Jump to content

New '77 620 - My first Ratsun!


Recommended Posts

1/4 inch should be more than enough,

charge the battery up.


point gap is about .020  on the high side of the point lobe




compression  I would check the valve lash if you have never done it yet since you bought he truck. More or less have the cam lobe pointing up the rocker arms should wiggle, if wiggles then you know the valve is closed.   Valve lash fell off  another proplem, cracked valve is another for no compression


reseat the connections on coil, ballast and behine the key switch if its a plug


maybe ck the condenser connection and grounded good

Edited by banzai510(hainz)
Link to comment
  • Replies 33
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

Well after an afternoon of diagnostics I'm still none the wiser. I rented a compression gauge from the parts store. Over 100 PSI in all cylinders with little variation between. I didn't get to checking the valve lash yet. Bought some new spark plugs because the ones I pulled out looked pretty fouled (black, like from over-fueling). I gaped them to .032 as suggested in my Haynes manual. Also gaped the points to .020 They were at .016 earlier. Ground on the condenser is tight. Dist cap is clean, all contacts on the high tension wires are clean. I have an in-line spark tester and I'm seeing spark (barely) coming to all plugs. I have another Pertronix 40,000V 1.5 ohm coil I could toss on there and test, but the old battery I'm using is pretty drained again so I tossed it on the battery charger again. I'm just waiting to walk out there and see something obvious like a vacuum line missing. It's been a while since a motor has given me this much trouble.


Thanks for your help.




Link to comment

Well, I'm getting good spark (with new NGK plugs) and compression. I went ahead and threw a new inline fuel filter, high tension wires, and a new coil on there for the sake of a full tune-up. Today I realized the electric choke solenoid on my Weber 32/26 was getting pretty hot and I also saw a little fuel leaking out beneath the carb onto the intake. With fouled plugs and a potentially faulty choke solenoid I'm beginning think the initial hypothesis of a fueling issue was right, but I'm over-fueling instead of under-fueling. Pulled the new plugs today after trying to crank it over with the new wires and coil and they were wet. I'll try and find a new solenoid for that Weber and see if that clears it up. If not, Ill probably pick up a rebuild kit and go from there.


Thanks for all the help Hainz!

Link to comment

with everything new  even with a leaky bad carb it should fire up esp with new sparkplugs but over time go bad in those situations. that would be a float bowl set too high.


a weak spark is a weak spark.


the choke coil is meant to be HOT that's how it works.


carb leaky could be a acell pump diapram has cracked, when one cyles the lnkage then one might see this otherwise the only moving part is linkage and the plate. which don't leak.  the needle valve stick could over flow the carb

Link to comment
  • 3 weeks later...

I’ve been pretty busy and unable to work on the pickup, but today I found some time. I ordered a carb rebuild kit for the Webber 32/36 (mine is a DGAV) and popped the carb off. After pulling the top assembly off (where the float connects) I could see inside the bowl. Lo and behold a jet for the secondary was laying in the bowl. I proceeded to clean all the jets and the main body of the carb with carb/choke cleaner. I did not disconnect any of the linkage for throttle. I put a new power valve in, a couple new gaskets and bolted it back up to the truck. It fired up and ran well but I had to feather the throttle to keep it idling. After it died (when I took my hand off the throttle linkage) it won’t fire back up. I got a little fed up with it and called every shop in town. “We don’t work on carbureted rigs anymore.” Is the answer I got from most of them. I’m pretty sure this Webber just needs to be tuned now, possibly re-jetted ( I bought it at sea-level and now I’m at 2500 ft). 

Not sure what direction to head in now. 

Link to comment
On 8/26/2020 at 6:18 AM, banzai510(hainz) said:

I rarely change my dist cap or spark plugs


on point dist its a worn out bushing. dist shaft wiggle. condenser bad(or loose ground) or point gap.

It was the f*@kin dizzy cap. Oh well, haha. The truck got a great tune-up!

Link to comment

must be the cheap aluminum  contack versions. better yet a Taiwan produced cap.

Havent bought a cap in like 10 years last one was from the A Junk yard a brass contack version . the blue streak copper ones are the best if you can even find them



most time water under the cap is the proplem after heavey rain or tempature change. like lots of snow to a fash warm up will cause lots of condensation

Edited by banzai510(hainz)
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.