Cams for 318's

-
cross ref TRW to Sealed power or Elgin (all the same) Elgin has maybe a dozen cams- way more than trw or (sealed power)ever had
same wit Wolverine Blue racer
x2 too much lift and they start reducing the base circle which leads to pointy nose cams which do not wear as well
always check seal/ guide boss
magnum keeper to seal is critical- some just shorten the keepers but you have to check
 
There are too many things involved to make the right cam choice, but I will say this......I would rather have a custom ground cam that is perfect for what I want the vehicle to do and pay the extra money for it.
Going the extra mile to set goals, doing the math from front to back on a combination, and talking to the best people that win in their respective fields will save time and money in the end. Ive wasted way too much guessing at a combo, and although the journey can be educational, it's too expensive these days.
I recently bought a 94 Dodge Dakota extended cab with a 5.2 Magnum and an auto to grudge race. I have two engine combos that I am considering, one heavy nitrous, the other bed mount turbo. The nitrous combo needs different cam timing events to not only make power but for thermal management, the turbo combo can be more like an NA grind with low to no overlap ( letting the boost do the work ). Either way, I want cheap 8s out of the truck. I know it can be done.
 
sorted by increasing seat duration at SAE or .004
mostly only SAE rated cams included
Some Part numbers may be big block but not to find the SBM equivalent HR marked HR some lifts are at cam some at valve easy to see which
lift duration .004 .(.004 timing if available) 050 Timing ICL excl lca
Mostly in this order Most have cam lift in column one- some have valve lift you can tell the difference

see also Mopar LA Smallblock camshaft specifications
ELGIN are E-PNs added available FM/Sealed power
351/351 no adv duration given ` 181/192 109 LCA Sealed Power CS-645 273-318 stock
.274/.278 251/271 188/194 -22 30 23 -9 116/107 111.5lca E-1807-S ELGIN E-PNs sealed Power 645 gives icl 110 excl 108 LCA 109

373/399 240/248 10 50 58 10 (20) 1970 318 FSM -MOPAR degrees
373/399 240/248 10 50 52 16 (26) 1971 72 -76 shows 373/400
405/410 240/248 204/211/24 110LCA P4452755 LA {10 50 52 16 (26) FSM}

.375/.375 240/240 188/188 114 LCA Cam Dynamics 1500 240H14 1000-3000 1500-2000 cruz
392/390 192/192 Cam Dynamics 15202 383 4bbl 315 Hp 2268405 big block

400/427 248/260 192/204 112LCA Crane 693971 H-248-2 HMV-248-2-NC
265/.280 260/270 194/204 8 22 27 13 45 105/115 110lca E 983P

.405/.405 248/248 200/200 112LCA Cam Dynamics 15001 248H12

368/398 250/260 184/194 110LCA 105 ICL-115EXCL WG-1183

.387/.403 253/266 184/193 MC 1309 HR 94---Melling

410/412 252/256 MOPAR DEGREES 16 56 60 16 (32) 360 stock PN 2566260 2 Bbl Cam
410 252 LA 360 PN 3512589 18 54 57 15 (33) FSM MOPAR DEGREES about .008
410/411 {276/283-56 (@.006}) 197/199 -24 ovlap @.050 111 LCA mopar pn2806823 (compare 006 with Mopar around here)

410 (273) 278 (59) 203 -7 30 32 -9 109 LCA 108 ICL 111 excl Elgin E-626-S ED s-645
TRW-TM 627
.410 /411 .273/.274 no adv 197/199 111 LCA 114 108 2806283 Wolverine CS 4115 marine

410 248/248-20 113 LCA DC P4286667 (1983 vintage) LA





.410/425 248/256 211/218 110LCA P4452757 LA 1000-5000
.410/.412 252/256 16 56 60 16 (32) 1971 > 360
.410 210 PN 3512589 LA

.410/.425 248/256 (32) 202/202 110LCA P4452757AB P4452756 revised mopar data
410 248 20 overlap DC 248-114 112icl P4286667 LA DC-248 MOPAR DEGREES
[email protected] [email protected] 117@200 30@275 MOON heavy vehicle cam big nose

