Project Underfunded / next phase - LSx carb'd to LSx efi

[68GMCCustom]

Boy have I chased my tail on that one! Not yet....but I think I may finally know what it is.

I've been focusing the whole time on something being broken/wrong. Intake gasket leak, cracked intake leak, broken vacuum check valve leak, etc. etc. Then it occurred to me the other day that the tune may have the TB open too much (does idle high - ported/polished TB has a hole drilled in blade), and controlling rpm with fuel trims....and this is not allowing the engine to create enough vacuum? Maybe its been something as simple as the tune the whole time? Wouldn't that be a laugh.

I've been busy wiring in a new Autometer GPS setup for the speedo and a Painless Perf. GM genIV tach setup to run my tach. Had to drop the starter which requires loosening up the header and exhaust, just to get to the crank sensor again. Painless?
I've made so many changes to the electrical I feel like ripping it all out and going back in with new. Maybe when I paint. If I wind up finding a VSS solution coming off the trans then I'll decide if I want to sell the GPS or not. I decided I did not want to dedicate my diagnostic port just to provide rpm and speed...particularly when I can look at so much more data with the Aeroforce scan gauge. Anyway...been doing all that along with adding some turn signals (where the holes are) and a high beam indicator to the OEM cluster... since I'm not running with the OEM gauges so I lost those.

Anyway....all that's about done and I'm about to try my theory. Hopefully tomorrow.

[68GMCCustom]

Finally!!!

Appears I've found the source of the vibration. After wasting time and money everywhere else is appears to be coming down to the d-shaft. If this is truly it, then I'm merely a tune away from a track day!

After direction from others to go back to the DS and have the balance re-checked...I finally removed it again (lost count) and took it up to it's builder. This was the 3rd DS he's built for me and I was happy with the other two...so it just didn't occur to me that it could be the source of the trouble. Even though I'm well aware of possible failures and have had "new" parts turn out bad before. Anyway, naturally I picked a time his balancer was out so I had to leave it with him. Machine would power up and then 1-2sec. later the power would just fade away. Anyway, w/o being able to balance it he used other ways to check it out and found my DS is bent/warped! Based on what I caught over the phone...on one end its roughly .025" off and it's roughly .030" off in the center. So he's built me a new DS and just waiting now for his balancer to be repaired. Hopefully I get it back tomorrow....and after a few highway runs if all is well I can head to the track this weekend and FINALLY get an idea what it's capable of. Should be able to lay down 13's at over 100mph with no problem (400hp TBSS runs high 13's @ 100mph)...hoping for a bit better then that tho (quite a bit based on race calculators), how much I'm not sure... anyone wanna take a shot at 1/8mi. and/or 1/4mi ET/MPH?


So.....does anyone think that a DS with .25-.030" runout may have been the source of my high speed vibration problem?

[JDon99]

Sucks about the driveshaft, but hopefully it will fix it! Are you running a one-piece? Do you happen to know the rough dimensions off-hand?

[68GMCCustom]

1 pc. I'll have to check the specs...been too long since I measured for it.

[68GMCCustom]

Originally Posted by JDon99

Sucks about the driveshaft, but hopefully it will fix it! Are you running a one-piece? Do you happen to know the rough dimensions off-hand?

old receipt showed 54" ctr to ctr (u-joint)...3.5" x .083"....but this one looks like he went up to a 4" with it.


Otherwise......if anybody's listening anymore...new d-shaft made it better but it still shakes like heck at anything over about 80mph. So...buying wheels/tires for it, been planning on a new torque convertor but will add a new sfi rated flexplate to match. Hopefully I'll get it calmed down good enough to head to an 1/8mi track this weekend.

[JDon99]

Have you checked runout on your hubs and axles? I am curious as to what is causing the vibration.

[mdw]

I just rebuilt my driveshaft this past weekend with new u-joints and carrier bearing What a Difference!!!Tha vibration is all gone at all speeds, but it is a two piece shaft, now a few years ago I had a 1967 Chevelle SS 396/4spd etc...it had a bad vibration at anything over 30 mph, now if I put air in the shocks it went away, changed pinion angle and problem solved on that one, not sure if it would help but maybe another avenue to look down.....

[68GMCCustom]

Originally Posted by JDon99

Have you checked runout on your hubs and axles? I am curious as to what is causing the vibration.

No, I guess that'll be my final puzzle piece if I get that far. I'd like to do an axle upgrade...like a Strange60 or Moser60 or maybe a 9.5" SF 14 bolt. Just too broke right now from new washer and dryer, new office furniture, and a house remodel... we're getting ready to put it on the market...plus still buying truck parts too gets tough.

[mcbassin]

Almost time for a video of your pre launch burnout or a few passes on the clock. Good luck with the drive shaft.

