I need tips (or advice) about restoring my 400 engine

[ppaavvss]

Hi friends,

1. I am rebuilding my 400 engine (6.6), it is stock at this moment, here in my country we have very hard rules about emissions so I would like to know if you can help me  or guide me, about parts or technics that could help me to lower emissions.

2. I would like to know wich intake manifold should I use to achieve this, also if you could recommend me a good carburator for the objective.

3. Do you know if this could be achieved with a good balance between power and low emissions?

By the way, I am from Costa Rica, thanks a lot for your time and help!

[Nacho-RT74]

IMHO ( being not an expert )

Correctly adjusted thermoquad to the needs, Magnum Camshaft and KB240 pistons... won't be able to get more juice on low emission controls.

Maybe the "MrSixpack" camshaft ?

Maybe the new Demon carb which is a copy of the Thermoquad?

Stock intake or 2186 edelbrock... edelbrock DP4B intake ( just used ) or offenhauser 360... I think the RPM is the max you can get... allways dual plane.

[ppaavvss]

IMHO ( being not an expert )

Correctly adjusted thermoquad to the needs, Magnum Camshaft and KB240 pistons... won't be able to get more juice on low emission controls.

Maybe the "MrSixpack" camshaft ?

Maybe the new Demon carb which is a copy of the Thermoquad?

Stock intake or 2186 edelbrock... edelbrock DP4B intake ( just used ) or offenhauser 360... I think the RPM is the max you can get... allways dual plane.

Thanks a lot Nacho, I am going to do research about those parts, in the evening!

[BSB67]

here in my country we have very hard rules about emissions so I would like to know if you can help me  or guide me, about parts or technics that could help me to lower emissions.

We need to know what this means exactly

[flyinlow]

here in my country we have very hard rules about emissions so I would like to know if you can help me  or guide me, about parts or technics that could help me to lower emissions.

We need to know what this means exactly

What year car? Are you passing emission tests now?

What are the emission standards that have to meet?  New car standards  for a 6.6L in 1972-1976 or in service emission standard, or modern car standards. (probably no chance of meeting the latter )

If you have a good working Thermoquad or a Demon version of it would work well on a stock intake. A dual plane intake designed to work in the 2000-5500 rpm range with a 670-770 cfm carb range would give you the best chance

of meeting emission tests and good drivability.

[Kern Dog]

You could make an old engine meet new car emission standards, you'd need fuel injection, catalytic converters, maybe air injected manifolds.

[alfaitalia]

Where are you in the world? In the UK we have some of the strictest emissions laws......but none of them are retrograde....in other words old cars don't have to pass modern standards....just the ones that were current when the car was built. Even with the items KD mentions it would be just about impossible to get a 50 year old car through 2017 exhaust tests. There would be next to no classics on the road if that was the case.

[c00nhunterjoe]

You could make an old engine meet new car emission standards, you'd need fuel injection, catalytic converters, maybe air injected manifolds.

You can never make the old engine meet modern standards. Thats why the LA engine was discontinued in trucks, why ford dropped the legendary 7.3 powerstroke, why cummins lost the 5.9... etc. Even the modern car companies can not meet the standards, but their gross numbers are skewed by what percentage of their engines are hybrid or california compliant.

[Nacho-RT74]

Where are you in the world? In the UK we have some of the strictest emissions laws......but none of them are retrograde....in other words old cars don't have to pass modern standards....just the ones that were current when the car was built.

By the way, I am from Costa Rica, thanks a lot for your time and help!

[Nacho-RT74]

The KB240 pistons I advised are about the only piston off the shelf for 400 you can get to increase CR so then the power, from the stock 7.8 to 8.2:1 to around 9:1 static CR, or bit more getting the block decked correctly to blue print specs and using metallic headgaskets

As mentioned, hard an old car will pass today's emissions standards, BUT increasing the CR will get the old Muscle era magic out of the detuned 400, which the main deal with them is the lower compression rate than its predecessors. With what I mentioned won't get more power or better emissions than a stock 383 Magnum ( 68/71 ). The power from the 383 Magnums is quite nice, better than a stock 400 magnum, with the advantage of more displacement out from the 400. Get the nice CR from old Magnums will be right on or slightly above the 383 Magnum due the extra displacement. Shouldn't be REALLY bad talking about emissions getting correctly tuned the carb and ign time. TQ carbs gets lot of options to be tuned nicelly getting nice metering rods to hold the emissions on low RPM range ( if you find them ), and then feel the power widelly opening the throttles.

the specs on the "MrSixpack" camshaft is widelly unknown. Has being kept as a secret, however has being advertised like a Hot street cam what feels like a stock and can be a straight replacement for the Magnum camshaft. I GUESS by the way is advertised it could be right on the limit for emission controls numbers

Once again is just an opinion

[ppaavvss]

Hi friends, here in Costa Rica emission test is a bit less strict that LA, My car is a 1974 Dodge Charger with the 400 engine.

I really appreciate all your replies, and pardon me if I can not answer your cuestions really fast (because I am doing some field work here).

Because Costa Rica is a "Green" country, the goverment create some weird laws so, we need to pass emissions to register a vehicle.

The configuration to pass emissions can be temporal, so as soon as I pass, I could modify any configuration to normality.

This car will not be used every day, so I belive that is not that bad doing a temporary modification just to pass!

