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1978 Trans Am - 400 - TH350 - 3.23 - Y82 - WS6
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Discussion Starter · #1 · (Edited)
I am looking to do some tune up procedures as I am unsure/not confident in previous owner. I am going to list them here for reference and advice, so please speak up if y'all see something questionable or missing. Doing this mainly to feel more comfortable getting back on road in one shot. The only timeline I'm shooting for is have it drivable by the new year.

Fluids

Ignition

Fuel

Air
Other


(1)* - Unsure if want to do now or wait to get some Amsoil. Any opinions?
(2)* - Unsure of weight of oil to use. Also not sue what gears are in it
(3)* - After brief inspection of carb still installed, noticed it missing the chock plate rod (need to order) Will inspect further as well.
 

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Hello again. Thanks for posting the additional carb pics the other day. In addition to the choke plate rod you will need the "s" shaped steel tube for your hot air choke that attaches to the threaded nipple on the front. A separate fresh or cold air tube attaches from your air cleaner assembly to the stove on your intake manifold I believe. Your Haynes manual may show a diagram for this routing.
 

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1977 Trans Am W72 400/4speed (swapped)
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I would skip the dexcool especially if the system isn鈥檛 flushed of green coolant already. Normal green coolant will suffice.

Rear diff should be 80W90 weight gear oil. Will need limited slip additive if you have a limited slip diff.
As for the ratio, without removing the cover and counting teeth, next best thing you can do is jack the rear axle off the ground and spin the tires one full revolution while counting how many times the driveshaft turns. Just less than 3 and a half turns would probably be 3.23 gears. Just over 3 turns, probably 3.08. You get the rest lol.
 

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Ditto on the Dex Cool. GM only recommends that for 1995 and newer. It requires an intrinsically air-free system. I did use it in my 94, with a high end aftermarket aluminum radiator with no problems, but that had an air-free system, at least if you filled and maintained the system properly. The caution regarding a clean, conventional coolant free system is also critical - do not mix, even in small quantities. There are currently non-Dex Cool extended life coolants that are more friendly with 鈥渃lassic鈥 car applications. Prestone makes those as well.

As far as the differential, if it's limited slip, both Eaton and Auburn recommend conventional lubes + limited slip additive, rather than synthetics.



If you're running something like a 12-bolt, and subjecting it to high HP racing applications, an 85W-140 non-synthetic lube should be used,
 
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1978 Trans Am - 400 - TH350 - 3.23 - Y82 - WS6
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Discussion Starter · #6 ·
Hello again. Thanks for posting the additional carb pics the other day. In addition to the choke plate rod you will need the "s" shaped steel tube for your hot air choke that attaches to the threaded nipple on the front. A separate fresh or cold air tube attaches from your air cleaner assembly to the stove on your intake manifold I believe. Your Haynes manual may show a diagram for this routing.
Yeah, I will definitely have to look up some reference pictures.

Do you still have a stock style fuel pump installed?
Honestly, not sure. I would say yes just based off everything else. Only thing previous owner told me was that it had new brakes but just needed to be flushed.

I would skip the dexcool especially if the system isn鈥檛 flushed of green coolant already. Normal green coolant will suffice.

Rear diff should be 80W90 weight gear oil. Will need limited slip additive if you have a limited slip diff.
As for the ratio, without removing the cover and counting teeth, next best thing you can do is jack the rear axle off the ground and spin the tires one full revolution while counting how many times the driveshaft turns. Just less than 3 and a half turns would probably be 3.23 gears. Just over 3 turns, probably 3.08. You get the rest lol.
Copy that regarding the coolant, didn't even think about the green!
Yeah it does have LSD so additive will be added, thanks. I actually found the stamped code on outside the other night: Posted here on build thread but as mentioned by other members, I will count 'em when cover is removed to be sure.
 

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IMHO If you still have a stock style fuel pump, I would consider these points. Stock style fuel pumps should have a 1/4" vapor return line nipple on the bottom. Hook up to it and you will not need the 3-nipple fuel filter you referenced above. Your plumbing scenario will be much simpler. Install a stock style pleated filter in the fuel inlet/filter housing on the carb. Stock filters do not become an issue until your car starts running faster than 12 seconds in the quarter. Get a correct all steel fuel pump to carburetor fuel line from any one of several sources. Throw out any and all rubber fuel hose pieces between the fuel pump and carburetor to eliminate possible gasoline leaks. I do this on my car and wouldn't recommend it to you if I wasn't doing the same. Getting your fuel delivery right and that choke functional will be good steps toward better driveability.
 

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1978 Trans Am - 400 - TH350 - 3.23 - Y82 - WS6
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Discussion Starter · #8 ·
IMHO If you still have a stock style fuel pump, I would consider these points. Stock style fuel pumps should have a 1/4" vapor return line nipple on the bottom. Hook up to it and you will not need the 3-nipple fuel filter you referenced above. Install a stock style pleated filter in the fuel inlet/filter housing on the carb. Stock filters do not become an issue until your car starts running faster than 12 seconds in the quarter. Get a correct all steel fuel pump to carburetor fuel line from any one of several sources. Throw out any and all rubber fuel hose pieces between the fuel pump and carburetor to eliminate possible gasoline leaks. I do this on my car and wouldn't recommend it to you if I wasn't doing the same. Getting your fuel delivery right and that choke functional will be good steps to better driveability.
Gotcha, will have to verify the fuel pump situation (need to get her in the air!) The kit I ordered does come with one of those inlet filters so I should be good there. Definitely not worried about track times/high performance at this point :).

