Re: Thoughts on mild 383
[Re: lewtot184]
#2803550
08/01/20 03:00 AM
08/01/20 03:00 AM
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Joined: Sep 2004
Posts: 523 Right here
HP2
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something to think about on solid cams is their advertised duration ratings. you need to look at how much lobe lift the seat timing is rated at. using the xs268 as an example I believe it is rated at .015" lobe lift, but the recommended lash setting is .016". to get 268 degrees on the seat with a true 1.5 rocker you'll need .022" lash setting. .016" lash setting is going to get you 8-10 more degrees on the seat. will that kill off some low end torque?, probably. looking at the 270 solid it's rated at .015" lobe lift but has .022" lash setting. would the 270 be more versatile?, perhaps. either way look before you leap. what got me into looking at this stuff is I bought a solid cam that was "rated" at 280 degrees. what I didn't know at the time was the 280 was at .020" lobe lift, but recommended lash was .020". long story short is my 280 cam actually has 295 degrees running duration at recommended lash. the only saving grace is the solid tappet. 295 hydraulic degrees would have been miserable for what i'm doing. You are absolutely correct. I agree in every way. Comparing a hydraulic cam profile to a mechanical is like comparing apples to bananas. My head went bananas and I lost it. In the middle of the banana field I started to think that the Hughes cam was mechanical.
70 W100 Power Wagon. 318 4-spd 70 Sport Fury 440 2dr HT 71 Duster 340 71 Charger Super Bee - 383/727 72 Charger "Sabotage" - 440/727 - Street/Strip 78 Warlock in beautiful patina
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Re: Thoughts on mild 383
[Re: HP2]
#2803573
08/01/20 07:19 AM
08/01/20 07:19 AM
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Joined: Feb 2005
Posts: 4,310 Prospect, PA
BSB67
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Posts: 4,310
Prospect, PA
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something to think about on solid cams is their advertised duration ratings. you need to look at how much lobe lift the seat timing is rated at. using the xs268 as an example I believe it is rated at .015" lobe lift, but the recommended lash setting is .016". to get 268 degrees on the seat with a true 1.5 rocker you'll need .022" lash setting. .016" lash setting is going to get you 8-10 more degrees on the seat. will that kill off some low end torque?, probably. looking at the 270 solid it's rated at .015" lobe lift but has .022" lash setting. would the 270 be more versatile?, perhaps. either way look before you leap. what got me into looking at this stuff is I bought a solid cam that was "rated" at 280 degrees. what I didn't know at the time was the 280 was at .020" lobe lift, but recommended lash was .020". long story short is my 280 cam actually has 295 degrees running duration at recommended lash. the only saving grace is the solid tappet. 295 hydraulic degrees would have been miserable for what i'm doing. You are absolutely correct. I agree in every way. Comparing a hydraulic cam profile to a mechanical is like comparing apples to bananas. My head went bananas and I lost it. In the middle of the banana field I started to think that the Hughes cam was mechanical. Be careful. Because hydraulic cams are generally rated at 0.006" lobe lift, their actual seat timing is also different than advertised. Two points: 1) you can do a reasonable on-paper comparison between solid and hydraulic cams, you just need to know what you are doing, and 2) a 0.004" lash change will change seat timing lot, and will be very noticeable in a 383 driving around town.
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Re: Thoughts on mild 383
[Re: HP2]
#2803593
08/01/20 09:06 AM
08/01/20 09:06 AM
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Joined: Aug 2005
Posts: 299 Hinckley, Ohio
KWF340
enthusiast
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[What I'm asking for is cam input from people who built something similar. Anyone? I just finished my 383 rebuild - my goals were a little different from yours but there are some similarities. My primary goal was to get the engine close to stock, so it has the stock crank, heads, valvetrain, intake manifold, exhaust manifolds, and carb. No porting/port matching was done. Engine is 30 over, combustion chambers are about 87-88ccs, head gaskets are stock steel shim (0.02 compressed), pistons are Speed Pro L2315NF30 and they sit 4 thousandths in the hole. Compression ratio is about 9.5:1. For the cam I wanted something that was close to stock. I ended up going with a Mr. Sixpack cam and so far it seems to work well. Vacuum is 17" and it idles smooth at 700 RPM. I only have 300 miles on the engine, so a little more break-in to go. It's definitely faster than it was prior to rebuild, and it suits my goals for the car.
Last edited by KWF340; 08/01/20 09:08 AM.
1968 Charger R/T, 440 Auto, GG1; 1969 Super Bee, 383, 4-speed, T5; 1969.5 Road Runner, 440-6, 4-speed, 96; 1970 Duster 340, 4-speed, EV2; 1970 Charger R/T SE, 440 (496), Auto, EB3; 1970 Dart Swinger 340 (416), 4-speed, EV2; 1970 Corvette coupe, LS5, 4-speed, Daytona yellow; 2000 Corvette coupe, LS1, 6-speed, Twin Turbo, Torch red.
