What camshaft spec for 425 hp

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Backfiring through the carb is a problem. Fine tune what you have got & you may get a pleasant surprise how you can 'do more with less'.
 
PG Duster said:
Thank you for that info. I had books like those in the 80’s when I had my 71 340 Duster bracket, and my C/stock Road Runner That I used to use religiously. Is there any way to get those now?
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A revised…. Yet now also probably outdated version exists… somehow my father in law got me this for Christmas like 2 years ago. It’s a 2003 revision.

How to Hot Rod Small-Block Mopar Engines https://www.amazon.com/dp/1557884056/?tag=fabo03-20

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RustyRatRod said:
Are those heads ported? I agree with the ratty one that you don't need 425HP to go 12s, but IMO you need the heads ported to see 425HP.
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The person that I bought the car from put Engine Quest Cylinder Heads on it, and said it was a mild port job with 2.02” valves . The 360 magnum engine was freshly rebuilt .030 over. When I bought the car last year.
 
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RustyRatRod said:
They'll take a 150 shot. As long as you don't lean it out.
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Really, I did not know that, I was told that a 75 shot is all I can use with stock pistons. That’s good to know. Maybe I’ll be a little conservative and put 100 shot on it. I did that with a mild 8.5 compression 350 in my old 1971 Camaro I used to have and it Picked up 11 miles an hour and drop a full second on ET, just from 100 shot.
 
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Reminder: That book has some wrong torque specs in it so I recommend to double check them from elsewhere if you plan to use them.
 
PG Duster said:
Really, I did not know that, I was told that a 75 shot is all I can use with stock pistons. That’s good to know. Maybe I’ll be a little conservative and put 100 shot on it. I did that with a mild 8.5 compression 350 in my old 1971 Camaro I used to have and it Picked up 11 miles an hour and drop a full second on ET, just from 100 shot.
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PG Duster said:
I have a 1974 plymouth Duster with me in the car it weighs 3500 lbs, with a .30 over 360 magnum 9.1 cr. Edelbrock airgap intake manifold, Holley 750 carburetor, Headers, MSD ignition system, engine quest cylinder heads with 2.02” intake valves, stock bottom end, the transmission is a 727 automatic, with a 3500 stall dice converter, 8 3/4 sure grip rear end with 3:91 gears, Calvert Caltrac bars, springs, and 9 way adjustable rear shocks, 275/60 15 drag radials. What camshaft will I need to make about 425 hp and 12 seconds et in 1/4 mile with my combination ? Your suggestions would help me a lot. This will be a street strip car.
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I would not take that cam out until you have the new cam in your hands.
 
PG Duster said:
Wow, thanks you guy's, I have a good base line to start with. I will work with what I have and make sure it’s tuned. Before I buy a camshaft. I don’t know what cam is in it. It’s has a 750 vacuum secondary with pro form center body. A few times on the launch at the track it popped through the carb. I’m using a .033 primary shooter with the Green Accelerator pump cam in the number 1 position and 72 jets in the Primary and 82 in a secondary. Any Suggestions?

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Did it dead hook or was there any amount of tire spin off the line?
 
PG Duster said:
The person that I bought the car from put Engine Quest Cylinder Heads on it, and said it was a mild port job with 2.02” valves . The 360 magnum engine was freshly rebuilt .030 over. When I bought the car last year.
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those heads( if everything else is close) should be capable of easily supporting North of 400 horsepower. Dont think they are an issue moving forward with supporting low 12’s or even high 11’s. Keep chipping away
 
PG Duster said:
Really, I did not know that, I was told that a 75 shot is all I can use with stock pistons. That’s good to know. Maybe I’ll be a little conservative and put 100 shot on it. I did that with a mild 8.5 compression 350 in my old 1971 Camaro I used to have and it Picked up 11 miles an hour and drop a full second on ET, just from 100 shot.
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I've never seen a 75 wet shot. I guess there are kits out there. I've never seen one, though. No way would I go with a dry shot on cast pistons. That's askin for it.
 
12many said:
Did it dead hook or was there any amount of tire spin off the line?
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On the last pass it dead hooked. Two of the passes were 13.0’s with tire spin and I made suspension and tire pressure adjustments and It started hooking up.
 
Rat Bastid said:
Yep. You may be waiting on a cam for months.
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Ok, that’s important info. I talked to isky cams and a tech person told me for my combination I would need 230-235 duration at .050 and . 515- 525 lift, on a 107 lobe center. And should put me at about 400+ Hp. That would be a custom grind, isky is right here in So Cali.
 
PG Duster said:
On the last pass it dead hooked. Two of the passes were 13.0’s with tire spin and I made suspension and tire pressure adjustments and It started hooking up.
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Launching off idle do you recall flash stall rpm? Just wondering if you’re seeing the 3500 or what ever of your Dice converter.
60' to 1/4 Mile Calculator - Wallace Racing

For my setup I can use this Wallace Racing’s conversion table to compare my various timing points. I pretty much always match the figures given for any of the timing marks aside from Mph (I have an aero disadvantage) Ive done a lot of test n tune s to get it dialed in.
Just enter only one of yours to see what all the others ideally should be , try your 60’ and so forth. Use as a baseline, in general. Something to gauge things by. Looks like everything is in range you just have a little more Mph for what times you’re running.
 
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I have a Holley vacuum secondary carb on it, will I pick some et and mph with a 750 mechanical secondary?your input would be helpful.
 
PG Duster said:
I have a Holley vacuum secondary carb on it, will I pick some et and mph with a 750 mechanical secondary?your input would be helpful.
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if the vacuum carb is tuned correctly you shouldn't see absolutely anything on an ET slip…same size carb to same size carb.
Regards checking where your convertor flashes, easiest way to check is put the car in high gear, idle it along, and mat the gas, look and see what the tach jumps up to. That is where it flashes at.
 
12many said:
Launching off idle do you recall flash stall rpm? Just wondering if you’re seeing the 3500 or what ever of your Dice converter.
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I only saw 2 passes it flashed 3300. When it started hooking I did not notice, I was rusty and working on my lights reaction times. I cut a .050 and .056 reaction times before the night was over, I made 8 passes.
 
B3422w5 said:
if the vacuum carb is tuned correctly you shouldn't see absolutely anything on an ET slip…same size carb to same size carb.
Regards checking where your convertor flashes, easiest way to check is put the car in high gear, idle it along, and mat the gas, look and see what the tach jumps up to. That is where it flashes at.
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I will have to do that.
 
B3422w5 said:
if the vacuum carb is tuned correctly you shouldn't see absolutely anything on an ET slip…same size carb to same size carb.
Regards checking where your convertor flashes, easiest way to check is put the car in high gear, idle it along, and mat the gas, look and see what the tach jumps up to. That is where it flashes at.
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I still have adjustments to make on my carburetor, every now and then it will pop out of the carburetor on the Launch, it got better after I change from the red to the green accelerator pump cam both were in the number 1 position and changed the shooter from a .031 to a .033, when I was at the strip it did pop on one of the passes off idle launch’s. Any suggestions where to go with the carb adjustment? I also have .074 jets up front and .080 in the back jets.
 
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