I am glad you brought up the hard fuel line, because that was also a question of mine. Is it truly needed? I was looking into Earl's Vapor Guard as an option. My first reaction was to do exactly what you said with getting all hard lines and no soft, but diverted as I wasn't sure if necessary.
 

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Not sure about Earl's Vapor Guard. Maybe someone can chime in who uses it. I like the steel or NiCopp line for safety. Let's say a v-belt breaks, flips off, or road debris flies up. It could possibly cut a fuel hose that is under pressure. Especially a full length piece routed all the way down to the pump. I've had v-belts fly off before. Clamps could also leak. Since I track my car, I tend to offer suggestions that have been rock solid safe for me.
 

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The NHRA rule book, Section 21 - General Requirements is a useful guide, even if you don't race your car. In this case para 1:5 Fuel System. The 鈥淟ines鈥 section requires that (relevant provision only):

- All non-OEM fuel lines鈥.. must be metallic, steel braided, or NHRA-accepted 鈥渨oven or woven-pushlock鈥.

- A maximum of 12-inches total (front to rear) of non-metallic or non-steel braided hose is permitted for connection purposes only.

- It is mandatory that fuel lines passing supercharger drive belts be steel-braided, NHRA-accepted woven or woven-pushlock, or be enclosed in protective steel tubing.

- All NHRA-accepted fuel lines must use ends that are specifically designed for the type of fuel lines being used.

- No hose clamps allowed on NHRA-accepted fuel lines.

When I was young and ignorant, I thought it was really cool to install a fuel block on the inner fender on my 1966 GTO Tri-Power, with three separate, big fat rubber hoses running to the three 2-bbl carbs. I'm embarrassed by the photo of that setup now.


Every fuel line in my 1994 Formula (which was raced at NHRA tracks/tech) was braided stainless steel. Old age occasionally brings wisdom.

DISCLAIMER - The above points are PARTIAL content of Section 21, page 5 of the 2022 鈥淣HRA Rule Book鈥. Every effort was made to transcribe the material accurately, but anyone using this information should consult the Rule Book for complete content and context.

 
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Discussion Starter · #11 ·
Y'all sold me! Hard lines it is.

Forehead Beard Jaw Ear Smile



Have y'all had bad experiences with the braided SS lines? That was the other option next to hard lines but I have heard nothing but bad reviews on longevity. Multiple reports of leaking, granted I do not know what brand they had (could be some cheapo version) but it was just the sheer volume of 'hate' towards braided lines that pushed me away.

Is it feasible to make main lines hard and have the visible potions (in bay) be braided SS?
 

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My fuel system was built in 2000. It鈥檚 capable of supplying 1,000 HP. Dual Bosch 205 LPH high pressure pumps, supplying eight 74 #/HR low impedance injectors, operating at 58 PSI. One pump is in the stock in-tank position, and supplies all the fuel required for the normally aspirated ~500 HP engine. The second pump, taking suction off a -10AN connection on the rear/bottom of the stock tank only runs when the ~300 HP dry nitrous system is armed.

In addition to the pumps and injectors, there鈥檚 a billet filter with replaceable media, an adjustable fuel pressure regulator, and the fuel rails have been modified to run in parallel rather than in series. There鈥檚 a pressure sensor bung added to the rails.

I bought the 1994 brand new, kept it for 27-1/2 years. Sold it early this year. It was raced and street driven on and off for about 14 years with the modified fuel system. Then it saw very limited use, until it sat in my garage for 8 years. Was not started during the last 4 of those years.

In the course of the 22 years since the engine/fuel system was built, never had a problem of any kind with the braided S/S lines, nor any other fuel component. When it was sitting in the garage, unstarted, it had a less than 1/2 tank mixture of 92-octane pump gas (10% ethanol) and VP Fuels C16 highly leaded 116-octane racing fuel. I warned the buyer that the fuel system need to be inspected and cleaned.

Other than one bad injector that needed to be replaced, and having the other seven cleaned, the system was intact. He drained the tank of some funky fuel and cleaned it, replaced the filter element, started the engine and it ran. Over the past months he's inspected virtually everything in the engine and drivetrain, and made some upgrades and further modifications. But the fuel system had no leaks, no damage, no problems with the braided S/S lines.

I addition to the fuel lines, all the lines in the nitrous system were braided S/S, as were the TH400 trans cooler lines. Even the line to the in-dash oil pressure gauge. He has replaced the fan assisted trans cooler, but as far as I know still using the braided lines. I've been very active on sites like this for 24+ years and cannot recall any unreasonable number of problems with the braided S/S lines. I would never use anything else. 4th Gens have black, plastic-like, 鈥渘ylon鈥 fuel lines. They were/are problematic. Easy to melt if they get too close to the exhaust, crack and leak as they get older. Was very glad to replace them with braided S/S, even though the cost was high.
 
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1978 Trans Am - 400 - TH350 - 3.23 - Y82 - WS6
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Discussion Starter · #13 ·
Edited main post to include:
Diff cover gasket, Thermostat+gasket, and PCV valve

Hello again. Thanks for posting the additional carb pics the other day. In addition to the choke plate rod you will need the "s" shaped steel tube for your hot air choke that attaches to the threaded nipple on the front. A separate fresh or cold air tube attaches from your air cleaner assembly to the stove on your intake manifold I believe. Your Haynes manual may show a diagram for this routing.
Along with hard and braided fuel line replacements I am still researching :censored:
 
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