Timing ??

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wigsplitter74

wigsplitter74

The Mopar Kid
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Janesville, WI
I'm 19 and have been around Mopars my whole life. I've had my Duster since age 16 and have since rebuilt the whole thing. I'm looking for advice on what to set timing at. Here's the specs: .030 over 360, stock 1.88/1.60 heads stock pistons, MP .430/.450 cam with .268 ADV. dur., Holley strip dominator single plane hi rise intake (might switch back to stock iron dual plane before saturday) Holley 750 cfm double pumper. everything else in motor is stock but rebuilt with about 4k on it. The car has an MSD 6AL box, MSD Billet dist. with I believe the "loose" springs in it. It's got Hooker headers and a 3" exhaust with an H pipe and flowmaster's. I've got a 727 that I just put a 10" 3000-3500 Coan converter in and a Turbo Action rev. manual VB. I've got a 4.56 gear in right now (8 3/4 rear) but might bump down to 3.91 if I run out of top end with the 4.56. The car weighs about 3150 with me in it and almost full tank. My best ET last year was 14.55 at 96mph with a stock converter, slushie shifts, 650 carb, feathering out of the hole or else bogging. at that time it had 2 1/2" exhaust and 3.55 gears. feel free to post what you think I should try for timing and what you think it might run.
 
38* total all in by 2500 check with vacuum disconnected.
 
sbknut said:
38* total all in by 2500 check with vacuum disconnected.
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No more vacuum advance canister, it left with the stock distributor, thanks for the tip tho I'll try it. hopin to get a mid to low 13 if me and the buddy's can get it tuned in right.
 
My dart is 100# lighter with a 318, pulls 13.0's on an average day. A mild 360 ran 12.7's just keep thrashing.
 
12-14* initial, 34* total all in by 2500-2800rpm. change to 3.91s before it blows up - unless you have ±34" dia. tires.
 
388dart said:
12-14* initial, 34* total all in by 2500-2800rpm. change to 3.91s before it blows up - unless you have ±34" dia. tires.
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4.56 with a 28" tire is a very good combination. A 318 will handle a 26" tire. 5.57 with a 30" tire is good to 120 mph.
 
I think you are undercammed for the rest of the combo. The issues for me are the torque peak and hp peak, vs the convertor choice and gearing. The engine sounds like it will have a flat torque peak between 2400 and 3500, with peak horsepower around 5200. Except your gearing will want it to rev to 6K. What I would suggest is raise the gears to 3.91s w/the 28" tire it looks like you have. Also, replace the iron dual plane with an aluminum Performer RPM. The stall may be ok with those changes. So long as it's a tight 3K. As far as timing, with the convertor, you can go full advance fast. I would go with initial advance of 15°, and a total around 36°. You will want to see what it likes when you are at the track and can repeat times over a few runs. but I think you'll end up around 34-36°.
 
This set up should be way ito the 12s. With that gear sounds like you are running out of cam by the end of the 1/4. I had a 4 spd duster with a big MP performance hydralic cam . I was running 4:56 gears . Same problem but I was into the low 13s with it.
Somthing is up!
 
4.56 with a 28" tire is a very good combination. A 318 will handle a 26" tire. 5.57 with a 30" tire is good to 120 mph.

I guess if your not going any place fast it is - lot more can be had with a lot less gearing.
 
Well just an update, Saturday was a huge dissappointment, ignition problems (take a look ath the thread in the electrical about an MSD cap) popping badly which turned out to be a dist. cap issue and then the voltage regulator went by by. I know I don't have enough cam, I was planning on doing cam and heads and converter, bought the converter, then lost my job so I gotta make this work for now. See if any of you can help solve my distributor cap issue in the electrical section.
 