.427 260 204 110LCA 260H10 Cam dynamics 15003

398/420 (265/280 ) 260/270 (45ovlp) 194/204 8 22 37 13 110 LCA 105 ICL 115 excl Elgin -983P WG 1184

427/454 260/272 204/216 112 LCA Crane 693901 1,500-4,500 H-260-2 HMV-260-2-NC

372/400 264/274(50) 180/192 -20 21 24 -12 114 LCA 110 ICL 108 EXCL Elgin 577S Engine Dynamics S-645
248/266 at cam

.372/.399 264/275 12 72 57 38 (50) 180/192 -20 20 24 -12 109 LCA 110 icl 108 excl Melling SPD 20

.458 (.305 lobe) [email protected] 202 @.050 120@200 Mike Jones Special any ex and LCA

.440 266 210 110LCA Cam Dynamics 266H10

459/480 268/272 212/220 112 LCA Crane (some crane shelf grinds are .904- check
459 268 212 127@200 57 intensity Crane .904 H3 race only .200 duration for intake lobe

398 270/259 205/196 MC1262 HR 92-93 Melling
459 268 212 127 66 *8 H3 Crane

420/420 270/270 204 110LCA 106 icl 115 excl WG 1105
420/420 270/270 204/204 4 28 36 12 110LCA 106 ICL Edelbrock 2177 16” vac idle -5500

420/443 270/280 204/214 112LCA 107 icl 117excl WG 1116K 204-214 cam

.410/.425 203/208 -5 28 38 -10 -14.5 (.050) 106/114 110 lca Oregon Cams #1006 (RT) 1.5 rocker

.259 271/271 191/191 -20 31 20 -19 115/115 115LCA E 861s HR

.303 272/272 216/216 3-33 43 -7 52 105/1115 110 lca E1789P at cam
454 272 216 110LCA Cam Dynamic 15005 s 272 H10
455 272 (52) 216 3 34 33 4 110LCA 105 ICL 115 excl Elgin 1789P at valve no idea why timing changes different catalog
454 272 216@050 110LCA SUM-1789 largest stock engine cam works best with 9:1 and gears 1,500-5200

454/454 272/272 216/216 110LCA 1,800-5200 Crane 272H10
454/480 272/284 216/218 112LCA Crane 2000-5000 H-272-2-NC “Max Velocity”

385 /401 274/264 13-80 61-23 37 ovlp 108 ICL 112excl 110 LCA P5249663- hyd roller 360/300 crate motor mech fuel pump
431 274 202 114 @200 H2 H-202/2880

480 276 220 136 61 Crane .903 H3 H-220/320 note difference .903 makes

451 unknown duration 205/209 209 lca Delta #836-203-2 regrind

.294 276/288 218/228 0-38 53 -5 54 109/119 114 lca E-1223P
441 276/288 (54) 218/228 0 38 53 -5 109 LCA 109 ICL 119 excl Elgin 1223P
441 276/288 218/288 114LCA 1,800-5500 Summit 6901
480 276 220 136 70 *4 H3 CRANE .904 lobe


.270 276/271 197/195 15 32 32 17 62 113/113 114LCA E 1722-S HR

.294 276/288 218/228 0 38 53 -5 54 109/110 113lca E1223P

.273 278/278 203/203 -7 30 32 -9 59 108/111 109.5lca E 626s

420 (.280) 278/278 (50) 204/204 106/114 110 lca Edelbrock Perf Plus Sealed Power CS-1006R 1500-4000

.273/.274 278/282 198 199 -15 33 27 -8 57 117/108 111 lca E-1578s 273 Hyd cam

421/444 278/288 204/214 112LCA 1,200-5000 SUM 6900
421/444 (.281/.296) 278/288 (59) 204/214 -6 30 43 -9 (-15)112LCA 108 ICL 116 excl Elgin 937P SP-CS 1089R 1500-4000
420/443 (270/280 adv)? 204/214 112LCA 107 icl 443 excl WG 1116 adv may be at different height)

