ginamic
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| posted on 7/5/13 at 10:58 AM |
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Xflow wont rev!
My first post!
Wondering if anyone can help me with a problem on my 1600 xflow engined locust.
it has a 32/36 DGV which seems to be the root of the problem.
After a carb refurb kit fitted with new gaskets, filters, clean up, needle valve float reset etc.
-The car struggles to start (it will go with a spray of easy start) it just wont rev up.
-It will idle sweet enough, all tuned up idle- mixture running lovely. if you build the revs up until about 2.5k then it just bogs down and wont rev
any more until it dies  almost like the revs hit a brick wall and wont go any further.
The engine ran spot on before the carb refurb which is so annoying. trying to solve this problem its had new distributor, points, condensor, leads,
plugs, coil swapped, engine gasket kit inlet rocker etc.
It has all been timed up, points checked, all good sparks present 10x + still to the same result.
As einstein said the definition of insanity is doing the same thing over and over again expecting different results.
Anyone had the same problem before? wisdom or suggestions would be extremely grateful, i just want this beast back on the road before the wife rehomes
me!
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MakeEverything
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| posted on 7/5/13 at 11:08 AM |
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Have you checked Vacuum?
Kindest Regards,
Richard.
...You can make it foolProof, but youll never make it Idiot Proof!...
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johnemms
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| posted on 7/5/13 at 11:09 AM |
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1243 firing order.. yer never know lol.. :p
Own chassis & Build - First time pass!!
"7's" aren't really "cars", they are 'experiences"
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ginamic
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| posted on 7/5/13 at 11:20 AM |
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quote:
Originally posted by MakeEverything
Have you checked Vacuum?
i have and all seems well, not measured it but dont appear to have any vacuum leaks, used the ether around inlet and carb and listened for any
changes.
quote:
1243 firing order.. yer never know lol.. :p
yes i've checked lol ... 2 or 3 times lol
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snapper
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| posted on 7/5/13 at 11:29 AM |
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It won't start without easy start and bogs over 2 1/2k
Sounds like your running weak past the idle and 1/3rd throttle progression
Perhaps cleaning has opened the jets or perhaps the jets have blocked with crud after cleaning has loosend
Check choke operation, throttle operation and second choke opening
I'm not sure on that carb if its a geared or vacuum secondary
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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ginamic
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| posted on 7/5/13 at 11:56 AM |
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thanks for reply,
quote:
Perhaps cleaning has opened the jets or perhaps the jets have blocked with crud after cleaning has loosend Check choke operation, throttle operation
and second choke opening I'm not sure on that carb if its a geared or vacuum secondary
i've dismantled the carb 3 times now to check for debris and any crud in the jets. i did hear about the linkages being to tight might be worth a
check. its a geared secondary, it appears to kill itself just as the secondary is opened. the only thing i didnt change in the refurb was the power
valve.
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minitici
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| posted on 7/5/13 at 04:31 PM |
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Have you mixed up the primary & secondary jets (both the idle and main jets)?
I did that on a 1500 pre-xflow and took me a while to figure out what I had done.
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Aaron_n_Sim
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| posted on 7/5/13 at 04:48 PM |
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I thought the same as above, the 32 jet is for start up and idle 36 for more economical foot down driving! Good luck!
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Dunbikin
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| posted on 7/5/13 at 06:03 PM |
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I had exactly the same problem when I bought my car. It took me weeks to get to the bottom of it, but it turned out that the gasket in the carb was
upside down ( I had checked this 3 times before I noticed it ), causing it to block off a little hole. Might be worth checking if the problem only
started after a carb rebuild.
Ron said it would cost 250 quid. My wife thinks it did.
