Have some questions.

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whitey

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I am currently working on a 1973 Dodge Dart Swinger. I have replaced the 318/904/7.25 with a 360/727/8.75 combo. This car is really for my enjoyment, not for big shows or drag. Basically just street driving and an occasional country drive; I live by a mountain so I would have to drive over the mountain to take it to work or to my car clubs cruise.
Here are my current specs:
’87 360 block bored +.030 / SpeedPro Hyp. Pistons (Internal Balanced)
9.5 CR
MPP 340 cam (268/276 adv 228/[email protected] 44 Olap 114 c-line .429/.444 lift)
Magnum head - stock valves (retrofitted on LA block)
Prof. Products Crosswind Intake
3” K&N
727 Trans w/518 pan/TransGo TF-2 Shift Kit/3.2 KD lever/B&M flex plate
8-3/4 rear / SureGrip / 3.73 gears / green bearings. 205/60R15 tires
Summit universal alum radiator with separate B&M trans. cooler
I’m planning on a TTI 2-1/2” dual exhaust and headers with an X-pipe and Flowmaster mufflers; an MSD 6A ignition module, and Royal Purple fluids throughout.

My questions are:
1.Which Holley Street Avenger carb should I use, the 670 or 770 CFM?
2. Which stall converter should I use? TCI suggested a 1600-1800 stall, I’ve been told that’s low.
3. Because of the X-pipe characteristics, which Flowmaster would give me the same sound range as
my stock 02 Dodge Ram, the 40 Delta or the 50 Delta Flow mufflers. Flowmaster techs won’t
give me an answer except that they offer a variety of mufflers. I don’t want an over aggressive
sound.
4. How much horsepower do you feel I could get with this combo using pump gas?
5. If I go with the MSD box can I still use my stock distributor or do I need to go with an MSD?

The engine/trans/rear is finished, so I’m not looking to replace anything. Thanks for your input guys.
 
Sounds like a good combo.

1. I'd go with the 670 if you aren't going to be running on the strip.

2. 2500 stall would be more fun IMO.

3. I have no idea what your 02 Ram sounds like, but, I put some cheap $15 Super turbo mufflers on my truck from Pep-boys and it is a pretty mellow sound, I like it.

4. I'd guess 275-300

5. Never used an MSD box, but I used my stock distributor with a Crane box just fine.

Just my .02.
 
I think Lars pretty much hit it on the head. The 50 series DeltaFlows will be quiter then the 40s
 
I only add;

I purchased some Thrush turbo mufflers for my Magnum. Out of summit racing for about $20 a pop. I drive the car daily and just made a round trip from Centereach L.I. (11720) to the Poconos (?) Strousburg P.A. (Exit 309 off of I-80) without any complaint. There quite on cruise and growl nice when the hammer is down.
A quite ride is the first order of biz with this particular car. It also has headers.

The MSD 6 or 6A is what is most likely what you'll use. I have hooked up the MSD box to the MSD ignition box many times. The instructions are easy and simple to follow. A slight timing adjustment may be needed for best performance. Gap plugs wider. I went to .055 without any problems.
The hardest part of the ignition upgrade is figureing out where you want to mount the box. I suggest on the drivers side inner fender between the battery and the brake booster.
A worthy and easy upgrade to do.
 
The 670 is good for your listed application. The 770 will be too much and definitely will not make up the 50 HP you want without, at the very least, a larger cam.
 
A little more cam would help as would the bigger carb but I think you have a pretty good street engine going together as is.
 
4. I'd guess 275-300 rwhp so more like 380 at the crank.
set the timing so you have 16-18* initial and 35* total all in by ±2600.
A 2500 TC would be good to.
 
OH!!!! OK !!! 275-300 RWHP I could handle. When I said I was looking for 340, I had meant at the crank.

Thanks for you input guys...appreciate it!
 
You are using the same cam as the factory 340 and 360 4 barrel engines, so I would use those HP numbers as an estimate. The 340 was factored by the NHRA at 300 hp so I would think thats a fair estimate. Either carb would work, but I'd run the 670 unless you plan on a bigger cam down the road. Those heads will easily support more cam, so keep that in mind. That being said, you should have a pretty good running street combo with what you have now.

