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Member Since 24 Apr 2015
Offline Last Active Yesterday, 01:12 PM

#1523880 74 620 V8 Swap

Posted by distributorguy on 16 October 2017 - 12:40 PM

Consider using a stainless steel overlapping band clamp at the header collector to the reducer.  No gaskets to leak.  Round clamp sealing  butted round pipe.  

#1522955 H190 Differentials (w/Pictures)

Posted by distributorguy on 11 October 2017 - 10:54 AM

If I'm not mistaken that LSD will only go down to a 3.89 gear ratio before the ring won't fit.  Correct?

#1520715 74 620 V8 Swap

Posted by distributorguy on 02 October 2017 - 04:37 AM

Nice work.  Sounds to be overfueling, but healthy!  


The header may be a good place for a MIG weld?   Now you've got me motivated to reassemble the truck sitting in the pole shed with the 327 sitting under my work bench and the turbo 350 trans in the shop.  

#1520030 A87 Mikuni 44 Forged Pistons upgraded Cam L20B Q's.

Posted by distributorguy on 28 September 2017 - 10:07 AM

Why is this a topic if you need to pass inspection?  I don't even think you can run a Weber DGV and pass.  Unless you re-license the truck as a '74?



There is an optimum length for header primary tubes.  If you go too long or too short, performance will fall off.  I didn't realize how critical header design is until I bought the software and learned how to measure an individual pulse volume.  You want a header tube that can hold 4, 8, 16, or 32 pulses.  Collectors go at one of those margins.    Dual exhaust would sound like burrito ass.  

#1519842 Should I buy this '73 620?

Posted by distributorguy on 27 September 2017 - 09:29 AM

There's a single truck here for sale in MN - a '73 rustbucket listed for $1300.  From my viewpoint, its a good deal even with a bad motor.  Between the nice dash, the wheels, and the weber someone put a fair amount of time and money into this thing and kept good care of it.  

#1519697 78 620, L20B foreign matter in combustion chamber.

Posted by distributorguy on 26 September 2017 - 01:49 PM

"Will have" scored the piston, likely won't have touched the cylinder walls, definitely bent the valve, definitely beat up the head.  The piston may be fine, but the head is going to get expensive to repair.  Likely welding to get a seat to take after it released then pounded against the head every time the valve opened and closed.  You'll need someone who can weld aluminum AND has a Serdi head bench to cut the head for a new seat.  Valves are cheap.  

#1519696 Possible KA Purchase

Posted by distributorguy on 26 September 2017 - 01:44 PM

All that Plus exhaust manifold.  Compression test above 150 is great.  Below 125 not so good.  

#1518792 78 620, L20B foreign matter in combustion chamber.

Posted by distributorguy on 22 September 2017 - 03:46 AM

A valve seat won't make it past the installed valve, until the head breaks off of the stem.  That looks more like someone let debris get down the carb throat.  Either way, the piston and cylinder wall will likely be pretty beat up - not to mention the combustion chamber, valves, seats, etc...  Focus on pulling the head to make repairs.  


If you want to see what's wrong, lower the piston in the cylinder around an inch and take a look.  

#1518580 Top speed on your STOCK engine

Posted by distributorguy on 21 September 2017 - 04:21 AM

620 with L20b.  Still 2 liter displacement, no boost.  Not stock however.  .600" lift cam, 300+ duration, dual Weber DCOE 50's.  110.7 on the Bonneville slat flats with tons of wheel spin at 8100 rpm in 4th gear.  The tach indicated the truck should have been going 151 if we could hook up.  Going for 130 next year.  


In an earlier life, 145+ in an Eagle Talon AWD turbo.  The needle went past the gauge at 140 and out of sight at 145+.  

#1518385 Bonneville Speed Week

Posted by distributorguy on 20 September 2017 - 04:12 AM

Here's our last run.  Only 110.7.   It shows the process of setting up, running, and how long it takes for us to drive out to tow the truck back.  


Our re-build for next year is already underway.  The rear axle is almost done.  Transmission in the works.  Ballast being acquired.  Plenty of smaller upgrades laid out on the white board for the winter.  

#1518014 Advice for evaluating L20b...or any used engine?

Posted by distributorguy on 18 September 2017 - 10:36 AM

You never really know until you remove the crank and inspect, look at the used bearings, check for wear.  Magnaflux and pressure test.  Only at that point is it a guarantee.  

#1517395 L20b u67 head

Posted by distributorguy on 15 September 2017 - 07:44 AM

Degree wheels are one of the most important engine building tools!!!  Agreed.  Checking to see if a notch lines up in a hole is silly.  They're all untrustworthy reference points - especially on a motor you know has been apart prior to your service.  I have 4 different cam pulleys in a bin here that are all supposed to be the same part number...???

#1517172 Closed chamber hp gains?

Posted by distributorguy on 14 September 2017 - 07:13 AM

The spare race motor I built was 12.5:1, and I plan on eventually assembling our parts truck, possibly using that as a street motor.  It was quite tame and controllable with a set of SU carbs on it.  

Knowledge IS key!

#1517131 L20b u67 head

Posted by distributorguy on 14 September 2017 - 04:38 AM

Its true.  Look at aftermarket offerings and they all share the same part numbers, which is good.  It allows us 4 cylinder guys to get performance goodies like the Z guys use.  The only problem I found was that the adjustable (8 hole) cam sprocket didn't have a single usable setting that worked in my race motor.  I had to go nearly to the far end of adjustment on an adjustable cam sprocket, but again - it was designed for the 6 cylinder motors, so I'm grateful they are shared parts.  

#1516400 Arp head studs

Posted by distributorguy on 11 September 2017 - 05:08 AM

You will need to install some of the nuts and washers as you set the head in place, if you mount the cam to the head prior to head installation.  Not a big deal - a little trickier than using stock bolts.  A LOT more time consuming.