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Old Fool
Dodge Dakota
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3/15/2005
22:40:44
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 Subject: RE: pre mag mods
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I have the Intake on E-Bay. This is the link Edelbrock Performer RPM part# 7176 for 340/360 and 318 with 340 or 360 heads, Will not work with the Magnum Engine
Later,
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Zac
Dodge Dakota
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4/13/2005
13:54:44
|  RE: pre mag mods
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Hey gen1dak i got another question for you. i havent posted in a while because of techinical difficulties. If i carb'd my engine what are the specs of the biggest possible cam i could run with my auto tranny. Also what size carb and which intake would be best. it is no longer my daily driver so i want to go all out.
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gen1dak
Dodge Dakota
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4/13/2005
20:52:24
| RE: pre mag mods
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Well now, you need to define "all out" a bit. Are you still talking about a good, streetable 318? With 360 heads? I'd still hang with something like CompCams Xtreme Energy 268. Despite their larger ports, the 360LA heads still run into flow issues once you start talking about gross valve lifts above .480ish..... Granted, extensive head porting and polishing will open this up a bit, but you're getting into the realm where it'll start being a fussy, tempermental engine. Generally, something with .470 intake/.480 exhaust, 220/230 @.050 duration, and 110 degree lobe separation (the XE268 is .477/.480, 224/230 @.050) will give you a dynamite street engine that'll still make enough low-end to work with the stock torque converter. This cam will pull in excess of 6,000 rpm, and that's a good cutoff. Go over 6,400 and you really need to look into heavier rod bolts, etc to handle the extra stress. I would use the Edelbrock RPM AIR GAP intake and an Edelbrock Thunder Series 800 cfm AVS carb. If I didn't already have the AFB carb, I'd get the AVS. They're similar, (and were both originally designed and made by Carter-AFB design is a little older) but the AVS is easier to tune on the secondaries, and it's had a fine rework by Edelbrock. The thing is awesome. These are the items frequently used by various magazines to extract 400hp @ 6,000rpm from a carbureted 318. Going much beyond that requires some serious parts for the added stress. If you want even more power (without turbo, supercharging, or nitrous), and plan on keeping it below 6,500rpm, you must have a larger engine.
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Zac
Dodge Dakota
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4/13/2005
23:04:03
| RE: pre mag mods
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Yes i still want to keep it a streetable 318 with 360 heads. I have a good solution to the lower compression ratio of the 360 heads. supercharge it. i am looking at the procharger centrifugal selfcontained units. On the procharger website they say with an intercooler i could run boost pressure as high as 20-25 psi. If i do supercharge it, would the engine be able to handle it?
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Zac
Dodge Dakota
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4/14/2005
00:04:15
| RE: pre mag mods
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you said those two books tell me how to bypass the autoshutdown relay so i can run a carb and ditch the computer right?
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gen1dak
Dodge Dakota
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4/14/2005
13:11:57
| RE: pre mag mods
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You're not gonna run that much boost with the stock pistons. You would need forged pistons for safe operation of much more than, say 12 psi since you'd have a lower CR to start with...(around 9psi with 9:1 CR). If you seriously want 25 psi, you will need the forged pistons, heavier connecting rods (forged), high strength rod bolts, and a forged crank. To put it into perspective, 25psi would make the 318 think it was roughly 600 cubic inches in desplacement. 1hp per cubic inch is easy, so there you are. Even 7psi will make a 318 displace more like 480 cu. in. Also, with supercharging, you would need a cam with lobe separation in the 114 degree range.
Bypassing the ASD does not mean the computer can be ditched. Rather, it means you can run with a carb and non-computer-controlled ignition, but other functions (charging system/voltage regulator/etc) will still function through the computer. To totally 86 the computer would require wiring in an external voltage regulator, air conditioner controls, etc. All of that can be done, though most just leave the PCM in place to handle everything else. You can bypass the ASD, then work on re-routing the rest of the electrical system afterwards, once back on the road. The book on "A" engines has specific information on bypassing the ASD.
Oh, and if you do build a 25psi 318...I wanna ride!
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Zac
Dodge Dakota
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4/14/2005
19:32:27
| RE: pre mag mods
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what would be a good compression ratio to start with for that much boost? I might just go that route with stronger rotating assembly and then if i want i could get a supercharger later when funds allow. Would the cam specs be the same except for the lobe seperation? and what would the 4 degrees of seperation change? how does it make a difference?
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gen1dak
Dodge Dakota
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4/14/2005
23:42:37
| RE: pre mag mods
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25 psi? Please, that's gonna take one helluva intercooler. Making that much boost is gonna make a lotta heat, but if I were gonna do that, I'd shoot for a true 7:1. Better to shoot for 8:1 and 12-15psi. You can run a milder cam since the boost will really kick up the cylinder filling. Otherwise, the hotter the cam, the more HP, just as without a supercharger. Spreading out the lobe separation makes the cam more blower-friendly. It has to do with the overlap between when the intake and exhaust valves are open. Particularly in more streetable applications, you want less overlap with a blower. This cuts down on possible blow-back into the supercharger, and helps maintain smoother intake flow in the proper direction. Basically, get too much overlap, and the blower gets into a battle with the engine, instead of working with it.
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Zac
Dodge Dakota
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4/15/2005
19:48:48
| RE: pre mag mods
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After the head swap without milling the heads, i should be close to 8:1 right?
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gen1dak
Dodge Dakota
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4/16/2005
00:39:39
| RE: pre mag mods
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Yeah, right in that area.
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Zac
Dodge Dakota
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4/16/2005
14:28:15
| RE: pre mag mods
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How much can I mill the heads without screwing up the valvetrain geometry? How many points of compression could I gain?