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ginamic
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| posted on 7/5/13 at 07:00 PM |
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thanks for the suggestions, they are both worth looking into.
i did notice the main gasket on the carb could go either way apart from a small hole at the side of the float bowl? iirc
i'll let you know the results 
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ginamic
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| posted on 11/5/13 at 01:24 PM |
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Right checked the jets and swapped for close to standard size, and flipped gasket over as the acc pump blank hole wasnt covered. re-checked the timing
too to see if it was 180 deg out, spot on as before...
still the same behaviour.
checked the revs to see when it bogs down, and it gets too spot on 2k rpm then it dies. while it was runnging i had a look in the chamber to see what
happens when it starts to die, the fuel stops squirting in the chamber? is this normal? should the fuel carry on going in as the revs increase?
still wont start cold without the easy start but starts fine when its got some temperature in the engine.
is anyone familiar with the 32/36, i'm not sure if the power valve is nackered. i've tested it (press down, cover the hole and let go) it
recoils by about 3mm is this right or should it stay at full compression when you press it down? cant seem to find any info on this side of the
carb.
thanks for any input/ ideas folks.
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dave_424
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| posted on 11/5/13 at 01:59 PM |
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Fuel should keep squirting no matter what the revs are, one thing springs to mind is what is your fuel set up? pump? pressure regulator?
It just could be that you aren't getting enough flow or something which means that your fuel can only sustain you up until around 2000rpm and
after that you are sucking the bowls dry.
If you are sure fuel is stopping then that is your issue.
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ginamic
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| posted on 11/5/13 at 02:19 PM |
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thanks for your reply,
had the fuel pipe off today and cranked over (its a standard mechanical pump btw) fuel flowing nicely, the bowl are always full to the correct level,
so i seems like the float is doing its job. measured the float again to check the levels 41/51mm.
it needs taking apart again to go through the jets.
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dave_424
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| posted on 11/5/13 at 02:50 PM |
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If fuel is sufficiently flowing, then you may have blocked/restricted jets, or you don't have enough of the venturi effect in the carbs to suck
out fuel, which could be a vacuum issue like others have stated.
Do you know the operation of the power valve? what is is supposed to do? if it might be broken like you possibly think, any way that could be shutting
off your fuel when it is trying to operate?
Sounds like a really frustrating problem.
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ginamic
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| posted on 11/5/13 at 03:33 PM |
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i think the basics of the powervalve and pv diaphram operations are if there is a vacuum behind the valve (accellerator operated sufficiently?) it
compresses the spring on the diaphram and stops/lets the fuel through the pv (base of the float bowl).
then when there is no vacuum (at idle?) the fuel is stopped/let through by the diaphram spring pressing needle on the pv.
not sure which way around it operates? any ideas.
quote:
Sounds like a really frustrating problem.
yes very frustrating, but theres light at the end of the tunnel
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Dingz
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| posted on 11/5/13 at 04:43 PM |
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looking down the carb, when you open the throttle there should be a jet of fuel pumped in from the accelerator pump. is this happening? sounds like it
isn't if it won't start without an additional spray of starter fluid.
Sounds like it could be a fuel supply problem though with only enough fuel getting through to run the engine slowly, check your fliters and could
there be muck in the tank blocking the outlet? Could you rig up a jury tank and feed the pump fom that?
[Edited on 11/5/13 by Dingz]
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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ginamic
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| posted on 11/5/13 at 05:01 PM |
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good idea about the fuel supply, the filter has been checked at the carb end but i've not checked tank end or even if it has one lol.
yea when looking down the primary chamber there is a squirt of fuel when its given some throttle, this is when running and not running.
soon as it gets to 2k rpm the jet of fuel stops coming out and it just sucks air, big sucking noise then it will die unless you let off the throttle.
doenst matter if you're gentle with the revs or sharp on the gas it does the same?
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redturner
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| posted on 11/5/13 at 05:06 PM |
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We have run several FF1600s over the years and the 32/36 dgv 5 a is the only carb allowed. A brilliant piece of kit which never seems to go wrong. We
remove the power valve and the complete choke assembly without any problems, we stick massive jets in and never have a problem. What jets do you have
fitted, is the accelerator pump and jet clear. Have you checked the air correction jets. Have you checked the manifold to head joint is sound.....
