Project 67 GMC custom 6.5 turbo diesel

[67_C-30]

Originally Posted by wildwilly4x4

I used a really sweet box that you can buy at circle track/ race fab shops. They cost about $20 and have a really nice battery hold down...the only thing bad is you have to fab your own mount tabs for it if you dont want put a couple of small welds to your core support. I was reluctant to weld mine, but I ended up doing that just to save some time. I will prolly also replace the factory passenger side one the same way. These boxes I am talking about are a much better/ clean looking setup.

Thanks for the advice! I just saw your build for the first time last night, and I'm very impressed. That is a tough looking truck, and will look great in IH red.

[mal68ibu]

I just put a manifold pressure gauge on my truck today and did a little driving around with a deep half inch socket to adjust my turbo master. After a couple runs down the hiway and some cranking down on the nut, I'm pulling 9PSI at hard acceleration, and 5 PSI at cruising speed. From what I've read on the dieselplace forum those should still be pretty safe numbers, so I'm gonna drive it around like that for a while and see how that effects my fuel economy. Its has a very clear effect on my acceleration.

[67_C-30]

Originally Posted by mal68ibu

I just put a manifold pressure gauge on my truck today and did a little driving around with a deep half inch socket to adjust my turbo master. After a couple runs down the hiway and some cranking down on the nut, I'm pulling 9PSI at hard acceleration, and 5 PSI at cruising speed. From what I've read on the dieselplace forum those should still be pretty safe numbers, so I'm gonna drive it around like that for a while and see how that effects my fuel economy. Its has a very clear effect on my acceleration.

Yeah, 9 psi should plenty safe. Some say you can go as high 12 as long as the EGT's stay below 1100, but I'm gonna stay on this side of conservative as well. I've been moving mine around the yard and on my asphalt driveway, and with this NP435, it feels strong enough to break something with just 5 psi. I can get it rolling in first about 2 or 3 mph, and stab it kinda quick to make the turbo spool up and it breaks the rear tires loose very easily. I would think the higher boost would help mileage (as long as you keep your foot out it, which like me, seems like a problem for you). If you don't turn your fuel up anymore, it shouldn't have any adverse effects on economy.

[mal68ibu]

When I got my reman pump I told the guy to turn the fuel flow all the way up. I found that will less boost the truck would chug (for lack of a better word) just before the shift from second to third around town (th400 trans). With the turbo turned up its smooth, and I'm finding that I have to back off the gas on the hiway at cruising speed, compared to what I was used to with the lower boost levels. So in theory I should be getting better than the 14.5 MPG that I was getting. I'll know after the first weekend in May as I have a swap meet to go to that is a 200 mile round trip.

[67_C-30]

Originally Posted by mal68ibu

When I got my reman pump I told the guy to turn the fuel flow all the way up. I found that will less boost the truck would chug (for lack of a better word) just before the shift from second to third around town (th400 trans). With the turbo turned up its smooth, and I'm finding that I have to back off the gas on the hiway at cruising speed, compared to what I was used to with the lower boost levels. So in theory I should be getting better than the 14.5 MPG that I was getting. I'll know after the first weekend in May as I have a swap meet to go to that is a 200 mile round trip.

That sounds good. I still have the military IP, but I did turn it up a little more than a 1/4 turn (probably like 5/16 - not quite 3/8). I'm planning on running about 8 maybe 10 psi max. I'm only getting about 5 psi now with the stock GM-3 wastegate actuator. How are you doing on temperature with the 4 row radiator? I have the same one you do (I think) and I'm hoping I can get by with it. I have a new one for an 80's diesel truck that I could use, but I don't want to modify the radiator support that much if I don't need to. After comparing the 2 side by side the older BBC radaitor is much thicker than the diesel radiator is, but the core dimensions are smaller. Its gets pretty hot in summer here, so this concerns me a little.

[mal68ibu]

I have not yet seen water temp past 215 towing 7000 lb
s. However the truck has not seen ambient temps over 80 yet. We should be in the 90's in a month or so. With my set up if this radiator does not work out I'm going to look at aftermarket aluminum ones and an electric fan.

[skoffice]

Hey I saw your truck today at the Reno swap meet! My friend and I were trying to figure out what you had under the hood haha we both knew it was a diesel because of the intercooler. Its a small world running across this thread the very same day. My friend has a 72 blazer he wants to put a 6.5 in as well. I have seen your suburban on my way home from Sac City and have had my eye on it for a while haha, is it still for sale?

[thirdstreettito]

Whats your mileage?

[mal68ibu]

Originally Posted by skoffice

Hey I saw your truck today at the Reno swap meet! My friend and I were trying to figure out what you had under the hood haha we both knew it was a diesel because of the intercooler. Its a small world running across this thread the very same day. My friend has a 72 blazer he wants to put a 6.5 in as well. I have seen your suburban on my way home from Sac City and have had my eye on it for a while haha, is it still for sale?

Yes the burb is still for sale. The city made me take the fore sale sign out under threat of a ticket if they see it again.

[mal68ibu]

Originally Posted by thirdstreettito

Whats your mileage?

No where near what I was told it would be. Best I've pulled is 14.5. I have one injector thats missing on me inconsistantly. I'm running 5 psi on the highway at 60mph, and it peaks at 11psi when i beat the hell out of it. I've still not installed the overdrive unit. I've just been busy as hell with ebay.

[skoffice]

What?? That's stupid. Sacramento sure is weird sometimes. Well I'll have to stop by sometime and check out your burb since school starts back up next week sometime.

