Project -underfunded - '68 shortstep/carb'd LSx/200-4r build

[68GMCCustom]

Ordered a cooler for the trans today along with some jets, squirters, and pump cams to tune the carb (air bleeds next)... and a new electric fuel pump to provide it with better fuel pressure. I bought Summit's "Holley black" equivalant. 140psi free flow and 14psi max. pressure. I haven't had the truck down the track yet but I'm pretty sure the old pump wasn't up to the task. Doubt I'd have made it a full 1/4mi at WOT.

My ACDelco(read-Carter) fuel pump only puts out about 5.5psi at startup....except after it gets hot it drops.....and was putting out only 1.5psi the other day (according to the gauge) during a quick check while on a short drive... prompting me to cut my drive short.

Hoping to get the carb dialed in a bit better and get it to a local track this weekend.... to get a baseline on it!

[85burb]

My rebadged holley pump was putting out 0-1.5 psi for about a week. Ran ok still. Must have had flow cause it kept running. Was going to order new pump but seems to be doing ok now. I will have to replace it soon i think. But it works for now.

[djw32]

What trans cooler did you go with?

[gearhead1985]

great job awesome drive train i read that you thought about putting a 14bolt ff rear axle and wonder why i have messed with a few of them and they heavy with weighing about 550 lbs and will require drive shaft modifications to make it work my recomindation would be a ff d 60 that weighs about 400 lbs or a ff ford 9" that weighs even less

the only con of the 9" is the price but when built right it will take a beating and will be just as good as a14 bolt pig


also do you have any problems with drive line vibrations from this pic it looks like your pinion angle is off i looks like it is nosed up about 5-10*from the pic

Originally Posted by 68GMCCustom

plenty of room for as much travel as I'll need

about half way down the link is a diagram about the degree of the pinion angle is a standard ds

[matthew20061]

The build is looking awesome, can't wait to see the burnout videos!!! jk
I fired mine up today after sitting all winter, and wow what an awesome sound and my roads are finally dry so I can go test out the 6.0L's new performance. . . . .

(but to get to the dry roads I have to drive though a muddy yard so that's not happening until it drys a bit)

[68GMCCustom]

djw....its a small Hayden. 7.5"x12.5".

gearhead...thanks! I actually meant the 14b SF, like our TBSS has. Its a 9.5" instead of the 10.5" 14b FF. Not sure why the pinion looks that way in the pic...its not now. I've had truck up around 100 a couple of times w/o any noticable vibration...other then the song that the motor and exhaust are providing.

soon matthew! Gotta get the new fuel pump in plus the carb and timing dialed in. I have a place to shoot in mind...but if I don't make it there, then there will certainly be track videos.... w/BIG burnouts! The BFG T/A's don't grip well cold. next big purchase will be new rear wheels and tires...unless I somehow came up with the money to buy a new set...which I'd still probably want seperate street and track rear wheel/tire combos. I'll need dr's or slicks to get this thing to stick. Burns right thru 1st and 2nd like the old 383 did and its not even running right yet.

hoping to get it ready for some track time this weekend.

[68GMCCustom]

a couple of new pics showing the stance and hood while outside. Getting it dialed in better...still having a trans noise that will be looked at this week....then I'll be looking to take it to the track!










still working on getting a new video...oh and it burns thru 1st and 2nd now better then the old 383. In fact...it seems to be loosing traction and moving around more thru the top of 2nd now...

[85burb]

That is one sweet truck you have built your self. It really does not look like it would have that beast under the hood. Hope to see it in person at goodguys this year......At least in the parking lot if you dont put it in the show....but i think it should be in the show. I plan on drivin my burb to goodguys. Prob the next spring show they have. Looks great!

[djw32]

Great pics!

How low did you go in the front?

[mcbassin]

Your truck looks great. I hope you decide to stick with the stepside bed. You just don't see many of those around any more. Awesome!

[68GMCCustom]

Thanks guys. Yes, I plan on entering the truck because I want to run the autocross, and do the track cruise. It won't be finished, or repainted for that matter, so I won't be out looking for trophies or ribbons....but it should be dialed in good enough to compete in the autocross.

Mike...if I do ever get a short wide bed for it...I'm thinking I'll still keep the bed that's on it. I might want to change the look/function every so many years or so just to keep things interesting. I'll never sell it....so it may see several "looks" before one of my kids inherit it.

[85burb]

Originally Posted by 68GMCCustom

Thanks guys. Yes, I plan on entering the truck because I want to run the autocross, and do the track cruise. It won't be finished, or repainted for that matter, so I won't be out looking for trophies or ribbons....but it should be dialed in good enough to compete in the autocross.

Mike...if I do ever get a short wide bed for it...I'm thinking I'll still keep the bed that's on it. I might want to change the look/function every so many years or so just to keep things interesting. I'll never sell it....so it may see several "looks" before one of my kids inherit it.

The autocross is pretty much the only thing i did when i was there. That and the swap meet. Kind of pointless to cruse swap meat now but there was realy cool avalnched 67-72 suburban in the swap.

[Bennett68C10]

Truck looks great, I want to use that hood on my 68. Can't wait to see the video of it.

[Hart_Rod]

The truck is looking great and should run even better when you get it dialed in. How about a shot of how your pinion angle looks now (tranny and rear)? Thanks,

[mcbassin]

Just curious if in the pic above the driveshaft is actually in the tranny? Seems like it's running down hill almost like it's resting on the cross member?