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ginamic
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| posted on 11/5/13 at 06:00 PM |
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quote:
We remove the power valve and the complete choke assembly without any problems,
silly question...permanently?
i need to get into the carb and clean it out again (will be the fourth time) just to make sure, the jets it has in atm are 120/135 but it was 135/150,
i changed back to smaller to see if that was the problem. whats annoying it ran sweet and went like stink before the refurb!
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redturner
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| posted on 11/5/13 at 08:06 PM |
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Yes, permanently, don't need them and my engines start instantly and rev to 6800 all day. Bog standard 1600, just put together properly. You
are missing something so start from scratch by stripping it and put it together again, preferably with a drawing to show which jets go where, making
sure the air correctors are in the right place as well. PS, have you checked the colour of the plugs.
[Edited on 11/5/13 by redturner]
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steve m
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| posted on 11/5/13 at 09:06 PM |
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Ive been reading this thread for a while, and can only add, what i would do,
Please tell, what else was done when you took the carb off, and rebuilt it, any engine mods, or taken to bits ??
you havnt left any rag in the manifold?
Are you sure there is fuel in the carb? as you can only start the engine with easystart, and once that runs out, the engine stops
I would, in this order, take the fuel feed pipe off the fuel pump, and connect a new tube into a jerry can of new fuel
This eliminates, any fuel delivery problems
If this is still produces the same problems, I would remove the rebuilt carb, and stick another one on, and someone on here must have one lurking
about in their garage!
Otherwise, you will need to film the whole process, stick it on youtube/whatever, and us the collective, can see and hear what is going on
Our xflows are so basic, that any combination of sparks and fuel will make it run, !!
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ginamic
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| posted on 11/5/13 at 10:40 PM |
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ta for replies
quote:
PS, have you checked the colour of the plugs.
yes new plugs, all normal light brown. plugs were first check when the problem arose. its had new parts from plugs back - leads, dizzy, rotor arm,
points, condenser. even valve timing has been checked. all comes back to carb.
quote:
Please tell, what else was done when you took the carb off, and rebuilt it, any engine mods, or taken to bits ??
the carb had a new gasket kit fitted along with float valve, filter, o rings etc. and general clean out. there is definitely fuel in the carb, it will
idle all day but soon as the revs reach 2k it will die, and once theres some temp in the engine you can switch it off and it will start again without
the easystart.
it'll be off again and stripped to see if theres any rubbish hiding inside.
and i agree the xflow is dead basic, lovely to work on!
[Edited on 11/5/13 by ginamic]
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minitici
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| posted on 12/5/13 at 06:09 PM |
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Sounds like an internal fuel passageway has got some crud in it.
Take your air filter off and run the engine then choke off the carb with your hand until it just about stalls.
Do this a few times and the suction may dislodge the obstruction.
This has worked for me in the past.
If there is an improvement, strip the jets out and clean out the passageways again.
What is your cold starting procedure?
All engines are a bit different in their start up requirements and can depend on ambient temperatures as well.
Usually a couple of pumps of the accelerator, foot off the throttle then crank when cold will get a crossflow to fire.
May take a few repeats to get the engine to run for more than a second.
Once it fires a little choke could help.
I don't like churning them with the choke out.
[Edited on 12/5/13 by minitici]
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ginamic
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| posted on 20/5/13 at 06:09 PM |
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well its finally sorted, it seemed a combination of a loose venturi and blokage was the culprit.
took it apart and blew all the jets and crevices out, and noticed the primary venturi was loose too. pucnched it back in to keep it from rattling
around, reassembled and gave it a try.
started first time after a couple of twists of the gas and revved past the bog once it was warmed up
just need tuning up again now as its got a slight flat spot just as you give it sharp throttle.
i know there are plenty of tuning guides online, and i know the base settings, any tips on how to tune the weber so its just right?
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minitici
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| posted on 20/5/13 at 08:01 PM |
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Glad to hear that your got it running better.
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