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GM retiree just joined

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billyg38120

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Hello,
I am a GM retiree. I have some knowledge of GM powertrains.

I have a 1977 Black Crew Cab Dually. It had originally a 7.4L THM 400 and 4.10 axle.

Now the truck has a 468 cu in oval ported head, flat top pistons, reman engine with a cam of higher lift/dur.

I have the first released design GM Marine (Arizonia Speed and Marine) Intake, Delphi Injectors 38 lbs, Twin 58mm Throttle body with the small diameter GM Distrubutor with Delco Wires AC CR43TS plugs at 0.55".

Exhaust is 1996 7.4L Ported manifolds dual exhaust 2.5" Transmission is a hand built 4L80-E.

Electronics are: ECM is a 1989 Corvette/Camaro ECM With Twin MAF's, Trans is GM TCM.

Both controllers use Moates APU1 for the PROM. Custom calibrations are all mine. (I learned from an old job I had for a while!)

Axle is modified to take one additional quart to cool the axle brgs.

Thermocoupled exhaust, Fuel tank, rear axle, trans, under hood, and ambient.

Cooling is 4 row rad, P/S cooler, 12x11x1 3/4" Long industries trans cooler. A/C is R134a A6 compressor.

Custom mod frt end scoop to channel air into the rad and keep it cool. Opened up fender wells to let the air excape.

Will tow 85MPH all day with a 7,500 lb trailer.

I do know where over 100 HP lies within the cylinder heads of the 6.5L and can advise you on a 4L80-E stand alone TCM using GM TCM.

I had my truck with a carb and 4L80-E. I used a Old gm HEI Module for the engine speed input to the tcm.

I used a TV cable off the carb with a fabricated 90 deg bracket to connect a TPS feeding the TCM signal.

I used the GM DRAC to run my electric speedo I installed in my 77 dash. (Speedo was a 95 g-van speedo electrically driven).

I had to cut out a bit of the dash carrier and it works like a new one. DRAC measured out and caculated it using the charts and it is spot on in MPH.

My goal was to use ONLY over the counter, any auto parts store parts only.

It is easy and you can do it as well.
I can help modify the 4L80-E and close so many false rumors about the trans if you would like.

Thanks for reading this.

Billy Graves
 
Last edited by a moderator:
Welcome! Sounds like you will have some fun around here. Also, sounds like you can contribute a lot. I am already intrigued by your 100hp statement.
 
billyg38120 said:
r.
I do know where over 100 HP lies within the cylinder heads of the 6.5L and can advise you on a 4L80-E stand alone TCM using GM TCM. I had my truck with a carb and 4L80-E. I used a Old gm HEI Module for the engine speed input to the tcm. I used a TV cable off the carb with a fabricated 90 deg bracket to connect a TPS feeding the TCM signal.

My goal was to use ONLY over the counter, any auto parts store parts only. It is easy and you can do it as well.
I can help modify the 4L80-E and close so many false rumors about the trans if you would like.
Click to expand...

Welcome to TheTruckStop Billy :)

I'm sure members will be all ears on these modifications...
 
Yeah hello there billy ,tell us your secrets.
it sounds like you're the GM version of the Johnny Cash song .." i've got me a 93-94-95-96-97-98-99 automobile":D
 
billyg38120 said:
Custom mod frt end scoop to channel air into the rad and keep it cool. Opened up fender wells to let the air excape.
I do know where over 100 HP lies within the cylinder heads of the 6.5L and can advise you on a 4L80-E stand alone TCM using GM TCM.
My goal was to use ONLY over the counter, any auto parts store parts only. It is easy and you can do it as well.
I can help modify the 4L80-E and close so many false rumors about the trans if you would like.
Thanks for reading this.
Billy Graves
Click to expand...

Welcome to TheTruckStop, Billy. I hope you like it here, I love it!
I look forward to your upcoming pictures and secret revelations (PLEASE?)
I loved Memphis every time I went through, and I really like the more wild parts of TN.
We have lots of different sections for many interests, but you probably noticed.
Thanks for coming in.
 
schiker,
no pic will do it right. The inner wells are opened up at the upper control arm. This allow the air that was scooped up to flow out. I had discussions with some truck cooling people about the 95 body with the diesel & Big Block that runs hot. Tried to eliminate this. Also asked about these motor homes that warp the exhaust manifolds with big blocks. These motor homes restrict the opening around the upper A-arm and force a larger amount of air around the exhaust manifold. This fix has to many inputs into the heat and to many things to type to correct. In a nut shell. Motor homes run hot from smaller rad + manifold are nodular iron that can't stand up to sustanded heat that long, bolt holes in manifold that restrict the expansion/contraction and no movement on the head to manifold. Fuel added to cool combustion chamber, inlet air to hot, rad that gets hotter, this increases the inlet temp to intake, and the temp goes very hi.
I used stainless steel manifold, 3 layer ss gaskets (OEM), opened up bolt holes in manifold, anti-sieze, inlet air to throttle body (and carb before EFI) was direct to front of rad support. Yes it could get icing on the throttle body on hi humid 40 degree days but I understand this going in. I packed air into the front of the rad and around the engine. This charged the underhood air and it needed a way out to aide cooling. I ran a 180 stat with a 1/8"steam hole. No problems on 100 degree day with A/C on max.
That's my 2 cents. One more important item. Adding the air scoop below the bumperto scoop air creates a low pressure area behind the scoop and aids in air flow through rad. I was going to add outlets at fender well upper like GM Med Duty trucks have for air flow out of the engine compartment.
 
Like so perhaps?

