318 low-rpm performance ........... for the NEWBE

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Dale Davies said:
Basically you are speaking of advancing the cam. You do have to watch piston to valve clearance as you advance the cam. "RV cams" had a bit more duration and lift and installed generally with no difficulty. Now add to that a .1 increase in rocker ratio, you will also benefit torque across the RPM band. As with any change in cam and valvetrain the PV clearance must be checked.
Click to expand...
So I look up comp xe250h specs (I'd say good choice for mild 318) and ran it through the Wallace V/P DCR calculator, AJ got with stock 8.1 318, 140 psi 7.1 DCR and V/P 116, with the xe250h I got 137 psi 6.98 DCR and V/P 111 nothing to write about but for the power gain I doubt this slight loss would kill the bottom end but say it will if you install at Intake center of 103 vs 106 you'd have the same as stock psi dcr v/p or could go somewhere in between and this is the 1st cam I checked.

His choice of ica of 64 I had to go up to the 5th cam in the xe line the comp xe275hl, a cam no one is suggesting for a mild 318 people aren't even suggesting a xe268h. Biggest I say is a xe262h cause we have dyno results of how it works in a low cr 318 282 hp @ 5000 rpm and 340 tq @ 3500 rpm and wallace calculates to 131 psi 6.75 dcr and 102 V/P far cry from his doomsday 91 V/P example.

At least use realistic specs.

Advertised Intake Duration:250
Advertised Exhaust Duration:260
Intake Duration at .050 Inch Lift:206
Exhaust Duration at .050 Inch Lift:212
Intake Valve Lift:0.432
Exhaust Valve Lift:0.444
Lobe Lift Intake:0.288
Lobe Lift Exhaust:0.296
Lobe Separation:110
Intake Centerline:106
Exhaust Close ATDC:16
Intake Open BTDC:19
Exhaust Open BBDC:64
Intake Close ABDC:51


Tell me which you rather have out of the choices below stock low cr 318 with headers BASE, or xe262h cam and 4bbl and spacer Mod 2?

https://www.motortrend.com/how-to/mopp-0312-318-long-block-bolt-ons/
HORSEPOWER SUPERFLOW 901 DYNO-TESTED AT WESTECH
RPMBASEMOD 1MOD 2
2,000112
2,500137
3,000164193192
3,500182224227
4,000189248252
4,500186265274
5,000179271282
5,500262270

TORQUE SUPERFLOW 901 DYNO-TESTED AT WESTECH
RPMBASEMOD 1MOD 2
2,000292
2,500287
3,000287338336
3,500272335340
4,000248326330
4500218309319
5,000188285296
5,500250258

Advertised Intake Duration:262
Advertised Exhaust Duration:270
Intake Duration at .050 Inch Lift:218
Exhaust Duration at .050 Inch Lift:224
Intake Valve Lift:0.462
Exhaust Valve Lift:0.47
Lobe Lift Intake:0.308
Lobe Lift Exhaust:0.313
Lobe Separation:110
Intake Centerline:106
Exhaust Close ATDC:21
Intake Open BTDC:25
Exhaust Open BBDC:69
Intake Close ABDC:57
 
So to get the stock 48* on a 250 cam would be 180 + 48 = 228, 228 - (250/2) = 103 + 4* (advance) = a 250 cam on a 107 lsa and 41* overlap, DV formula recommends a 107.6 lsa, you could make a pretty decent cam for a 318 with a 250 on an 107 lsa no reason to say no cam upgrades, and I'm sure you could go a few degrees from 48* or 107 etc.. without screwing things up to much with your V/P system, Also you could add Rhodes lifters shave off a few degrees down low, so why is it always no cam upgrades are possible ??
 
273 said:
So I look up comp xe250h specs (I'd say good choice for mild 318) and ran it through the Wallace V/P DCR calculator, AJ got with stock 8.1 318, 140 psi 7.1 DCR and V/P 116, with the xe250h I got 137 psi 6.98 DCR and V/P 111 nothing to write about but for the power gain I doubt this slight loss would kill the bottom end but say it will if you install at Intake center of 103 vs 106 you'd have the same as stock psi dcr v/p or could go somewhere in between and this is the 1st cam I checked.

