Correct Carb for 1970 521

[MD_Spencer]

My son and I are in the process of restoring a 1970 521 and we have removed the aftermarket Weber carb and put this carb back on the truck. We were told that it was the original Hitachi to the truck but some things are not lining up quite right. Before we go any further we are wondering if this is indeed the correct carb for a 1970. Any ideas?

 

 

 

[kelowg]

almost impossible to tell, someone else might if u find the model# on it. but the weber is a great upgrade, so why remove it? smog?

[DanielC]

No, it is not.  The correct 521 carb has a manual choke, and a smaller diameter solenoid on the left side. (drivers perspective)

 

There are also two switches on the carb on the back of the carb, actuated by a cam attached to the throttle shaft.

[MD_Spencer]

Figures. So rebuilding the old weber would be better than trying to find the original Hitachi you think?

[DanielC]

If you were on the west coast, no problem finding a stock carb.  In North Carolina, it probably will be more difficult to find a carm for a 44 year old Datsun truck.

 

The carb you have, (not the weber) might be off an early 620, the first year of 620 trucks had a 1600 engine, like a 521, then in 1974, I think the 620 got a 1800 engine.

 

I cannot tell the condition of either this carb, or the Websr carb, from three time zones away.   I would think that if either carb was in decent shape you should be able to get your 521 to run OK with either carb.

 

Before condemning the carb, is the compression good?  (159 to 171 PSI).  Valves adjusted?  Timing set?  If you can, get a matchbox distributor.

After you know everything else is good, then deal with the carb.

[datzenmike]

Daniel, I have two parts descriptions for 521 L16 carbs... with and without electric choke. The one with electric choke also has the BCDD on it like that picture.  BCDD and elsctric choke are an emissions reducing device and likely used on later 521s and 620s.

 

The same (similar) carb was also used on the '73 620 but the '74 L18 had an electric solenoid on the BCDD.

 

One thing for sure there were only 521, 510 and 620 L16s and only the trucks had cable throttles. It should work close enough.

[Rays74]

My son and I are in the process of restoring a 1970 521 and we have removed the aftermarket Weber carb and put this carb back on the truck. We were told that it was the original Hitachi to the truck but some things are not lining up quite right. Before we go any further we are wondering if this is indeed the correct carb for a 1970. Any ideas?

 

Hi MD,

What exactly isn't lining up for you guys?

 As long as it's a "truck carb" with cable type linkage then you are fine using it......it's actually a little larger carb than than the orig for your truck so there should be a slight HP increase :)

With this type carb (it's a DCH340 btw) there will also be one or two extra electrical connections to make (depending on whether the truck orig had an electric choke or not) ....just above the throttle cable run there should be a solenoid with a single wire and from the choke mechanism "dome" there will be another wire or connector. Easiest way to work these is to pair them and run them off of a "keyed hot" connection ( coming off the + side of the ign coil is simplest IMO).

If it's clean and in decent shape you should get good service from it.......I like the Hitachi's, all four of my Datsoon's use them :D

--Ray

[DanielC]

I know the electric choke was introduced on all 521 trucks in the 1972 models.   This truck is a 1970.  I do not think the electric choke was on 1970 521 trucks, even in California, but I could be wrong about that. 

This is a service manual for the emissions systems on Datsuns, years 1970-1971.

 

No mention of the BCDD in that manual.  The manual does have a chart of carburetors used on the L-16 engine, in sedans, wagons, and pickups.  The carb listed for the pickup is a DAF-328-10.

[datzenmike]

I owned a 5 year old '71 for 8 years and seem to remember it having a pull choke.

[banzai510(hainz)]

very late 71 and model year 72(really late made 71s) had elecctric choke..

I would stayed with the Weber

[MD_Spencer]

After all the excellent help my son and I have decided to rebuild the weber (I ordered the kit yesterday). We pulled the weber because it had been sitting unused for a year and had gummed and varnished up form sitting. 

 

So next step is getting the carb rebuilt. The valves have be set and then distributor and timing. After that comes clutch and break issues.

 

 

Thanks again.

 

Matt & John

[DanielC]

Brakes come first.  Then get it running.  Do not ask me how I know!