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What Cam for this 318? Setup performance?

rt-man

rt-man

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I've gone around the horn, from a 408 stroker to a built 360 to a stock 340 and back to the 408. A hard look in the mirror says a $$ engine build doesn't have the value for me. I've had my fun with two HP 440s, I'm gonna dial it way back and...go the poor man's route on the 318 in the car. Objective: smooth idler with some balls between 2,000-4,500rpm. A cruiser, pure and simple. And it has to look as factory as possible. Here's the plan:

Car: the '73 SSP in my signature
Weight: about 3,600lbs
Rear differential and gears: SG, 8.25", 3.55:1
Tires: 205/60R15, or 215, I don't recall
Transmission: 904, stock TQ
Accessories: AC, power brakes
Engine: LA 318, 81k miles
Heads: stock
Bottom end: stock
Intake: either Edelbrock LD4B or Edelbrock Performer 318/360
Exhaust: 340 HP manifolds, duals
Carb: Carter AVS 4640SA

Cam choice: since I'm doing nothing to the heads, I'm thinking either the Hughes 318 Whiplash or a stock 340 grind. Don't wanna kill any low-end with a large cam. I want the AVS 'cuz a vacuum secondary will only give the engine what it needs and its on my shelf. I have the 340 HP manifolds already. Dual exhaust is on it.

Do I need to replace the springs if I keep the lift around 270?

No need to tell me I should get 340 heads with bigger valves, I'm not putting that $1,000 into it. I know the heads are the weak link here.

Thoughts on the cam? How do you think the combination will perform? I'm not trying to recapture BB glory, but I think these mods will wake up the 318. Thanks.
 
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s-l1600 (14).jpg
 
I've played with a couple of teens over the years and the best bang for the buck is more gear, OD if you can swing it and then even more gear! :D The 340 cam is good but at least pocket (bowls) port the heads. The factory valve pockets are crap at best. IMO, you don't need any porting other than that and then just blend the ports into the bowls and make sure the intake matches the heads. That intake usually has larger ports than the teen heads and you will end up with a step up and over the head port side and that's never very good. The intake and cam change will help but why bother if you're not going to help out the heads....and if it were me, good quality headers would get thrown on too.
 
Cranky said:
I've played with a couple of teens over the years and the best bang for the buck is more gear, OD if you can swing it and then even more gear! :D The 340 cam is good but at least pocket (bowls) port the heads. The factory valve pockets are crap at best. IMO, you don't need any porting other than that and then just blend the ports into the bowls and make sure the intake matches the heads. That intake usually has larger ports than the teen heads and you will end up with a step up and over the head port side and that's never very good. The intake and cam change will help but why bother if you're not going to help out the heads....and if it were me, good quality headers would get thrown on too.
Click to expand...

Okay, Cranky, what intake would be best matched for this setup, in your humble opinion? Weiand 8007? LD340?
 
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rt-man said:
Okay, Cranky, what intake would be best matched for this setup, in your humble opinion? Weiand 8007? LD340?
Click to expand...
I like the LD340 mainly because I haven't had any experience with the Weiand and I know the LD works very well....just make sure the the transition from the intake to the heads match up just like any intake should be done. The best intake in the world won't do well if the runners do not match with the ports in the head and both the heads and intake can have core shift. Nothing that is cast is 100% perfect as cast whether or not it's aluminum or iron and especially so with 50 year old stuff. Nowadays, things are controlled better in the casting process but not back then......and I even check the new stuff to make sure.
 
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I used the Comp Cam XE 256 H in a +.030" 318 (323) and was extremely happy with it. Performer and 625cfm.
 
Been down this road.

IF you really want to use the AVS over the TQ, your leaving power on the table.
TQ with a Performer or OE Iron. There equal.
AVS with the LD4B

Both carbs are mechanical secondary carbs with both having an air valve that is spring loaded and tuneable. (Sp?)

Crane Cams 272/284-.454/.480-112
(218-226 @.050 IIRC)

This cam will generate decent vacuum for power brakes and the idle is smooth enough not to cause suspicious intent.

