TRIPLE CARBS BACK FIRING help
#1 _troy_
Posted 24 October 2007 - 03:11 PM
#2 _CraigA_
Posted 24 October 2007 - 03:13 PM
#3
Posted 24 October 2007 - 03:23 PM
#4 _threeblindmice_
Posted 24 October 2007 - 05:34 PM
#5 _troy_
Posted 24 October 2007 - 05:38 PM
There are only 3 things i have done to the motor since it was running
1.Used ARP HEAD STUDS
2.Replaced fuel pump with a universal electronic fuel pump 2-3.5psi 105 litres an hour or 28 gallons an hour.
3.used an ACL head shim to lower compression ,now that may be the problem???
I just had the car down at a performance shop and they cant even work it out,its like its pre igniting or something.
i replaced the distributor and coil and plugs and its still doing it...
if anyone has any suggestions or knows a good mechanic in perth metro area can you let me know,cheers troy
#6
Posted 24 October 2007 - 08:10 PM
Does it have adjustable rockers?
#7
Posted 24 October 2007 - 08:49 PM
Backfiring off idle under no load usually points to a big timing problem in my experience. Umm, otherwise, what are you using for lifters, valves, and rockers? Maybe you've overadjusted the lifters on reassembly, and some valves aren't completely closing after the lifters have had a chance to pump up.
#8
Posted 24 October 2007 - 08:50 PM
Presumably they are SU or Stromberg CD carbs.
You say the carbs were tuned ?? How ? on the running engine or the work bench ?
Get them to do an exhaust analysis or borrow a coloutune plug and see whats
going on in the combustion chambers. It will get hot quickly if its too lean so
whats the temp guage telling you ?
Good luck.
JR.
#9
Posted 24 October 2007 - 08:52 PM
#10 _Bomber Watson_
Posted 24 October 2007 - 09:07 PM
#11 _troy_
Posted 25 October 2007 - 11:29 AM
#12
Posted 25 October 2007 - 12:14 PM
Or
Any of the 3 randomly?
#13 _rorym_
Posted 25 October 2007 - 04:25 PM
R
Edited by rorym, 25 October 2007 - 04:27 PM.
#14
Posted 25 October 2007 - 04:47 PM
#15 _troy_
Posted 25 October 2007 - 06:21 PM
Edited by troy, 25 October 2007 - 06:22 PM.
#16 _rorym_
Posted 25 October 2007 - 06:26 PM
R
#17
Posted 25 October 2007 - 07:55 PM
Is it still idleing O.K?it was mainly the middle carbie backfiring now its all 3 doin it,
How do these plates seal? Do you need 2 head gaskets?
I read in the other post that you had trouble getting the ARP's to seal.
What exactly was that issue?
#18 _sunburst_metalic_
Posted 25 October 2007 - 08:35 PM
Sunburst
#19 _troy_
Posted 26 October 2007 - 12:00 AM
#20
Posted 26 October 2007 - 09:12 AM
#21
Posted 26 October 2007 - 01:29 PM
A common cause of side-draught carbies backfiring is that the pistons are rising too quickly, try a slightly heavier grade of oil in the dampers.
Retarded ignition timing is also a cause, but I guess you've already tried advancing the dissy a bit.
Dr Terry
#22 _gtrtorana_
Posted 26 October 2007 - 02:37 PM
#23
Posted 26 October 2007 - 04:40 PM
#24 _troy_
Posted 27 October 2007 - 04:14 PM
#25 _willo_
Posted 27 October 2007 - 04:45 PM
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