Cams for 318's

-
Wyrmrider said:
I'll look at those summits again tomorrow, if those are the only things you can get in Columbia
I'm tempted to say do the carb and be happy
low compression, tall gears too big a cam can kill your driveability and gas mileage
I'm thinking the 250 @.006 cams or the 248 Mopar performance are as big as I'd go
smallest voodoo is
Advertised Duration (Int/Exh): 253/258 @.006 ;Duration @ .050 (Int/Exh): 208/213 ;Gross Valve Lift (Int/Exh): .454/.454 ;LSA/ICL: 112/108 ;

Summit/ Cam dynamic cams are measured at .004 not .006 so you have to convert
Click to expand...

Can I just compare duration at @.050? K6900 is close with the specs you posted.

Summit cams are the ones I can afford (I actually buy them on Ebay, not locally)
 
Finally we are getting somewhere with a "one step up" 318 cam that won't lose low end power/torque with only basic mods (4 barrel and dual exhaust) like a whole bunch of people do or are planning.


Thanks to all.
 
Cam Design
still true after all these years

I'll take a look this am at those two cams
I think they are my list near the top of this stickie
all you can afford? you might want to check out the Elgin industries catalog, very wide choice of cams and usually less expensive
 
Wyrmrider said:
Cam Design
still true after all these years

I'll take a look this am at those two cams
I think they are my list near the top of this stickie
all you can afford? you might want to check out the Elgin industries catalog, very wide choice of cams and usually less expensive
Click to expand...

Great info, thanks!
 
Well I went to Summit and plugged in your paramaters and came up with Three

expanded the criteria a little and came up with the auto recommendations all over the place
Sealed Power 645 stock 181/192 @.050 .351/400 lift
Crane 693971 248/260 192/204 400/427 112 LCA H-248-2 1,000-4,000
Crane 693901 260/272 204/216 427/454 112LCA H 260-2 1,500-4,500
Comp XE250H 250/260# 206/212 .432/.444 110LCA 800-4800
Comp 252H 252/252# 206/206 425/425 110 LCA IC 52 ABCD 800-4800
Comp XE-250-10 250/260# 206/212 432/444 110LCA IC about 51 ABDC
Vdoo 10200701 250/262# 213/220 454/275 108 LCA 1,000-5,500
(IC about 49 ABCD

Jones 254 @.006 # .458 lift
howard 255/261# 208/214 .479/.494 110LCA 1400-4800 128@200
Comp 20-221-3 256/268# 212/218 447/455 110LCA CRS XE256H-10
IC 54 ABCD
Vdoo 10200700 259/256# 208/213 454/454 112 LCA 1,400-5,700
Comp 20-210-2 260/260# 212/212 440/440 110LCA 1200-5200 CRS 260H-10
DC 260 is 269 degrees @.006#
360 cam @.006 276/283# 197/199 410/411 111LCA pn280823 &&&&

Jones 264 @.004 .458 less actual seat and fattest at this duration
Crane 693511 268/272 212/220 460/480 112LCA .904 master
Sum 6901 276/288 218/228 441/441 114 LCA 1800-5500 **
Melling Class 1 278/282 198/199 410/412 111LCA
278 203 410 109LCA Elgin E-626
SUM 6900 278/288 204/214 421/444 112 LCA 1,200-5,000 ***
Same Cam as Melling MTD-1
340 CAM 279/289 @.004 209/219 429/444 114LCA some
say 210/220 (rounding) see 340 cam specs?
DC 260 is 284 @.004
Notice the seat durations on the Summit 6900 and 340 are about the same but the Chevy based Summit is much less at .050 and less lift- and the Melling Class 1 !
Mom Molar knew what she was doing- but read on experiences with 340 cam in 273 or 318
I don't like either in any case

# at .006 adv rest are at .004 # compare with # without with without with each other you have to fudge- my best guess on relative duration
** 9:1 and higher compression, and gearing.
*** one of our Summit® classic cams
&&&& There were two 360 cams, above is the earlier 252/256 Mopar the later was 252/252 in FSM degrees (around .008)
comp 260 closes intake 56ABCD 4 degrees later than 252H
4 degrees does make a difference voodoo 701 is even earlier- you can figure it out
I sorted sorta by intake duration- where the intake closes to get dynamic compression with your low compression

