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My god that’s a Mickey Mouse build, you gotta lot of work ahead cleaning that mess up.

I don’t even know where to start proper fuel fittings, filter and lines I suppose at least for safety’s sake. No glass or plastic filters either. Untangle the electrical wiring from the fuel lines. Braded steel lines contained by screw clamps is a fire waiting to happen. Just get rid of that crap starting at the fuel pump.

Can’t have vacuum leaks in lines, connections and caps. That includes the vacuum advance unit if so equipped and if the tranny is a TH350 the vacuum modulator but that would be sucking ATF if it’s bad.

An air filter you can’t see light through is over the hill. If this is pumping oil and see the pic’s it looks like chty build to my eye I’d start with the presumption the engine was assembled with the same precision as you see on the outside. I’d even suspect about it being a 383. Run down the casting numbers to see if the block is even a 4 inch bore block that you’d have to start with to build a 383.

This thing looks like it was built in an automotive butcher shop. You got way bigger problems than to worry about than the exhaust system.

Hate to bear the bad news but you got a big job ahead of you just straightening the mess in front of you out.

Bogie
 

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Discussion Starter · #22 ·
Sorry for only replying now, had to bring the young lad to football.
Its a stick shift, so I think there's no vacuum to the transmission.
But yeah, I see what your saying, to be fair the vacuum pipes cracked could be age related,
but its hard to defend not putting in the fuel regulator, when its so accepted in rebuilds.
The shop that did the work it is a well known engine performance company in Dayton Ohio.

But I have to work with what I've got now, and was just wondering about the fuel lines.
The plumbing is very basic, 2 lines go from the tank to the pump (one is plugged at the tank)
and then one line goes from the pump to carb (with an inline filter).
So still have to figure out whether to use vented or unvented cap?
And I would think the fuel pump return line should be reconnected to the tank,
which would mean the regulator would not need a return line. Does this make sense?

My friends and family say i'm mad, especially as all the parts have to be shipped from USA.
But I lived in the States for 10 years and my happiest memories were when I had a Chevy V8,
and I'm just trying to get that same buzz again, before its too late. I'm 50 now, ouch!
 

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what you think is the return line on the tank is actually the vapour line from the tank to a charcoal filter. That charcoal filter should be found beside the radiator. It’s about 6 inches in diameter by 6 inches deep.It acts as your tank vent. It’s hooked up to manifold vacuum port on your carb.
if the line on the tank is capped off you must have a vented cap.
You don’t need a return style regulator.
First you need to check your fuel pressure. If it’s at or below 6 psi you might be okay.
 

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Either the line at the tank was for a closed tank vent system that is no longer there or for a regulated fuel pressure return. For sure the original tank vented through a charcoal filter under the hood so I suspect that was a vent line but you really need to get a 1981 service manual so you can trace out what is wreckage you see. If that was a vent line and the source is plugged then unless something else was done to provide a vent the tank is doing without. The simplest is a vented cap whether purchased or a modified original. The other should be a fear looking at the sloppy workmanship you certainly don’t want a fuel tank that can puke in an accident.

Like I said this car has been through a butcher shop, now you need to fix it. By that I don’t mean to return it to original condition but you need to know what was there so you can trace down what needs to be properly terminated if no longer going to be used compared to fixing what needs to be there and making it safe and as orderly as possible.

You need to look at the VIN code and back that into the original configuration of the vehicle.
I suppose it depends on you whether you want to clean the swap up make it look reasonably professional or live with it like it is. Fixing it will take some time and money, this is what project cars are for.

Bogie
 

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Discussion Starter · #25 ·
what you think is the return line on the tank is actually the vapour line from the tank to a charcoal filter. That charcoal filter should be found beside the radiator. It’s about 6 inches in diameter by 6 inches deep.It acts as your tank vent. It’s hooked up to manifold vacuum port on your carb.
if the line on the tank is capped off you must have a vented cap.
You don’t need a return style regulator.
First you need to check your fuel pressure. If it’s at or below 6 psi you might be okay.
That makes sense. I know where the charcoal filter is and it is not being used.
There have installed an engine and disconnected all the emissions stuff that ruined the horsepower
of these cars. The EGR is gone, the Oxygen sensor is disconnected, and charcoal filter not used.
Seems they put the vented cap to vent the tank and have one line to the pump.
Its a simple fuel to engine setup, to increase the HP, I guess.
I imagine this is what was requested of the rebuild to increase the hp to be the same as the older Trans Am's.
Thanks for that, I understand it a bit better now.
 