I suggest matching springs, but if yours aren't old and worn and are within the specs suggested by Crane...
 
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IMO the LD4B with an AFB/AVS would work very well. My AFB did really well for more than 5 years on the street. Then i was not able to correct it's problems. I used a Comp High Energy 260, not sure what the current comparable version is. Mine was very street friendly but made really good power.
 
So far, the best street carb I've ever had was a TQ but it has such a lousy reputation due to the lack of knowledge most have on it and the fact that the tool that makes adjusting the air door a breeze is nearly non existent, I rarely mention it anymore. The majority called them Thermobogs back in the day and the main reason they bogged was because the air door was opening too fast. The great thing about them is that it really doesn't matter if the engine is smaller as they are so tunable and can deliver very decent fuel mileage. My old 71 340 Cuda knocked down 17 in town driving briskly with 3.55 gears.
 
Good choice rt (on the 318 deal).
I would go with either the 268H, or XE262 Comp cam, Comp 901-16 springs, and the Performer 318/360. Keeping the 318 heads is the right move, but you will need to upgrade the springs to match, and I would avoid any of the 340/360 port size intakes. Even the stock ones. I don't think a cam with duration at .050 of more than 218* or so and you're asking for issues with the idle vacuum and brakes.
 
Oh No! I have thrown the BS flag on
340-6.jpg
myself. A deal came by me yesterday that was too good to pass: in my budget and my area of operation. I apologize for this wild goose chase. But here it is:


1972 340 block
Steel crank 0.010/0.010" U/S
Crank accepts A.T. or 4-speed, NOS pilot bushing installed
0.030" O/S 10.5:1 forged pistons, floating pins
File-fit moly rings
Internally dynamically balanced
Resized forged rods w/ MP bolts/nuts
Tri-Metal bearings
Original heads - induction hardened exhaust seats - 2.02/1.60 valves - professionally bowl-ported
MP Purple stripe hydraulic cam & springs
Fel-Pro gaskets throughout
Edelbrock Torker intake - no hood clearance issues
New "cop" big-bearing water pump
New 340 fuel pump
New Mopar distributor, NOS tan alkyd cap
New stock oil pan, original crank scraper ("windage tray")
New oil pump, drive gear, and bushing
Stock damper
M/T super beefy cast valve covers
New cr-moly pushrods, mint stock rockers

Just needs my carb, my exh manifolds and my accessories. Bye bye low-end torque, hello heavy-breathing, high-winding SB.

Thinking to swap out the Torker for an Edel LD340 or similar dual-plane low rise intake.

Thanks for all your responses!
 
Hooker Super Comps at 1-3/4!
No fitment issues unless you have a manual trans with a scatter shield. Then I tube needs to be clearanced.
 
If you're considering the comp "262" cam, take a look at the desktop dyno s/w versus the "256" results.

All my tests showed only a 10 HP peak increase with the 262 on a much narrower peak.
The 256 had a much broader torque curve with more HP under the curve.
Shame to give that up for 10 more peak HP.
 
I got fantastic 318 results using "302" casting heads with 360 valves and bowl-relieving and chamber de-shrouding, and a (free/giveaway) 272*/.454" lift Crane Energizer cam. Nice stable choppy idle, great powerband. This was in a heavy 1986 D250 pickup with 16" tall wheel/tires and 3.55 gears. Headers are always a plus and I'd make sure to stay with a dual plane intake (Performer Edelbrock, not RPM) with correctly sized ports, or the Holley Street Dominator low-rise single plane.
 
First off, head over to forabodiesonly.com and ask this question in the Small Block forum. TONS more insight over there than here. I know this because I have a 340 in my Coronet. I dont bother asking questions about it over here anymore. Not that these guys dont know what they are taking about, just way more experts over there.

Second, I just put in a Comp XE 268 into my 340. I love the torque in the low end. Replaced a 285 that was in the car previous.
 
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