The factory converter used with that cam had a 2200-2400 rpm stall speed, so I would look for a converter in that range as a minimum, 2800 max.

Flowmasters are LOUD. If you like that sort of thing, great, but there are other mufflers which will flow well and not drive you nuts.

The MSD box does not know what distributor is giving it a signal. A factory dist will do fine. The curve should be similar to what the factory used for that cam or perhaps a bit more aggressive.
 
388dart said:
4. I'd guess 275-300 rwhp so more like 380 at the crank.
set the timing so you have 16-18* initial and 35* total all in by ±2600.
A 2500 TC would be good to.
Click to expand...

275-300rwhp seems kind of high for basically a stock HiPo motor. That's almost Mopar crate motor territory with the .500 lift cam.
 
According to a Mopar small block race engine 'manual' I have the HiPo 360's had the 340 cam (not 6-pack) in them and J-heads. I just used the magnum heads instead since they are still kind of plentyful and supposedly flow better; and I added the Prof Products air gap intake. MPP suggests a 750 carb for their crate engines, which made me curious if I should go with the bigger carb. I wanted to stay as close to 9.5:1 CR so I can run lower octane if I wanted (it's actually is 9.6), the the origional pistons were so far in the bore I needed a flashlight to see them. But the 360 +.030 over (.010 shy of the 340 and bigger stroke) should have more grunt than the 340.
 
I have the HiPo 360's had the 340 cam (not 6-pack)
Click to expand...
Same cam. There was basicly 2, 340 cams. The second one being a slightly hotter one than what is normaly listed.
MPP suggests a 750 carb for their crate engines, which made me curious if I should go with the bigger carb.
Click to expand...
If your racing it, it may produce 2-5 HP more at best. It is best used with a numerically larger gear ratio. 4.30's and up in a lightened car. It's alot of carb.
I wanted to stay as close to 9.5:1 CR so I can run lower octane if I wanted (it's actually is 9.6),
Click to expand...
Good, stay right there. Thats about max for the street, cam dependent. (Larger cams bleed of cyl. pressure.)
the the origional pistons were so far in the bore I needed a flashlight to see them. But the 360 +.030 over (.010 shy of the 340 and bigger stroke) should have more grunt than the 340.
Click to expand...
OH, it will, it will.
 
Thanks for the input guys....I've gotten alot of advice from alot of guys. I've been doing some looking around...

I went to the buyers guide for mopar crate engines, it states that for THESE engines, Mopar recommends a 750 Holley, but the only thing the crate engines has in common with mine is the Magnum heads.
I went to holley.com and ran through their interactive carb selector, and the Street Avenger carb that came up was the 770 w/ vacuum secd's.
I went back to the one book I bought, "How to Hot Rod Small Block Mopar engines", Chapter 13, pg 178, under carb selection, it states for a 360 for performance/racing applications to use a 750 CFM.
When I go through the equation: CFM= (RPM x CID)/3456, I get 6500 x 365/ 3456 I get 686.4873.

so it seems I can go either way, go 670 and fattening it, or 770 and leaning it back. Am I right? If so which wouldbe better?
 
That would be for a mild engine (686) and more so street freindly/Hwy. freindly gears. A 650 would perform fine or the 670 Avenger as the case may be. But to get the max from the engine, a 750 (770 Avenger) would be the choice I would recomend to anyone.

With the smaller carb, you'll be restricting the engine in it;s effort to make the power. Basicly, you would want your vacuum gauge to drop to zero at W.O.T. from start to finish. This won't happen with the smaller carb. The engine now works alittle to get the air and fuel.
 
You stated at the outset that you want to street drive the car. Use the smaller carb, its manners will be nicer for regular driving. If you want more power put a bigger cam in it. The 340 cam is a great piece, but like others have said I'd guess your motor will make around 300-325 Hp at the flywheel. Youve got gears - (373's) so why not run a bigger cam, and a 2500 stall converter ?
 