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Discussion Starter · #26 ·
Either the line at the tank was for a closed tank vent system that is no longer there or for a regulated fuel pressure return. For sure the original tank vented through a charcoal filter under the hood so I suspect that was a vent line but you really need to get a 1981 service manual so you can trace out what is wreckage you see. If that was a vent line and the source is plugged then unless something else was done to provide a vent the tank is doing without. The simplest is a vented cap whether purchased or a modified original. The other should be a fear looking at the sloppy workmanship you certainly don’t want a fuel tank that can puke in an accident.

Like I said this car has been through a butcher shop, now you need to fix it. By that I don’t mean to return it to original condition but you need to know what was there so you can trace down what needs to be properly terminated if no longer going to be used compared to fixing what needs to be there and making it safe and as orderly as possible.

You need to look at the VIN code and back that into the original configuration of the vehicle.
I suppose it depends on you whether you want to clean the swap up make it look reasonably professional or live with it like it is. Fixing it will take some time and money, this is what project cars are for.

Bogie
Yes Bogie, I can see what your saying, and i'd say your right they changed the car from what it was originally.
And listening to you guys is a great help to me. And i am doing exactly that and trying to tidy it up.
I know that while it has been in Ireland for the last 5 years the guy I bought it from did nothing with it.
Which I think is a sin, if you own a piece of history like this, you have a responsibility to improve it or at least maintain it.
The Chevy V8 I had in the States, I am very proud to say, that I had it for 10 years and it was better when I sold it
than when I bought it, and I sold it for more than I purchased it for, and I did all the work myself.
When the overdrive was jumpy, I went to a Transmission shop and asked them about it, they wanted to replace it,
for $2,000 but I went through the Manual troubleshooting guide and figured it might be the lock-out solenoid.
So I ordered the lock-up solenoid ($50) from the Chevy dealer and I changed it and that fixed it.
And what's more disturbing is I asked the so called transmission expert, could it be the lock-up solenoid!
I'm no mechanic, but it is my ambition try to improve this car, and I really appreciate you guys advice.
So what practical steps do you suggest I take to improve it, as obviously it's not practical to restore to original.
Thanks again
 

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1981 T/A had one of 3 engines

301 Pontiac
301 Pontiac Turbo
305 Chevy

Lets figure out what it originally had and what it has in it now. It does have a small block chevy motor of some type.

8th digit of car serial number is original engine code.

Please provide stamped numbers on pad located on front of block where passenger head meets block.

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Actually the external emissions equipment do little to power output. The killer of power is inside. Mild cams, leaned fuel curves, hardly and ignition advance, low compression, open chamber head’s, low amounts of squish and quench. These are the big time killers of power, removing the charcoal tank vent, EGR, PCV, and air injection pumps is just dicking around on the edges. Now converters are a bit different there being good converters with little restriction and not so good converters.

You can easily build an powerful engine that SMOGs probably without the external pieces named above, but if you live where these are inspected you won’t get by on clean exhsust only. In this case you will find that the external emissions window dressing‘s power debilitation on the engine is down in the noise level. A competent engine builder can use a pretty big cam fairly high compression, obviously not an over rich carb but on the money AFR, a PCV with a pretty aggressive curve and easily pass a sniffer test, especially with dual cats.

I’m not blowing smoke, I’ve done this for years but on the fortunate side the state I live in checks the tail pipe not the under hood equipment. They do, however, check for your missing closed tank venting system and for an illuminated Check Engine light. While this state tests the tail pipe to the California and Federal standards aren’t bent too far over on the factory external equipment. The law on modified vehicles is if you can’t pass the test you have to have it ‘tuned’ by state licensed garage. If it still can’t pass the test then you must return it to the factory built configuration or forego license tags. If it’s as stock and can’t pass the ‘tune up‘ed retest then you get a waver.

All the builds I put on the street easily passed, I used to joke that my pizza and PBR breath put more pollution out that the engines I’ve built. My own 350 powered S15 which is one hell of a kludged engine being roller block 350 with LT1 head’s modified to conventional cooling, mounting the GMPP LT1/4 4bbl intake with an Edelbrock Thunder AVS carb using the LT4HOT cam and 1.6 roller rockers with spark provided by a ProComp7000 distributor with headers into H pipe duals and a pair aftermarket cats and a pair of Cherry Bomb glass packs passed always emissions by a huge margin. I built that thing 23 years ago and it still runs fine though it’s on its second transmission. It’s now so old it’s passed beyond emissions testing.

