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PostPosted: Wed Mar 31, 2021 12:58 pm 
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Turbo EFI
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Location: Houston, TX
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So this past weekend we had our latest "shakedown" race for the Turbo Dart. Only real running changes we made for this race after MSR were having our massive intercooler cut in half (to increase airflow to the radiator) and scabbing in a cheap 50 mm wastegate to help control boost. The WG came with two springs, rated for 6 and 7 psi each, or 13 when both are used. We used the 6 psi spring. We also pulled the boost line off the controller for the turbo's integral wastegate (so it should stay closed unless we're making enough boost to open it against spring pressure).

Friday's test and tune quickly told us a few things. First, we were only making 2 psi of boost. Very repeatable, 2 psi every time. Checked and rechecked everything and found no leaks. We concluded that our cheap Chinese wastegate is probably opening earlier than it should. No big deal. It was fun enough with 2 psi (ever so slightly faster than our old NA race engine), so we decided to leave it as-is for this race rather than opening up the WG to add the other spring.

The main reason for this is because even with 2 psi of boost we were seeing coolant temps at 210-215 °F when under full race throttle. I'm guessing if we were getting 5-6 psi of boost, we'd also be seeing temps at 230. I bought a tri-flow "universal Chevy-style" radiator of the same size as our current simple crossflow radiator, but it was just different enough that we didn't have time to install it before this race. Adapting our electric fan shroud would have taken a day we didn't really have. That's on the agenda before our next race at Sebring.

The other issue was high transmission temps; 6 or so laps in anger were usually enough to get the gauge up to 240 °F, and although it was slowing down, it didn't look like it was going to level off there. I don't remember it being this bad at the MSR race in November, but we were never really out for more than 4 laps at a time, so maybe we never saw it get high enough. We used to run an oversized trans cooler with our NA engines and never saw fluid temps above ~150, so when the turbo was added and we also needed to fit an oil cooler and intercooler, we downsized the trans cooler for the sake of packaging. I'm guessing we downsized too much, but this transmission was also a very fast build from a bunch of random parts so it might be questionable as well. More testing is required before Sebring.

Anyway, after the test session we were all set to have a nice, laid-back, low-boost race, keeping an eye on the trans temp gauge and seeing if we could shake loose any other problems. I got out on track right before the green flag dropped on Saturday morning. I made about 1.5 hot laps, then when going around the back corner complex I felt a bit of a stumble or breakup. I checked the gauges once I straightened out, and saw oil pressure at dead zero. Engine was still running, so I goosed the throttle a bit just to check: no movement. I shut it off, coasted off the track, and waited for the tow truck.

We pretty quickly ruled out an instrumentation problem. We're not running a distributor anymore, so we pulled off the cover plate and found this:
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For the record, I can now testify that it is possible to remove a 1" rotor (high-volume) oil pump from a slant six in a '64 Dart without pulling the engine, as long as you don't care about pushing your transmission all the way up into the tunnel and bending your dipstick tube. We unbolted the passenger side engine mount from the frame (leaving it and the bracket bolted to the engine), left the driver side bolted up, set a foot-long piece of 2x6 up against the passenger side oil pan rail, and jacked against that to raise the side of the engine up for access. Then we pulled all the mounting bolts, jacked until the front of the car barely started to lift up, and monkeyed with it in vain for 10 minutes. Finally, we pulled the rotor cover plate bolts, removed the cover plate and slid out the outer gear, and tried again. That gave just enough room to get the end of the pump shaft out of the block.

Once we got the pump out, we realized the camshaft gears were in even worse shape. Here's a picture taken much later after we got the camshaft pulled. This is a stock 1973 factory camshaft, and one of DD's blueprinted Melling M-66HV high-volume oil pumps with a special hardened gear installed.
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We sent some team members to get a new Melling M-66HV in Baton Rouge, but camshafts are harder to get on short notice. We spent a couple hours calling parts houses, searching junkyard inventories along with Craigslist and FB Marketplace, and canvassing the entire paddock looking for anyone who knew where we could find a used slant six. Everything came up empty. More than once we considered just hopping in the truck and making the round trip back to Houston, as I had two spare cams in the cabinet of my garage. But by the time we realized this would be necessary it was already pushing 4 PM, and nobody wanted to make a 10+ hour round trip drive just to get back to the paddock at 2-3 AM and then have to start putting the car back together.

