Archive for the LT-1 Category

Problem found…

Posted in LT-1 on 28 December 11 by Mark

and it ain’t good.

They found out the problem on my truck.  It’s been having a high rpm misfire above 4200 rpm, and they haven’t been able to tune it.  Turns out there was a problem during assembly (likely I screwed it up, but it’s possible there was a part failure).

Here’s a picture of the timing cover:

From top to bottom, that’s the water pump drive gear (driven off the camshaft), the Optispark distributor drive interface, and the crankshaft snout.  The Optispark distributor drive interface is really just the front of the camshaft; that dowel pin goes into the Optispark, which is a pancake shaped distributor that sits between this timing cover and the water pump.

Here’s a picture with the cover removed.

Again, a picture of the front of the cam, which drives the distributor:

And now a picture of the back of the Optispark distributor, which is what goes on that camshaft:

SO, take a look at the front of the cam again:

Those two bolts on the sides hold the cam plate against the face of the motor, which holds the cam in.  SOMEHOW, they worked themselves out.  As they did, that allowed the front of the cam to move around a bit, which caused that dowel to break.  The broken dowel caused the opti to not be directly in time with the engine when a high rotational force was applied (high rpm), causing the misfire.  It also caused enough vibration in there to get one of the distributor rotor bolts to back itself out inside the case.  You know, looking at those two bolts, I definitely put locktite on there; I wonder if I didn’t get them torqued right?  Huh.  I’m pretty sure I did; not sure what happened.

I guess it’s good that they found the problem; it could have been much worse if the thing had completely come apart going down the highway.  As it is, the shop is going to try and pull or drill that dowel out, and press a new one in.  Hopefully, they won’t have to pull the lifters and replace  the camshaft.  Then put the timing set back together, then the distributor back on, then the water pump back on.  Gah.  This is going to be EXPENSIVE.  I’m sorta glad they’re doing it though; it’s not fun work at all.

But damn, is it going to be expensive.


Fuel Injection Woes

Posted in LT-1 on 12 December 11 by Mark

I’m about ready to put a carburetor on there and call it good.


The shop has had it now for over a week (two Thursdays ago), and they’ve fixed the couple things that prevented them from putting it on the dyno.  They’ve got it all setup for idle and cold tuning, but they’re running into a misfire above 4200 RPM or so.  They’ve checked spark out of the distributor, signal to the ignition module, timing signal to the PCM, coil output; they’ve checked valvespring pressure, spark plugs (I had the wrong depth plugs in there–apparently I needed a different plug with aluminum heads than stock, although I didn’t see that in the paperwork); they’ve tried pulling their tune out of the PCM, they’ve checked & set fuel pressure, checked knock counts, everything.  Just keeps the misfire.

I’m starting to think that I’ll pay as much for the tune as I did for the exhaust work (WAY too much).  But the shop seems to be covering all the bases, and they definitely know what they’re doing, so hopefully it will turn out.

I’m heading to India on Wednesday, and will be back on Thursday the 22nd.  Then we fly to Omaha for Christmas on the morning of the 23rd for 4 days.  So…maybe a late Christmas present for me?

Just keep saying it’s another step closer…

Posted in LT-1, Other Vehicles on 3 December 11 by Mark

Well, the Carb Conn appointment went pretty well.  The guy there, Alex, was great.  Met me after his morning workout, showed me around the shop (they’ve got some amazing rides there).  Then he pulled his laptop and his communication gear over to the truck, but wasn’t able to hook up to the PCM with either EFILive or his HPTuners equipment.  SONOFA….

We talked about possibilities, and he said I should go ahead and give the DMV a shot at emissions testing.  He had a tester and shoved it up the tailpipe, and it it passed with flying colors!  Unfortunately, I could hear an exhaust leak starting up pretty bad.  I took it into the state emissions inspection shop, and they passed me!  I went straight to the DMV (DoL in this state), and got fresh tabs for the license plate.  So that made me legal, at least.

I drove it to work for a couple days, and it ran great, but that exhaust leak got immensely worse quickly.  T came back over and helped me get it back into running shape–retightened the exhaust headers after the couple hundred mile break in, change the oil for the first time (more dino oil going in), and fixed the exhaust leak.  Turns out, BOTH COLLECTORS had come completely off.  I guess the nuts backed off or something.  That exhaust is the only thing I didn’t do myself on this build, and I paid REAL good money (i.e., he robbed me blind), and all six collector bolts backed off. 

Anyway, got those bolted back up, and it’s suddenly tolerable to drive again.  Alex at Carb Conn told me to try Vince at Trifecta, a mail order tune & logging place, but he apparently has sold all his LT1 equipment, even though that’s what he drives.  HE told me to try Blood Enterprises down in Auburn, and they DO tune LT1s!  So I drove it down there on Thursday.

While it was there, they gave it a once over before they put it up on the dyno.  They found a few problems that keep them from doing the dyno tune:  a couple plug wires had burned on the exhaust headers (these things are beginning to be a pain), the clutch hydraulic line had apparently fallen and was resting on the driver’s side catalytic converter, and finally the main wiring harness loom was too close for comfort to the header.  They’re going to take a swag at fixing those three things, then they’ll put it up on the dyno early next week.  Again, i’ll post a dyno chart as soon as I can.