[68GMCCustom]

OK guys I'll get new pics. Pic above shows driveshaft as it is coupled to rear axle. Attached is a diagram I had found....and though my pinion angle isn't at 0* with the driveshaft...it is parallel with the output shaft of the trans I think? And my dangle was like 3.5* IIRC?

I have a small vibration on the highway at/above 60-70mph....but with exhaust pulses mixed in... not so where I can determine whats causing it. I suppose I should look into getting some of those degreed spacers for the rear.

[Dieselwrencher]

Your build has turned out awesome! A lot of that decline in the pic may be to the lowering of the truck. Your rear axle center line may be higher than your transmission output center line. In some cases I bet you can't get the drive shaft straight or in a decline situation from front to back.

[mcbassin]

Originally Posted by 68GMCCustom

OK guys I'll get new pics. Pic above shows driveshaft as it is coupled to rear axle. Attached is a diagram I had found....and though my pinion angle isn't at 0* with the driveshaft...it is parallel with the output shaft of the trans I think? And my dangle was like 3.5* IIRC? I have a small vibration on the highway at/above 60-70mph....but with exhaust pulses mixed in... not so where I can determine whats causing it. I suppose I should look into getting some of those degreed spacers for the rear.

Okay, now you have me confused? Any chance you could explain the 3.5* IIRC?

Is the issue with lowering the rear suspension? How much drop do you have? The reason I ask, I just intalled the perches on my rear diff. to the same angle on the original, I'm certain it was like 12.5 degrees on the original. So I made my new diff. the same thinking the lowering springs wouldn't affect the pinion angle excessively. Check it out HERE. Another thing, the engine/tranny in our trucks usually runs downhill right? the rear diff. runs uphill right? In your pic it looks like they should be level?

[68GMCCustom]

the 3.5* I spoke of is the blue line in the pic above. its not supposed to exceed 3*? Yes, I believe the trans and diff point down/up respectively.

[5150.4.67]

Make sure your driveline/trans angle (example 3 degrees) inversely matches the driveline/rearend angle: -3 degrees.
U joints accelerate and decelerate as they make their way through a revolution. To counteract those pulses, the other joint must inversely match that angle. If they don't you could get a vibration.
This is partially why constant velocity (CV) joints are used (they turn a constant speed through the revolution and are also more efficient at angles)..... they eliminate those pulses or vibrations.
You can also measure the angle of the trans output shaft from plumb, and do the same on the rearend (at ride height). Correct with angle shims on the axle pads.
I hope I didn't over-explain it........
Good luck!

[85burb]

Where have you gone? Did you get your carb set up?

[68GMCCustom]

Pretty close....still tweaking here and there. Haven't gotten the MAP sensor working properly for cruising. New converter grabs a bit better down low for street use yet still has enough stall (was supposed to be 2025 but its more like 2500?) that it should do well at the track.

Been going all over it last night and this morning. Driving it about 150mi RT today.....taking it to my grandfathers farm for what will be its, and his; last family reunion at the ranch. He's 96 and unfortunately his kidneys are failing and with other issues... he's just riding it out. I really hoped he would be with us to age 100 or more!


Once I'm done with this cruise tho.....next focus will be to get it to the track!

[85burb]

Sorry to hear about your grandpa. Good to hear your truck is doing good still. Got my efi installed to day. Its amazing. Cant wait to see some track slips. Where do you plan on taking it to track at?

[68GMCCustom]

Thanks. Truck did great today.....except for the same damn oil or trans puking problem raising its ugly head that smokes the cab. Seems to be when the motor is under load...like lugging in a taller gear or something. Not sure what mpg's were, but ran hard out, and normal back....only burnt a little over 1/4 tank on a 19gal. tank. The wife tried me a little in the SS from about 60-90...she was staying even until I realized it only went from OD down to 3rd and I needed to do a manual downshift (still tweaking tv cable)...then she was losing ground pretty quick so she got out of it.
Punched it at about 55mph on the highway (next to my son in his car ) on the way back....and was spinning the tires until the shift to 3rd.

as far as racing....Denton, Crandall, Ennis..... not sure where else. I'm really interested in seeing how my trans does......not sure its not slipping a little in 3rd.

[85burb]

Originally Posted by 68GMCCustom

Thanks. Truck did great today.....except for the same damn oil or trans puking problem raising its ugly head that smokes the cab. Seems to be when the motor is under load...like lugging in a taller gear or something. Not sure what mpg's were, but ran hard out, and normal back....only burnt a little over 1/4 tank on a 19gal. tank. The wife tried me a little in the SS from about 60-90...she was staying even until I realized it only went from OD down to 3rd and I needed to do a manual downshift (still tweaking tv cable)...then she was losing ground pretty quick so she got out of it.
Punched it at about 55mph on the highway (next to my son in his car ) on the way back....and was spinning the tires until the shift to 3rd.

as far as racing....Denton, Crandall, Ennis..... not sure where else. I'm really interested in seeing how my trans does......not sure its not slipping a little in 3rd.

Good to hear you put wife to shame in fancy suv race car. Does it smoke in every gear if you lug it down. At least your trans builder is in town so he can at least diag it with you not take it out and send it to different state and have no ride for weeks on end. My next one will be built in town. 55 mph burnouts are always fun.....I guess have never done one..... I am pretty sure if i slowly roll into the throttle in 4th locked up i can slip something. That or it down shifts and i think it is slipping and i let out of it. But if i just hammer on it in 4th it will shift to 3rd i think. So i just dont get it to far down in froth it only happens at 3/4= throttle so i think i am safe for now. I want to go to dallasrace way or what ever it is called. My snapon dealer races his camaro there sometimes. I figure i sponser his habbit why not go watch it.