Charger Build Advice

[Slapstik]

I am looking for advice on what to do with my Charger. I am looking to make it all it can be for the street, while maintaining a factory appearance.

The car:
1973 Charger SE Brougham, power windows, A/C, slapstick, F70-14, 80k original miles, 3,963 lbs.
Rear: 8.75" 3.23 open 489 case
Transmission: 727 unmodified
Engine: Late 1972 (original to the car) 400 M code (2v single exhaust)
Rebuilt in 1999 (6,000 miles on rebuild)
Bottom: bored 0.030" new stock replacement pistons, chrome moly rings, high volume oil pump
Crank: Cast, external balance, turned 0.060" (!)
Rods: reused original
Heads: milled slightly, hardened valve seats installed
Cam: Mopar Performance .474 lift 280 duration
Intake: 1973 4 barrel iron, EGR blocked off
Carburetor: Holly 750 vacuum secondaries (have a Thermoquad too)
Ignition: Mopar Performance orange box with high advance distributor, 38 degrees total mechanical advance, vacuum advance plugged
Exhaust: Year One 440 HP manifolds, Accurate Exhaust full dual 2.25" straight through mufflers

The car currently has 6.5" of vacuum at idle in gear, not quite enough for the power brakes, eyes water from the exhaust, had to wire the choke open because it would load up bad with the choke part closed (no pull off adjustment), black soot in exhaust, black soot in carburetor (changed power valve from 65 to 25 & jets from 72 to 71 which created a dead spot off idle so I went the wrong way apparently) fowls out Champion RJ12YC and doesn't want to idle cold, so switched to RJ14YC which fixed those two issues. I believe the cam timing is retarded a good amount causing the low vacuum and loss of the bottom end, but I have not yet confirmed this to be the case. I suspect that while the cam and timing want to give at the top, the stock heads and iron intake aren't up to the task, so it's a dog.

I ran the car at the drag strip and I wonder if it would be useful and entertaining to ask you to guess its time along with giving your advice. Might help determine your credibility a little.

Budget: I don't have a particular budget in mind, I'm more interested in making it all it can be for the street while appearing stock. I want to run the tires and exhaust manifolds I have.

Thanks to all in advance.

 

[440 Charger]

Bet you will have fun running that one.

 

[HawkRod]

First of all, it sounds like it is not running right to start out with. If you want to stick with the engine as is, find some "old codger" near you and have him tune it. This alone will likely make you much happier with the car.

If you "want the most for the street while looking stock", then stroke the 400 and make a 500 cubic inch engine. I have one that dyno'd at 550 HP before adding aluminum heads. With aluminum heads, it is likely in the neighborhood of 600 to 650 HP. This can look 100% stock. Of course, if you do that, you will need to strengthen the 727. If you stick on the street with street tires, you should be fine because you will simply break the tires loose when you gun it. If you take it to the track and really hook up the tires, you will likely need a stronger rear and driveshaft, better motor mounts, etc.

Good Luck

Edit: I see you are new here. Please go to the Welcome Wagon and introduce yourself and the car. We love pictures - any condition!

 

[BSB67]

I ran the car at the drag strip and I wonder if it would be useful and entertaining to ask you to guess its time along with giving your advice. Might help determine your credibility a little.

15.4 @ 88 mph

Am I credible?

 

[70chall440]

Put some aluminum heads, roller cam and EFI on it and enjoy the car.

I would guess something similar ref ET, something around 15.8 or so.

 

[tmaleck]

Congrats on joining. First off, because Roadkill. Idle vacuum seems low, sounds like you're fighting carb issues. I know many here don't like it, but throttle body fuel injection is a great solution. Holley offers a Hyperspark distributor that fits the low deck B blocks and integrates with the Sniper EFI, so you can get full control of fuel and spark curves. Looks like the Sniper and distributor are less than $1500. I agree with alum. heads, worth it for flow, compression and weight. Also, ditch the Champs for NGK or Denso plugs.

 

[RemCharger]

15.4 @ 88 mph

Am I credible?

15.40s???? Are you serious???
I would have thought it might have a 30 in it..

 

[66 Sat]

I was thinking low 16's, maybe 16.2, bearing in mind the weight of the car, the gearing and the fact it runs like crap.

 

[440 Charger]

15.40s???? Are you serious???
I would have thought it might have a 30 in it..

Work on that a tad.

 

[440 Charger]

I was thinking low 16's, maybe 16.2, bearing in mind the weight of the car, the gearing and the fact it runs like crap.

Even a 318 does 14s or better.

 

[RemCharger]

Even a 318 does 14s or better.

Just one credible magazine road test of a 318 doing a 15 and I won't say you've been day-drinking

 

[Runcharger]

I am looking for advice on what to do with my Charger. I am looking to make it all it can be for the street, while maintaining a factory appearance.