Comp XE 250 110LCA 106 ICL dyno COMP Cams XE250H Dyno Results
so what I get out of this is that the SUM 6901 with the wide LCA would idle great but close the intake late whereas the SUM 6900 would get the intake closed earlier with the slightly narrower 112 LCA look at the difference in the rev ranges
however both are really long cams for the amount of lift- you are leaving a lot of power on the table
you want more exhaust given the poor exhaust with LA heads and no headers

even the smallest crane is 10 degrees larger than stock

the 701 Voodoo gets the intake closed early with that 108 LCA most likely the best choice if you can find one in your budget more like a short Thumper/ Whiplash cam
IMHO you do not want the intake close point of either of the summit cams
If you do get the 6900 stick it in with an extra 4 degrees advance (but mileage will suffer)
you can compare the SUM 9600 directly with the Crane 901 almost the same at .050 but look at the difference in seat -both are measured the same way
The Melling and the SUM have the same .004 duration but look at the differnence at.050 they would idle the same but power??
BTW I just put Comp in because their Intake Close is easy to find
Crane because they grind Cam Dynamics/ Summit and measure the same way as does Melling
Comparing the Melling and the Summit shows why you can't rely on .050 timing
Howard may be one of those "fast acting" cams you hear about- sure looks like it
 
Last edited:
Wyrmrider said:
Well I went to Summit and plugged in your paramaters and came up with Three

expanded the criteria a little and came up with the auto recommendations all over the place
Sealed Power 645 stock 181/192 @.050 .351/400 lift
Crane 693971 248/260 192/204 400/427 112 LCA H-248-2 1,000-4,000
Crane 693901 260/272 204/216 427/454 112LCA H 260-2 1,500-4,500
Comp 252H 252/252# 206/206 425/425 110 LCA IC 52 ABCD 800-4800
Comp XE-250-10 250/260# 206/212 432/444 110LCA
Vdoo 10200701 250/262# 213/220 454/275 108 LCA 1,000-5,500
Comp 20-221-3 256/268# 212/218 447/455 110LCA CRS XE256H-10 IC54ABCD
Vdoo 10200700 259/256# 208/213 454/454 112 LCA 1,400-5,700
Comp 20-210-2 260/260# 212/212 440/440 110LCA 1200-5200 CRS 260H-10
Crane 693511 268/272 212/220 460/380 112LCA
Sum 6901 276/288 218/228 441/441 114 LCA 1800-5500 **
Melling Class 1 278/282 198/199 410/412 111LCA
SUM 6900 278/288 204/214 421/444 112 LCA 1,200-5,000 ***

# at .006 adv rest are at .004 # compare with # without with without with each other you have to fudge- my best guess on relative duration
** 9:1 and higher compression, and gearing.
*** one of our Summit® classic cams
comp 260 closes intake 56ABCD 4 degrees later than 252H
4 degrees does make a difference voodoo 701 is even earlier- you can figure it out
I sorted sorta by intake duration- where the intake closes to get dynamic compression with your low compression

Comp XE 250 110LCA 106 ICL dyno COMP Cams XE250H Dyno Results
so what I get out of this is that the SUM 6901 with the wide LCA would idle great but close the intake late whereas the SUM 6900 would get the intake closed earlier with the slightly narrower 112 LCA look at the difference in the rev ranges
however both are really long cams for the amount of lift- you are leaving a lot of power on the table
you want more exhaust given the poor exhaust with LA heads and no headers

even the smallest crane is 10 degrees larger than stock

the 701 Voodoo gets the intake closed early with that 108 LCA most likely the best choice if you can find one in your budget more like a short Thumper/ Whiplash cam
IMHO you do not want the intake close point of either of the summit cams
If you do get the 6900 stick it in with an extra 4 degrees advance (but mileage will suffer)
Click to expand...

That's an awesome analysis!

I'm really thinking of going on the Lunati, but now my question is if I would have to buy new springs with that cam. Been told I don't have to if I buy the 6900.

Also thinking of getting a double roller timing chain, but if I go with the voodoo there's no money for it.
 
just do the 4 bbl and save your money
how is your chain NOW? you might have to do it first
added a howard cam and some notes
the cam above is a .904 grind as is the Lunatis
all the rest are .842
for comparison howard's Street Farce .842 is
259/267 205/213 .420.430 lift 112LCA
see what you give up- more duration- less lift
You might see if Racer Brown or Doug Herbert have something similar to the Lunati in your price range
Herbert has Mopar cams not in their catalog
of course so does Crower and Engle but not in your price range
Low compression small motors are tough
What say you AJ/FormS?
what springs? ask lunati and explain your problem
maybe they have a return...
and shop around google, e-mail, e-bay
 
AS much as I hate to say it a used 360 cam would be better than the Summit
A regrind- you would need pushrods which throws off the savings
You might e-mail regrinders that members here have used put a wanted in the wanted section
Delta and Oregon Cams and see if they have the Lunati look alike or the 248 Mopar performance
 
Will do the 4bbl upgrade. Seems the right choice for now and later I can go for a better cam.

Thanks.
 