moper said:
I think you are undercammed for the rest of the combo. The issues for me are the torque peak and hp peak, vs the convertor choice and gearing. The engine sounds like it will have a flat torque peak between 2400 and 3500, with peak horsepower around 5200. Except your gearing will want it to rev to 6K. What I would suggest is raise the gears to 3.91s w/the 28" tire it looks like you have. Also, replace the iron dual plane with an aluminum Performer RPM. The stall may be ok with those changes. So long as it's a tight 3K. As far as timing, with the convertor, you can go full advance fast. I would go with initial advance of 15°, and a total around 36°. You will want to see what it likes when you are at the track and can repeat times over a few runs. but I think you'll end up around 34-36°.
Click to expand...
Soon as I read this I had the same thought. Rather than change the whole combination(gears, intake) to suit the cam, plug a bigger cam in it. You will go WAY faster, make more noise, and have more fun. I would look for something with duration around [email protected], on 108 deg lobe separation to help crutch the low compression. 106 would be even better, but you might have a hard time finding something like that. Run LOTS of initial with this combo, its gonna idle pretty rough. the Perf. RPM would be marginally better than the Strip Dom. with this combo, but I wouldn't lose any sleep over it, especially considering you already have the holley intake & you are on a tight budget. Dont get caught up in worrying about having the latest parts, they arent a cure-all, contrary to what car craft might tell you on behalf of thier advertisers.(hint, hint)
 
Aother thing to consider, if you move to a more aggressive combo later with more compression, cam & cylinder head, the Strip Dominator will out-perform the RPM.
 
You can also try to crutch the intake by running a 1" 4-hole spacer. This should help with mid-range torque a bit with this combo, but its not a cut & dry deal, you will have to test it at the track. You will need to play with shooters & jetting either way.
 
388dart said:
12-14* initial, 34* total all in by 2500-2800rpm. change to 3.91s before it blows up - unless you have ±34" dia. tires.
Click to expand...
I run a 4.88 gear with a 28" tire and am good to 115 to 120.
 
george said:
Soon as I read this I had the same thought. Rather than change the whole combination(gears, intake) to suit the cam, plug a bigger cam in it. You will go WAY faster, make more noise, and have more fun. I would look for something with duration around [email protected], on 108 deg lobe separation to help crutch the low compression. 106 would be even better, but you might have a hard time finding something like that. Run LOTS of initial with this combo, its gonna idle pretty rough. the Perf. RPM would be marginally better than the Strip Dom. with this combo, but I wouldn't lose any sleep over it, especially considering you already have the holley intake & you are on a tight budget. Dont get caught up in worrying about having the latest parts, they arent a cure-all, contrary to what car craft might tell you on behalf of thier advertisers.(hint, hint)
Click to expand...
Just checked the Lunati website, they have a cam almost identical to my off the cuff cam recommendation, [email protected], .520 lift, 106 lobe separation. i would check the retainer to valve seal clearance, other than that you should be good to go. What valve springs are in the motor?
 
george said:
Just checked the Lunati website, they have a cam almost identical to my off the cuff cam recommendation, [email protected], .520 lift, 106 lobe separation. i would check the retainer to valve seal clearance, other than that you should be good to go. What valve springs are in the motor?
Click to expand...


Not real sure, trying to find out. I've got to put a new cam in it tho, the old one must have been walking cuz the gear on the Dist./oil pump drive is chewed and shot and the gear on the cam has seen better days. Any ideas what I can do? Does anyone make a cam button?
 
SBM doesnt need a button, the cam plate keeps the cam from walking forward. Check to make sure the distributor isnt bottoming in the drive, distributor pushing down on the drive when you tighten it?
 
Is the gear bronze or steel? Should be steel for a flat tappet cam. It's very common for people to re-use oil pump drives with a new bushing in the block. It's a combo with a very short life. If the drive is lose (like you can wiggle it side to side with a large flat screwdriver) you need to replace it and the drive.
 
moper said:
Is the gear bronze or steel? Should be steel for a flat tappet cam. It's very common for people to re-use oil pump drives with a new bushing in the block. It's a combo with a very short life. If the drive is lose (like you can wiggle it side to side with a large flat screwdriver) you need to replace it and the drive.
Click to expand...
Another good possibility.
 
moper said:
Is the gear bronze or steel? Should be steel for a flat tappet cam. It's very common for people to re-use oil pump drives with a new bushing in the block. It's a combo with a very short life. If the drive is lose (like you can wiggle it side to side with a large flat screwdriver) you need to replace it and the drive.
Click to expand...

The gear is (or was) steel. So my best bet might be to go with new cam, gear, oil pump, and I figure while I'm there new timing chain ? sound good?
 
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