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620 Land Speed Record


distributorguy

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I'm really enjoying watching the build!  My dad and I should be on the salt as well this year in our I class lakester (our build thread: http://www.landracing.com/forum/index.php/topic,16445.0.html).  Hopefully I'll have enough time to come by and check out your truck.  Glad to see a Datsun heading to Bonneville.

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I couldn't use that manifold if I wanted to.  I moved the ports in the head.   :thumbup:

 

I've had issues with isolators causing vacuum leaks.  I'd rather add bracing to a stiff air box to prevent vibration instead.  Fewer problems overall, at least for me.  I have a set, but I can't force myself to use them.  I've always ended up taking them back off.  

 

My rod ends for the carb linkage just showed up - in time for me to leave for a long weekend.  I guess I have along list of things to attend to when I return.  

FYI - Unless you moved the ports so much that you had to weld the head, that manifold will work. Even then, you could weld the manifold too. Anything's possible. I angle cut the manifold on a mill sometimes too.

 

It sounds like you're thinking of the o-ring type isolators. I'm talking about the vulcanized rubber isolators with two plates and studs coming out of both sides. I use Threebond 1211 to seal them and I've never had vacuum leaks using this method. 1211 is so strong, once we ran a motor on the dyno for a few minutes before we realized that the intake manifold was not bolted on. The only thing holding it was the 1211.

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We're going gangbusters wrapping up details on the build, so we can finally get a good test drive in soon.  In the last couple days I installed a new Wilwood master cylinder.  It meant I needed to adjust the pushrod length, as well as pedal clearance so I could get more pedal stroke since the master has 1 1/8" stroke versus the stock (roughly) 3/4" stroke.  The pedal feel is great without having to use a power brake booster, and front/rear bias seems best without any bias adjuster installed.  In fact, so far we have the rears set up a little loose so there's no rear brake drag with stock drums.  

 

Tonight I machine the parts need to mount ballast in the box, yet have it attached securely to the frame.  Plus we'll get the carrier bearing shimmed to height so the driveline angles are pretty much straight, and install the original grille and tape the headlights so they are considered shatterproof.   If there's time, we'll install the roll-over valve system for the fuel tank so it can't leak fuel in any position of the truck, if it were to land on its roof, side, nose, tailgate, any possible configuration.  Basically, they make us wrap vent hose around the fuel tank front to back and end to end.  

 

Time allowing, we do some paint touch-up, keep modifying the roll cage to meet the rules, and try out yet another seat.  Then install the last (front) piece of the box cover.  

 

 

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  • 2 weeks later...

I just got home from a quick vacation to find a ballistic blanket for the transmission has arrived!  Since there's no 1/4" wall steel scatter shield available, this will have to do.  

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Last night we got our driver behind the wheel for the first time!  Since the truck is nowhere near street legal, he drove it around our place in the country a bit to get a feel for the steering, clutch, and brakes.  Then he drove from the end of our driveway up to the house, which is roughly 1/4 mile of uphill gravel, over and over.  By the end I got him to push rpms up close to 6k, and he was never able to get the truck squirrely or out of sorts.  That means we can pull the practice motor and install the race motor!!!!  Its getting close to race time.  This is getting real!

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Last night we got our driver behind the wheel for the first time!  Since the truck is nowhere near street legal, he drove it around our place in the country a bit to get a feel for the steering, clutch, and brakes.  Then he drove from the end of our driveway up to the house, which is roughly 1/4 mile of uphill gravel, over and over.  By the end I got him to push rpms up close to 6k, and he was never able to get the truck squirrely or out of sorts.  That means we can pull the practice motor and install the race motor!!!!  Its getting close to race time.  This is getting real!

That sounds like some street outlaw shit. I love it. Hope you guys do well.

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After Thursday. I realized that I never should have pulled one of the leaf springs out of the pack to soften the ride.  Now that we have ballast bolted in the box, the springs sagged enough to make the axle touch the frame on the passenger side, ever so gently.  I reinstalled the second leaf in the pack, and now we have a LOT more room.  I also moved the entire crossmember and rear driveshaft loop up about 1 1/2" to allow more clearance.  

 

I don't think we can get the truck any lower without risking digging up the salt, which would not make us a favorable race team.  

 

In preparation for the race motor, today I installed an Aeromotive 13 psi fuel pump.  It should provide the volume we'll need to the 50 mm DCOEs at 8000+ rpm.  In case it doesn't work, I made the mount universal so we can bolt the classic Carter pump right back in place.  

 

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The practice motor just came out of the engine bay.  No more screwing around.  This shit's real now.  Once the flywheel is resurfaced, the race motor goes in, and all the BS that goes along with a custom install has to happen and right quick!  It may take me a month to get the Webers dialed in so we can get on the chassis dyno.   The only good news there is that the dyno session will be free - repayment for a huge favor on a Sunday for the dyno owner.   :thumbup:   And he's stoked to see what it'll do!  Surprising for a guy that only works on Mustangs.  

 

BTW, the favor was shaving the nose off a '13 GT350 overdrive crank pulley that kept throwing belts when its making over 650 hp.  Cool stuff.  

