Moparts

building 360, need cam advice

Posted By: dughuff

building 360, need cam advice - 01/17/11 12:11 AM

I'm ready to start assembly of a 1976 360 block for my 71 Demon. Got it punched 30 over and bought stock dished pistons which are only rated at 8 to 1 compression. I wonder if I made a mistake there, since I bought a summit racing cam with 284 advertised duration (228 @ .050).

This engine will be pretty much stock except for the cam, double roller timing chain, and hi volume oil pump, so I'm worried about the lumpy cam I bought. I read that I should be going with 9 to 1 compression with this cam. Am I going to bend my valves or pushrods?
Should I exchange these pistons before its too late?

I'm building this engine for street use. Of course I want good power but it doesn't need to be super fast. A 14 second qurter would be nice. I've got an aluminum intake and 4 bbl Holley for the top.

Any suggestions are appreciated! This is the first v8 I've built myself.

Also - I'm getting the heads redone: Is it worth the extra money to get the intake valves widened to 2.02? They are stock 1.88 right now.

Attached picture 6421769-1971.Demon.jpg
Posted By: GTX MATT

Re: building 360, need cam advice - 01/17/11 12:15 AM

I would return them just because of the fact that being dished stock replacements your compression ratio will likely be in the 7s. That cam isn't really big, but it would really like more compression for more low end response but it would work. It really depends on your gearing and torque converter. In my opinion under 8 to 1 compression isn't good no matter what cam you run.
Posted By: 2boltmain

Re: building 360, need cam advice - 01/17/11 12:18 AM

I believe new KB107s are still under $200 a set brand new.
Posted By: 71valiant

Re: building 360, need cam advice - 01/17/11 12:23 AM

I built the same motor. Stock block, 292/292 duration 484/484 lift. 230@.050. Headers, RPM airgap intake, I cleaned the heads up. Stock mopar ignition, holley fuel pump 4:30 gears and a 2600 stall converter. It runs well for what it is. I like the motor for what I built it for money wise.
Posted By: RapidRobert

Re: building 360, need cam advice - 01/17/11 12:28 AM

Quote:

I would return them just because of the fact that being dished stock replacements your compression ratio will likely be in the 7s. In my opinion under 8 to 1 compression isn't good no matter what cam you run.

X2, refund them & get some KB's. I'd want ~mid 9's, or more if you wanted to get quench (EXCELLENT plan but will take more time/$$)
Posted By: dughuff

Re: building 360, need cam advice - 01/17/11 01:02 AM

thanks for your input. I'm running an a833 4 spd w/ overdrive and 8 3/4 rear end w/ 323 gear.

What do you thnk about the heads? stick with 1.88 intakes or widen to 2.02?
Posted By: dughuff

Re: building 360, need cam advice - 01/17/11 01:05 AM

Thanks for your input. I'm running an a833 4 speed w/ overdrive and 8 3/4 rear end w/ 3.23 gear.
What pistons did you use?
Did you stick with 1.88 intake valves on the heads or have them widened to 2.02?
Posted By: ohiodemon

Re: building 360, need cam advice - 01/17/11 01:24 AM

i used the kb-107's in my 360.with stock unmilled heads you will be around 9.3-9.7cr.
those pistons worked great.Pay attention to the ring gap assembly instructions.
stock valves will be fine.
some 3.91 gears would help too
Posted By: 7D9LRE

Re: building 360, need cam advice - 01/17/11 01:48 AM

I'm happy with my Comp Cams XE268. SpeedPro H116CP pistons from Summit. 3 angle valve job, pocket ported small valve J heads. Everything gasket matched and opened up. Factory intake and Thermoquad. Boss Hogg converter. Best 1/4 of 14.7 before getting the tune right.
Posted By: 451Mopar

Re: building 360, need cam advice - 01/17/11 01:57 AM

Get the higher compression pistons. The mentioned Keith Black 107 are likely going to be the least expensive and easies to install option.
The larger 2.02 valve is good if you are porting the heads. If your not porting the heads it won't make that much difference.
Posted By: RapidRobert

Re: building 360, need cam advice - 01/17/11 02:14 AM

port em as far as you dare (they are expendable stock heads)/have your shop add 2.02's & unshroud the combustion chambers/bowl hog the bowls. dulcich has some excellent SB porting articles which might be avail on the Mopar Muscle archives
Posted By: calrobb2000

Re: building 360, need cam advice - 01/17/11 02:51 AM

hi
keep the 1.88 valves .
get the flat top pistons .

my son has a similar combo in a duster .
360,small cam ,headers,3' exhaust , ld340 intake , 750 vac holley ,727, 3.55 gear, runs 13.8 consistantly !