What we finally managed to do was convince one of our team members in Houston to break into my garage, retrieve a good camshaft, and then hop on a 9 PM flight from Houston to New Orleans (we obviously paid for his ticket). Part of the team picked him up and got back to the track about 10:30 PM, shortly after the rest of us had finished disassembly. We slathered our trusty old Isky camshaft in oil, slapped it in with the cam gear lined up on the dots, and started putting the front of the engine back together. I think we finally got it back together about 4 AM, but then it wouldn't fire. It would sputter and cough, and backfire when you gave it gas. Dead tired and worried that we'd massively screwed up the camshaft timing, we hit the sack and decided we'd look at it with fresh eyes in the morning. The good news was that it made oil pressure after cranking.

The next morning our guest driver and good friend Chris, who was scheduled to take the first driving stint if we got it running again, suggested looking at the crank position sensor. It was a tiny bit off center, owing to our adventures getting the balancer reinstalled early that morning. I grabbed a big screwdriver and bent our homemade bracket into a slightly better position, and then the engine fired right up. Chris got out on track shortly after the green flag dropped, accompanied by my helpful new gauge panel markings:
Image

Chris was out for a little less than an hour in clear weather. He took it easy, and after ~40 minutes the trans temp gauge was about maxed out, so he backed off to let it cool down a bit before coming back in. Bob was sick and napping in the trailer after a combination of bad food, no sleep, and stress, so I was the only other driver. I went out and got 30 minutes or so of dry track fun (easing off every few laps to let the trans temp recover) and then the rain rolled in. I got another 30-40 minutes of track time in the wet, during which the trans temp was much better! It got down to 180 in moderate rain. I knew there was another B-Class car that had broken badly on Saturday, so I stayed out just long enough to get us ahead of them in the standings. No longer last in our class!

With nothing left to prove, I came back in and let the car cool off for a while. Checked and topped off the trans fluid. Bob was still not feeling well, so I went out for the last 30 minutes before the checkered flag. All things considered, the car was fun to drive. We just need to fix our cooling issues (both water and trans fluid) and figure out how to make a few more psi without breaking anything. I also need to go do some more homework on oil pump gears. I know this has historically been a big problem for a lot of people, but it's the first time we've ever seen this failure. We previously used an unmodifed Melling M-66C (7/8" rotor) on this same old Isky cam, and then on the stock 1973 cam that we just garbooned, with no obvious signs of wear. The new pump with the case-hardened gear went in at the same time as the turbo, so it didn't have very many hours on it. I'm wondering if hardening the oil pump gear isn't such a good idea after all.

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PostPosted: Wed Mar 31, 2021 1:46 pm 
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Joined: Mon Oct 21, 2002 11:08 am
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Thanks for the lovely rundown, Frank. Youse guyz are my kinda crazy. Guess there were some lessons learned there and hopefully you can bring it to fruition for Sebring. I will be very excited to see your setup in the flesh.

I have not had an oil pump or cam gear failure - knock on wood... Personally, I ONLY use old used or NOS pumps these days on cams that are reground on old cores. I guess I started doing that around 2000 when this pump gear thing started coming up. I do not feel used junk is any problem as long as it makes the oil pressure you want. Mine always have. I have a 190k mile HV pump (can't recall 7/8" or 1" rotor) on my turbo car that does fine oiling the big turbo. I suspect a stock low vol pump would do fine as well.

Can't wait to see you and dice it up on the Sebring track in May!

Lou

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PostPosted: Wed Mar 31, 2021 2:26 pm 
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Joined: Wed Jan 29, 2003 4:42 am
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Location: Fort Bragg, NC
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I always enjoy reading your write ups, Frank!

Good development stuff. I applaud your efforts.

To be honest though,... it makes me want to keep it simple on ToadRacer rather than wrenching like that at a race. I ain’t as young as the rest of y’all... :lol:

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PostPosted: Wed Mar 31, 2021 4:04 pm 
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Joined: Sat Oct 19, 2002 12:06 pm
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I'm not a fan of the HV pump. I feel it is not necessary. I run a "older" stock replacement manufactured pump. The only possible oil related failure I have had, was a lobe on a "newer" 528 MP cam. I run full groove mains, and have run a turbo, that has a 1GPM requirement with no problems.
PS; looking forwrd to meeting you at sebring

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PostPosted: Thu Apr 01, 2021 3:37 am 
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Supercharged
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Joined: Sat Nov 27, 2004 8:03 pm
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Location: IRWIN PA
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Good Report!

That was sure a busy weekend.

Greg

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PostPosted: Sat Apr 03, 2021 7:41 am 
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Turbo EFI
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Joined: Tue Nov 23, 2004 6:05 pm
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Location: Desoto Texas
Car Model: 1972 Dodge Colt
Sorry about your troubles.
I like Lou have never had an oil pump/cam failure.
I used to throw a new pump on every time the pan came off, but now, I will just reuse my oil ones.

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