Distributor Cap Help!

[Spikehaus]

Today, I decided to remove the spark plug leads from the distributor cap and give the cap a clean due to the years of debris from the donor vehicle on the top (Pretty much the only untouched part of the original car. (Leads replaced not so long ago)

I also removed and replaced the oil pressure sensor.

Upon re-assembling the cap and leads, the engine will not fire. I did not touch the rotor arm or dizzy housing other than give it a quick wipe over. I have checked, checked and checked again the firing order from the Haynes book locating position 1 on the cap against the raised round moulding mark and book diagram.

I have tried this with an without the cap tower.

There are no cracks or carbon tracks in the cap

Photos on the build diary

Each time it makes a loud bang and blows a hole in the induction pipe, (it did this a few time when it was working if you did not press the accelerator down during cranking)

Do I need to manually turn the engine to TDC or make sure the rotor aligns with spark plug 1 before refitting the cap?

The cap only seems to sit in one position due the moulded lug below.

What was meant to be a simple maintenance job has gone wrong?

[jason 82]

Check your rotor arm, give the contact a quick rub with some sandpaper, and make sure that it is located properly. If the car fails to start, check that you have a spark at the plugs, the safest way to do this is to get a push in led tester, they are about £3. If you get zapped its hurts like hell ! If you have no spark, disconnect the lead from the cap that comes from the coil and try again for a spark. If you still have no spark replace the coil. It wouldn't hurt to check the timing to make sure it isn't out a little. But if you haven't touched it its highly unlikely. Check each ht lead in turn, as you could have a lead or 2 down. Hope this helps ?

[Spikehaus]

Got a plug tester on order to check next weekend, not seen one of these before.

[twinturbo]

rotate the plugs leads through 180 degrees.

TT

[Spikehaus]

Having working back in my mind the process, it started raining heavily while the cap was off, so I pushed the car back into the garage? Could this be the cause?.

How best to re-align the rotor to plug 1?

[vmax1974]

i normally just line up the timing marks on the crank & cam pullies that should be TDC on cylinder 1 if that fails take the cam/valve cover off the top of the engine and look for tdc when both valves are closed this will be TDC firing on cylinder 1 a bit of a pain i know but if it solves the problem......

almost forgot you also gotta know what direction the engine rotates

[Not Anumber]

Originally Posted by twinturbo

rotate the plugs leads through 180 degrees.
TT

+1 If nothing else was touched and all you are getting is an occasional nasty backfire then the leads are 180 degrees out.

Given the crank turns twice for every turn of the distributor and camshaft there is always a 50% chance it will be wrong if guaged just by TDC on the crank. The firing order is 1342 so just swap leads 1 and 4 and then 3 and 2 over at the cap and try the starter.

[twinturbo]

Originally Posted by Not Anumber

The firing order is 1342 so just swap leads 1 and 4 and then 3 and 2 over at the cap and try the starter.

That will realy screw him up

TT

[Spikehaus]

Managed to sort it out today and all running again!

I aligned the crank shaft timing marks to TDC, then checked the marking in the distributor housing under the dust cap, it was still 180 degree out, so gave it another full rotation. The rotor arm then aligned with the mark in the distributor housing. I ignored the Haynes manual for the position of the spark plug leads, and placed them in accordance with the firing order 1,4,2,5,3,6, and position of the rotor arm.

Started first time.

Thanks for the help guys. Quite simple when you know and appreciate the logic behind it all.

The engine still seems to pop on rapid deceleration or engine braking when hot, any ideas?

[vmax1974]

Could just be a timing issue get hold of a timing light and check it