420/443 278/288 27 71 76 32 204/214 5 29 44 10 112lca 107 in 117 excl Melling MTD-1
.281/.296 278/288 204/214 -6 30 43 -9 59 108/116 112l ca #937P Melling MTD-1 Summit 6900 421/444 w 1.5 “1200-5000”
467/494 278/290 222/[email protected] 114LCA 2,200-5,200 Crane H278-2 and HMV-278-2-NC

.286/296 279/290 210/221 -13 43 40 1 51 118/110 114 E-1579S 340 & 360 Marine retarded


.429/.444 .286/.296 279/[email protected] 209/220 -8 37 46 -6 50 112/116 114LCA #578S ELGIN CAM Melling SPD-22
429/444 (286/296 279/289 .004 (50 ovlp)210/220 -8 37 46 -6 (-14) @.050 114 LCA 112 ICL 116 excl E-578-S` S644 SP-CS-644 Melling SPD-22
429/444 .2861/2958 279/290 (50)trw TM578 Sealed Power CS-644 2899206 340 CAM 1500-4500
429/444 268/276/ 44 228/235/) 114 LCA P4452782 340HP idle-5800 ??? .050 numbers
429/444 268-/276 22 66 74 22 (44) Motor Manual
429/444 286/.296 210/220 114 LCA 110-118 Wolverine CS 4109 marine (LH available)

450/455 268/272 50 26 62 68 24 (50) 228/231/ 110 LCA 108 ic 112 excl P4452761 LA
429/444 {268-276 MOPAR DEGREES } 210/220 WG 1118 oem #4214671 275hp 340
Catalog lists P4452782 as a replacement cam for "Muscle car-factory original", lift is .429/.444", and duration at .050 is 228/235, 114 deg. centreline, the same as the 69-73 340 cam.
450 268 / 284 22 55 74 22 (44) FSM PN 2899206 LA 340 MOPAR DEGREES

.504" .336" 268° 224° 140° K-56HYD Engle @.008 for comparison with Mopar 268
440 Magnum 447 268 213 intake for comparison
429/444 210/221 Crane 963901 276hp 340 114lca Cam dynamics 15002 220-221 H14 Crane blueprint

at .006
429/442 279/290 -51 (@.006) 210/220 -13 overlap @.050 Chrysler 2899206 1500-4500 Speed Pro CS 644 3675869

421 (.280) 280 (58) 208 -3 31 39 -11 (-14) 111 LCA 107 ICL 115 excl Elgin E-938-P SP cs 1006R 1500-4000
443 (295) 280 ( 60 ) 214 1 33 41 7 110 LCA 106 114 Elgin E-1087P WG 5023

460/450 280/288 224/232 112LCA HIT-280-2-HIT CRANE
443/465 280/290 214/224 112LCA 107 in 117 excl WG 1161

431 283 212 112 Direct Connection 260 @.004
430/430 284 @.004 212 @.050 115@200 Direct Connection “260” early cam P4286669 MEASURED single pattern cam
430 DC 260 measured 261 @.008 with cam doc 212 @.050 115@200 42@275
430 260 (34 ovlp) 113LCA P4286669 LA “DC260-113 110icl

430/450 {260/268 advertised .008) 221/[email protected] 110LCA P4452759AE newer grind, dual pattern
430/450 260/268/44 221/228 110 LCA P4452759 LA 1200-5000 mild comp -perf RV
DC 260 measured 261 @.008 but it's 269 @.006 if you want to compare with comp, lunati,
YOU CAN SEE THAT THE DC 260 IS 14 DEGREES LONGER AT .004 THAN THE 260 THE WAY MOPAR MEASURES you can use this number to estimate timing and duration for other MP cams for use in Dynamic compression ratio calculations as the MOPAR number gives unreal results. The difference in factory cams is even more than DC/MP cams as the DC/MP cams have steeper ramps than factory oem cams. Factory cams have eally long and even longer exhaust ramps

I Found a vintage 1988 cam Doc of the DC 260 cam
431/430 DC 260 212.3 211.9 113 lca 109 Icl/117excl -2.8 34.6 43.1 -10.8 -13.6 olap @.050 Mopar DC 260
434/430 (260/268) 206/209 113 lca 110ICL/116excl -7 __33 ___40 -11 __ -18 olap @.050 stock440
the 260 MOPAR duration comes out to be about .008 cam lift
so it does look like DC is Fatter than Stock 260/268 factory stock 440 eventhough lift is the same