DSC03877copy2_zps6dee37ee.jpg


:)
 
great white said:
Oh, it's also nice to see someone comment on the importance of pressure differential and cooling performance.

:thumbsup:
Click to expand...

I see you are thinking! A bit larger on the outlet so the air can flow out.

One item I have NOT seen talked about is the gas or especially the diesel air inlet on the body style you have. The truck NEEDS a few important changes.
A bit larger radiator. Larger frontal area with an air dam to get air though the front. Air inlet to the air cleaner that DOES NOT pull under hood air when the fan clutch engages. With the fan clutch ON, the engine compartment pressure is VERY HIGH. (Air can't escape and add the fender a-arm cuts and fender exits). With the stock design, the inlet to the air cleaner will not pull water in BUT it WILL pull HOT AIR into the engine. This starts the downward spiral to overheat.

The design of the Engine Oil Cooler is POOR. You can put a thermocouple on the OIl Cooler inlet and outlet. It WILL measure a good TEMP DROP. BUT IF YOU LOOK AT HOW IT IS, it works on the PRESSURE DIFFERENTIAL OF THE OIL FILTER. THE cleaner the filter, the less flow. PUT A FLOW METER ON THE OIL COOLER LINE. It has LOW flow. I had a person place a thermocouple inside the engine at the oil entrance to the MAIN BEARING on # 2 on the 8.1L. (The oil cooler design and function is identical to the dsl). The fleet of development trucks drove up a 10,000 ft mountain out west. He drove one pass with the oil cooler ON and another pass with the cooler shut off at the flow meter. Same day same outside temps. No rain. August day. The difference was 2 degrees F between the two passes. 2 degrees.
I had though about using a Hi-Volume oil pump, and bleeding off a two 1/8 holes to a oil cooler and retun the oil to the pan. It works and does drop the sup temp about 30 dgrees F but the risk of a leak in the oil system I didn't like. So I talked to the engine boys and got a power steering pump (a low volume one) Used the crank to spin the pump at low speeds with pulleys and pushed the oil through a oil over water cooler. The engine group was very interested in my thoughts and wanted the outcome. I still have not installed this. Divorce.

I hope this will help. If you buy a cooler, the tube type is a 1950's design and the WORST for cooling. Get a Long Industries stacked plate, a LARGE ONE.
 
billyg38120 said:
I see you are thinking! A bit larger on the outlet so the air can flow out.

One item I have NOT seen talked about is the gas or especially the diesel air inlet on the body style you have. The truck NEEDS a few important changes.
A bit larger radiator. Larger frontal area with an air dam to get air though the front. Air inlet to the air cleaner that DOES NOT pull under hood air when the fan clutch engages. With the fan clutch ON, the engine compartment pressure is VERY HIGH. (Air can't escape and add the fender a-arm cuts and fender exits). With the stock design, the inlet to the air cleaner will not pull water in BUT it WILL pull HOT AIR into the engine. This starts the downward spiral to overheat.

The design of the Engine Oil Cooler is POOR. You can put a thermocouple on the OIl Cooler inlet and outlet. It WILL measure a good TEMP DROP. BUT IF YOU LOOK AT HOW IT IS, it works on the PRESSURE DIFFERENTIAL OF THE OIL FILTER. THE cleaner the filter, the less flow. PUT A FLOW METER ON THE OIL COOLER LINE. It has LOW flow. I had a person place a thermocouple inside the engine at the oil entrance to the MAIN BEARING on # 2 on the 8.1L. (The oil cooler design and function is identical to the dsl). The fleet of development trucks drove up a 10,000 ft mountain out west. He drove one pass with the oil cooler ON and another pass with the cooler shut off at the flow meter. Same day same outside temps. No rain. August day. The difference was 2 degrees F between the two passes. 2 degrees.
I had though about using a Hi-Volume oil pump, and bleeding off a two 1/8 holes to a oil cooler and retun the oil to the pan. It works and does drop the sup temp about 30 dgrees F but the risk of a leak in the oil system I didn't like. So I talked to the engine boys and got a power steering pump (a low volume one) Used the crank to spin the pump at low speeds with pulleys and pushed the oil through a oil over water cooler. The engine group was very interested in my thoughts and wanted the outcome. I still have not installed this. Divorce.

I hope this will help. If you buy a cooler, the tube type is a 1950's design and the WORST for cooling. Get a Long Industries stacked plate, a LARGE ONE.
Click to expand...

That's about all that will fit in the available space. The fender has a "wall" inside to create a high pressure area that is ducted from in front of the rad to the air intake. at least it does on the passenger side. The vent location ties in nicely to a cavity formed at the back of the engine bay in the fender structure. It's almost like they planned to have a heat extractor there. There's just not a lot more real-estate available in the area for more ducting/venting.

As to the front:

3393c2f2.jpg


Already gone down that road. :)

I already have the biggest oil cooler that will fit in the available space and I monitor temps in the cab on a digital gauge.

The rad, well....biggest one you can get without cutting the rad core support.

Currently formulating a way to duct from the high pressure area in front of the bumper to the air intake vice letting it fight and spill it's way to the inner fender around the rad core support. The core support face is still a high pressure area, it can just be done better when talking about air intake. Problem is I don't want to loose too much of the OEM look to the truck, otherwise it would be easy.

There may be a bit of CAC going on also. ;)

Have also toyed with some underbody fairings to increase the low pressure zone behind the rad over what the stock design makes. It's also part of the reason I keep the "splash guard".

Truck holds it's temps in check in low speed higher altitude towing, I'm looking to make it better though. Still on the drawing board though...
 
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