Eliminating elephant ears, changing headers

[Uncle Bob]

I've got a 71 Duster that I bought as a pig-in-a-poke. It currently has a 400 on elephant ears and Doug's headers. The car has power steering and a v-8 K-frame with stock suspension.

I'm going through the process of figuring out if the engine's any good or not - it has no vacuum - so I may be in the position of replacing it soon. It starts, it idles, and it falls flat on it's face when I rev it. The vacuum jumps up once it gets past the bog, but two different vacuum gauges register zero with the engine running. Yes I replaced the intake gasket and the timing's set at 23* and I've tried it as far advanced as 30* with no improvement. (Any advice on this is welcome)

So it seems like at best I will need to pull the front off the engine to figure out a cam problem, at worst the engine is just worn out and will need to be pulled. The only thing I know about the engine is it's a 400 and has 915 heads. The ears and headers have discouraged me from taking it apart to find out more. Either way it will need to be unbolted from the ears.

I got a wild idea last night that it might be a wise thing to replace the elephant ears with some transdapt mounts and change to Schumacher Tri-Y's or TTIs when I do that. So I wondered if anyone has experience with that combo, and is it as straight-forward as it seems? How much banging will I need to do on the headers to get them to work? Is it likely I can get the headers installed by myself in a no lift garage? Also, every time I hit the key I thank my lucky stars the starter works - can you remove/replace the starter with the Tri-Y or TTI headers?

This is something I would do whether I can fix the current engine or if I replace it. FWIW installing a small block was considered but that will cost over 10k and there's a 10 month backlog at Blueprint Engines, and I've got a good 440 and 727 here that I could just install and be done with it if the mounts and header idea is valid.

Thanks in advance for any info.

 

[67Dart273]

A good part of what I've read "on here" about B/RB swaps is that ears make things easier, generally. I would not be too quick to ditch them if they were done decently. If you mill the thickness of the ears off the water pump housing, you can even use factory pulley spacing

So far as vacuum readings are you CERTAIN you car connected to manifold vacuum? I cannot imagine an engine that generates zero vacuum. It would not be unheard of for the vacuum gauge to have a problem--sticky, etc. In fact I HAVE one.

 

[Uncle Bob]

It's got factory pulleys on it now.

I'm certain I'm connected to manifold vacuum - under the front bowl coming out of the baseplate. All other vacuum ports are plugged. I unplug the hose from the gauge and there's no suck. When I first noticed it after changing the valley pan I took the carb off thinking there must be something blocking it like maybe I need to turn the spacer over, but there's not.

 

[Uncle Bob]

It's got factory pulleys on it now.

I'm certain I'm connected to manifold vacuum - under the front bowl coming out of the baseplate. All other vacuum ports are plugged. I unplug the hose from the gauge and there's no suck. When I first noticed it after changing the valley pan I took the carb off thinking there must be something blocking it like maybe I need to turn the spacer over, but there's not.

I picked up a new gauge at HF, this one says I've got 2 inches of vacuum at idle. 23* timing.

 

[Dcuda69]

Every time a piston goes on the intake stroke it creates a low pressure area(vacuum).....doubtful an engine starts and runs with 2' vacuum. Stock style engines create 17-21" at idle. My engine with an aggressive roller cam creates 12". Try another port like the big one connected to a PCV or brake booster.

 

[67Dart273]

I believe there is something AFU with that "vacuum" port somehow. I agree with the above, I don't think it would run that low

 

[Uncle Bob]

I believe there is something AFU with that "vacuum" port somehow.

Yeah I agree but don't know what it could be. It doesn't seem to be the carb - I can draw air through the hose and have looked at it and there's nothing blocking it.

Try another port like the big one connected to a PCV or brake booster.

I meant to check the PVC yesterday but forgot when it fired up and had a little bit of vacuum. I got happy and took a chance to drive it a few miles to the gas station. It's got a dead bog but if I baby the throttle until it's rolling it runs pretty good.

 

[Demonracer]

Start with the basics, check plugs, timing with & without vacuum advance hooked up. What carburetor & ignition does it have? Without more information, it' a little tough to try & help diagnose the source of the problem.

 

[Uncle Bob]

Start with the basics, check plugs, timing with & without vacuum advance hooked up. What carburetor & ignition does it have? Without more information, it' a little tough to try & help diagnose the source of the problem.

I had the plugs out for the compression test and they're fine, and the timing is 23* w/o vac advance. It's got a 750 vac secondary Brawler carb, mopar electronic ignition, and an MSD coil. I started with the idle mix screws at 1-1/2, they're out 3 turns now IIRC. It came with an 850 double pumper with a bog that wouldn't go away too.

It idled OK in gear yesterday. It idles at about 1k in neutral, drops down to about 500 in gear. I don't really trust the tach. It runs hot, it was > 210 when I parked it yesterday. Oil pressure is about 80 cold, 40 hot. The motor pulls good once I get it past the bog.

Compression averaged about 110, not good, but both that and low vacuum could be caused by the cam installation, right?

 

[Demonracer]

Have you checked to see if the primary power valve is blown, if it has one? Do you know the jet sizing in the carburetor?

 

[Uncle Bob]

Have you checked to see if the primary power valve is blown, if it has one? Do you know the jet sizing in the carburetor?

The carb is new and I have not taken it apart yet. The specs:

Barrels 4
Billet Color Black
Booster Down Leg
Brand Brawler
Carburetor Use Street
CFM 750
Choke Electric
Circuit 2
Condition New
Emission Code 3
Finish Shiny
Fuel Gasoline
Fuel Inlet Dual
Fuel System Carbureted
High Speed Air Bleed 33;33
Idle Air Bleed Size 70;70
Marine Use No
Material Aluminum
Model Brawler Street
Primary Main Jet 72
Primary Power Valve 6.5
Primary Pump Nozzle Size 32
Primary Venturii Size 1.380"
Product Type Carburetor
Secondaries Vacuum
Secondary Main Jet 76
Secondary Venturii Size 1.430"
Supercharged Application No
Throttle Bore 1 11/16"
Warranty Limited 90 Day
UPC 090127003589
Part Number BR-67208

 

[Uncle Bob]

I checked it at the PVC and got a better reading. It wants to idle in two places - 500 and 900. When its idling at 500 the timing is 15 and the vacuum is 6-7, then I rev the engine and when it settles down it's at 900 where the timing is 23 and the vac is 11-12.

Apparently the mechanical advance is sticking.