His choice of ica of 64 I had to go up to the 5th cam in the xe line the comp xe275hl, a cam no one is suggesting for a mild 318 people aren't even suggesting a xe268h. Biggest I say is a xe262h cause we have dyno results of how it works in a low cr 318 282 hp @ 5000 rpm and 340 tq @ 3500 rpm and wallace calculates to 131 psi 6.75 dcr and 102 V/P far cry from his doomsday 91 V/P example.

At least use realistic specs.

Advertised Intake Duration:250
Advertised Exhaust Duration:260
Intake Duration at .050 Inch Lift:206
Exhaust Duration at .050 Inch Lift:212
Intake Valve Lift:0.432
Exhaust Valve Lift:0.444
Lobe Lift Intake:0.288
Lobe Lift Exhaust:0.296
Lobe Separation:110
Intake Centerline:106
Exhaust Close ATDC:16
Intake Open BTDC:19
Exhaust Open BBDC:64
Intake Close ABDC:51


Tell me which you rather have out of the choices below stock low cr 318 with headers BASE, or xe262h cam and 4bbl and spacer Mod 2?

https://www.motortrend.com/how-to/mopp-0312-318-long-block-bolt-ons/
HORSEPOWER SUPERFLOW 901 DYNO-TESTED AT WESTECH
RPMBASEMOD 1MOD 2
2,000112
2,500137
3,000164193192
3,500182224227
4,000189248252
4,500186265274
5,000179271282
5,500262270

TORQUE SUPERFLOW 901 DYNO-TESTED AT WESTECH
RPMBASEMOD 1MOD 2
2,000292
2,500287
3,000287338336
3,500272335340
4,000248326330
4500218309319
5,000188285296
5,500250258

Advertised Intake Duration:262
Advertised Exhaust Duration:270
Intake Duration at .050 Inch Lift:218
Exhaust Duration at .050 Inch Lift:224
Intake Valve Lift:0.462
Exhaust Valve Lift:0.47
Lobe Lift Intake:0.308
Lobe Lift Exhaust:0.313
Lobe Separation:110
Intake Centerline:106
Exhaust Close ATDC:21
Intake Open BTDC:25
Exhaust Open BBDC:69
Intake Close ABDC:57
Click to expand...
For a mild build I might pick the XE262H. I like the lift number. The XE268H has been a good cam also and is not that lumpy in idle. Build the engine for 10:1 or 10.5:1 SCR and use DV's 128 formula to determine the LCA and conyrol the amount of overlap with how much duration you chose. Better with less duration, the correct LSA and fairly high lift. I like to see 0.500" lift for ported OEM heads. It depends on what lift the flow tops out at. For most '70's engines that is going to be about 0.500". Gen 3 LS and Gen 3 Hemis can take more.
 
Dale Davies said:
For a mild build I might pick the XE262H. I like the lift number. The XE268H has been a good cam also and is not that lumpy in idle. Build the engine for 10:1 or 10.5:1 SCR and use DV's 128 formula to determine the LCA and conyrol the amount of overlap with how much duration you chose. Better with less duration, the correct LSA and fairly high lift. I like to see 0.500" lift for ported OEM heads. It depends on what lift the flow tops out at. For most '70's engines that is going to be about 0.500". Gen 3 LS and Gen 3 Hemis can take more.
Click to expand...
I'm just trying to work in the frame of AJ's V/P requirements, personally I believe you could go xe262h/xe268h.

But he's so adamant that you can't go with a larger cam at all within his V/P index, so was looking for a solution that works within it, and basically right of the bat I found that you just need a cam like a comp xe250h but ground on a 107 lsa, which is what I thought would work in his system narrow the lsa on a small ish cam and your good, xe250h @ 50 & lift wise is similar to a 340 cam specs just short on advertising specs. The xe262h only need to be bumped up to 8.8 cr to be at stock level V/P which is like an average 10 hp at best, a loss of 10 hp difference ain't gonna turn the motor into a turd. Ultimately I believe in more average hp you can put to the ground even if it's built inefficiently is gonna make a faster car overall.
 
That’s the problem of working with numbers and even more so when it gets the nod to follow so much in a hardline fashion you blow past what could be thinking it is a shouldn’t be. Living and rising by the mathematical numbers is a bad idea or can be.

A small loss in power you’ll never notice is not a big thing
If you notice a loss, then you know you went in the wrong direction.
 
Mtrhead said:
You've got to be a nuclear physicist....
Click to expand...
I knew a couple and they couldn’t do a tune up.

However! They can make nuke bombs and create a engine to power a spaceship into the next galaxy.
 
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