Some advice

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Rockerdude

Rockerdude

Rock n' Roll and A-bodies
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I'm getting ready to help my good local friend take his beautiful 73 Dart build a V8 and install it in his car. The car has a 225/904 now and he wants some more go and that V8 rumble. I told him that a hot 318 would be an easy swap with the conversion mounts, and all the necessary V8 stuff (Rad, Trans, Exhaust manis, ect). Ive done that swap before in a couple cars, so I am familiar with mild 318s (I was thinking 360 heads, cam, nice dual plane intake, 360 exhaust manis). But I'm starting to think that before we are committed to a 318, to look into doing a 360. I know the oil pan is different, and that they are externally balanced, but what other costs should I look at in terms of 318 vs 360? He wants to completely go through the engine (bore/hone it, new pistons, connecting rods (maybe if they are cost effective), bearings, performance cam, ect.) before we put it where it belongs. Just looking at some parts on summit and it looks like there's a much bigger selection of pistons for 360s, which is awesome.

What we have planned now is to buy a good core engine and slowly get the stuff done as we get the car ready. First is Bbp discs up front and a 8.25 in back, so the car is still drivable up until the engine is ready to go in.

What do you guys think? I'm pretty damn excited to help him get the tires spinning on his car!
 
If he builds it, the 360 will be slightly cheaper since they have the ever popular 4" bore. Those rings are everywhere on the cheap.

You don't want to put 360 heads on a 318. If you're doing this to help your friend, you will want to act like you know a little about Mopars and putting 360 heads on a 318 ain't acting like it. That will get his compression on a 318 down into the 7s. That won't pull a greasy string outta a cat's *** and will make you look like a dumbass, so lets not go there.

That said, the 318 can be made to run great, but it's all in what he wants. What kinda power level is he lookin for? Up to 325 or so? The 318 is a good choice. Over 350? The 360 all day long.
 
Yes, all good points. He really wants something that has a good amount of power, sounds good, and will spin a set of 245's at will (pretty vague, I know). But if the cost is pretty much the same, more cubes makes more sense.

Btw, when I said 360 heads I was thinking 360 Magnum heads. But with that I know it would need a magnum bolt pattern intake, and to oil through the pushrods to feed the valvetrain..
 
Do the 360LA! Get a good core cheap, have good overall machine work done on the block & heads along with some KB pistons, and he's good to go. As far as the "total" combo, $$$ will equal out when it comes to the cam & bolt on's. We can deal with that later when the converter/gear ratio is narrowed down?

Don't forget that you'll need a V8 904 to go behind it?
 
So, RustyRatRod, I was wondering how much power it takes to pull a greasy string out of a cat's ***? LOL, I'd never heard that one. By the way, I agree with the 360.
 
OldmanRick said:
Do the 360LA! Get a good core cheap, have good overall machine work done on the block & heads along with some KB pistons, and he's good to go. As far as the "total" combo, $$$ will equal out when it comes to the cam & bolt on's. We can deal with that later when the converter/gear ratio is narrowed down?

Don't forget that you'll need a V8 904 to go behind it?
Click to expand...

I agree with this ^^^^^^^

A good healthy 360 will not spin 245s, it will annihilate them. Slap. To. Pieces.
 
He did say that he wants a lopy idle, but not to loose drivability with the stock converter.. So with a 360 and this cam, it would probably do the job.

http://www.summitracing.com/parts/cca-cl20-600-4/overview/make/dodge

I've never been a fan of the Thumpr cams myself, I actually really like Voodoo cams. But Im up in the air about what he wants over what he needs.
 
I personally would not use that cam but even more so important is the intakes duration. With a stock converter, your limited in duration. A safe duration @ .050 is 218. Going beyond that the starting power RPM starts to go beyond what the OE converter is designed to do/handle/work right.

"That muscle car sound" is due to the cam's lobes and centerline. A quicker acting lobe and a cam on a 110 will have "That sound." Moving down to 108 increases that "Chop" and rhythm. At 106, it increases more, and so on...

A smooth idle can be obtained with a 112. Very smooth at 114.

Before we start in wit cam specs, can you tell us the gear ratio?

Or were you looking for a suggestion on how to possibly build this like a combo?
The 360 is the way to go for sure. If you keep the external balance, it will only take a B&M flex plate to use a neutral balanced converter. Cheap part to purchase!
 