[68GMCCustom]

I suppose I could shoot a few "low speed" videos....as long as I keep the speed down.

[68GMCCustom]

Went to the tire store today to have wheels/tires checked out. Found another source of vibration!

Wound up with 2 bent wheels and the other 2 out of balance. These were installed by a local NTB that happen to mention something about a wheel being "slightly" bent as I was leaving. One was more then slightly! Since the BFG tires are speed rated at 112 and almost 7yrs old and already cracking.....I ordered a set of TTII's in 17x8 with Nitto NT450's in 275/50-17's....but may change that to 255/50-17. They will get it all in next week.





Oh....also decided I needed to replace that stock convertor so I ordered a Circle D 258mm Pro II 4L80E Torque Converter in a 3000-3200 stall. While I was at it I decided to add a new SFI rated flexplate. Should get this by the end of the month.









so yay! hopefully it'll be smooth now.... I'll be able to hop on the highway and do 120 or so w/o shaking the truck apart I'm ready to race it. I'll be getting a new set of wheels for my drag radials or just get a new set and sell the 15x10's and MT ET Street's.

[BigDan3131]

Are you sure your truck wouldn't be better off named the Money Pit? lol

[68GMCCustom]

seriously? you're kidding right? money pit...that would be a boat.

compared to some of the builds on this site mine would be considered modest at best? I do all the work myself (vs those that have some very talented professional builders that aren't free), I generally sell parts I replace, etc. to keep costs from ballooning and don't have a fancy IFS setup, air suspension, etc. Add that to the fact I received this efi setup after I'd set it up the truck LSx carb'd...that's complete efi intake w/rails, injectors, throttle body and sensors; harness, ecm/tcm, free tune(s) and support...all in trade that cost me almost nothing. Money pit? Is that how people see it? Really?

For perspective...the truck is a toy, not a driver....and I'm an empty nester that has had pent up "hot rod" interests left on hold for many years while kids grew. I've promised the truck to my 2yr old grandson... when I feel he's good and ready in 16-19 yrs...so its a long term project and "toy" to be enjoyed along the way.

[BigDan3131]

You can calm down now...I'm sorry I didn't think you would overreact this bad. Thankfully you don't have a hunger for more HP yet that is. That opens up a whole new world of add ons. Trust me, we have all started with "lets just get it running and drive it" for me that lasted about a year. Then it was lets put in a bigger cam, but wait the stock heads can't handle it so lets buy a set of aftermarket heads. Now with this added power we need bigger headers and a stronger driveshaft. Nope still not enough, I need a looser convertor and 3.73 gears. That was six years ago and I still need 4 wheel disc brakes, a Dana 60 rearend and new wheels and tires.

That's just on my El Camino...I'm setting a strict budget for my 65 GMC and I will force myself to stick to it [yeah right] until I get a fat bonus check.

[68GMCCustom]

ahhh.......calmed down before writing the 3rd paragraph

and more HP is what this trucks been about.....Dana60 or should I say Strange60 or Moser60.... in the future!

[68GMCCustom]

just got home with my new wheels and tires. 275/50-17's on 17x8 TTII's. They fit nicely. thinking I'll also buy a pair later in 15x10 or 15x12 for my d/r's.

[68Stepbed]

Those look like CRAP!!!! Just kidding.

Looking good! Do they hook at all? My Hankooks sure don't.

[68GMCCustom]

can't say yet as I had a load in the back and until I put in a c notch the fender is a little too close to the tire when hitting a dip with it loaded.

what size are yours?

[68Stepbed]

The fronts are the same, but I have a 17x9.5 with 275/55/17 rear tire.

[mcbassin]

Congrats on the new wheels and tires they look great!

[68GMCCustom]

Matt - got ya.

Thanks Mike!

[68GMCCustom]

got some parts in...Circle D billet 258mm 3000-3200 stall convertor w/single disc lockup, and a new sfi rated flexplate. Had trouble getting the old stuff off though, rounded the last of 6 convertor bolts. After 2 days of buying "special" craftsman sockets for removing bolts...I finally dropped the header and got my sawzall in there and cut it off.



purdee even with hand prints all over it!


flexplate and convertor in place


got the convertor and flexplate bolted in and trans bolted back up to motor, starter, header, exhaust all back in place. Just have to recheck trans mount height...possibly adjust it and pinion alignment one last time. This is going to solve the vibration problem.....I just KNOW IT!

[85burb]

That is one nice converter. I sure hope this fixes your issues. Seems like there is not a hole lot left to vibrate.
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[68Stepbed]

I've heard nothing but good things about Circle D converters. Fingers are crossed for ya, bud.

[68GMCCustom]

Thanks guys.....and its done and ready to test drive. Got to make a run to the county dump with some junk...will give it a good test run on the way back!