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Zac
Dodge Dakota
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4/16/2005
14:46:20
| RE: pre mag mods
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I was reading the car craft 400 HP 318 article and they used magnum heads. They also did a lot of machining to the block. What would be better, 360 heads or magnum heads without any machining
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Zac
Dodge Dakota
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4/16/2005
23:20:23
| RE: pre mag mods
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What would be the best years for 360 heads? Is there a difference between 2 and 4 barrel versions?
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gen1dak
Dodge Dakota
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4/17/2005
23:13:15
| RE: pre mag mods
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The 360 heads with the most performance potential are the last ones, circa 1988-1992, but Hot Rod Magnagine did a "Junkyard Jewel" article on the 400hp 318, and they used the original 318 heads, and hogged the ports out to 360 size with a die grinder, then ported it accordingly. Easiest would be the Magnum heads, ready to go, but even they can benefit quite a bit at the hand of a skilled port/polish pro. There is no 4-barrel 360 head, so don't get taken like that. The 360 had 1.88" intake valves, 1.60" exhaust. Since the head is the same as the 340 head, it can easily be opened up to 2.02" intake valves, just like the 340. Chrysler suggests a maximum of .060 head milling, but that's way too much. If you want to supercharge, don't mill at all. If you want around 9:1, a good .020 should handle it, probably closer to 9.5. Don't have the figures on that. Also remember to mill the intake. For example, if you take .020 from the heads, you'll need to mill .028 from the bottom of the intake, and .020 from both sides of the intake.
For the LA heads, and their rocker shafts, you can use these: http://store.yahoo.com/chucker54/rocshafshim1.html
to regain lost height (and reduce hydraulic lifter preload) after the milling.
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Zac
Dodge Dakota
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4/18/2005
01:33:46
| RE: pre mag mods
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I was on the comp cams website and was looking at other XE cams. The larger ones said they needed a 2200 stall converter. Is this absolutely neccesary or could i use the truck for a while and just not gain full power while i save for it? And which combo would make more power, the magnum or 360 heads? Which would be cheaper and easier?
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gen1dak
Dodge Dakota
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4/18/2005
11:44:59
| RE: pre mag mods
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You want real power, get some W-2's. Properly ported, the 360 heads are so close to ported Magnums, it's a coin-toss as to who'd win, but the Magnums will pull just a hair more (we're talking less than 5cfm at max flow according to Mopar Performance). Now, out of the box, the Magnums handily outflow LA heads. The cost depends. You score some good LA heads at the yard, clean 'em up and get a port job, you'd undercut the Magnum cost, but the Mags will be ready to bolt on. If you get the Magnums, you'll need the Magnum rockers, holow pushrods, and lifters that oil via the pushrod, so the costs will still be higher with the Magnums. There are also new LA heads that can be had, so again, the cost issue is a little more involved than just the price of the heads. I'll look up some prices for example purposes. I'll do it tomorrow sometime, working now, and have a concert tonight in New Orleans.
On the torque converter deal, that's a relative term. Basically, it means you need a looser converter to let the engine get up on the cam. Another way to help this is the use of looser gears (3.90/4.10/4.56). This lets the engine pull through the lower rpm's so it can get up on the cam that way. You can use the converter you have now, get a higher stall later. If it's a little soft on the low end, you can bump up the ignition timing, boost the accel. pump shot on the carb. Remember that higher stall speeds will generate more heat, and an external tranny cooler might as well be considered mandatory.
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Zac
Dodge Dakota
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4/19/2005
20:18:54
| RE: pre mag mods
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how hard would it be to convert to a flat tappet cam? just to save some money. Is it worth it? or would i lose power?
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Zac
Dodge Dakota
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4/19/2005
20:51:09
| RE: pre mag mods
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Would it be better to open the ports, mill .020 off and put 360 valves in my stock 318 heads, or port and polish the 360 heads and take .030 or .040 off of them? I was reading the Hot Rod 400 HP 318 and they reused the stock heads just opened up the ports to the size of a 360, and put big valves in the heads.
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gen1dak
Dodge Dakota
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4/20/2005
11:29:09
| RE: pre mag mods
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It's not a big problem changing to a flat tappet cam in a pre-Mag. It'd be quicker to just clean up a set of 360 heads. Either head will need machining to take the 2.02 intake valve. The 318 will also have to have bigger exhaust valves installed, which adds to the cost. Starting with 360 heads would be cheaper. Mopar sells new ones, already ported and ready to go. They're cast iron, and actually, a pretty good deal. If you're serious about really pumping up the engine with compression ratio and boost, you should plan on o-ringing the block, otherwise you'll be blowing head gaskets like crazy with the boost levels you're talking about.
There's been a lot of conjecture about the virtues of roller cams in street vehicles. In racing, rollers allow the most radical cam profiles, but nothing like that is run on the street. Street rollers are good for decreasing friction in street vehicles. When installed in 318's in the 80's, they managed a whole 4% increase in EPA mileage. The ultimate power benefits of a roller are with much bigger cams than anything you'd run on the street. There's nothing wrong with running a good flat tappet cam, and again, anything you can run on the street, can be done with a flat. The friction losses with a flat cam seem to be pretty well offset by having lighter lifters, and reduced reciprocating assembly weight, which lets the engine rev better at higher rpm's. Nothing wrong with running a street roller either. And, no, you won't lose power.
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Zac
Dodge Dakota
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4/20/2005
14:44:43
| RE: pre mag mods
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so a flat tappet cam will bolt right in? Just like a replacement roller cam? All i would have to do is get new lifter and pushrods? Are the pushrods different?
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