1980 Indy 500 TTA

[Radge]

I have a 1980 turbo T/A. 4.9 V8 301 with the garrett tb0305. I am only getting 5psi off the turbo. I have shortened the wastegate actuating rod as much as possible and removed the vacuum line (vent) below the actuator which gave me 2 - 3 psi. (If I lengthen the rod psi drops exponetially).

I tapped into the actuator's inlet to run a boost gage. It does not come stock with a boost gage only 3 lights (low, med. High) 2 of which do not light anymore.

Anytime I ask someone they shake their head and say I cant help you or just swap that motor out for a 400. Well I just want to keep it original as much as possible and no one wants to help. No one has seen a TA like this, let alone want to work on it. I even went to the Pontiac dealer, and they could not help!!! Useless, needless to say. I bet if i had a GN it would be a lot easier!!!

Here are my questions:

I think I should be getting between 9 psi and 11 psi, how can I troubleshoot the problem? (Vacuum lines are good, turbo is working, wastegate actuator is new).

Carb. is new vaccum non-electric (exact match Q-jet from GM), new coil, new springs, plugs, cap, wires, rotor, altenator, belts, vaccum lines, set timing, etc.

Having a choke problem, cant seem to set it right it right. Takes a long time to warm up but once it does, no stalling or hesitation.

Will a rebuild kit (bushings, seals, etc.) help restore my boost or is it not worth it as opposed to trying to locate a new one? Is there any other turbo's that can be substituted since this one is hard to find.

The boost lights do not light up anymore. Bulbs are good, I think it is because of the lack of boost pressure. At what psi intervals should the boost lights activate? Normal is on all the time, how much psi for the medium light and high light? Again people I talk to say "I doubt this model turbo make the gage light up." Well why would it be there if it was not possible? Plus, I know it used to light up years ago, but the response I get is "that's impossible" with this car. Well i know it is not the fastest motor, but it aint bad.

To be honest, I can chirp the tires when it shifts from 2nd to 3rd and so on. Brake stands too. Once again not a GN, but not too shabby.

Hopefully someone can help and not tell me to rip that motor out and swap it for a 400. As of yet no one has helped. so i guess all I can say is
HHHHHHHHHHHHHHEEEEEEEEEEEEEELLLLLLLLLPPPPPP!

Thanks in advance!!

Roger

 

[Radge]

just to be clear (as i wasn't) i only get 5 psi AFTER i removed the vent and shortened the rod.

Sorry!

 

[b4black]

You've come to the right place. The Buick Carb/Turbo V6 and the Pontiac 301T share the same turbo set ups. You're right, you should be seeing ~9 psi. The things I can think of to cuase low boost are:

Weak ignition - but you have addressed that.

Weak actuator spring - Try adding an external spring along the rod, or even temporarily locking it closed with a turnbuckle (be careful for overboost though)

Exhaust Restriction - plugged converter?

Intake restrition - Make sure the secondaries are open up. This one got me on both my cars.

SECONDARIES NOT OPENING? - One of the most common sources of low power (or low boost on Turbo V6's) is that the Quadrajet's secondaries are not opening. The secondaries are open via mechanical linkage, so the vacuum or load doesn't matter. When you are looking to see if the secondaries are opening, you are mainly concerned with the lower butterflies (throttle plates) in the throttle body, not the upper butterflies (air valves) in the air horn. Those should be held shut by spring pressure and easily opened with your finger (just make sure they aren't binding).

In the throttle body (base of carb) there are two shafts. The secondary shaft, when viewed from the driver's side, is green, with a slot, wrapped by a spring and have a black "pointer" sticking up towards 12 o'clock. When you work the linkage by hand, the pointer will move from 12 to ~3 o'clock. Notice the slot in the end fo the throttle shaft. It may not turn. If it isn't, then the throttle plates aren't opening, but this may be normal. As Scott mentioned, there is a lock out on the passenger side that keep the plates from opening when cold. You can either push it out of the way, or drive the car until warm. Then when you work the linkage, you should be able to see the slot move. The seconadries do not open until about 90% of full throttle. They are really good for WOT blasts.

HTH, a tuned 301T can outperform a 400.

 

[Audiowizard]

Hey Radge! why dont you show another turbo T/A owner some pics of your ride! You can see pics of mine in the links in my sig but it is no where near what it will be when I'm finished, thanks!

 

[dhauser]

Radge, I think you should just give up and buy my 9700 mile Indy Pace Car Turbo TA. That'll fix 'er!

Good luck getting her back to boost!

 

[Radge]

progress report

Checked secondaries- they are fully functional.

Intake and exhaust from turbo are free and clear.

Cat seems ok. but wil check further. plenty of exhaust out of the pipes.

Finally found the blower motor for the HVAC. It is behind the passenger wheel skirt. you can see it from the fender vent!!! un-freakin-believable!

keep the advice coming... please.....

 

[Scott Adcock]

The stock bead type cat is junk and can cause serious backpressure. If you can't get it out nothing can get in either. If you want this car to perform better then the cat should be changed to a modern type at the very least. I would make sure that the Secondary lock out tab is out of the way and that the secondaries will open. I have had this happen a bunch and if it stays locked, the max you can get is about 5psi.

 

[81nascar]

I agree. Get rid of that stock cat as soon as possible. Those old pellet style ones like to clog up over time. Their could be a chance that your turbo is tired. They say(so I've been told) that after about 60,000 miles on these cars is about all you get out of the turbo, but I am sure there are exceptions. You can buy a rebuild kit from Turbo City for about $200.00 and do it your self if $$$ is an issue.