Dave J
|
| posted on 14/11/05 at 11:26 AM |
|
|
backfire thru carb
Hi all,
Sorry if this is all a bit basic but.......
Tried starting my Rover 3.9 V8 lump yesterday. Frightened me to death!!
Didn't start but I got an alarming backfire thru my carb (edelbrock performer 500).
I'm sure I saw some flame accompaning the fuel shooting out the top of the carb.
As I don't want to torch my engine, the question is this:
Could my ignition timing be so far out as to cause this? (HT leads one position out?)
My intention is to check the position of the rotor with the No1 cylinder at approx 8deg BTDC.
can somebody advise me on a quick and easy way to acheive this. I don't have any fancy DTI's that I can use in the spark plug hole.
This may seem sad but I'm a complete newbie on Rover V8's. Can anybody tell me the order of the inlet and exhaust valves when looked at
the rockers?
Obviously I need to know when the inlet valve is opening with relation to No1 cylinder and ignition.
I've tried to identify by the inlet and exhaust manifold positions but it just isn't obvious.
For those of a nervous disposition, backfiring thru the carb aint funny
Any further ideas about how to sort the problem would be a great help and go some way to prevent the greatest bonfire since nov 5th
Probably a silly question but, how likely bearing in mind the above, is the possibility of my engine / fuel etc completely going up in smoke if I
continued cranking after the first backfire thru the carb?
Thanks Guys
Dave
|
|
|
|
|
Tiger Super Six
|
| posted on 14/11/05 at 11:40 AM |
|
|
I had the same problem on a pinto - it turned out that the dizzy needed to be turned 180 degrees.
Basically what was happening was that it was firing on the exhaust stroke and not the induction.
HTH
Mark
Tiger Avon
|
|
|
Gazza
|
 posted on 14/11/05 at 12:06 PM |
|
|
Backdraft....
Had the same problem on my twin cam 4AGE - tried everything - eventually found that one of the cams was 180 degress out - ie. both cams in the same
position - so it would of never started!
Can honestly agree - seeing flames and unburnt fuel exiting out both manifold and carbs - can be a bit of a shocker!!!
Just a bag o' rusty spanners
|
|
|
greggors84
|
| posted on 14/11/05 at 12:57 PM |
|
|
Can agree with both the reply posts, its likely that you have set it to 8 deg BTDC on the exhaust stroke so the inlet valve is just opening. Turn the
dizzy 180 deg or rotate the engine again till it gets to BTDC compression stroke and set the rotor from there.
p.s. and yes it can be a bit scary starting the engine for the first time especially as it spits flames at you. At least you know to check it next
time you start a new engine, you could have got lucky and it been right first time, but then you wouldnt have learnt this.
[Edited on 14/11/05 by greggors84]
Chris
The Magnificent 7!
|
|
|
Dave J
|
| posted on 14/11/05 at 01:41 PM |
|
|
Thanks guys,thats very helpful.... ain't kit building fun!
I guess when youv'e spent the last couple of years or so building a car, nerves set in when trying to start the engine especially when flames
appear where they shouldn't.
All I've got to do now is figure out which are the inlet and exhaust valves so I can get BTDC on the compression stroke (as opposed to
exhaust)
A friend of mine spent a couple of years and a load of hard earned ,completely rebuilding a classic motorbike.
Looked concourse when he finished.
First time he kicked it over, it burst into flames....complete write off. He never built another. His experience has made me a bit twitchy....always
have a fire extinguisher at the ready.
Anybody with a V8 know the order of the valves?
Thanks again.
Dave.
|
|
|
David Jenkins
|
| posted on 14/11/05 at 01:47 PM |
|
|
Um... a visit to the library for an appropriate Haynes Book of Lies would seem appropriate...
David
|
|
|
Dave J
|
| posted on 14/11/05 at 02:37 PM |
|
|
Hi David,
I did try that ages ago to try to get as much info as poss on the V8, but wouldn't you know it, although the Haynes book of Range Rover lies was
listed, turns out some lowlife had half inched it.
Good suggestion though, I reckon I'll try them again.
Cheers
Dave
|
|
|
NS Dev
|
| posted on 14/11/05 at 02:51 PM |
|
|
Aha, see you are in leicester!
I know of a very nice chap in Leicester with a rover v8 in an Opel Manta who will be very willing to help you out with any Rover V8 info.
Give him a call (between 5:30 and 9 in the evening) and say that Nat gave you his number. His name is Clive by the way.
0116 2249509
|
|
|
Dave J
|
| posted on 14/11/05 at 04:59 PM |
|
|
Hi Nat,
Thanks for that, it's always nice to be able to contact someone local.
I'll be doing a few checks prior to the weekend and having another go. If I get myself into the doo dah, I'll certainly give him a
bell.
Thanks again
Dave
|
|
|
rusty nuts
|
| posted on 14/11/05 at 07:42 PM |
|
|
Try removing all the spark plugs and while holding a thumb over number one spark plug hole turn the engine over using a spanner on the crankshaft
pulley bolt. You will feel the pressure building up when the piston is rising on the compression stroke, watch the crankshaft pulley until timing is
around 8degrees BTDC.. Check the rotor arm is pointing towards no 1 lead . I have a whistle in an adaptor that screws into the plughole, very handy
for finding the compression stroke without taking off rocker covers HTH
|
|
|
DarrenW
|
| posted on 15/11/05 at 09:12 AM |
|
|
I had similar problem with Pinto.
At first - wouldnt fire properley, leads 1 2 3 4 !!! easily remedies.
Later - backfire thro carb with flames!!! Scary, not nice experience. Solution - replaced Facet red top with mech pump. Turned dizzy to retard approx
8deg (set up by ear for now). Now runs sweet. Main issue was very high pusling pressure - regulator couldnt cope with pulse and carb was ringing wet
with fuel.
|
|
|
Dave J
|
| posted on 15/11/05 at 09:40 AM |
|
|
Thanks for all the replies everyone. I like the idea of putting a whistle in the spark plug hole to find compression. The ingenuity of you guys never
fails to amaze me.
If all else fails, I'll put a whistle in all the holes, .....probably get Colonel Bogey
I'll do some checks over the next few evenings ready to have another crack at the weekend (gotta give the valium a chance to kick in)
I'll keep you posted
Cheers for now
Dave.
|
|
|
Dave J
|
| posted on 21/11/05 at 04:54 PM |
|
|
Hi all,
Update...... You guys were spot on!
The timing was 180 deg out. Got it running on Sunday Morning, sounds very nice
Thanks for all the help.
All the best
Dave.
|
|
|
.jpg)