My buddy also has a 6.2 in his 71 K10 with just a stock 4 speed and he's getting around 20-22 mpg with that, so you should see a big difference with that O/D.

[thirdstreettito]

What size tires do you have? Also, how much did you turn up your IP?

[mal68ibu]

Originally Posted by thirdstreettito

What size tires do you have? Also, how much did you turn up your IP?

I'm running 245/75/16 and the IP is ALL the way up. I'm sure its turned up more than it needs to be, but I had a shop do it and they leaned on the side of overfueling versus potential damage from overboosting.

[mal68ibu]

On the fun side of life, I'm putting rear discs on the dana, since the drums no longer work.............so I hope to have a sweet burnout vid coming.

[mal68ibu]

Sorry but no burn out vids. The rear discs were a total pain in the ass to install. One side lined up really nice and the other side was a total battle. But they are on the truck and fully functional now. After 12K miles I've got a new laundry list of stuff to do to the truck.
1. rebuild the turbo. I'm going through oil at a horrifying pace. Rebuild kit is on the way.
1.a. Install heater. It has only been media blasted and refinished since January.
2. Install pyrometer and have injection pump properly tuned.
3. New Injectors if needed. Fuel economy sucks.
4. Brand new aluminum radiator, and electric fans in the summer. The stocker is not in as good of condition as I had hoped.

[thirdstreettito]

Originally Posted by mal68ibu

Sorry but no burn out vids. The rear discs were a total pain in the ass to install. One side lined up really nice and the other side was a total battle. But they are on the truck and fully functional now. After 12K miles I've got a new laundry list of stuff to do to the truck.
1. rebuild the turbo. I'm going through oil at a horrifying pace. Rebuild kit is on the way.
1.a. Install heater. It has only been media blasted and refinished since January.
2. Install pyrometer and have injection pump properly tuned.
3. New Injectors if needed. Fuel economy sucks.
4. Brand new aluminum radiator, and electric fans in the summer. The stocker is not in as good of condition as I had hoped.

1. Sounds like the turbo oil restrictor isnt working, hopefully the rebuild kit has one in it.

2. Good idea!

3. Have your current injectors tested by an injection shop.

4. Make sure you get a rad with an oil cooler and trans cooler built in, it's worth it in the long run. Also, go back to the mechanical fan. As Bill Williamson from Ron Davis Radiators said to me "New trucks still have mech fans. There is a reason for it. If your truck isnt staying cool then switch to an aluminum radiator. The stock fan is more than enough."

[mal68ibu]

I rebuilt a GM8 turbo I had on the shelf. Now I have to make a turbo master for it as the GM3 bracket will not fit the GM8 turbo. I also don't want to shell out another $120 for a new one. So I've found a few links to show how to use the vacuum unit to make a home made turbo master. Other reason I want to ditch the mechanical fan is I have no shroud for it, and honestly I have no desire to make one. The fan is 21" so a stocker is out of the question.

[mal68ibu]

Well I blew the motor up today. I'm drowning my sorrows at the bar now. Going back east for vaca and gonna ponder my options. Thinking of **** canning the gmc for a new truck right now.
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[67chevy1series]

i say put a nice 327 in it or parting it out it does have nice parts and if you do i would like to have first dibs on the passenger side fender and the port windows and some of the dash knobs not to be like a vulture

[mosesburb]

Sorry to hear of your loss. Keep an eye on craigslist or on other boards classifieds as 6.2L and 6.5L motors come up typically for $500 or less. Just some food for thought.

[skoffice]

PM me how much you would want for the whole thing. My buddy might be interested in it as is.

[mal68ibu]

Originally Posted by mosesburb

Sorry to hear of your loss. Keep an eye on craigslist or on other boards classifieds as 6.2L and 6.5L motors come up typically for $500 or less. Just some food for thought.

Going to buy an 85 2500 with a 6.2 and 700 to get me by for now. Its from a good friend of mine who will stand behind it.

[mal68ibu]

Drove the 84 GMC 6.2 and 700r4 home today. Runs and drives great. Gonna reg. it tomorrow and put it to work. I'll be pulling the wheels, and receiver hitch off the gmc but I'm thinking that I'm going to part it out. This truck has been that girlfriend that keeps cheating on your and you still go back to her. I think its now time to part ways. To everyone who has been watching the thread have a good holiday and new year and I'll see you next year. If I determine that parting it is best for me the truck will run through ebay in pieces.

[67chevy1series]

Originally Posted by mal68ibu

Drove the 84 GMC 6.2 and 700r4 home today. Runs and drives great. Gonna reg. it tomorrow and put it to work. I'll be pulling the wheels, and receiver hitch off the gmc but I'm thinking that I'm going to part it out. This truck has been that girlfriend that keeps cheating on your and you still go back to her. I think its now time to part ways. To everyone who has been watching the thread have a good holiday and new year and I'll see you next year. If I determine that parting it is best for me the truck will run through ebay in pieces.

could everything but the passenger fender run to ebay not to tell my sad story but i buitl my truck as a basket case and my dad gave me a 68 front end so i found a driver fender but have been looking for ever for a good passenger fender so i found you and yours looks okay you can keep all the trim and emblems but all i need is the fender

[1968CHEVYC10]

Hey sorry to hear about your motor. I'm working on swapping a 6.2 into my '68. Trying to get the motor mounts figured out. Did you use the SBC stands and mounts? or did you have to get BBC stands?