Gary Hart's 1951 GMC Half Ton - now with Teaser video!

[dieselgeek]

Re: Gary Hart's 1951 GMC Half Ton

Ohh, I have to wait 'til I get home to watch the video :'(

Saturday was spent mostly on completing the installation - it would have run if it weren't for a configuration mistake I made on his Megasquirt-2x, which resulted in a handful of dead LS coilpacks : (stupid EFI tuners)

Any pointers ??? PM me if you don't want to accidently jack this thread.

It's simple really: don't be in a hurry, and double check the status of your spark outputs at 0 rpm (ignition on, but engine not running) - for LS packs, the status of the spark outputs needs to be "low" or 0 volts. That's the exact opposite of say, an MSD box where you want the spark outputs to be "high" at rest (12v).

I missed the proper setup and skipped the check, we figured the problem out just as the coilpacks called it quits. Just a stupid mistake, they happen some times. These guys are family friends so the atmosphere was "have fun getting this thing to run" - in the hilarity of the weekend I totally missed the spark output check.

But, you should see his logs - battery voltage stays at 14.5v, never moves! no noise, perfect tach signal, basically nothing else wrong. Once the mechancal bugs are worked out - it's on!

I have a feeling there will be a new front suspension under the truck soon too. That old school stuff is scary over 45-50mph. This thing clearly wants to wang up to 80mph without breaking a sweat so, I expect there will be an upgrade in the near future.

[TheSilverBuick]

Re: Gary Hart's 1951 GMC Half Ton

Ohh, I have to wait 'til I get home to watch the video :'(

Saturday was spent mostly on completing the installation - it would have run if it weren't for a configuration mistake I made on his Megasquirt-2x, which resulted in a handful of dead LS coilpacks : (stupid EFI tuners)

Any pointers ??? PM me if you don't want to accidently jack this thread.

It's simple really: don't be in a hurry, and double check the status of your spark outputs at 0 rpm (ignition on, but engine not running) - for LS packs, the status of the spark outputs needs to be "low" or 0 volts. That's the exact opposite of say, an MSD box where you want the spark outputs to be "high" at rest (12v).

That's exactly the type of info I was looking for Especially if I go from an MSD to LS coil packs in the future. Thanks!

[squirrel]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

I have a feeling there will be a new front suspension under the truck soon too. That old school stuff is scary over 45-50mph. This thing clearly wants to wang up to 80mph without breaking a sweat so, I expect there will be an upgrade in the near future.

There might be something wrong with it then....I've put a lot of miles on old trucks with the stock steering/suspension/brakes. As long as it's not worn out, they drive just fine.

[TheSilverBuick]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

Sweet. I like that DIYautotune sticker on the valve cover, nice touch! I wonder how one would look on the air lid on the Skylark.

[Brian Lohnes]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

Hehe...Scott said "wang up" -- I'm dumb.
:D

[dieselgeek]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

I have a feeling there will be a new front suspension under the truck soon too. That old school stuff is scary over 45-50mph. This thing clearly wants to wang up to 80mph without breaking a sweat so, I expect there will be an upgrade in the near future.

There might be something wrong with it then....I've put a lot of miles on old trucks with the stock steering/suspension/brakes. As long as it's not worn out, they drive just fine.

Fine to what speed? curious.

[Tazracing]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

what fried in the coils?

[squirrel]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

Fine to what speed? curious.

100 is all I've got up to.

If it's wiggling around, something is wrong.

[GH]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

Jim, I put trailer springs that are about 26" long. Everything else is stock, took it all apart and cleaned all pieces. Put in new king pins and used the tapered shim for caster and put another 14 ga. strip of steel with it to increase the caster. It appears to have bump steer, when went down hill into a dip it wanted to left and right, kinda scary, was nothing like the Stude at 248 MPH. I checked toe in with a tape measure it was close to 1/16" toe in. I'll have to look into this problem.

[dieselgeek]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

what fried in the coils?

The transistor overheated, and shorted the TTL input (trigger input) to ground.

[Tazracing]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

Jim, I put trailer springs that are about 26" long. Everything else is stock, took it all apart and cleaned all pieces. Put in new king pins and used the tapered shim for caster and put another 14 ga. strip of steel with it to increase the caster. It appears to have bump steer, when went down hill into a dip it wanted to left and right, kinda scary, was nothing like the Stude at 248 MPH. I checked toe in with a tape measure it was close to 1/16" toe in. I'll have to look into this problem.

whats the tie rod angles look like as the front goes through it's travel?

[squirrel]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

It looks like the drag link is level like it's supposed to be. But the springs probably have more arc than the originals, and this could be causing the axle to move forward when you hit a bump, which effectively pulls the steering arm back, and steers the truck. That's just my guess.

The original springs used metal bushings and were rather long and stiff. I think there's a good reason for all that.





My suggestion: either put the springs all back stock, or put in a different suspension like you were thinking of doing. At least you didn't put too much money into this setup. It's too bad it didn't work.

[Tazracing]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

whats the width of the rails, if the same as the 60 up. 67-72 or 73-87 front crosmember and front arms are a total bolt on(you'll have to drill the holes, but)

[squirrel]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

The later truck suspension will make the truck sit up high, and the wheels are very far apart so they wont fit under the fenders nicely.

[GH]

Re: Gary Hart's 1951 GMC Half Ton - now with Teaser video!

Jim, you are right, I need to get under it and see what happends when it works up and down. Right now I have to rework the intake plenom.