Posted By: GO_Fish

Re: building 360, need cam advice - 01/17/11 03:44 AM

Slow down and do more research before dropping your $$$ down. You don't want to go off "half cocked", then be very unhappy with the results and $$$ down the drain.

No sense in 2.02 valves on the street usually. If it is usually running 4500 rpm or less, 1.88 valves will be fine. Save your money for elsewhere. Don't say what trans you are running. If automatic, you will be much better spending money on a better converter than on big valves.

If you rush and throw something together half arsed, you will be wasting money and leaving performance on the table.

Carefully, patiently, get a plan together, then you will be happy with the results.
Posted By: dughuff

Re: building 360, need cam advice - 01/17/11 08:30 AM

Thanks man, good advice
Posted By: dughuff

Re: building 360, need cam advice - 01/17/11 08:32 AM

much appreciated, thanks for the advice!
Posted By: MoparforLife

Re: building 360, need cam advice - 01/17/11 12:08 PM

Also make sure to upgrade the valve springs to match teh cam. OEM 360 springs don't like much cam. Also get rid of the rotator retainers found on a lot of 360 exhuast valves.
Posted By: patrick

Re: building 360, need cam advice - 01/17/11 02:30 PM

KB107's, comp XE268, comp #901 springs and matching retainers, and leave the 1.88's unless your valves are severely sunk...if the heads need more than a valve job (if they need new guides or valves, etc), I'd buck up the extra $$ and buy these heads

granted, stock dished pistons, headers, and a comp XE262 will get you into the high 13's/low 14's and run fine on 87 octane.
Posted By: dennismopar73

Re: building 360, need cam advice - 01/17/11 02:41 PM

being i built this very same motor,,
put it in a 4000# boat,,
street car drove everyday
with a smaller cam, 270 h comp,
it ran best of 14.22, with 391,gears
with stock heads, and what everyone said was junk
intake a torker 360, and a 600 holley carb
mmmm
so in somthing thats lighter than 4000#
little bigger cam, bigger carb,
low 13s high 12 now prob easy!!!!
Posted By: MY340

Re: building 360, need cam advice - 01/17/11 08:08 PM

My 360 motor is a PAW shortblock, 9:1 final compression with rebuilt 1.88 /1.60 heads, Comp 280H cam, Weiand Stealth manifold, Hooker headers and 750cfm Eddy carb. 2600 stall convertor with 3.91 gears.

Combo pulls strong thru all rpms ranges.
Posted By: west

Re: building 360, need cam advice - 01/17/11 08:30 PM

#3400
kb's 9:1
xe284 and eddy heads,rest of block is stock
air gap,headers,700 cfm,converter and 3:73's
does low 12's on street tires all day long.
shootin for 11's but prob won't get there without spending more money.
Posted By: MoparforLife

Re: building 360, need cam advice - 01/17/11 09:15 PM

Quote:

#3400
kb's 9:1
xe284 and eddy heads,rest of block is stock
air gap,headers,700 cfm,converter and 3:73's
does low 12's on street tires all day long.
shootin for 11's but prob won't get there without spending more money.


Shouldn't be too tough tapping into the 11's. Been there. 4:30 gear, slicks, LD340 intake unported heads with 1.88 valves. 271 hdp crower cam ran me 11.70's all day Hughes cam and heads put me in the 11.40's.
Posted By: HYPER8oSoNic

Re: building 360, need cam advice - 01/22/11 01:12 AM

Quote:

Slow down and do more research before dropping your $$$ down. You don't want to go off "half cocked", then be very unhappy with the results and $$$ down the drain.

No sense in 2.02 valves on the street usually. If it is usually running 4500 rpm or less, 1.88 valves will be fine. Save your money for elsewhere. Don't say what trans you are running. If automatic, you will be much better spending money on a better converter than on big valves.

If you rush and throw something together half arsed, you will be wasting money and leaving performance on the table.

Carefully, patiently, get a plan together, then you will be happy with the results.



And he IS running a 4-speed, so the bigger valves would work.

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