I am building a 318 for 74 Duster...... Wanted to put nice cam in it for the late 60s muscle car sound.......Any suggestions on what cam......Bottem end is 60 0ver and 10 over on the crank....... Everything basiclly stock except that and using Flat top pistons..... I am not a engine guy so this is the info my motor guy is telling me...... Was concidering a Thumper Cam but have found out that there are some driveablity issues with this.....so just wanting the most cam without issues to get that old sound and that muscle car sound....Hope yall can help..............

 

If you would like to email me tommy@southernmotorcycleradios.com or call me 901 489 5369



Thanks in advance

 

You can easily over--cam a 318, and you can VERY easily over--cam a low compression engine. I can see that guys want that "I've got a cam" sound, but you may very well end up with a dog that has absolutely no bottom end.

I would not put anything in there larger than the factory 69 340 "stick" cam or close equivalent. ANY of the popular cam folks can supply a close substitute.

 

The most important thing to consider is if your pistons have valve notches and the compression height. A stock piston and build specs won't accomodate alot of lift. Most of the "sound" cams do it by decreasing lobe centerline, which increases overlap creating that lope or chop noise. This can reduce cylinder pressure in a low compression engine and take away full potential.

My suggestion is to browse the cam manufacturers learning materials and get to understanding cam timing basics to aid in your choice.

I think going faster is cooler than sounding fast.

 

i just finished rebuilding a 318
cam comp cams/kit dual duration 275 284 462 482
edelbrock air gap manifold avs 650 carb
Mallory ignition
the engine was a factory replacement for a lean burn roller motor not sure the compression
the heads are from a 360 they dont have the large valves in them but i did port the heads for more flow
my heads have been milled to aid in the compression
my approach was maintaining best possible vacuum by leaving key parts of the motor whats the word "bigger is not always better" and the key here is not always
the carb is a spread bore which give you strong pulse off the primaries these being smaller check out my post tuning my avs
the intake is a single plain ram type with closed plenum its the closed plenum also aids in this
but the heads i opened these up to the max the intake runners are larger than the manifold but i left the original valves in it the set cam off a 360 2bbl with a towing package i was tempted to max the valves but decided not too jst under cut valves
after talking with an old timer we new this would ruin the vacuum on this combo/318
the combo works
after the trany rear swap too a 518 390 combo shell be very fast out of the hole but for now shes fast out of the hole from a 20 mpr roll shes very competitive my vacuum is 15 the car is very responsive the ignition gave me a wide range of advance curves to work with
finding ur combo is the key the more u try and error the more u learn this combo is a well thought out plan
i have been running 318's for about 18 yrs and 1 360
the motor is very tough believe u me i push them they always see 3000+ shifts every day, they out last my chevy motors when i ran them back in my younger days
this motor has been too 7000 and back on stock crank /rods

 

..............like I said. That cam is a little more lift and about the same duration as the old 68 340 cam. Since different manufacturers MEASURE lift and duration differently, it could be closer, or further, from the original.

But you bring up an interesting point, which is, if the OP is using 318 heads, small ports, a big cam can quickly become bottled up from small ports and valves, not to mention what might be behind it for manifolds and exhaust.

And you said you shaved the 360 heads. To the OP---don't forget that other than 273/318 heads have larger combustion chambers, so 340/318 heads will drop the compression, and make a 318 even MORE doggy, unless you change pistons or mill the heads

 

Hey 440.....Is it possible to pick your brain a little more on a phone call.....If you would like me to call you , you could inbox your # to me or give me a call at 9014895369....... Trying to get some info to my builder by monday...........

 

Couple things are needed to make sure you get this is done correctly..

Post your combo in it's entirety..
Tranny, gears, stall, exhaust ( headers?), exhaust primary diameter, intake manifold, carb, heads, power brakes, castings, stock valves, over sized valves, bowl work, etc.. No such thing as TMI here. Flat top piston and how far in the hole? Were you shooting for a bump in CR?

Your builder would have (should have) asked you all these questions.

 

LOL I'm probably the last guy to ask on specific recommendations. I've been "out of the loop" on cams for some time, and there are actually bettery grinds, but my point is, "be careful" not to over--cam it.

I would get ahold of comp cams or some other respected regrinder for specific info, but the CLOSEST I know to recommend is either "the" or a modern improved version of the 68 340 cam.

 

wat can i say my combo works
the original comp cams i used in the motor before this one was 268 454 they claim its the same grind 340 had the cam was noticeable in the 318
and about the 318 heads they are very restrictive not a lot of material to wrk with / remove so we remove them melt them down and forge them into swords LOL where as the 360 heads have allot of meat to be removed if i lowered the compression it doesn't act like it she demands 93 to run the best the timing is just about at factory...11 but i still have the 270 rear gear so the timing is touchy until the swap for the new trany rear axle combo
the only reason i dint swap out the pistons with the 30over included in the trw rebuild kit the cylinders where in great shape so i saved a dime, my brother keeps pushing me to do a compression check to see what compression she has maybe this week i'll do it