Need some extra eyeballs ... backfires through carb but won’t start after rebuild

[ericgbauer]

Hello all,

Happy Labor Day Weekend!

Am trying to finish up my 63 IIa 109 so I can go out and drive it, and am stumped. I need an extra pair of eyeballs to point out the (probably obvious) thing I’m clearly missing.

Due to a cracked head, I tore the engine apart and have rebuilt nearly everything. To be clear this was a running truck, just super down on power due to cracked head.

This truck will have a new lease on life once it actually fires up.

This is a 2.25L petrol with a new 2.5L camshaft, new pistons, new bearings, new everything.

12v negative ground
It was already negative ground before the rebuild

Triple and quadruple (and then some) checked engine timing:

Flywheel pointer at 6deg for 91oct
Distributor rotor pointing at #1 spark plug
New distributor w/ new rotor and condenser
Timed distributor with light, can hear condenser clicking on/off as I rotate distrib body.
Spark plugs new - ngk bp5es - same as I used before
Spark plug wires new (checked resistance across wires, all 2.9~3k ohm)
Spark plug 1 3 4 2 counter clockwise when standing on right side of engine (ie U.K. driver / US pass side)
Fuel pump new - primed carb with hand pump action
Fuel is newish - a couple weeks old now - fuel doesn’t go bad that fast (91)
Carb new rebuilt Rochester - confirmed it squirts gas as it should
New starter
New Autospark UK wire harness with alternator mod
Alternator is a Lucas - worked fine before rebuild
New battery

Coil is 1 year old - same cool I used when it ran last
Tested it has 12v at + lug with key in ignition turned to ON
Negative lug of coil connected to distributor
Checked that I have spark:
Spark plug connected to lead from coil and ground to engine - yes there is a nice spark
Checked each spark plug and wire coming off distributor - pretty faint but there is spark at all 4

Tried a second (brand new) coil
No change

Tried the distributor I had in the truck last time it ran
No change

Tried with choke all the way out and choke all the way in
No change

Ground straps from starter to frame
And from neg battery post to frame and to engine front cover

Starter turns engine freely
With a couple pumps of gas pedal, and/or addition of starting fluid down carb throat all I get are a couple backfires through carb

Rest of electrical functions as it should
Fuel level gauge
Headlights / taillights / turn signals
Horn
All ok

But truck won’t start

What gives?
What am I missing?

Any and all help is appreciated...

Thank you

-e

[mearstrae]

Sounds like your distributor is 180 degrees out. Firing the plugs opposite of the compression stroke. How is this possible? The crank turns once but the cam goes around twice. How did you get the Dist. at 6 degrees before TDC if if wasn't running? Move the crank to the TDC pointer and pull the dist. up until it clears the drive and rotate the rotor arm 180 degrees and refit. Set the timing after it's running. (At least I think I remember that's the drill for correcting this..) Or the cam may have been incorrectly installed. Spark should be strong.

'99 Disco II
'95 R.R.C. Lwb (Gone...)
'76 Series III Hybrid 109
'70 Rover 3500S (Gone...)

[jp-]

Agree with above post. Typically, I will remove all the plugs, put a finger in the #1 and turn the engine over by hand until I can feel pressure pushing my finger out. That way, I'm 100% sure I'm actually on TDC at compression.

Next, if an engine won't run even on starting fluid (ether) something serious is wrong. Either it's completely out of time, as above, or you aren't getting spark at all. Double check that the coil is hot both with the ignition on and when actually cranking. It's rare, but I've seen a bad ignition switch and/or wiring issue where power at the coil was lost during cranking.

Lastly, are the spark plugs visibly wet with fuel after cranking attempts? If yes, not getting any (or good enough) spark. If no, double check fuel system.

[ericgbauer]

Mearstrae & Jp-

Thanks for the feedback
I’m out of daylight over here
So will have to check later this week or this weekend


Will check 180 on distributor

thank you

[ericgbauer]

Gents,

You were right
Finally had a chance to work on it last night
Distributor was in fact 180 out
Fixed that and it fired right up

Many thanks for the tip!
Onwards!