Use the Comp 265 DEH. It will blow the tires slap off.
 
rumblefish360 said:
I personally would not use that cam but even more so important is the intakes duration. With a stock converter, your limited in duration. A safe duration @ .050 is 218. Going beyond that the starting power RPM starts to go beyond what the OE converter is designed to do/handle/work right.

"That muscle car sound" is due to the cam's lobes and centerline. A quicker acting lobe and a cam on a 110 will have "That sound." Moving down to 108 increases that "Chop" and rhythm. At 106, it increases more, and so on...

A smooth idle can be obtained with a 112. Very smooth at 114.

Before we start in wit cam specs, can you tell us the gear ratio?

Or were you looking for a suggestion on how to possibly build this like a combo?
The 360 is the way to go for sure. If you keep the external balance, it will only take a B&M flex plate to use a neutral balanced converter. Cheap part to purchase!
Click to expand...

He now has his stock 7.25 with 3.23's. He actually wants to go to a highway gear in the 8.25 so that he can cruise on the highway at a lower rpm. I was thinking 2.76 would probably work for him, but that also depends on what we find for a rear end when that time comes. Also note that he has 14 inch sbp wheels now, (245/60r14s in the back) and when we go to bbp I will get him to upgrade to 15s and a taller tire in the rear which will help out too.
 
If this is a street engine, it is easy to overdo it. A big square-bore carb doesn't cost much more than a smaller one, likewise an aggressive cam grind isn't that much more than a tamer one. Unless something is done to the raise compression ratio and the rear gear ratio, the sum of the components becomes less than the whole. If money is an issue, suggest bumping the compression ratio now, catch the rear gear later.

For the rear end, a 3.23 to 3.55 will work on the street. Compression ratio should not go past 9.5:1 with cast iron heads, 10.5:1 with aluminum heads and pump gas. For cams, take your pick from those that have a 215º-225º duration at .050". Remember to budget for springs and keepers while you're at it. For carburetors, it's kind of a toss-up for me. A 625-650 cfm will yield better throttle response, a 750 cfm will give you better top end. Automatic transmissions tend to work better with a vacuum operated secondary.

If bumping the compression ratio and rear gear are not in the cards, suggest going with a 340-spec cam and a 650 cfm carb with a vacuum (air valve) secondary.
 
What about the Voodoo 60402? Specs:

Advertised Duration (Int/Exh): 262/268
Duration @ .050 (Int/Exh): 220/226
Gross Valve Lift (Int/Exh): .475/.494
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1400-5800
 
A 360 engine will probably have Speed Pro Hypers because of the price, not entirely what the compression would be with mid 70's 360 heads.
 
You MAY be headed for a world of disappointment.
Highway gears and choppy idle dont play that well together.The path you are going down needs almost extreme attention to parts selection. If you are married to highway gears,tall tires, and the 904, you will need the 360 for sure, and a shortish period cam.Concentrate on keeping port velocity up, and maximizing compression for the available fuel.
IMO, do not be misled by horsepower numbers. Concentrate on building torque and let the hp fall were it may.You will have a much funner car.
There is no better feeling IMO than rolling on the throttle at sub-2000 rpm in second gear, and hearing the tires scream for mercy.First they whimper. Then they moan, and wail, and scream in agony. Thats torque.If you dont have torque, you will need more cubic inches or torque multiplication. And that leads to more gears in the tranny.
But WTH do I know.
 
Put in a cam for torque, and don't tell him. With decent mufflers the idle will sound fine. Choppy idle is for race cars, not street cars, or wannbees with street cars. The types of guys that wander around every cruise night saying they have a 500hp engine 'cause it's painted orange. Building for that is simply a mistake. If you want to help - get him the cam that will work and sound like whatever it sounds like.
 
Rockerdude said:
A 360 engine will probably have Speed Pro Hypers because of the price, not entirely what the compression would be with mid 70's 360 heads.
Click to expand...
There basically the same as the KB-107's except with a coated skirt for longevity and *I think* a slightly shorter height. With a .039 thick head gasket on a zero deck height & a 72cc head, it will have a 9.8-1 ratio. A .055 will drop it to (IIRC) 9.5-1.

Do not mill the deck if you don't need to. Have all the block work done and install the rotating assembely first. Check the deck height of the slugs first. After you measure how far down in the hole first, add this to the compression ratio mathematics to figure out the ratio. As stated above, a slight alteration of the ratio can be made with the head gasket.