68 4 SPEED CAM
.444 289 220 68 4speed intake lobe @.004 note 13 degrees longer @.004 than at .008
444/453 276/284 114 112ICL LCA P3423044 68 340 MT
.444/453 276-284 MOPAR DEGREES around .008
Int open: 26° BTDC
Int close: 70° ABDC
Exh open: 78° BBDC
Exh close: 26° ATDC
Overlap: 52° Mopar degrees around .008
Per the 68 factory service manual... Thanks Krazykuda

we always thought the 4 speed exhaust was a big block lobe "off the shelf
there are a couple of possibilities
450 268/284 PN 3512907 2843564 67 GTX/RT 4071002?
450/458 268/284 208/221 115 LCA 21 67 79 25 (46) 113 ic 117 excl P4452783 B/RB

AJ/FormS writes "This 276er on a 114LDA(in at 112) leaves just 110*of compression distance to make the charge hot enough and dense enough to make power"
Well in a LC teener this works after the torque peak, but not so much at rpms that it spends most of it's street life at.
And the 102* of extraction means there's still a lot of energy in the cylinder when the exhaust valve opens. Energy that could have been used to propel the vehicle.So with this energy going out the pipe, hey you paid for that! and now it's wasted. It comes out the end of the tailpipe as sound and withturn-downs, ends up making little dust-devils in the graveldust on the road when idling,stopped.

But if you take that same 276er and tighten up the LDA to108 and install it at split overlap of 106*, the you will get 116* of compression, with the ICA falling to64* from 70*. This leaves the Dcr up and the cylinder pressure probably 10 or more psi higher. Furthermore the extraction moves this same 6* to 108* delivering more energy to the crank, and less out the exhaust.
The "penalty" for this is the extra 6+6=12* of overlap which is now 64 degrees. At this point the overlap is beginning to become a 5th element to the 4-stroke principle.
If headers are now used, this element can be exploited to increase engine output by virtue of bringing the V.E. closer to 100% during a portion of the powerband beginning from around the torque peak and up. 64* ain't much yet, but the effect is better than at the previous 52*.
The real penalty is the slightly lumpier idle(which most guys like) and a wee bit of a tuning learning-curve.


455 272/272-48 LCA 112 DC 272 some old sources

454/454 272/272/48 231/231 112 LCA 112 LCA 110 IC 113 Excl (P4286671 LA 108 LCA)

455 272 (48) P4286671 LA D.C. 272-112 108 icl 26 66 70 22 (48)

520 347 272 224 K-56HYD . Engle @008 to compare with MOPAR duration 272 cam
537 (358) 278 230 144 ENGLE KV-2 HYD for comparison with MOPAR durations
474 280/280/60 LCA 110 DC replaces street hemi purple shaft 1987

474/474 280/280 (60 ) 34 66 74 26 (60) 238/238/ 110 LCA 106 icl 114 excl P4445992 LA

474 280 (60) [email protected] P4286630(A) newer profile D.C. 280-110 106icl

470 284 P 3692013 LA Hemi profile from 70's
484 284/284/68 LCA 108 DC early
484/484 284/284/68 34 70 70 34 (68) 241/241 108 LCA 108 IC & excl P4120231 LA late DC street hemi profile “DC 484”
484/484 284/284/ 56 241/241 114LCA P5007695 LA “improved driveability

528 /528 284/284/60 LCA 112 DC Modified comp
.537 (.358) 284 235 (150 @200) Engle KV-3 HYD for comparison with MOPAR adv durations

434 284 206 ??? 74 IC stock 440 @.004


456 284 212 125 74 0 Crane H2
501 284 228 145 74 0 Crane H3
480/480 284/284 228/228 112 LCA 284 H12 Crane 3000-6200
480 284 228 112LCA Cam Dynamics 284 H12 2800-5800