If timing chain is oem you need todo it yesterday
especially if it is a nylon cam gear
keep us posted
and if you do do a compression check post it up thanks
 
Wyrmrider said:
If timing chain is oem you need todo it yesterday
especially if it is a nylon cam gear
keep us posted
and if you do do a compression check post it up thanks
Click to expand...

I don't know if it's nylon but it is the stock chain.

Engine sounds and works excellent but will do a compression test next weekend and post it.
 
Do the chain before it skips a tooth and bends your valves- you are way past being lucky
new valve stem seals are also a DIY task that you should know how to do
Warm it up, put some power to it, back it of and coast down, get on it again and look for smoke- best with someone behind you to block traffic and look for the smoke
report back
Start a new thread on your 4 bbl and these tests
 
Wyrmrider said:
Do the chain before it skips a tooth and bends your valves- you are way past being lucky
new valve stem seals are also a DIY task that you should know how to do
Warm it up, put some power to it, back it of and coast down, get on it again and look for smoke- best with someone behind you to block traffic and look for the smoke
report back
Start a new thread on your 4 bbl and these tests
Click to expand...

Any suggestion on the chain for a tight budget? Maybe Sealed Power KT3160S?
 
.004 DC is 20 degrees longer on the seat 284-264 = 20
danielr410 said:
Any suggestion on the chain for a tight budget? Maybe Sealed Power KT3160S?
Click to expand...
START A NEW THREAD DANIEL like best new chain on a very tight budget
DAniel Do you have an automatic
if so you need the correct 4 bbl trans linkage or the hyd kit

Your question post 101
"Can I just compare duration at @.050? K6900 is close with the specs you posted?"
I think you can see from the posts above why you can't for drieveability, dynamic compression
you sorta can for top end horsepower

from the comparison post and the 340 thread
DC 260 measured 261 @.008 but it's 269 @.006 if you want to compare with comp, lunati,
.004 or SAE Jones is 264 and DC 260 is 284 @.004 20 degrees different
That's about a 10 degree earlier intake close-
IC is really important for low compression motors
checking at .006 instead of .004
@.006 Jones 254 and DC 260 is 269 degrees
Jones takes 10 degrees to go .002 the DC 260 15 degrees to go .002
The Howard is going to be similar to the Jones (but worse below .004)
The Lunati may be in between the Jones and the DC
The rest get worse and worse as you can see
@.006 DC 260" is 15 degrees longer than the Jones 269-254 = 15
however at
@.275 lobe lift DC 260 is 42 whereas the Jones is 64 @.275
50% bigger where the power is
 
Last edited:
Ramm wrote in another thread
I've run the factory dog-bone style roller to .638" and 6700 rpm in a 365 that makes about 500 hp. As far as I know it is still going. Keep in mind though that was 2011 and I have had hydraulic lifter problems ( across all brands ) since about 2013. J.Rob

anyone with hard data on stock or iron rockers?
 
So of the above is too simplistic- here is some moe depth
I said that DC was 20 degrees longer than the Jones at .004 and 15 @.006
Jones takes 10 degrees to go .002 the DC 260 15 degrees to go .002
however those durations were for both the opening and closing ramps
so it used to be simple to just take half that amount for the opening and closing ramps for a symetrical cam
However modern cams are asymetrical
from the comp cams lobe catalog we are given the opening "Intensities" and closing "intensities" (see Harvey Crane's article linked above)
comp does not give intensities for the older series like the H
RPM 29.9 (13.3/15.6) .842
HE 25.7 (12.3/13.4 .842
XE 22.9 (11.1/11.8) .842

PP 24 (11.6/12.4) .904 (Purple Plus)
XM 23.1 (11.2/11.9) .904 (the HE HL Mopar grinds)
X4X4 23.5 (11.3/12.2) .904

so for those of you doing simulations just estimate the opening side/ ramp of the lobe to be a degree quicker than the closing side of the lobe (not for stock mopar cams where the closing is MUCH longer)


a big ending to the oft stated falicy that .904 lobes are more radical
the comp Chevy XE lobes of Harold Berkshire are quicker than any of the Mopar lobes .006<.050 or .050>.006
 
Last edited:
We took a 1974 stock 318 - 2BBl and updated it with the cam for the 340 Auto. (The stick version has more duration). 3 angle valve job. Milled .015 off the heads and used a little thinner gasket to bump compression back up close to 9:1. Stealth intake with Holley 600. Did a little gasket matching and used a Dremel tool to remove the casting high points. 2 Inch duel exhaust with no H pipe thru short Thrush mufflers.
The car runs great on the street. 1974 Dart Swinger runs mid 15's with 2.76 open diff. The 340 cam is a great MOPAR upgrade. Idles a little high, about 900 RPM.
Winter upgrades are 3.55 gears and 10" torque converter after tying the sub-frames. Also took 50 pounds out of the front by removing the non-working A/C and power steering.
 