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No pics, but last week we installed the race motor.  Yesterday the exhaust, intake, and carbs went on.  The air/fuel meter on the dash got wired and the new O2 sensor installed.  We filled holes in the cab/cockpit to keep salt out.  The last of the ballast sheets (1/8" thick 75 lb steel sheets) got drilled for the mounts in the box and put in place.  A template was made for the cold air box around the Weber carbs.  The throttle linkage pairing the carbs was finalized, although not yet hooked up to the pedal - that'll be a bit of a Rube Goldberg solid linkage arrangement TBD.  We also straightened all the fins in the radiator, flushed the last off the anti-freeze out of it, and prepped it to mount a pusher fan.  

 

Lots more details will be finished up very soon.  We hope to fire up the engine and get to carb tuning in the next 10 days.  Then finalize some cage details and pack it up for the race!

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Optical illusion?   The line is significantly behind the U-bolt.  I'll recheck once its up on the hoist again when we nut-and-bolt the whole truck.  Its a 15 minute job to make a new line and replace it if need be, but for now, the ride height is 1" higher on that side - the other side was bottoming out.  I think its a torsion bar tension issue.  They're not even.  Again something to get dialed in on the drive-on hoist.  

I did fix the weld on the brake line tee though, so the lines stay out of the way.  

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Last night we got a lot more work done.  Well, really we chased water leaks and got oil pressure up.  Compression figures fall in right at 200 psi on a new motor with the rings not seated, so I suspect we'll see 230 after a good cam break-in and dyno session.  Oil pressure came up nicely.  The battery was low, but we still saw about 20 psi cranking it at 200 rpm.    

 

The solid throttle linkage is done, complete from pedal to carbs.  That was a chore.  A month of planning and a week of toiling, with about 12 hours of fab work.  3rd time's a charm and voila!  It works!  

 

It turns out that my 1200 mile (from original) core motor was left outside too long.  Both the thermostat housing and the lower radiator hose adapter had cracked, and I hadn't noticed before installation.  Either that or I cracked them when installing plugs.  I took the ones off the practice motor, so now we're good to go.  No leaks anywhere.  Its ready for plugs and a distributor, which I built 3 of yesterday.  I had installed the wrong pedestal as well, so the distributor was clocked wrong.  The two options are clocked about 35 degrees different.  Pick the wrong one and you'll have either no spark or a horrible misfire.  

 

The electric cooling fan relay is DOA, so I'll replace and test that, then static time the motor, and add fuel...   :thumbup: 

 

How many of you have fired up a new motor with higher than 15:1 compression?    Its daunting.  Plus tune dual Weber DCOE 50's on the fly, before the cam dissolves.  Daunting.  

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The best fan controller I ever saw came from SPAL. It was able to control two fans independently, at different speeds. It had soft start and variable RPM for both fans. It also had a built in timer to run them after shutoff.

 

Sadly, they discontinued it before I ever got to use one.

 

Some of these modern electric fans have high amp draw (50 amps) and finding a relay setup to handle the high amps is difficult. On my Volvo V70 Type R I had replaced the original fan controller with a Ford continuous duty solenoid (which is basically a large starter solenoid, but capable of handling constant load). I use them in high amp incandescent headlight systems too.

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Too much bear being consumed by build team ?

 

Well, I have to admit I'm the one who tapped and plugged both pieces, sober.  Later after we replaced them, we drank beer.  Cheap beer.  PBR.  Hopefully we have a successful night next Thurs getting it running (I promised I'd wait for the team to get together) and then we can drink good beer.  I have a couple special packs of IPA in the fridge waiting.  

 

I have the Spal 14" pusher fan run through a SPAL 40A relay - the thing is HUGE.  40 Amp fuse.  It'll only be turned on for a few minutes after the run is over, unless we run hot during the run.  If I get the fuel mixture right, the 120+ mph wind should cool the motor without running the fan.  Its just on a simple dash switch.  Although the system only holds 6 qts of water (including water wetter).  It'll be interesting to see how that plays out.  No coolant allowed.  

 

Today I built an air box that takes a '91 Caprice air filter, and breathes through the  hood scoop.  

 

Question for those in the know with DCOEs.  The float bowl vents are inside the air box.  Will they work properly, or do I need to vent them with tubing outside of the air filter enclosure?  I figured this would collect any overflow if the needles stuck open, preventing fuel from dripping on hot exhaust.  I'm assuming the filter won't allow a negative pressure to develop inside the air box.  Its roughly 14x4" 1 3/4" thick paper element for dual 50mm Webers.  Lots of surface area.  I could rig up some simple plumbing to vent them outside the box if anyone here has had known issues with this setup.  

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Mikunis also have the vents in the front and I've used air boxes charged with frontal air for years. We did a test once and we found that at 100mph the air box, with properly ducted frontal air, had about 4-5 lbs of boost. It would be an interesting experiment to make back to back runs with the vents in and out of the air box.

 

Have you not used water wetter before? It gets to smelling bad after a while, but works just fine on its own. Use distilled water to cut down on the smell and build up of crud.

 

I'm curious, what's your take on engine bay cooling? Aerodynamically speaking, do you think a cowl vent would help or hurt? Bending the back of the hood upwards (by placing a 4x4 on the valve cover and shutting the hood, or whatever...) helps get rid of a lot of that hot air, but I wonder what it would do to the aero at speed.

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