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First start trouble rebuilt 1275

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TulsaFred

TulsaFred

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I tried to start my freshly rebuilt 1275 on the test stand today.
After some checking, i used starter fluid and it immediately fired off and ran for about a second or two. Can't get it to do anything without a shot of starter fluid.

Am I correct in assuming that, based on the above, my Static timing, valve/cam assembly, and ignition system are all ok?

The problem would then appear to be fuel delivery, most likely carbs.

Advice on next step(s)

Thanks

Fred
 
Yes. Likely fuel delivery.

Disconnect the hose at the carb. turn over the engine and see if fuel flows out of the hose. If it doesn't, it's the pump (or a clog). If it does, it's the carb. If it is the carb, the likely culprit is the front "first" carb.
 
Thanks JP
I get delivery to the carb based on above, and I checked the fuel bowl on the front carb, it's full.
Seems that with a full fuel bowl it should fire and run at least a while. ? Jet plugged

What to test next?

Fred
 
Fred
Undo the two screws on each dashpot and carefully pull off each dashpot and plunger. Lay them aside.
Now- turn on the fuel pump and watch that the fuel rises up the jets until it almost runs over.
If you don't see the fuel rise in the jets until it almost runs over then you have some cleaning in your future.
BillM
 
Bill
Did as you said, and I had fuel almost running over the jet. When I "shook" the stand the fuel spilled over the jet a little.
I didn't do anything other than look and then replace the dashpots, but now it starts and runs! Not sure what black magic occurred, but hey it works.
Of couse starts and "runs" is a little generous. It coughs and spits a bit and seems to cough a little fuel mist out the carb, especially the rear one, but it will stay running.
I guess next will be checking timing with a light and fine tuning the carb settings. I've got them each 12 flats/ 2 turns out.
Before that I'll need to hook up temp and oil pressure gauges to be sure it's safe to run. I do know that oil started coming out of the pressure sending fitting before I capped it off, so the oil pump is at least circulating some oil.
We'll see how it goes.
Thanks!
Fred
 
Any advice on how rhe gauges connect?
On my chinese built test stand the included gauges didnt come with any instructions.
There is a temp sending unit with a single electrical "blade connector" and the gauge itself has a black and a red wire. Ditto for the oil pressure sending unit and gauge.
Does the electricity ground through these units and the gauge read a variable resistance to ground?
If so, then I guess I should hook the reds to some positive juice and the blacks to the respective sending units. Well actually the oil sending unit has a screw on brass connector marked "G".

Or am I mistaken?

Fred
 
Oops, on closer inspection the black and red wires on the gauges look to be for illuminating lamps.
Each of the gauges has 3 blade connectors with nothing hooked to them.

Fred
 
You may need to show photos of the backs of the gauges for us to be of any help
 
I think Ive got the gauges sorted out.
The 3 blades are ground, hot/ pos., and sending unit. A little trial and error got it figured out.

Im thinking the reason for my starting problems are from flooding. I suspect the float levels, but on these HS 2 carbs the float levels seem fixed. I didnt see any way to adjust the plastic floats.

Thoughts?

Thanks
Fred
 
The plastic floats with no visible means of adjustment can only be adjusted by shimming under the needle and seat. Least as far as I know.

Kurt.
 
How exactly is the shimming done.
The manuals I have state that no adjustment is possible on these floats.

Fred
 
TulsaFred said:
Im thinking the reason for my starting problems are from flooding. I suspect the float levels, but on these HS 2 carbs the float levels seem fixed. I didnt see any way to adjust the plastic floats.

Thoughts?

Thanks
Fred
Click to expand...

Yes, don't touch anything! If it starts and runs, tune it, time it but then don't mess with it. My guess is that something was binding or not fully turning or the kind of thing that might be expected on a fresh rebuild. But, now that it is working, leave well enough alone.
 
Yes, I know what you mean JP.

However, I continued to work on tuning today. It runs, but not yet correctly.

It sputters for a few moments at around 1200 rpm, but then begins to race up to 2500-3000 and at that point I shut it off with the key.

Timing is correct.

Seems like a possible vacuum leak but I can't find any obvious.

Fred
 
TulsaFred said:
Yes, I know what you mean JP.

but then begins to race up to 2500-3000 and at that point I shut it off with the key.


Fred
Click to expand...

that sounds very much like a throttle return spring issue.
 
Would a weak return spring allow the throttle to open on its own?
 
MANY things will cause the throttle to not close fully!!
On thing that I always do on any car that I get is to unscrew the two brackets that hold the throttle peddle, take the assemble to the workbench and clean/lube the pivots so that the peddle swings freely.
Next- I either get a new throttle cable or at least pull the cable out of the housing, remove any frayed strands and then grease the wire and put it back together making sure that everything moves very freely.
THEN I start looking for vacuum leaks or return springs.
BillM
 
Agree that it probably is not needed but the float needle assembly unscrews from the housing and you can fit different thicknesses of washers under the assembly to shim up the needle and seat. You then have a float that shuts off the gas before the chamber is quite as full as before. Tiny shim makes a big difference.

Kurt.
 
Thanks for the help, guys. I fiddled with it some more this evening.

I made a shim out of a small brass washer but it was too thick. I used some teflon tape somewhat bunched up toward the end of the needle seat threads to act as a kind of washer. It worked to an extent, enough that it was within spec of .062-.125 inch.

Re-set timing with vacuum advance plugged and then reconnected the vacuum tube. 5 degrees advanced without the vacuum. I didn't recheck after attaching the vacuum tube.

Now it runs a little better, but still:

a. kind of coughs back frequently and spits some fuel mist out of the carbs. Doesn't really backfire with a bang or with fire, but just coughs and spits back and runs rough.

b. it will do that for a while, then it gradually begins to smooth out, and then the rpms will run up. Now only to around 2000-2250 rpm. Then it gets rough again and slows back down back to repeat the cycle. The rpm run up is less severe and less "frequent" now.

Still didn't find a vacuum leak.

Making some progress, but more to do.

I reused the old distributor cap, rotor and plug wires for the reassembly. I'll put on new when I get back to the shop next. Maybe that will help, or some other ignition related issues.

Can you set dwell on a Lucas distributor? I just set the gap with a feeler gauge.

Fred

p.s. Yes , it's still on the test stand.
And I put all 3 throttle return springs on (had been only 1).
 
Have you got it all hooked up to coolant and guages? Sounds to me as if it just isn't warmed up and maybe a bit lean.

Kurt.
 
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