75' 620 l20b swap question

[paisa13]

I replaced all bearings, rings, gaskets and had head cleaned! I did all the work myself and still probably spent the same amount of money a used KA would be! If i had to do it again I would probably find a KA and have some friends help me with the wirings its gonna need to drop in the 620

[Radim]

I want 6 Lug Appliance mesh. :(

[datzenmike]

passengers side is wet. also oil from valve cover gasket.

 

You sure don't want to remove the head to find out later it was something else. Carefully inspect the two heater hoses that run along that side of the motor. Check there isn't a small hole that only leaks when revved up or under pressure. Check to see if the hose is soft or rotted. Check the hose clamps are good and the fitting on the back of the head is good. Also inspect the lower rad hose and replace if soft or swollen.

[cdreandrade]

You sure don't want to remove the head to find out later it was something else. Carefully inspect the two heater hoses that run along that side of the motor. Check there isn't a small hole that only leaks when revved up or under pressure. Check to see if the hose is soft or rotted. Check the hose clamps are good and the fitting on the back of the head is good. Also inspect the lower rad hose and replace if soft or swollen.

 

I will check it out. I found another l20b that looks to be in a little better shape and still in the truck running. Motor and 5-speed for 250$ i think I'm going to get it and just use my other motor for parts.

 

Well see what happens when I test drive it and do a commpression test. what would be a good pressure to look for? and any common bad stuff?

 

Thanks

[datzenmike]

Even numbers all the way across. 150 and higher would be good. 130 is ok. You could have 90 on all cylinders as long as it is even it will run quite well just lack some power. Two low adjacent cylinders might indicate the gasket is blown between them. One cylinder low might be a bad valve or badly adjusted valve. On a low cylinder squirt some oil in and re-test. If the rings are bad the oil will seal them (temporarily) and the reading will go up. If no change it's one of the valves not sealing.

[cdreandrade]

thanks, im going today to get it so i will post up what I have found when I get back. got the truck loaded up with crane and lots of tools for a 2 hour drive. wish me luck

[banzai510(hainz)]

Just get the truck running for now.

If you cant take care or fix a L20 dont worry about KA/SR swaps!!!!!!!!!save this

 

http://www.olddatsuns.com/620tech.htm

[kgrantkey]

I will check it out. I found another l20b that looks to be in a little better shape and still in the truck running. Motor and 5-speed for 250$ i think I'm going to get it and just use my other motor for parts.

 

 

 

Thanks

 

This sounds like a great way to go. The L20B has good performance for this truck. You can get the head reworked for about 75-100 dollars. A re-ring kit with gaskets and bearings for about 150.00. The 5 speed doesn't add performance but an overdrive. The carb you have should add power and top end speed. Get a dizzy distributor. I've done this to 3 620 trucks less the carb, and have got my money back or more on each one. I am down to only 1 620 now but it runs great and is dependable.

 

-One more thing about a 75 model. I would change the generator to an alternator. Get one off a 280z or comparable. I paid 25.00 for a good one. The wiring change is easy and it bolts right up.

[datzenmike]

Generators haven't been in use since about '62. All Datsuns since the mid '60s will have alternators in them. However, the trucks got the lowest output ones. The '75 output would be 35 or 38amp. Any car made until the end of '77 will have a 50/60 amp output that will work with your external regulator. The problem is that they are physically larger and it will be a very tight fit with the truck lower rad hose and idler arm in the way.

[Wide14u]

i think you should fix what you have to and enjoy your truck and remember its not a honda you don't need to be driving up and down the street trying to get the v-tech to pop it is 35 years old just have fun with it

[cdreandrade]

Got the motor and tranny.

 

compression is as follows

 

cyl. 1 - 132

 

cyl. 2 - 95

 

cyl. 3 - 150

 

cyl. 4 - 130

 

I put some oil in the number 2 and it boosted right up to 180+

 

I figure the tranny alone is worth 250 and since I have this motor out I might as well do gaskets and rings. as long as the cylinders check out. if not I have extra parts. I am going to look into rings, gaskets, clutch, and possibly building it up to one of those strokers. but we'll see.

 

where is a good place to get the rings, gaskets and clutch?

 

 

I am going to be holding on to this truck as long as I can so I'm not too worried about value.

 

any tips are greatly appreciated

[kgrantkey]

Generators haven't been in use since about '62. All Datsuns since the mid '60s will have alternators in them. However, the trucks got the lowest output ones. The '75 output would be 35 or 38amp. Any car made until the end of '77 will have a 50/60 amp output that will work with your external regulator. The problem is that they are physically larger and it will be a very tight fit with the truck lower rad hose and idler arm in the way.

 

 

Yes. I stand corrected. I changed mine for the built in regulator and extra amps when I installed the dizzy.

 

[datzenmike]

Yes. I stand corrected. I changed mine for the built in regulator and extra amps when I installed the dizzy.

 

 

I knew that. :poke: :D

[banzai510(hainz)]

ck the valve lash on number 2 cylinder. maybe the rocker is tight and letting some comp out.

 

point lobe up,intake and then try exhaust, and it should wigge abit(the rocker),if it wiggle then you know the rocket isnt pushing on a valve