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Posted: Wed Apr 25, 12 7:10 am
by Jon Connolly
Paul
I also have a Demon 650 that you can borrow if you like while you rebuild yours
Need it back, but if it helps you run the car the offer`s there
Posted: Wed Apr 25, 12 7:27 am
by autofetish
Posted: Wed Apr 25, 12 8:40 am
by ANTON
db I have a 650 double pumper that I only use at the NATs if you want to borrow it and that runs great on my small block.
Posted: Wed Apr 25, 12 9:47 am
by db
Thanks for the kind offers guys, thats three carbs i've been offered now! Adrian is local so I'll try his first. If I have no luck with mine or Ade's I'll shout out.
Will- there's some interesting stuff on those links. BG certainly split opinions!
Two things stand out-
These carbs take a lot of setting up but work brilliantly when they're right.
They're very susceptible to dirt, leaks, etc (possibly no more than any other good carb tho...)
Posted: Wed Apr 25, 12 9:57 am
by Pete
Any Holley-based carb has the same basic weaknesses -
The Needle assembly - either the soppy little "O" ring around the assembly which gets damaged or will flood if the needle is set too low, or the Tip which shrinks when not in petrol and then will not seal against the seat.
This results in flooding and inconsistent metering of the fuel bowls and leaks, usually out of the vent pipe but also into the venturi.
Also I have never liked the transfer tube on the smaller carbs, another problem waiting to happen.
Posted: Wed Apr 25, 12 10:32 am
by Dave-R
Sorry I missed the "fuel pouring in" bit. If fuel really is pouring in that is definitely the fuel bowl valves not seating.
Posted: Wed Apr 25, 12 1:40 pm
by db
Great, i'm glad thats a clear problem that i can fix easily and fairly cheaply. I'll see how it behaves after thats done.
This Holley seems to be very similar to mine, but mine has no air bleed screws and only two idle mixture screws.
http://www.holley.com/data/Products/Tec ... 6-2rev.pdf
This is a great read anyway, if you want to learn a bit about what the various components of the carb do and what effect altering them will have on throttle response, etc.
Posted: Wed Apr 25, 12 1:59 pm
by db
I dunno if you can tell from this crappy photo but my valves are different sizes.
Would this be intentional?
Should i keep them different?
Would the front or rear be bigger ( i didn't notice til i'd got them mixed up
)
Posted: Wed Apr 25, 12 2:13 pm
by Dave-R
The pin on the end doesn't matter. That is what the float pushes against.
It is the black plastic seal and seat in the middle that the fuel comes through.
Posted: Wed Apr 25, 12 2:38 pm
by db
The needles and the seats are different too Dave, sorry it doesn't come out well in the pics.
The one on the left has a larger bore and narrower needle.
There's no mention in Real Steel, BG or Holley info about using different sizes so i'll just get a matched pair.
Posted: Wed Apr 25, 12 2:40 pm
by Pete
They do 2 types - one is a high flow for grown up engines.
It should not be an issue as long as you can maintain the float bowls at the correct level without flooding.
If you constantly have to adjust the float bowl levels its a sure sign the assembly is kippered..............
Posted: Wed Apr 25, 12 2:43 pm
by Pete
Also make sure all the internal passages and air bleeds are free from blockages.
The other big mistake is using the wrong metering gasket that leaves the pump shot (I think) exposed which also causes flooding...2 different types of gasket that look similar..........one has a semi circular cut out in it that wraps around the power valve and causes flooding if used in the wrong situation.........
Posted: Wed Apr 25, 12 2:47 pm
by db
Real Steel list half a dozen Pete!
I'll get a full rebuild kit, but with this valve... if they ever answer the bleedin phone
Posted: Wed Apr 25, 12 2:48 pm
by db
Pete wrote:Also make sure all the internal passages and air bleeds are free from blockages.
The other big mistake is using the wrong metering gasket that leaves the pump shot (I think) exposed which also causes flooding...2 different types of gasket that look similar..........one has a semi circular cut out in it that wraps around the power valve and causes flooding if used in the wrong situation.........
Thanks, i'll look out for that
Posted: Wed Apr 25, 12 5:25 pm
by Mick
When i bought my 950, the needles were leaking all over the place, i replaced them and haven't had a problem since.
I ran that carb for a couple of years and never had a leak, standing for a long time doesn't help, especially, if there's any fuel left in.
Mick