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Re: Thoughts on mild 383
[Re: KWF340]
#2803786
08/01/20 03:43 PM
08/01/20 03:43 PM
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Joined: Sep 2004
Posts: 523 Right here
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[What I'm asking for is cam input from people who built something similar. Anyone? I just finished my 383 rebuild - my goals were a little different from yours but there are some similarities. My primary goal was to get the engine close to stock, so it has the stock crank, heads, valvetrain, intake manifold, exhaust manifolds, and carb. No porting/port matching was done. Engine is 30 over, combustion chambers are about 87-88ccs, head gaskets are stock steel shim (0.02 compressed), pistons are Speed Pro L2315NF30 and they sit 4 thousandths in the hole. Compression ratio is about 9.5:1. For the cam I wanted something that was close to stock. I ended up going with a Mr. Sixpack cam and so far it seems to work well. Vacuum is 17" and it idles smooth at 700 RPM. I only have 300 miles on the engine, so a little more break-in to go. It's definitely faster than it was prior to rebuild, and it suits my goals for the car. Sounds like a sweet motor I'll try to get a little more punch out of mine without sacrificing bottom power
70 W100 Power Wagon. 318 4-spd 70 Sport Fury 440 2dr HT 71 Duster 340 71 Charger Super Bee - 383/727 72 Charger "Sabotage" - 440/727 - Street/Strip 78 Warlock in beautiful patina
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Re: Thoughts on mild 383
[Re: HP2]
#2803844
08/01/20 06:11 PM
08/01/20 06:11 PM
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Joined: Mar 2005
Posts: 3,138 Central NC
gch
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I believe a favorite of many years ago was the Crower 271 https://www.summitracing.com/parts/cro-32242 .Yours may benefit from a slightly smaller profile or different lobe separation.Call Duane at Porter Racing Heads or pm him here for a recommendation addressing your specific needs/specs. ^ fast68plymouth
Last edited by gch; 08/01/20 06:41 PM.
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Re: Thoughts on mild 383
[Re: gch]
#2804088
08/02/20 09:58 AM
08/02/20 09:58 AM
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Joined: Sep 2004
Posts: 523 Right here
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I believe a favorite of many years ago was the Crower 271 https://www.summitracing.com/parts/cro-32242 .Yours may benefit from a slightly smaller profile or different lobe separation.Call Duane at Porter Racing Heads or pm him here for a recommendation addressing your specific needs/specs. ^ fast68plymouth Thanks, sent Duane a PM
70 W100 Power Wagon. 318 4-spd 70 Sport Fury 440 2dr HT 71 Duster 340 71 Charger Super Bee - 383/727 72 Charger "Sabotage" - 440/727 - Street/Strip 78 Warlock in beautiful patina
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Re: Thoughts on mild 383
[Re: LaRoy Engines]
#2804150
08/02/20 12:01 PM
08/02/20 12:01 PM
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Joined: Jan 2003
Posts: 14,491 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
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RPM......Iron 301 TQ/HP......Street Dominator TQ/HP
2500.....349/166..................308/147 2700.....343/176..................310/159 2900.....351/194..................330/182 3100.....364/215..................343/202 3300.....361/227..................349/219 3500.....356/237..................350/234 3700.....349/246..................350/246 3900.....338/251..................350/260 4100.....336/262..................351/274 4300.....325/266..................348/285 4500.....315/270..................344/295 4700.....312/279..................338/303 4900.....298/278..................328/306 5000.....284/276..................320/305
Thanks Jim
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Thoughts on mild 383
[Re: fast68plymouth]
#2804156
08/02/20 12:17 PM
08/02/20 12:17 PM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
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RPM......Iron 301 TQ/HP......Street Dominator TQ/HP
2500.....349/166..................308/147 2700.....343/176..................310/159 2900.....351/194..................330/182 3100.....364/215..................343/202 3300.....361/227..................349/219 3500.....356/237..................350/234 3700.....349/246..................350/246 3900.....338/251..................350/260 4100.....336/262..................351/274 4300.....325/266..................348/285 4500.....315/270..................344/295 4700.....312/279..................338/303 4900.....298/278..................328/306 5000.....284/276..................320/305
Thanks Jim so if the engine makes something like 25 more horsepower on the engine dyno at about 1000rpm higher then how much of that 25hp will be ate up thru the chassis to spin the drive train about 1000rpm higher to get the 25hp? just asking.
Last edited by lewtot184; 08/02/20 12:18 PM.
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Re: Thoughts on mild 383
[Re: lewtot184]
#2804165
08/02/20 12:42 PM
08/02/20 12:42 PM
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Joined: Jan 2003
Posts: 14,491 So. Burlington, Vt.
fast68plymouth
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1000rpm higher...... than what?
Both of those tests have the engine making peak power within 200rpm of each other.
If you “assume” the power numbers lose 20% from the engine dyno to the chassis dyno, then looking at the numbers at 4700..... 279 vs 303....... 24hp on the engine dyno...... x .80 = 19.2hp at the wheels.
I think it’s pretty safe to assume anyone running around with a hot street 383 will be running it to at least 5000 during some wot blasts.
To me that test illustrates the classic hot rod part “trade off”.
The manifold gained about 20-25hp from 4300 up....... and the downside was the 20+ft/lb it lost from 3100 down.
Depending on exactly what you’re doing with the motor...... it’s either a win or a loss.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Thoughts on mild 383
[Re: fast68plymouth]
#2804236
08/02/20 02:08 PM
08/02/20 02:08 PM
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Joined: Jun 2008
Posts: 3,916 usa
lewtot184
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1000rpm higher...... than what?
Both of those tests have the engine making peak power within 100rpm of each other.
If you “assume” the power numbers lose 20% from the engine dyno to the chassis dyno, then looking at the numbers at 4700..... 279 vs 303....... 24hp on the engine dyno...... x .80 = 19.2hp at the wheels.
I think it’s pretty safe to assume anyone running around with a hot street 383 will be running it to at least 5000 during some wot blasts.
To me that test illustrates the classic hot rod part “trade off”.
The manifold gained about 20-25hp from 4300 up....... and the downside was the 20+ft/lb it lost from 3100 down.
Depending on exactly what you’re doing with the motor...... it’s either a win or a loss. just asking.
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