[ppaavvss]

here in my country we have very hard rules about emissions so I would like to know if you can help me  or guide me, about parts or technics that could help me to lower emissions.

We need to know what this means exactly

I am going to look for the exact numbers, but just to have an idea, it is a bit less strict that LA.

[ppaavvss]

here in my country we have very hard rules about emissions so I would like to know if you can help me  or guide me, about parts or technics that could help me to lower emissions.

We need to know what this means exactly

What year car? Are you passing emission tests now?

What are the emission standards that have to meet?  New car standards  for a 6.6L in 1972-1976 or in service emission standard, or modern car standards. (probably no chance of meeting the latter )

If you have a good working Thermoquad or a Demon version of it would work well on a stock intake. A dual plane intake designed to work in the 2000-5500 rpm range with a 670-770 cfm carb range would give you the best chance

of meeting emission tests and good drivability.

I can modify it just to pass emissions, and then turn back to normal, I am doing research about those Thermoquad or Demon carbs and the intake!! Thanks a lot!

[ppaavvss]

You could make an old engine meet new car emission standards, you'd need fuel injection, catalytic converters, maybe air injected manifolds.

I have been thinking in that, do you know a store or web page that you would recommend to start looking at?

[ppaavvss]

Where are you in the world? In the UK we have some of the strictest emissions laws......but none of them are retrograde....in other words old cars don't have to pass modern standards....just the ones that were current when the car was built. Even with the items KD mentions it would be just about impossible to get a 50 year old car through 2017 exhaust tests. There would be next to no classics on the road if that was the case.

I am located in Costa Rica, here we say that we are a "green" country, most of the laws are related to conservation and emissions (talking about cars).

The real test is to pass emissions, for example if you have a car registed before 1990, they use a different test of emissions. I imported this car in january 2017, it means that my test will be harder. I need to do any modification to register it.

Each year we have to pass the test, so I know that it will be a headache, but for me is a dream to have this car running and with the possibility to drive it some times.

[ppaavvss]

The KB240 pistons I advised are about the only piston off the shelf for 400 you can get to increase CR so then the power, from the stock 7.8 to 8.2:1 to around 9:1 static CR, or bit more getting the block decked correctly to blue print specs and using metallic headgaskets

As mentioned, hard an old car will pass today's emissions standards, BUT increasing the CR will get the old Muscle era magic out of the detuned 400, which the main deal with them is the lower compression rate than its predecessors. With what I mentioned won't get more power or better emissions than a stock 383 Magnum ( 68/71 ). The power from the 383 Magnums is quite nice, better than a stock 400 magnum, with the advantage of more displacement out from the 400. Get the nice CR from old Magnums will be right on or slightly above the 383 Magnum due the extra displacement. Shouldn't be REALLY bad talking about emissions getting correctly tuned the carb and ign time. TQ carbs gets lot of options to be tuned nicelly getting nice metering rods to hold the emissions on low RPM range ( if you find them ), and then feel the power widelly opening the throttles.

the specs on the "MrSixpack" camshaft is widelly unknown. Has being kept as a secret, however has being advertised like a Hot street cam what feels like a stock and can be a straight replacement for the Magnum camshaft. I GUESS by the way is advertised it could be right on the limit for emission controls numbers

Once again is just an opinion

All options are well received Nacho, you know very well this cars, so I am going to look and try every tip you could give me.

I really appreciate your help!

[Brass]

Already mentioned but you could try universal catalytic converters.  Make sure the car is fully warmed up before testing.

[Nacho-RT74]

Thermoquad is indeed the stock carburator on all 400 Magnums. Is your one 2bbls?

( if increase the compression rate will affect the emission controls, forget the pistons and will nee to stuck with stock ones. That's not something you can install and remove maybe like a chamshaft, intake or carb )

[ppaavvss]

Already mentioned but you could try universal catalytic converters.  Make sure the car is fully warmed up before testing.

That is a good consideration, at this momment it does not have any catalytic converters!

[ppaavvss]

Thermoquad is indeed the stock carburator on all 400 Magnums. Is your one 2bbls?

( if increase the compression rate will affect the emission controls, forget the pistons and will nee to stuck with stock ones. That's not something you can install and remove maybe like a chamshaft, intake or carb )

Got it! Also I am thinking about it, what do you think about convert from petrol to LP gas?

[c00nhunterjoe]

We still havnt established what you are being tested for and what the expected readings are?

[ppaavvss]

We still havnt established what you are being tested for and what the expected readings are?

For cars imported after 1999 these are the limits:

COR: 0,55%V
HCR: 130ppm
COA: 0.54%V
HCA : 103ppm
CO2R: 14,53% V
CO2A: 12.62% V

[alfaitalia]

I'm no expert but those readings, especially the HCA/HCR look just about impossible to achieve on a car as old as this. Are you sure they are the correct figures? 103 and 130? In the UK a brand new car only had to get below 200 on most models.

[ppaavvss]

In the attachmets you can see the actual state of the engine, I already bought some NEW parts from RockAuto.com.

[ppaavvss]

I'm no expert but those readings, especially the HCA/HCR look just about impossible to achieve on a car as old as this. Are you sure they are the correct figures? 103 and 130? In the UK a brand new car only had to get below 200 on most models.

Reading in forums for Costa Rica they give those numbers to me, but I am going to ask the company that area in charge to do the technical revision test on cars for our country.

But I believe that those are correct, or at least close to.

Looks like an impossible mission!!!