.305 284 /284 218/218 4-34—44- 6 65 105/115 110lca E-1042P

.320 284/284 228/228 7-41 51 -3 61 107/117 112lca E 1798P

.473 286 226 106LCA Cam Dynamics 15007 2600-5500

.320 287/287 231/231 8-43 46-5 69 108/111 109 lca E 935p

458/465 288/292 226/230 110LCA H-288-2 Crane 2,500-5,500 @.004

.444/466 288/298 (61ovlp) 32 76 81 37 (69) 214/224 -1 35 48 -4 69 108/116 112lca E-936P , Melling M23203 1,700-5200
highly recommended by some 20 degrees more duration than a MOPAR .904 lifter cam and less lift- go figure Sealed Power CS-1019R 2200-5200




522 292 236 153 H3 78 Crane @.004
480 294 222 136 H2 79 Crane @.004
543 300 244 161 H3 82 Crane @.004
447 302 213 440 83 Magnum Intake @.004
459 324 225 440 Magnum exhaust @.004
BradH measured an original 440 HP cam: 292/309 @ .006 lifter
not how it takes 10 degrees to rise from .004 to .006 on the intake but 15 on the exhaust

534 356 285 238 152 K-60HYD. @.008

485 286 108.5lca 108 icl Racer Brown SSH [email protected]
485/510 286/292 108 P4007619 Racer Brown SSH-25-44
517/517 3345 288 236 K7 Engle hyd
534 356 288 238 K 60 hyd Engle
.501/.513 288/292 P4876348 360/380 crate HR 1.6 rockers
552 (368) 288 242 (156 200) KV4-HYD Engle

539 359 291 244 K-62 @.008
522 292 236 153 H3 78 @.004
508/508 292/292/ 76 248/248 38 74 74 38 108LCA P4121233 LA modified competition P4120237 B/RB ( “DC 509”

508/508 292/292/ 64 248/248 P5007936 LA “improved driveability P5007698 B/ RB (.509)

509/509 292/292 38 74 74 38 (76) 248/248 108 LCA 108 icl 108 excl P4120237 B/RB

.510 -----292 old grind SSH-44-108 106 icl Racer Brown

509 292 needs 410 gears Largest for street/ strip manual trans – early grind

“DC509” 292 P 4120233 LA P4120231 D.C. 292-108

510 292/292 P3690812 Racer Brown AT B/RB 108 LCA 110ICL? SSH-44-108 LA P3690769

508 292/292/76 LCA 108 DC

539 359 294 244 156 K-62HYD here second number is cam lift
 
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Within the confines of the same duration at .050-inch lift,
the hydraulic roller will allow you shorter seat-to-seat or running duration numbers.
This will buy you some better off-idle throttle response and higher engine vacuum.

Alternatively, you can achieve higher power output if you maintain the seat duration numbers and gain area under the lift curve with more peak lift and greater duration at not only .050-inch, but all the other higher-lift area checkpoints (.100-, .200-, and .300-inch lobe lift) as well.

Nolan Jamora Isky cams
Same O same O with .904 lifter vs 842 cam designs
and inverse radius vs flat flank rollers
 
I ran the "Summit Racing manual trans" cam in my 318 with 4 speed and 391's stock heads with edelbrock intake and 600 Holley, didnt run bad. In fact alot of people would ask if it was a 340. I had an older fella in a gas station say "that thing sounds good is it a 340...? totally a street car just to be clear, but I raced a couple a buddies and won against all of em. one guy in a 70 Mustang with 351, the other in a Chevy truck LOL! chevy guys :)
 
[QUOTE="AJ/FormS writes "This 276er on a 114LDA(in at 112) leaves just 110*of compression distance to make the charge hot enough and dense enough to make power"
Well in a LC teener this works after the torque peak, but not so much at rpms that it spends most of it's street life at.
And the 102* of extraction means there's still a lot of energy in the cylinder when the exhaust valve opens. Energy that could have been used to propel the vehicle.So with this energy going out the pipe, hey you paid for that! and now it's wasted. It comes out the end of the tailpipe as sound and with turn-downs, ends up making little dust-devils in the gravel dust on the road when idling,stopped.