The car:
1973 Charger SE Brougham, power windows, A/C, slapstick, F70-14, 80k original miles, 3,963 lbs.
Rear: 8.75" 3.23 open 489 case
Transmission: 727 unmodified
Engine: Late 1972 (original to the car) 400 M code (2v single exhaust)
Rebuilt in 1999 (6,000 miles on rebuild)
Bottom: bored 0.030" new stock replacement pistons, chrome moly rings, high volume oil pump
Crank: Cast, external balance, turned 0.060" (!)
Rods: reused original
Heads: milled slightly, hardened valve seats installed
Cam: Mopar Performance .474 lift 280 duration
Intake: 1973 4 barrel iron, EGR blocked off
Carburetor: Holly 750 vacuum secondaries (have a Thermoquad too)
Ignition: Mopar Performance orange box with high advance distributor, 38 degrees total mechanical advance, vacuum advance plugged
Exhaust: Year One 440 HP manifolds, Accurate Exhaust full dual 2.25" straight through mufflers

The car currently has 6.5" of vacuum at idle in gear, not quite enough for the power brakes, eyes water from the exhaust, had to wire the choke open because it would load up bad with the choke part closed (no pull off adjustment), black soot in exhaust, black soot in carburetor (changed power valve from 65 to 25 & jets from 72 to 71 which created a dead spot off idle so I went the wrong way apparently) fowls out Champion RJ12YC and doesn't want to idle cold, so switched to RJ14YC which fixed those two issues. I believe the cam timing is retarded a good amount causing the low vacuum and loss of the bottom end, but I have not yet confirmed this to be the case. I suspect that while the cam and timing want to give at the top, the stock heads and iron intake aren't up to the task, so it's a dog.

I ran the car at the drag strip and I wonder if it would be useful and entertaining to ask you to guess its time along with giving your advice. Might help determine your credibility a little.

Budget: I don't have a particular budget in mind, I'm more interested in making it all it can be for the street while appearing stock. I want to run the tires and exhaust manifolds I have.

Thanks to all in advance.

How fast is your ignition curve coming in? You want probably 15-20 degrees initial timing and coming in as fast as it can without pinging to 36-38 degrees total. Your car should be in the high 14's, if it isn't the tuneup is not optimized. No use adding parts if it isn't tuned correctly to start with. There are better cam choices but let's see if you can get it tuned for this combo to start with. I had a stock 1992 Dodge 150 with a 318 magnum that ran 16.22 factory original with 3.55 gear and probably 5000lbs, so lets get your Charger running right. Either the TQ or the Holley should work well with your combo.

 

[BSB67]

I was thinking low 16's, maybe 16.2, bearing in mind the weight of the car, the gearing and the fact it runs like crap.

Yep, could be. Poor driving technique can have a large negative impact on et too. The mph will better reflect the engine's power

 

[QOTHL]

I would guess something similar ref ET, something around 15.8 or so.

I've done that with a stock '72 Charger Rallye with regular tires survivor car.

 

[QOTHL]

NGK

 

[Slapstik]

Wow thanks for all the replies!

@440 Charger: I sure hope to!

@HawkRod: What exactly would the "old codger" adjust? Could you elaborate? I would consider a stroker, but I don't want to modify the block so I'd have to choose the right crank (B size journals). What do you suggest if I were to go that route? I don't have a horsepower number in mind, but if it gets up there I agree with your assessment using street tires. I will get on the welcome wagon soon. I have to get the wife to take a picture of the cars first, I have no cell phone!

@BSB67: Thanks for the reply, I'm sure you are credible, hahaha.

@70chall440: I'm open to aluminum heads, and a roller cam, but not EFI.

@tmaleck: Thanks. I don't want to go EFI. I did run the Thermoquad but switched to the holly for no particular reason. I didn't notice any difference in the way it runs and smells. I also ran Autolites plugs once and fowled them out too before switching to the alternative Champions.

@RemCharger: Thanks for the comment.

@66 Sat: I wouldn't say it runs like "crap" really... it is just not making near the power it is suppose to and the mixture is a bit lean. It starts runs and drives... well my wife can use it, let's put it that way.

@440 Charger: Actually I have a 1974 Charger SE with a 318. I'm the second owner of the car, it was my first car. It is bone stock, never even had the valve covers off it. The 400 is definitely faster. No question. Although I didn't run it at the track, I can tell you without a doubt it would not be in the 14s at all.

@Runcharger: It's been a while since I set the timing with a total timing light, but as I recall I'm all in by 3k. I don't know what the idle timing is (should I care?) but total mechanical was set to 34, then 36, and finally 38 degrees total mechanical. I had the vacuum advance hooked up at one point and was around 58 or 59 degrees but I disconnected it. Regarding the carburetors, I ran both and didn't notice much difference in the smell or the way it runs. Regarding the tune, I followed Holly's instructions for tuning the carburetor starting with the power valve, then the Jets but that's where I left off. It needs bigger jets because it isn't getting any signal with such low vacuum. It should probably have a smaller carb, but then again, the TQ has those small primaries and the car really ran the same if anything not quite as good with the TQ. The TQ is a 1975 400 9100 series. I remember having to really richen the idle mixture screws in that TQ. The holly ones are out 1.25 turns each.

