost any drag strip in the country.

[71SATELITE]

Hey man just my 2 cents. I was having the same problem finding that annoying ping. I chased and chased it and dam near spun the dist. of come to find out it was weak valve springs. I read your combo and didn't see them mentioned or mabye I missed it. Just a thought.