Need Help.. Issues with firing??

Tech tips and how to's

Moderators: notoptoy, S Allen, Solex68

Post Reply
mok662
Roadster Newby
Posts: 12
Joined: Wed Aug 22, 2018 11:47 am

Need Help.. Issues with firing??

Post by mok662 »

Hey guys, I could really use some input on this from others who know more than I do.

The last time the car was "normal", I was driving it normal and all of a sudden the car slowed down and the gas peddle force me to drive very slow on a level road, no hills thank god. The car got towed to my home and there it sits.

I tried to fire up the car a month or so ago, and it wouldn't turn over. I ordered and swapped out:

1. Points
2. Condenser
3. Cap
4. Spark Plugs
5. Spark Plug Wires
6. Car Battery
7. Rotor

With all that swapped out, the car was able to fire up, but it was only firing on 2 cylinders. It sounded very rough, and the motor was shaking like crazy.

I want to lean towards a blown head gasket, but I have yet to perform a compression test. I need to purchase a kit.

The car has a leaky rear main and the exhaust header is busted, so I had planned on pulling the motor and taking care of that in one swoop.

Besides the compression results, any thoughts on what I have in front of me?

Thank you
User avatar
bossbob
Site Supporter
Posts: 460
Joined: Thu Aug 24, 2017 3:44 pm
Location: Central Coast
Model: 1500/1600
Year: High Windshield-68-70

Re: Need Help.. Issues with firing??

Post by bossbob »

I would verify spark to all cylinders, then start it and pull each plug wire 1 at a time and listen for RPM drop, if you get 2 cylinders next to each other that are affected, cylinders 1,2 or 3,4 right next to each other, then maybe look into the carb that delivers to those 2 cylinders. Just a thought, compression test will of course tell you if you have dead cylinders.
68 Roadster 1600
70 Boss 302
65 K-Code Fastback
69 Mach 1 393 Stroker 5 spd
63.5 Galaxy Conv. 427 Dual Carb, 4 spd
72 Ranchero
65 GT Coupe
User avatar
jrusso07
Roadsteraholic
Posts: 1691
Joined: Sat Aug 02, 2008 9:02 am
Location: Penn Yan, NY
Model: 2000
Year: High Windshield-68-70

Re: Need Help.. Issues with firing??

Post by jrusso07 »

R16 or U20?

If U20, rdmove the cam cover and check cam follower (some may say rocker arms) gap settings. If too sloppy due to loose adjustment locknut, it will not fire on that cylinder. Ask me how I know....

I have no experience with R16.
Joe

1969 SRL311 - Solex
1970 SPL311 - U20 mod
1970 SRL311
JT68
Talented Enthusiast
Posts: 2920
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Need Help.. Issues with firing??

Post by JT68 »

doesn't sound like a head gasket- would have to be really bad-they usually just leak here or there..If SU car, sounds like one SU choke (nozzle) is stuck or one carb is out of gas if literally running on 2 cylinders. If running on 3 cylinders could be a failed(burnt etc.) valve so your compression check will reveal this.
LT/JT
https://www.datsunrestorationproducts.com/
Only the very BEST parts for your Datsun- 10000's of items in stock
New, Used and Reproduction!
User avatar
spl310
Roadster Guru
Posts: 13202
Joined: Sun Dec 29, 2002 10:38 pm
Location: In front of this keyboard... in Jacksonville, Florida!

Re: Need Help.. Issues with firing??

Post by spl310 »

Triple check the plug wires for the proper firing order
"Wow, a Roadster!" Stuart Little

1967.5 2000
1967.5 2000
1964 1500
1964 1500
1967.5 1600
1968 chassis
2006 Acura MDX
2013 Volkswagen Jetta TDI wagon
1995 F350 Powerstroke!
More...
User avatar
Gregs672000
Roadster Fanatic-Site Supporter
Posts: 8923
Joined: Fri Aug 07, 2009 11:47 pm
Location: Tacoma, WA

Re: Need Help.. Issues with firing??

Post by Gregs672000 »

Sounds more fuel than spark. As suggested, confirm spark to all cylinders. If good, then check for fuel especially if it's 1 and 2 or 3 and 4 that are dead, as indicated above. Purchase some starting fluid and spray that into the dead carb and see if it smooths out... if so, no fuel, somethings plugged or not working right.
Greg Burrows
'67 2000 #588
Tacoma, WA
User avatar
Gregs672000
Roadster Fanatic-Site Supporter
Posts: 8923
Joined: Fri Aug 07, 2009 11:47 pm
Location: Tacoma, WA

Re: Need Help.. Issues with firing??

Post by Gregs672000 »

Agreed on firing order for sure... 1 3 4 2 counter clockwise as I recall but I no longer run a dizzy so I don't think about it much.
Greg Burrows
'67 2000 #588
Tacoma, WA
JT68
Talented Enthusiast
Posts: 2920
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Need Help.. Issues with firing??

Post by JT68 »

He says it was driving normal then suddenly started this operation - firing order would not suddenly change while driving, although he could have messed it up when changing dist parts.
Last edited by JT68 on Sun Dec 16, 2018 2:30 pm, edited 1 time in total.
LT/JT
https://www.datsunrestorationproducts.com/
Only the very BEST parts for your Datsun- 10000's of items in stock
New, Used and Reproduction!
JT68
Talented Enthusiast
Posts: 2920
Joined: Sun Jan 27, 2013 9:43 am
Location: Cumming, GA

Re: Need Help.. Issues with firing??

Post by JT68 »

My guess is this wasn't ignition from the start- sounds more like a carb if it was literally running on 2 cylinders.
LT/JT
https://www.datsunrestorationproducts.com/
Only the very BEST parts for your Datsun- 10000's of items in stock
New, Used and Reproduction!
C.Costine
Roadster Nut-Site Supporter
Posts: 1731
Joined: Fri Feb 13, 2015 8:08 pm

Re: Need Help.. Issues with firing??

Post by C.Costine »

You said that it would not turn over. What does "turn over" mean to you firing and running? or cranking with no firing? or car is on its roof?
located in Chester NH
1967 1600 in restoration
2013 Arctic Cat F-1100 turbo
Ford F-350 6.0
Ford 9000 puller, Ford 960 puller, Ford 901show, Ford 971 worker, Oliver 70 waiting its turn
roadsterred
Roadster Nut
Posts: 42
Joined: Sat Mar 26, 2011 10:35 pm
Location: Honolulu, Hawaii

Re: Need Help.. Issues with firing??

Post by roadsterred »

Perform a compression test before going any further. If the compression on all cylinders are normal and you have replaced the ignition system, the only thing left is fuel.
User avatar
jhayden
Site Supporter
Posts: 477
Joined: Tue Oct 25, 2011 4:16 pm
Location: Tyler, TX

Re: Need Help.. Issues with firing??

Post by jhayden »

Once bought a SRL ($400) in the 80s from a widow whose husband had "rebuilt" the motor. Drove normally for a few hundred miles, then the cam snapped in two whilst driving, and it "sounded really rough, and the motor was shaking like crazy" as described above, b/c it was running on only the front two cylinders. Not that uncommon on a U20 if the cam isn't checked for ease of spin (head torqued, rockers removed) after a rebuild.

Hope this is not the case here, and if not, perhaps may still be useful information for new owners of 2000s.

Jon
Post Reply