• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

72 Midget 1275

Share this page

G

gregsdrums

Senior Member
Offline
Picked up a 72 midget with the 1275 engine that had been stored for 16 yrs. Did all the usual maintenance; drained/cleaned fuel tank and filter, changed all fluids, belts, hoses, plugs, wires, dist. cap, rotor, carb kits, etc. Had to replace the intake manifold because it was cracked and broke. Installed new gaskets there and for carbs/spacers/air filters. When it started it sounds like it's only running on 3 cyl. All cyl. have spark and I adjusted valves. Still sounded the same. Can see unburned gas vapor coming out of the rear carb. Adjusted carbs/timing by the book. It will run but very unsteady and backfires at times. Think the next step is removing the cyl. head. Any suggestions would be greatly appreciated. Thanks in advance.
 
A few things to try before taking the head off.
Check the compression.
Check the rocker arms and make certain clearances are correct.
Check and clean the carb float bowls, make certain the pistons are moving freely, the needles are centered and the jets clear. Also that fuel is reaching both carbs.
Roy
 
If you are getting vapour pushing back out of the rear carb, there is a chance that there is some garbage stuck in the intake valve and seat.

First question:

When you checked valve lash, did you have to change anything?
Like, maybe, #3 was too loose by a bunch on the intake?

If so, remove the offending cylinder sparking plug, rotate engine by hand until the intake is wide open.

Prop the throttle wide open, prop the piston fully up, and with a rubber-tipped blow nozzle on a charged air hose, apply to the offending cylinder and pull the trigger, whilst standing clear of the carbs.

Sometimes that works, if it ran before it was parked on all cylinders.

If you check valve lash when done, and you get a big change in the intake, you will know you're okay.

Another thing can cause this is a broken intake spring.


Dave
 
Check the firing order.
If #3 is bad, check the rear carb, sometimes gunk clogs the jet tube.
Remove the carb piston, fully choke it, and back blow air into the jet tube and see if it bubbles out in the float bowl.
Do not use 100 psi, a tube and your mouth should blow it out, or 15 psi max or you could blow the jet tube out of the carb.
 
Back
Top