Try the 60401 cam over the 60402 with the (tall tires) Hwy. gears, stock converter combo.
(It will just simply work better with the fire size you have now.)

If all else fails, and "That sound @ idle" MUST be had, install the Hughes Whiplash or That other small whatcha-ma-call it ruff idle Mutha Thumper cam and be done with it. Don't look back. Just forget about it.

With the Hwy. gears, stock converter and the possible taller tire later, any cam not designed for the street, towing with a duration of greater than 218 @ .050 will just disappoint. Pay attention to the cam manufactures cam descriptions! Do not ignore them!
Read them! Use your head.

Or I'll be saying, "I told you so!"

Have a good one, I'm out.
 
I'd find out/nail down what he wants and expects from
his car.
Make him write it down.
You guys are all over the map with gearing and motor mods.
Build from the rearend forward.
A 3:55 gear with a 2200 stall behind a 300hp motor will blow the tires off from a standstill, chirp second gear and still be a
good daily driver.

Even a good running motor with no stall or gearing will
end up a dog that sounds good and drives like ****.
 
RustyRatRod said:
You don't want to put 360 heads on a 318. If you're doing this to help your friend, you will want to act like you know a little about Mopars and putting 360 heads on a 318 ain't acting like it. That will get his compression on a 318 down into the 7s. That won't pull a greasy string outta a cat's *** and will make you look like a dumbass, so lets not go there.
Click to expand...


One trick that I stumbled onto once, my brother gave me a 318 short block with new 10.5 compression pistons. It had too much compression with 318 heads, so I swapped 360 heads on it, and it came down to a perfect 9.2 compression...

If you buy 10.5 pistons for a 318, then you can use the larger port heads and still have good compression...
 
Hey, I can take him for a ride in mine, and throw his plans into all kinds of directions.
As for a stock converter for a 904/V8 style, I have one with the stall raised to about 2200 that would help a mild 360 work better. It worked nice in my mild 318, before the crazy motor came along.
 
No offense but sounds like he wants to have his cake and eat it too. Choppy idle, good power, highway gears and stock converter. Those don't go together in my opinion, it'll be a dog
 
harrisonm said:
So, RustyRatRod, I was wondering how much power it takes to pull a greasy string out of a cat's ***? LOL, I'd never heard that one. By the way, I agree with the 360.
Click to expand...

Let's just say that it doesn't take much. lol

....and I've heard the expression all my life.
 
moper said:
Put in a cam for torque, and don't tell him. With decent mufflers the idle will sound fine. Choppy idle is for race cars, not street cars, or wannbees with street cars. The types of guys that wander around every cruise night saying they have a 500hp engine 'cause it's painted orange. Building for that is simply a mistake. If you want to help - get him the cam that will work and sound like whatever it sounds like.
Click to expand...

Preach on brother Dave. That's why I recommended the Comp 265 DEH. It will have a noticeable idle, but GAWD those things pull HARD.

You just cannot tell people anything once they get the Thumpr syndrome. Ask me how I know.
 
Rockerdude said:
A 360 engine will probably have Speed Pro Hypers because of the price, not entirely what the compression would be with mid 70's 360 heads.
Click to expand...

Probably JUST south of 9:1. Why worry about that? That's the least of your worries as long as compression is above 8:1 and it will be.

Once again, we can thank the magazine and forum geniuses for telling everyone their engine will run like crap with anything under 9.5. Just ain't true.

That 265 DEH is very similar to a Thumpr grind, BUT it's smaller and ground on a 110 and not a 107. It will build cylinder pressure in a similar manner. Hell, you could even jump up to the 275 DEH for a tad more chop and not lose much bottom end, but not in a 318. I think the 275 DEH would be a little large there.

Go to the Comp site and actually LOOK at those cams. Short intake duration, long exhaust duration and ground on a moderately tight 110 LSA. That's goin in the Thumpr direction without losing a lot of bottom end torque.

Don't choose the DEH line. I don't care. But if you go another route, it should be a similar grind.

Compression on a street engine is really not important. As long as it is not under 8:1 and not over 9.5, you will make respectable power without detonation.

Cylinder pressure is what you are looking to maximize. With a 360 you'll have a good bit of cubes for a small block, so stop the panic about compression. Those Speed Pros are what the two eyebrow? If so, you're looking at compression at or a touch over 9:1. The 4 eyebrow a little lower. You'll have plenty of compression either way. Get your panties in a wad about something else.
 
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