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BIG BACK FIRE-HELP ME!
wibble - July 11th, 2003 at 06:42 PM

getting a 1600(I think!) TP motor together for the baja, checked timing/valves clearance etc but all I am getting is back firing and pressure in sump (blew a tappet cover clean off!!) this cannot be good, possible causes any-one? maybe shot rings/hole in piston.
really rather not pull this thing down but what do ya's reacon??

wibble - July 11th, 2003 at 06:43 PM

cam 180 degrees out?????
HELP!!!!!!!!

Herbie - July 11th, 2003 at 06:56 PM

I would first be looking at the compression.
if its drasticaly different in one cylinder then Its got issues.
It does sound bad, I dont know if you can put the cam out of whack and even if you could you wouldnt get pressure in the sump, I shouldnt think, but if you have a hole in a piston and are trying to start it you may be filling the sump with a a fuel air mix which has nowhere to go when it does ignite and you could really get hurt if it goes bang. with no spark connected just see what the compression is like.

wibble - July 11th, 2003 at 07:15 PM

yeah, was hoping not to have to perform surgery but looks like the only option at this point:( any short cuts??

Andy42 - July 11th, 2003 at 08:03 PM

Hehehe it spat the oil out of the filler tube all over the shed roof and it is about 3m up. Damn i wish I would have been home to see that:D

Herbie - July 12th, 2003 at 12:28 AM

Just check also incase you have a perferated diaphram in the fuel pump.
On some motors that can allow fuel to enter the sump thru the fuel pump.
worth a check.

wibble - July 13th, 2003 at 09:47 AM

yeah already checked the fuel pump! going to pull the heads off it and see if I can find a big hole in a piston:(
would have checked compresion but I'm too tight to buy a gauge set up.
oh well wish me luck!

LOWBUG - July 13th, 2003 at 03:27 PM

what are your push rods like are they straight?
did this problem just start or were doing somthing to your engine first.
was it running smooth the back fire.
how old is engine
was it rebuilt with old parts etc'....
need more info

wibble - July 13th, 2003 at 03:30 PM

Just another motor I picked up on the weekend, problem sorted, it was like my weekend: piston broke!!

wibble - July 13th, 2003 at 03:30 PM

Just another motor I picked up on the weekend, problem sorted, it was like my weekend: piston broke!!

wibble - July 13th, 2003 at 03:34 PM

Oh yeah here's one for ya's timing was out by 180 degres with the foot on the dissy put on wrong!!

Herbie - July 14th, 2003 at 11:46 PM

The old pesky porous/perferated piston trick eh chief?

I was concerned, as I knew of a guy, blew himself up on the side of the road because unbeknownst to him, his Valiant had suffered the same hole in the piston trouble and as he pumped and cranked and pumped and cranked he put a lot of petrol into the sump and then it ignighted when he was cranking and went big bangs.

yes my weekend was the same. pist and broke.
Cheers Tony:D