They were able to communicate with the PCM, but unfortunately, the ABS codes that I’ve got are in the V6 computer, which ISN’T on the OBD port, so they can’t pull them.  I’ll call CPW next week, I guess.

In the meantime, I’ve got the amp to install to power the 4 component speakers that have been powered off the head unit all this time, the auxiliary input for the stereo, new carpet, a new shift boot & hold-down ring, and an LED dimmer ready to install.  I’ve also been planning out the center console, and I think I have an idea of how to incorporate a couple cup holders, the exhaust cutout switch, the center console tray, a cubby for your wallet & cell phone, and maybe room for some gauges in the future.

I’ve also got a new sub & amp for the car, and I’ve installed the aux in for that as well.  That’ll keep me busy until the truck comes back from the shop!

Another day, another drive…

Posted in LT-1 on 10 November 11 by Mark

Took it out yesterday for another spin, again with no issues!  I ran it through the rev band again, and found that 1st gear’s redline of around 6000 RPM whether ECU induced, or power-limited, I can’t tell yet) yielded 50mph, assuming the speedo was accurate.  I know it’s not–call it 45 for a conservative guess.  I also made about half a run with the cutouts open…it sounded okay 🙂

Don’t have much else to say.  Calling Carb Conn tomorrow to see if I can schedule some time again, even though I bailed on them last Saturday at the last minute.

Until then, here’s some pictures from a few weeks ago.  Some day soon I hope to get a video up.

You can see the change in odometer reading there with the new cluster (on the bottom, the black one).

Here’s the problem with the starter solenoid that I ran into.  I ended up replacing it since this didn’t appear to have a way to ensure it wouldn’t back itself out again.  My replacement was too thin, by about a quarter of an inch.   I was able to use a couple washers as spacers on the stock bolts, and it worked great.  Hope that sucker is in there for the long haul; it’s a PAIN IN THE REAR!  I’ve heard the F bodies are even harder though, involving pulling an engine mount.  No thanks!

More repairs done.

Posted in LT-1 on 1 November 11 by Mark

New alternator power cable is on and the hood latch cable stop is replaced.  I didn’t drive it last night, but I’m going to try and give it a spin before Formula 1 tonight.  I’m out of town the next two days, so I won’t drive it again until Friday night at the earliest.  Drill this weekend, so I won’t be driving it then either.

Patience, patience, patience, right?

another setback

Posted in LT-1 on 31 October 11 by Mark

Didn’t make it to the dyno.  Friday night, I took the truck out for  a little bit of a shakedown run, and realized the alternator wasn’t doing its job.  I brought it back to the garage, ran a couple tests, and found the regulator was shot.  No output.  So I pulled the alternator.

I was at the auto parts store when they opened at 7:30, and they gave me a new one (reman) since this one I got from them in FEBRUARY.

Alternator went on, truck fired up with good voltage, and I was GONE.




I got about 10 blocks down the road when the dash went blank and the engine died.  NOTHING.  No dash lights, no buzzers, no engine, nada.  I pulled off Market St., parked in a driveway to an apartment complex, and then saw smoke coming out of the engine bay.  NOT GOOD!

I opened the hood (breaking the 16 year old piece of metal that holds the hood latch cable to the handle), lifted the hood, and found flames snaking up from behind the alternator.  SONOFA!!!!!  I ran to the cab, grabbed the handy bottle of water I used to keep the V6 radiator topped off, and luckily had plenty in there to douse the flames.  Pant, Pant, Pant.

Turns out that I didn’t get the alternator wire (BATT+, remember) far enough away from the engine, and it had been contacting the headers on occasion.  As I charged up the Market St. hill out of Ballard, the up angle on the truck caused it to continuously rub on the header, which burned the insulation off.  When the bare wire contacted the header next, it sparked, and the battery started discharging directly through the engine back to the negative post.  This welded the wire to the header, and caused all the electronics to shut down, including the fuel injection system.  I quickly disconnected the battery and was able to pry the wire off the header with a screwdriver.  Hopefully, the ceramic coating isn’t TOO badly damaged from the electricity (yeah right..I’m not that lucky), but what can I do except see if it fails?

I taped up the wire, reconnected the battery and everything appeared to work well, although the battery had drained sufficiently to be incapable of starting the truck.  My wife came with a car and I got a jump start, and it ran fine all the way home.  I was so frustrated, and even afraid, that I cancelled the dyno appointment (I would have been late anyway), and didn’t touch it the rest of the weekend.
I did buy a replacement battery cable and some cable stops to hopefully fix the hood pull.  I’m out of town two days this week, but I’m going to try to do some driving tonight and tomorrow night, and next week in the evenings.  Hopefully by next weekend, I’ll have enough confidence to get it over to Kirkland to try and do some tuning again.

Incidentally, I found a build on Car Craft’s website where they did heads, a cam, roller rockers on an LT1 and the motor gave 412hp/402lb-ft.  Not too shabby, I say!


Posted in LT-1 on 29 October 11 by Mark

Got everything ready to go last night, and the alternator wasn’t charging!!!!  Got a new one at 7:30 this morning, now I’m off to the dyno shop!  Uh, I hope.