But if you take that same 276er and tighten up the LDA to108 and install it at split overlap of 106*, the you will get 116* of compression, with the ICA falling to 64* from 70*. This leaves the Dcr up and the cylinder pressure probably 10 or more psi higher. Furthermore the extraction moves this same 6* to 108* delivering more energy to the crank, and less out the exhaust.
The "penalty" for this is the extra 6+6=12* of overlap which is now 64 degrees. At this point the overlap is beginning to become a 5th element to the 4-stroke principle.
If headers are now used, this element can be exploited to increase engine output by virtue of bringing the V.E. closer to 100% during a portion of the powerband beginning from around the torque peak and up. 64* ain't much yet, but the effect is better than at the previous 52*.
The real penalty is the slightly lumpier idle(which most guys like) and a wee bit of a tuning learning-curve.[/QUOTE]

So this explained it better than when I first started to understand cams-and they can be installed to do exactly what you want-I know this will help others understand too-Thanks!!
I didn't notice Clay Smith Cams.
We have a 318 in a 75 Sport, that got shopped last year, had a flat cam, low compression on some cylinders almost non existent on others-it's our project that will never be finished-completely.
When we got her it was dead of winter, started and ran the 27 miles home at around 9 gallons for the trip. Ratty old holley 600, hedman headers, Edlebrock intake and heads-thats what I saw. The old place where it was 20 years ago said they started it after putting the cam and lifters from a 2 ton truck in it, and it was a mechanics car.....yeah, OK, sure, like no one's ever going to look? Came time to pick a cam and Clay Smith had one designated "H 274 0 B", which has been a good one so far. I like it for the most part, there is that "waiting on the vacuum", and the Comp vac can add on is....I'm gonna hold on that, only thing vacuum is brakes and crankcase venting....yeah, had to actually look to make sure, thats it. They stop me so no complaints, yet. And idling does sound pretty good, no crossover/H or X pipe, 2½ & 2¾ to the rear bumper, sometimes I get that 360 question, but the form of the idle has a deep sound in it, not big block throaty, deeper, but not as loud as BB's. Empty Flowmasters huh? Yep. Paticulars are cam timing 107°, ex and in lift are .450, and center line is 110°, duration is 224°, total timing on ready run dist is 36°, curved and no vacuum adavnce line attached-(for some who think vacuum has to be used on a ready run-I have been told countless times it would run a lot better if I would put that hose on-NO JOKE, and sometimes they come to understand mechanical curve)hedman long tube. I should just post spec and dyno, make it easier, and I don't ADD/ADHD on you....It is like in town it kinda dogs with 2.45 highway gears in the 8¼ non sure grip. Highway? Flat out cruising along not in a hurry, it has a spot it falls into @ 2300 rpm @77mph+/-, anda questionabley correct spedo.
It's set up for exactly what it's doing, and it's doing it well.....like I said, it is a forever changing project that will never be totally finished, but we know what we want, and stock ain't gonna get it, soooo, one piece at a time, every change is geared towards a "finished" product, that we love to drive everyday.

318 Spec Sheet (2).jpeg


DynoJet 3 passes.jpeg
 
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Overcammed some 318s growing up....lift is free HP match your cam with your converter,intake and carb. What is your goal?
Big cam that pulls up high isn't doing anything with 2.94 gears...always call the cam manufacturer and LISTEN to there advice even if it isn't what you want to hear.

20170918_152331.jpg
 
Fwiw In my working with 273/318 heads...the 1.78 valve "ported" hit NEAR their peak flow by .450 and only marginally pick up after that...till the valve and entire port grows ..so you can get a lot done with just duration/lsa and staying in or around .455-.510 lift.
They also daily drive longer.
 
MOPAROFFICIAL said:
Fwiw In my working with 273/318 heads...the 1.78 valve "ported" hit NEAR their peak flow by .450 and only marginally pick up after that...till the valve and entire port grows ..so you can get a lot done with just duration/lsa and staying in or around .455-.510 lift.
They also daily drive longer.
Click to expand...
Dang, I wish I would have flowed my 273 heads. Valve size would hold me back though.