 

[furious70]

That is more cam than that engine needs, but something is going on with the vacuum reading, have you checked for leaks by spraying carb cleaner around the intake and carb flanges? Power brake booster not leaking?
Do you have a known good carb to toss on?
Have you tuned for max idle vacuum by adjusting timing and idle circuit on carb?

 

[HawkRod]

@HawkRod: What exactly would the "old codger" adjust? Could you elaborate? I would consider a stroker, but I don't want to modify the block so I'd have to choose the right crank (B size journals). What do you suggest if I were to go that route? I don't have a horsepower number in mind, but if it gets up there I agree with your assessment using street tires. I will get on the welcome wagon soon. I have to get the wife to take a picture of the cars first, I have no cell phone!

What would the "old codger" adjust? Mostly what we can do is guess here on the internet. The point of an "old codger" is to take it to someone who knows old carburetors well and can adjust it as needed. To do this well, you need a timing light, vacuum gauge, years of experience and test drives to get the car running well. It obviously isn't running well now since it is fouling plugs. If the car is exclusively a race car, then yes, go ahead and disconnect the vacuum advance. You should not do that for a street car. At low load while driving the mixture goes lean. You need more timing to burn that mixture well. By the way, I suggest about 10-12 degrees of static/ initial (idle) timing (must be set without vacuum advance hooked up).

There are loads of stroker kits that do not require you to use 440 journal size. For example, 440source has drop in kits that you can install easily in the 400.

Finally: Building a stroker is great, but I suggest you truly diagnose and tune the engine you have. You may have to pull some of it apart so you can check cam timing too. There are lots of good suggestions in this thread, but you will need to sort them out and test them on your car.

 

[Curiousyellow71]

Some more time with carb tuning and a nice stall converto and shift kit is likely the best you can do with your current combo. Run the vacuum advance. You could advance the cam. If it is retarded that would make everything worse. You likely are in the upper 7s for compression with a oem style piston. Mp 474 needs closer to 9:1. If you want more you can't beat a stroker kit.

 

[Slapstik]

@furious70: I agree with you that the vacuum seems low for that cam. 20 years ago when I got the engine back from the machine shop, I noticed right away that I had a hard brake pedal so I looked back then for vacuum leaks. I removed all lines from the intake manifold and plugged them, then I used several different methods of looking for leaks including sprays, propane, and water. I am confident there are no vacuum leaks.

The Thermoquad was on the engine prior to the rebuild and the car ran great. I reinstalled the Thermoquad as soon as I got the engine back from the machine shop and the car ran as it does now. I then bought the 750 Holly brand new and installed it with no significant difference.

I tuned the idle circuit with a vacuum gauge. The timing was set using a professional Mac total timing light for full mechanical advance.

@HawkRod: Ok, I understand what you mean. When I built this engine 20 years ago, I was a young man with no experience and even less money. The build was planned by a man with whom I worked at the time that drag raced Mopars. It was he that suggested the cam and the instructions that I mill the heads to achieve 9.5:1 compression. When I got the engine back and running he came over and tuned it and gave it his approval all while my eyes were watering and throat burning. So I hired a very highly regarded older mechanic with years of racing experience to come take a look at the car. He revved the hell out of the engine and gave the distributor a twist and the mixture screws as well. He then said, "Well it's better than it was." Then he finished by adding, "If you want to go faster, buy a Chevy." It's been 20 years and I have advanced in knowledge and experience. I worked as a full-time mechanic (A tech) at an independent garage, I've worked in auto body refinishing, and I've maintained my hobby at home too. I am not a racer nor an engine builder, but I know my way around a car now.

Regarding the timing, I had the vacuum advance hooked up for a long time but I had to back off the mechanical advance and adjust the vacuum advance to the minimum. At 38 degrees mechanical and the vacuum advance hooked up the car would occasionally buck off idle. Rather than run 36 mechanical and have the vacuum advance hooked up, I thought it more advantageous to maximize the mechanical advance since at wide open throttle there is no vacuum anyway.

I'm familiar with 440source kits, and I would consider using one. Do you have any experience with that company? Do you know if the journal radii are too big and interfere with the bearings? I've heard this can be the case with some of these stroker kits but I don't know if so with 440source.

I am in the middle of diagnosing the engine I have. I am preparing to check the cam timing as I suspect that is one of the culprits for the low power and low vacuum. I also don't believe the machine shop took any significant amount of material from the heads to raise the compression. If I am correct and the intake valve closes at 74 degrees and my static compression is 8.2, then my dynamic compression would be 5.86:1. That would sure explain poor performance, I reckon.

@Curiousyellow71: If that's the best I can do, then I want to start over. The vacuum advance doesn't help at wide open throttle, which is my priority. I agree with you regarding the cam timing and I suspect it is several degrees retarded which would explain the low vacuum and low performance. I calculate a dynamic compression ratio of 5.86:1 with 8 degrees retarded cam timing. I will confirm soon. I am considering a stroker. If I go that route, which do you suggest?