340 cam can work and 9:1 is about the minimum
where it is a dog is on low compression motors
however you can do a lot better for mid range and the low lift limits top end
those 340 cams are also usually cheap
some like the 360 cam better
both have the problem of really long closing ramps and wide lca which cuts the dynamic compression
run some simulations
however- great jobs and thanks for the report
 
340 cam
Intake Duration, Nominal 268° about .008
Exhaust Duration, Nominal 276°

Intake Duration @ .050” 208° some say 209 or 210
Exhaust Duration @ .050” 214°

Installed Centerlins
Intake Lobe Centerline 112° ATDC
Exhaust Lobe Centerline 116° BTDC
Lobe Separation Angle 114°

Overlap 44° @.008 WITH 114lca
Note: as installed on 112° intake lobe centerline per Chrysler
Intake Opens 22° BTDC Intake Closes 66° ABDC
Exhaust Opens 74° BBDC Exhaust Closes 22° ATDC

Intake Lift .429"
Exhaust Lift .444"

Note: original high-performance 340 4bbl. cam LATER CAMS VARY NOT 68 STICK CAM
from Chrysler High Performance Cam Data
you can go to above and compare intake close data and see how a larger cam can have a similar intake close at the expense of more overlap

Direct connection small block cams

p4529963 .521 lift

p4529970 .526 lift


STX21-105. 305 duration

336/348 duration DC


P3412016 - for a small block......Cam # was ST21-108
Duration - 28x?? my data sheet has a bad spot on the third digit, sorry
Lift - 0.520" (at the valve)
Centerline - 110*
Lash intake - .018"
Lash exhaust - .022"
Recommended spring - P3412068


.533 p/n4529317

The biggest hydraulic was the .533/320. That was a rowdy hydraulic grind.


Chrysler High Performance Cam Data
 
I'd love to have the time to graph all these out on one of those 4 event hump screens, overlapping and comparing. Fascinating subject! Thanks for the effort!
 
From the Victory Library listings here's a start looking at dynamic compression differences here
you will have to do your own conversions to .006 or .004 or whatever your simulation program wants-- see above for hints NOT SHOWN IS THE INTAKE INSTALLED CENTERLINES
340 cam 268 @.008 IC 66 ABDC 114LCA 208@.050
MP268/272 268/272 IC 62 ABDC 110LCA 228@.050
MP 280 280 IC 66 ABDC 110LCA 238@.050
MP 284 284 IC 70 ABDC 108LCA 241@.050
MP 292 292 IC 74 ABDC 108 LCA 248@.050
some notes from my experience
Even if the 340 and 268/272 MP cam close the intake the same at 66 ABDC that's at .008
you can see from an above post that the seat timing at .006 or .004 is going to be much longer with the stock 340 cam
The DC cams are still relatively mild compared to aftermarket cams
you can go the victory library posted above and check other paramaters such as exhaust open and overlap
looks like for a low compression motor the MP268/272 would be the best choice however the DC 248 might be even better for a 318 low compression motor
 
Wyrmrider said:
From the Victory Library listings here's a start looking at dynamic compression differences here
you will have to do your own conversions to .006 or .004 or whatever your simulation program wants-- see above for hints NOT SHOWN IS THE INTAKE INSTALLED CENTERLINES
340 cam 268 @.008 IC 66 ABDC 114LCA 208@.050
MP268/272 268/272 IC 62 ABDC 110LCA 228@.050
MP 280 280 IC 66 ABDC 110LCA 238@.050
MP 284 284 IC 70 ABDC 108LCA 241@.050
MP 292 292 IC 74 ABDC 108 LCA 248@.050
some notes from my experience
Even if the 340 and 268/272 MP cam close the intake the same at 66 ABDC that's at .008
you can see from an above post that the seat timing at .006 or .004 is going to be much longer with the stock 340 cam
The DC cams are still relatively mild compared to aftermarket cams
you can go the victory library posted above and check other paramaters such as exhaust open and overlap
looks like for a low compression motor the MP268/272 would be the best choice however the DC 248 might be even better for a 318 low compression motor
Click to expand...

MP268/272 has almost the same specs as summit 1789, but they say that is for a 9:1 or higher compression engine.

Why is that?
 
remember a 268 MP cam has similar seat durations to a 275 comp (@.006) or 280 crane (@.004)
what compression does a 275ish comp want?
you can see the durations of the stock 340 cam in an above post at .004 and .006
the summit cam is @.004 and is an oldie but goodie chevy grind
with similar durations a mopar lobe will have more area under the curve
and a mopar lobe can have less "intensity" than a chevy lobe as it has more lifter face to work with even if not as radical (the Harold Berkshire 268 comp pushes the envelope for a chevy lifter)
 
You must log in or register to reply here.
-

Back
Top