After looking at so many different cam specs many of which wouldn't support the power brakes, a friend of mine told me to consider the 340 cam, the 340 were pretty snotty engines, so I went with it. The engine is all put together waiting for the body work to be finished and painted. I just need my converter yet. TCI recommended their Sat night spec (2k stall), but that was with the 670 carb. As far as the gears, I had two choices, 3.55's & 3.73's, but I would have to wait minimum 6 months for 3.55's becasue they were on back order and a long waiting list.

Rumblefish, you said I want the vacuum gauge to drop to zero at WOT, what would that do for the brakes if I need them?
 
Whitey, I had a long winded resonse, but I hit the wrong key and sent it into the great beyond. The short, short version..
670 CFM is wet flowed, MPs 750 cfm is dry flowed..they are the same result. 770 will be much to big a carb.

Power brakes need vaccum during cruise and idle. You always have vaccum during decel. Vaccum during full throttle at rpms over peak torque mean you have too small a carb.

TCI as a whole stinks. MP convertors from Mancini Racing are cheaper and as good a product if not better. Dynamic or PTC would be my top choices, and I wouldnt go higher than 2200 with your current combo.

Flowmasters rule. I love them. But you will not have a sound anywhere close to a Ram unless you add resonators or cats ahead of the X pipe. I like SUmmit or Dynomax bullets for the resonators, then the flows out back.

Where were you looking for 3.55s from? I'm pretty sure they are available right now for most center sections...
 
Rumblefish, you said I want the vacuum gauge to drop to zero at WOT, what would that do for the brakes if I need them?
Click to expand...
Well, if you attempt a 4 wheel lock up while traveling at speed with the right foot on the floor.....Wait, normal people don't do that.
Once your foot lifts off the gas, vacuum returns. Full brakes return.

If you opt of a smaller cam and less gear than 3.90's, I'd go with the 670.
Otherwise, the higher stall, larger cam and 3.90's, 4.10's etc... describe a different car than one with 3.73, 3.55's and a milder cam.
While you could use a larger carb, it isn't really needed. The 670 is more inline with the engine than the 770 would be.
The idea being to keep a well balance package.
 
:pain10: Sounds like your going to have alot less compression than the stock 340 with the same cam and it made 275 horses. but what do I know. :)
 
whitey said:
Thanks for the input guys....I've gotten alot of advice from alot of guys. I've been doing some looking around...

I went to the buyers guide for mopar crate engines, it states that for THESE engines, Mopar recommends a 750 Holley, but the only thing the crate engines has in common with mine is the Magnum heads.
I went to holley.com and ran through their interactive carb selector, and the Street Avenger carb that came up was the 770 w/ vacuum secd's.
I went back to the one book I bought, "How to Hot Rod Small Block Mopar engines", Chapter 13, pg 178, under carb selection, it states for a 360 for performance/racing applications to use a 750 CFM.
When I go through the equation: CFM= (RPM x CID)/3456, I get 6500 x 365/ 3456 I get 686.4873.

so it seems I can go either way, go 670 and fattening it, or 770 and leaning it back. Am I right? If so which wouldbe better?
Click to expand...

Whitey, keep in mind that you are comparing a crate motor that uses a 288-292 duration .501"-.513" cam. This is much more than the 340 spec cam you are planning to use. The Mopar crate designates 750cfm with the larger cam and 1.92 or 2.02 intake valves to achieve estimated HP between 380HP-395HP. Taylor your expectations with a smaller cam. The Avenger 670 or 750 cfm is a good carb to use with the 340 spec cam. You can even step up to a Comp Cams XE262 or XE268 and still be ok. But anything over 750 would be too much unless you start camming deep into the .500" range...and then you will have other things to plan for.
 
But don't forget, engines back when were under rated, I can't really beleive the 340's were only 275, 360's were 300, and 383's were 330.

I really wasn't trying to compare with the crates, just trying to get some sort of base line to follow. I have 9.6:1 cr compared to 9:1, and the cam from a strongly known powerplant. I wanted to use the magnum heads for obvious reasons (didn't have the $1200. for the RT's), but had an LA block. I wanted to keep the power brakes and didn't want a cannister. I do have the 440-6 pak scoop (functional) and K&N's xstreme top, so I am moving plenty air, I'll just use the 670 and jet it as needed.
 
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