11_14_0.JPEG


013.JPG


016.JPG


041600951718[01].jpg


041600951720[00].jpg
 
toolmanmike said:
Yep.
Click to expand...
Everything's right they should do pretty good. The valve is so small that you wont get much over 205 without going to a bigger valve.
Opening the window to 360 gasket netted 3cfm for me. #'s from a set of 273 heads 1.78 I did.
Int.
1.59
2.122
3.175
4.199
5.205
6.206
Exh
1...
2. 94
3. 114
4. 133
5. 148
6. 153
 
MOPAROFFICIAL said:
Everything's right they should do pretty good. The valve is so small that you wont get much over 205 without going to a bigger valve.
Opening the window to 360 gasket netted 3cfm for me. #'s from a set of 273 heads 1.78 I did.
Int.
1.59
2.122
3.175
4.199
5.205
6.206
Exh
1...
2. 94
3. 114
4. 133
5. 148
6. 153
Click to expand...
Wow that small valve really chokes things down doesn't it. Oh well, the porting didn't cost me much and when the seats go away I can always machine in some larger valves. The factory racers used some late 50's Hemi valves to make the 273 heads better. They were at least 180's which isn't much bigger. Have you seen much increase by back cutting?
 
toolmanmike said:
Wow that small valve really chokes things down doesn't it. Oh well, the porting didn't cost me much and when the seats go away I can always machine in some larger valves. The factory racers used some late 50's Hemi valves to make the 273 heads better. They were at least 180's which isn't much bigger. Have you seen much increase by back cutting?
Click to expand...
They definitely pick up with back cutting them you just get less faces out of the valve. Seen 4 cfm on one head and 7 on another. Seen it cause turbulence up top too.
 
so anybody else use 30 degree seats for these .450 lift heads?
My theory is to get to .450 -500 as quick as possible, dwell, and close so the valve does not bounce
 
Wyrmrider said:
so anybody else use 30 degree seats for these .450 lift heads?
My theory is to get to .450 -500 as quick as possible, dwell, and close so the valve does not bounce
Click to expand...

I typically dont, but you can gain area and flow that way. The seat life is about the only trade, minor.
 
Wyrmrider said:
so anybody else use 30 degree seats for these .450 lift heads?
My theory is to get to .450 -500 as quick as possible, dwell, and close so the valve does not bounce
Click to expand...

I thought 30 degree seats were fine for a lower rpm engine. Pontiac used them. Seems like the wrong way to go for a 273...
 
It's not the rpm it's the limited lift or limited heads
you get more "curtain" area at lower lift points with 30 degrees so you can use a for more area under the lift curve at same duration or use less duration and have the same area
The head shown was maxed out before .500 and maybe near stock lift
I like to get max head flow at as low a lift as possible and keep it there
also avoid turbulence
Now with better heads all changes
 
Cams cannot be selected from just engine size, many things to be considered about the engine and car, and to much focus on cam lift.
 
ir3333 said:
comp XE 268 .477 .480 .224 .230 is way too much for a 318.
go to comps website and get their dyno sheets.You'll see the xe 256 and 262 are better than the xe268 in a warm 350 sbc with Dart heads.
.410 .420 or .429 .444 and maybe .204 .214 would be a good choice for a stock 318, but you didn't want to hear that.
Click to expand...
The comp xe is actually a great cam for 318 I had stock 4 valve relief pistons .30 over , 360j heads with thin head gaskets , old edelbrock street dominator and a Holley 750 cause that's what I had on the shelf and it ran great !!! Revved to the moon
 
This is what mine did with the 268

IMG_20160324_225814237.jpg


0924192154.jpg
IMG_20160325_144012905.jpg
IMG_20160325_144037890.jpg

1972 318
The numbers are low because of a mis matched intake, that has been corrected by taking .080 off the manifold. The mis match was pretty severe, about .220, double that for .440 choked down. Made good vacuum 17+.
The engine has .040 over kb167 pistons, machined block .005 below deck, .010 off the heads, heads measured 65cc, .028 composite head gasket, edelbrock performer 2176 because I had it, 1406 edelbrock, compression works out to 9.46.

904 low planetary gear in first, 3.55 sure grip. It should get out of the hole pretty well.

I'm guessing the mis match cost around 40hp. Cam signs off at 5600rpm.
 
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