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Re: Thoughts on mild 383 [Re: lewtot184] #2803550
08/01/20 03:00 AM
08/01/20 03:00 AM
Joined: Sep 2004
Posts: 523
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HP2 Offline OP
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Originally Posted by lewtot184
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
Re: Thoughts on mild 383 [Re: HP2] #2803573
08/01/20 07:19 AM
08/01/20 07:19 AM
Joined: Feb 2005
Posts: 4,234
Prospect, PA
BSB67 Offline
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Originally Posted by HP2
Originally Posted by lewtot184
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.

Re: Thoughts on mild 383 [Re: HP2] #2803593
08/01/20 09:06 AM
08/01/20 09:06 AM
Joined: Aug 2005
Posts: 290
Hinckley, Ohio
KWF340 Offline
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Hinckley, Ohio
Originally Posted by HP2
[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.

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.
Re: Thoughts on mild 383 [Re: KWF340] #2803786
08/01/20 03:43 PM
08/01/20 03:43 PM
Joined: Sep 2004
Posts: 523
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HP2 Offline OP
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Originally Posted by KWF340
Originally Posted by HP2
[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 up
I'll try to get a little more punch out of mine without sacrificing bottom power wink


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
Re: Thoughts on mild 383 [Re: HP2] #2803844
08/01/20 06:11 PM
08/01/20 06:11 PM
Joined: Mar 2005
Posts: 3,053
Central NC
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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.
Re: Thoughts on mild 383 [Re: gch] #2804088
08/02/20 09:58 AM
08/02/20 09:58 AM
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Posts: 523
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Originally Posted by gch
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 up


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
Re: Thoughts on mild 383 [Re: LaRoy Engines] #2804150
08/02/20 12:01 PM
08/02/20 12:01 PM
Joined: Jan 2003
Posts: 13,916
So. Burlington, Vt.
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Quote
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 up


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Thoughts on mild 383 [Re: fast68plymouth] #2804156
08/02/20 12:17 PM
08/02/20 12:17 PM
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Posts: 3,699
usa
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lewtot184 Offline
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Originally Posted by fast68plymouth
Quote
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 up
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.
Re: Thoughts on mild 383 [Re: lewtot184] #2804165
08/02/20 12:42 PM
08/02/20 12:42 PM
Joined: Jan 2003
Posts: 13,916
So. Burlington, Vt.
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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
Re: Thoughts on mild 383 [Re: fast68plymouth] #2804236
08/02/20 02:08 PM
08/02/20 02:08 PM
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Posts: 3,699
usa
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lewtot184 Offline
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Originally Posted by fast68plymouth
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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