Bogie
 

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Discussion Starter · #33 ·
Yes, I could find that, and the 350 is a Chevy also, I think.
I was just wondering if the GM42 had any significance, but it doesn't matter.
I took some more pictures, and there is actually 2 hoses connected to charcoal canister,
one goes to side of air filter housing and the other goes into the passenger side of the carb.
And there is a red wire connector just sitting there (on fuel filter in picture),
don't know if that should be plugged in to anything, as nothing obvious.
Also you can see the oxygen sensor in the manifold is not connected to anything (taped off),
but there is something in beside the plugs on the drivers side with a wire attached to it, what is it?
Hope these help give a clearer picture of what's there.

Automotive tire Wood Bumper Gas Automotive exterior


Automotive tire Gas Auto part Automotive fuel system Automotive wheel system



Hood Motor vehicle Fixture Automotive exterior Automotive tire
 

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Nothing in 1981 had an O2 sensor....that existing sensor is a left over, still in the stock manifold from whatever that swapped-in engine was taken from.
That driver side exhaust manifold is not stock for the '81 305 F-body application
 

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Time to start afresh!
pull that motor out of there, tear it down, fix whatever needs fixing, clean it up, paint it and put it back in the freshly cleaned and painted engine bay.
 

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Nothing in 1981 had an O2 sensor....that existing sensor is a left over, still in the stock manifold from whatever that swapped-in engine was taken from.
That driver side exhaust manifold is not stock for the '81 305 F-body application
Actually, 1981 was the first year for computer controlled carburetors. I remember it well (worked in dealership).

I'm really doubting this was a completely rebuilt 383 6000 miles ago. What I can't figure is why the intake/exhaust manifold selection on what is claimed to be a fairly expensive build. I'm guessing probably just a novice-swapped-in used 350 and it's tired.

If it wasn't for the 14010207 casting number photo, I would guess this was the original 305 engine with different carb and distributor.
 

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To evaluate engine condition I would recommend starting by pulling/changing all the spark plugs and noting the problem cylinders (keep plugs in order). Time to do both static and running compression tests - and a leak down test with a true tester. This is what you can do without tearing the engine down. You will need a compression gauge, an air compressor, and the apparatus for the leak down testing.

https://support.alldata.com/article/tech-tip/running-compression-tests
https://support.alldata.com/sites/main/files/file-attachments/cylinder_leak-down_testing_011019.pdf

Good luck
 

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I see they left the O2 sensor in place from the old Q-Jet carb that used a computer controlled diddle metering rods. The old Carter that was installed doesn’t have this function.

Just before Electronic Fuel Injection became common around 85-87 on GM American vehicles they (being GM) played around with refining the mixture ratio of carburetors with servo controlled main metering rods on the Q-Jet. I really doubt this was very effective as the hugest problem with carburetors or Throttle Body Injection for that matter is the uneven mixture ratios delivered at the cylinders by the intake manifolding. This being a forever problem, the general solution to which is to jet the carburetor to where the leanest running cylinder is at the correct AFR and the others run rich.

TBI cleans this up better than a carb as it is not dependent on air flow variation through a venture to start, modulate, end fuel flow. So carburetors are pretty sloppy at this to where they need an accelerating pump to initiate engine acceleration before main metering picks up, then they overshoot on closed throttle due to the fact that fuel has weight and in the carb passages because it is flowing it has inertia so snapping the throttle closed does not instantly stop main metering. At least TBI gets rid of these fuel inertia lag and overshoot issues.

For intake manifold designers this has been a forever tough nut to crack. Even today there are only a handful of hotrod intakes that do this fairly well most are pretty bad and that includes all of GM’s production intakes in iron or aluminum.

Bogie
 

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Discussion Starter · #40 ·
Actually, 1981 was the first year for computer controlled carburetors. I remember it well (worked in dealership).

I'm really doubting this was a completely rebuilt 383 6000 miles ago. What I can't figure is why the intake/exhaust manifold selection on what is claimed to be a fairly expensive build. I'm guessing probably just a novice-swapped-in used 350 and it's tired.

If it wasn't for the 14010207 casting number photo, I would guess this was the original 305 engine with different carb and distributor.
Here are some pages from the 10 page receipt and tech details provided on cam and carb from shop.
I confirmed with the original owner and shop, that they replaced the 305 engine with a 350 bored to 383.

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