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Member Since 24 Apr 2015
Offline Last Active Yesterday, 01:05 PM

#1534855 Oil pressure on Z20 engine?

Posted by distributorguy on Yesterday, 11:32 AM

Mike, the warning light just gives you time to shut the motor down before you lose a rod through the block.  How many motors run at 7 psi???  None.  You either run out of oil pressure or you have oil pressure.  Who cares if its 5 psi or 10 psi or 15 psi?  Either way, its essentially the same margin of safety.  If you're going 60 mph when you lose oil pressure, we're talking semantics.  

#1534682 Can you use a L18 distributor on a Z24?

Posted by distributorguy on 14 December 2017 - 11:16 AM

Yes.  As Stoffgren says you need the assembly from the donor motor - distributor, plate, pedestal and set the timing to the specs from the donor using the intake side spark plugs.  

Basically treat it like an early motor and the spare plugs become just plugs, not spark plugs.  Wire it in with one 3 Ohm coil, or a 1.5 Ohm ballast with a 1.5 Ohms coil if you're using points.  

#1533694 Air fuel ratio gauge to achieve the correct fuel mixture at idle

Posted by distributorguy on 08 December 2017 - 11:08 AM

Whenever you're only a little bit out of tune, its difficult for most people to tell if you're rich or lean.  The gauge only lies in certain circumstances - usually at idle (reversion) and when you're grossly out of tune, when common sense has to weigh in and start making big tuning adjustments.  The gauges are a way to get that last 5% that most people leave on the table.  


Dash mounted gauges are ok for basic tuning.  Very distracting for the driver however.  An LM-1 or LM-2 is invaluable for data logging so you can record and watch a playback.  Its almost like having your own mobile dyno.

#1533468 78 620, L20B foreign matter in combustion chamber.

Posted by distributorguy on 07 December 2017 - 05:33 AM

Tie straps on rubber hoses don't fix vacuum leaks.  Buy new hose!

#1533117 short shocks for front

Posted by distributorguy on 05 December 2017 - 12:35 PM

We almost ran one at Bonneville instead of the 620.  Too light, no way it'll make 200+ hp without coming apart, and flimsy as hell. Aero was good, but it'd need to hit 180 to break a record in class.  Scary for the wheelbase.  Plus they have that goofy balance/jackshaft in the motor.  


As for shocks, the best way to increase shock rate is to straighten its compression to get more travel.  When I see guys using the same coil over shocks and changing the installation angle by 30% to make them fit, that's just a mess.  When you get to that level, figure out how to make them fit, THEN pick a shock and spring combo.  I'm all for modifying, just do some basic homework.  In the 620, almost any shock will do if it fits.  If you ARE using it as a truck, use gas charged in back.  

#1533079 short shocks for front

Posted by distributorguy on 05 December 2017 - 09:22 AM

Actually when you add weight to the rear, it shifts weight off the front.  Yes, under hard braking the fronts will gain more weight but that won't affect the spring rate, which is more important.  The shocks are there to absorb road abnormalities.  So I guess if you hit a bump with a  loaded bed in a lowered truck  while braking hard, it might matter?   You can however blow out a shock if it bottoms out or over extends to where its supporting suspension weight.  Hell, I blew out shocks every 2 years in my Ford just from the snow plow weight, but we're talking about a 3000+ lb front corner weight.  


I wish those compression and expansion numbers you list for the 620 shocks were opposite Mike.  Don't assume the manufacturer does what's best.  Sometimes they just use an existing design because its functional and saves design/manufacturing dollars.  Its always cheaper when the tooling is paid for.  I'm sure there's no way to improve the ride of a 620 because the designers got it perfect?  

#1532915 Electric cooling fans - Two pullers or One pusher?

Posted by distributorguy on 04 December 2017 - 01:02 PM

FiTech EFI does a good job controlling dual fans, independently.  Not many "cheap" controllers can do that.  They can't handle the Amp load.  

#1532048 Electronic Ignition Upgrade for your Datsun 320 Truck

Posted by distributorguy on 30 November 2017 - 05:53 AM

I'll have to check, but the E1 drive with the offset slot looks a lot like an air-cooled VW. Bosch made good dizzys.


But it spins the opposite direction and the "teeth" are a different offset and width.  

#1532047 Electric cooling fans - Two pullers or One pusher?

Posted by distributorguy on 30 November 2017 - 05:51 AM

Spal makes relays that can handle a 50 Amp spike.  They're the only ones I have seen that require a jumbo spade terminal - bigger than the hard to find extra large ones.  

#1532046 Z20 build

Posted by distributorguy on 30 November 2017 - 05:49 AM

I used the Detroit Locker with 3.89 gears.  Truck truck acted like we were on solid pavement instead of slimy salt.  

Next year we are using a 10-bolt Chevy with 2.72 gears and a spool.  All or nothing.  The locker will go into our spares pile to bring along, or into the parts truck we're assembling to look like a Matchbox version of the 620 I was given as a gift a few weeks ago.  


DO NOT use a puller on the distributor.  You will damage it.  Period.  I have a system to get them apart without damage.  Its simple and effective.  I'd like to offer this to you.  I'd like more than one other person on this forum to know how big of a difference a properly recurved distributor can make.  Its the most overlooked tuning parameter, and nearly the most important.  

#1531855 Z20 build

Posted by distributorguy on 29 November 2017 - 05:26 AM

Feel free to send it to me Wayne.  I feel like I owe you one for the locker you sold me last year.  You really saved our butts!

#1531731 74 620 V8 Swap

Posted by distributorguy on 28 November 2017 - 10:06 AM

There's been a V8 kit for the S10 as well, and it fits with only a couple dents added to the firewall near the starter location.  Did it in a 4x4 with a tuned port IROC motor back in '91.  Fun truck!  

#1531693 Seized J13

Posted by distributorguy on 28 November 2017 - 05:31 AM

The best rust penetrant made is Kroil, which is essentially ATF and Acetone mixed 50/50.  You can get acetone for a couple bucks at your local hardware store.  It evaporates quickly, so apply every 4 hours for a day and you'll be free if the problem is related to rust in the cylinder from the engine sitting with open valves.  A quick flashlight inspection will show you which cylinders are actually rusty - usually only 1 or 2 will be bad.  

#1530799 Z20 build

Posted by distributorguy on 22 November 2017 - 05:45 AM

Wayne, you have a great recipe, but like any recipe if you don't follow through with ALL the ingredients, its not going too turn out well.  This is one that won't work if you put a stock worn distributor in it.  A heavy stock flywheel also won't allow it to perform as it should.  Shave that flywheel down to 16 lbs and have it balanced.  Then you need a distributor set up to run at 14-16 degrees BTDC at idle with an advance curve that won't ping like crazy at 2700 rpm.  Unshroud the valves in the head so they can breathe clear out to the cylinder walls.  Remove anything remotely close to a sharp edge on the valves, in the chamber, and lightly bevel the edge of the bore.  Make the edge/head of the exhaust valve round.  Then time the cam to 107/108 Intake CL and you'll have a strong puller without needing race fuel.  You will likely need premium or at least non-oxy real fuel.  

#1530629 Electronic Ignition Upgrade for your Datsun 320 Truck

Posted by distributorguy on 21 November 2017 - 06:12 AM

The A-series needs a slot cut into the shaft to mate to the drive.  

The J will interchange with Lucas, and even some Dodge.  Also a few 60's Volvos if you swap the drive dog.