280z su conversion, no start

[vale2489]

Picked up a rusted out 280z donor car with good motor, got it to run on with efi intake on it ( just with carb cleaner through the tb). Pulled that motor and dropped it into my other car with su's slapped on it...I have spark, timing has not been changed/messed with , new plugs, wires cap/rotor fuel not hooked up yet...im just looking for signs of life with starting fluid until i get a low pressure pump. I can't get a single pop out of it, firing order has been checked several times....I am stumped to say the least. Car/motor are 77'

Edited April 2, 2014 by vale2489

[dexter72]

Do you have spark at the coil wire going to the cap and the plug wires??..

[vale2489]

Yes, as well as good spark at the plugs.

[seattlejester]

You need air

You need fuel

You need compression

You need spark

 

With the throttle open a bit you have air

With the starting fluid you should have fuel

You have checked spark

And it was running with the EFI so it should have compression

 

Short of the firing order being incorrect or timing being out of whack it is a bit difficult to answer without being there. I think 153624 for firing order, I know the book I was using had it wrong. 

 

Are you spraying the ether under the pistons? The pistons are nearly closed without engine vacuum even with the throttle open, I know I had to lift mine up to add a little bit to get my engine to burp a bit.

 

The most likely culprit seems to be spark misorder or maybe the distributor was moved out of adjustment? I know the timing for the L24 with SU carbs is different then the L28 with injection. If possible get a timing light on spark wire number one while someone is cranking?

[vale2489]

I'm lifting the pistons up when spraying into the carbs...timing sounds like the next step. It just seems like if the timing was off it would still pop...Is the timing different enough from an l24 that I would need to re stab the oil pump shaft? I'm using the transister ignition also...Should I just hardwire the coil?

[seattlejester]

If you have compression you should be able to get the motor to essentially detonate under cranking with fuel or get it to stutter if the mixture is being lit off at the wrong time.

 

I am doubtful that the difference would be so great that you would have to clock the oil pump shaft, but it is something to look into. If I recall there is quite a significant difference, it will be up to you to decide if the difference is the changeover from carbs to efi or from points to electrical ignition. On my L28 with carbs, I think the number I used was 16btdc?

 

I might take a look at how the ignition wiring is done. Making sure that the coil is getting power and sending power via visual/multimeter will be the next step. Use a multimeter and confirm that the coil has power both when the car is on ignition on and during cranking. Alternatively, yes you could just hard wire the coil to the battery for testing purposes. To check that the spark is making it from distributor to coil, pop off the lead and leave a bit of a gap so you can spy the jump. Just be careful not to be anywhere near the distributor or the coil when you are checking if the wire is sending the arc.

 

It sounds like you are familiar with the process, so my apologies if this all seems trivial or explained in too much detail.

[vale2489]

The oil pump shaft was 180 off!!! I have no freakin' clue how that happened, I am perplexed how it ran fairly well in the parts car ( even with a huge hole in the efi intake manifold that was plugged up with crud). Im still a tooth off but it atleast runs now, probably gonna have to rebuild the carbs but I'm happy with some progress finally. Thanks for the input, looks like my next step is open a credit line with ztherapy.

[seattlejester]

It can happen, I've heard more then one story of people just changing the spark plug wires around instead of going through the hassle of reclocking the oil pump. This makes it a problem when the next owner decides to take the plug wires off for some reason.

 

If the throttle shaft isn't leaking/worn and you are familiar with the carbs, the rebuild kit is ~20$ a side for the SU carbs. I bought LM needles, gross/grosse valves, and the two rebuild kits front and back for I think 90$ + a nice synchrometer for 50$ I think. Mine ended up running pretty well so I never actually had to take them apart, I was convinced that the old fashioned method of tuning using RPM and lifting the piston wasn't as accurate and bought an LC-1 to check. Found out it was within 0.2 or 0.3 AFR of what was recommended less then half a turn of adjustment. If you choose to go the same route with the AFR meter, SU's for our cars idle rich and lean out as you rev in standard form with the stock needle on a 2.8L. Idle was hard to dial in without going to lean on the high end, I've heard the LM needles will flatten the curve so instead of 10-13.5 it is more of a 11-12 kind of curve.