Davidrad
Well-Known Member
I have a 318 in my 76 Coronet. I want to bolt on some power adders. Intake and a holley carb. Should I add a cam, and if so which specs for an engine I don't want going much higher than 5500 rpm.
318 4 Barrel
- Thread starter Davidrad
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A common belief is that the heads are the bottleneck in a 318. You can swap in a 4 barrel and split into dual exhaust but if the heads do not flow, the gains will be minimal. When the 318 was redesigned into the 5.2 Magnum with the better heads, it went from a 145 HP engine to 230.
Slap Stick
Well-Known Member
The big throttle body helped too.
PurpleBeeper
Well-Known Member
1. Is this a totally new, rebuilt motor or a used 100,000+ mile motor? Big horsepower can break old motors. Just my opinion here.
Older Motor - $800-$1000
a. 318 4 bbl. police intake
b. small carb...maybe even 500cfm Carter/Edelbrock, MAX would be 600cfm Holley (still too big)
c. Set of headers & high flow mufflers
New Motor $2000-$3000
a. Magnum heads (or older 340/360 style heads)
b. cam/springs/lifters/maybe hi-perf valve gear
c. headers/hi-flow exhaust
d. transmission upgrades
e. 3.55 or higher rear end gear ratio
f. If you have forged pistons/good rods/good rod bolts - then add nitrous oxide
Older Motor - $800-$1000
a. 318 4 bbl. police intake
b. small carb...maybe even 500cfm Carter/Edelbrock, MAX would be 600cfm Holley (still too big)
c. Set of headers & high flow mufflers
New Motor $2000-$3000
a. Magnum heads (or older 340/360 style heads)
b. cam/springs/lifters/maybe hi-perf valve gear
c. headers/hi-flow exhaust
d. transmission upgrades
e. 3.55 or higher rear end gear ratio
f. If you have forged pistons/good rods/good rod bolts - then add nitrous oxide
rumblefish360
Well-Known Member
On my 318 Duster hop up build, a stone stock '79 - 318 was given a Crane split duration cam. 272/284 (advertised, [email protected] intake) .454/.480-112.
https://www.summitracing.com/parts/crn-693941/overview/make/chrysler
A 600 cfm carb. NOT TO LARGE AT ALL, no way no how.
LD4B Hooker headers into a Jegs 2-1/2 exhaust. The rest was a stock 904, 8-1/4 rear with 3.21's on stock tires.
With your cars weight and gear ratio I highly recommend this Crane cam as the largest one to use.
https://www.summitracing.com/parts/crn-693511/overview/make/chrysler
https://www.summitracing.com/parts/crn-693941/overview/make/chrysler
A 600 cfm carb. NOT TO LARGE AT ALL, no way no how.
LD4B Hooker headers into a Jegs 2-1/2 exhaust. The rest was a stock 904, 8-1/4 rear with 3.21's on stock tires.
With your cars weight and gear ratio I highly recommend this Crane cam as the largest one to use.
https://www.summitracing.com/parts/crn-693511/overview/make/chrysler
moper
Well-Known Member
Engines are air pumps. Air has to go in, and it has to go out. Start with the "out" side first. Headers are best (IMO), but a good set of dual pipes will help a little over a single exhaust as I assume that's what you have. Next is ignition. Stock sucks. A modern multi-spark, or a Standard Ignition LXC-101 module and a non-lean burn passenger car distributor with a performance curve. After that - the 4bbl is good, but you really need a set of valve springs, and the intake and 4bbl for this to all work. I like Comp's 901-16 springs, and as was mentioned - a cam with less than 215* at .050".
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