Hi all,
I've recently put a stroked 308 in my Torana, (offset ground holden crank, hemi rods, chev pistons.. 333ci)
The past couple of months have been spent sorting out all the teething issues associated with fitting a V8 thats been sitting around for 8 months into a previously 6cyl Torana.
The motor is now running well and the car is driving beautifully, but when I try to have some fun I've been facing fuel issues.
At wide open throttle, (only when the secondaries open up) it will accelerate hard and then die in the ass, or cough a bit and then go hard again.. it feels like its not getting enough fuel.
This is a very healthy motor and should be putting out 400hp+ at the flywheel once I sort it out, I'm running a Rochester Quadrajet on it.
I bent up a 3/8 steel fuel line that runs from the drop tank to the engine bay, which should be sufficient.
What do I have to do to sort this out?
Replace/upgrade the mech fuel pump?
Play with the fuel level/float in the fuel bowl?
In what location should the fuel filter be? - I currently have it fitted very close to the carby.
Sledge
Fuel supply issue - 333 Stroker motor
Started by
_SLEDGE_
, Feb 05 2012 06:26 PM
30 replies to this topic
#2
_Mint_
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Posted 05 February 2012 - 07:28 PM
Jack..i'm no expert on the quaddy(holleys yes)but it may have to be tuned..i've heard the secondaries sometimes wont open fully on quaddys?
you said 3/8" tube ..do you mean od?..so it's 5/16 id.imo you need 3/8" id tube or hose and a hv pump ..stocky holden pump runs 3-4 psi not enough..hv pump runs 7 psi
or you could get electric holley blue with reg or a carter black..plenty of volume then..which is what i'm thinkn of doing
Tim
you said 3/8" tube ..do you mean od?..so it's 5/16 id.imo you need 3/8" id tube or hose and a hv pump ..stocky holden pump runs 3-4 psi not enough..hv pump runs 7 psi
or you could get electric holley blue with reg or a carter black..plenty of volume then..which is what i'm thinkn of doing
Tim
#3
TerrA LX
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Posted 05 February 2012 - 08:27 PM
If there is not a blockage in the carby then I would be looking at the tank for surge issues.
Try again with a full tank.
Try again with a full tank.
#4
_SLEDGE_
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Posted 05 February 2012 - 08:48 PM
Jack..i'm no expert on the quaddy(holleys yes)but it may have to be tuned..i've heard the secondaries sometimes wont open fully on quaddys?
you said 3/8" tube ..do you mean od?..so it's 5/16 id.imo you need 3/8" id tube or hose and a hv pump ..stocky holden pump runs 3-4 psi not enough..hv pump runs 7 psi
or you could get electric holley blue with reg or a carter black..plenty of volume then..which is what i'm thinkn of doing
Tim
Thanks for the reply. The secondaries are opening up completely and the engine pulls very hard for a couple of seconds and then seems to run out of fuel. It used to have a 5/16 line but I changed it to a 3/8 id line. And it has a HV mech pump. I'm having a look at electric pumps now.. I didn't think I would have to use one but maybe I will.
#5
_SLEDGE_
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Posted 05 February 2012 - 08:52 PM
If there is not a blockage in the carby then I would be looking at the tank for surge issues.
Try again with a full tank.
That's a good point.. I havn't checked for blockages. I'll start with the filter.
Its a brown davis tank, but is just the standard holden pickup and fuel guage...
I'll see if the same thing happens with a full tank! (i'm pretty poor at the moment and I don't think I filled it up more than half full haha)
#6
_Mint_
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Posted 05 February 2012 - 09:03 PM
sounds like fuel starvation..the stocky holden tank pickup was a 5/16 tube (1/4 id)..tiny..unless youve got an A9XIts a brown davis tank, but is just the standard holden pickup and fuel guage...
so affectively that nice 3/8" tube you bent up now becomes 1/4"
#7
_LH SLR 3300_
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Posted 05 February 2012 - 09:10 PM
I'd be investigating the carbaretor a little more closely. I know of a genuine 500bhp 304 powered Torana that recently ran an 11.2@124mph using a standard 5/16" factory fuel line, standard Torana fuel tank,OZRACE mechanical pump & 750HP Holley & it had no fuel issues to my knowledge. My point is, it could me a tuning issue more so than fuel delivery & it might pay to check this out before throwing coin at parts etc it may not need. JMO
#8
_SLEDGE_
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Posted 05 February 2012 - 09:12 PM
sounds like fuel starvation..the stocky holden tank pickup was a 5/16 tube (1/4 id)..tiny..unless youve got an A9X
so affectively that nice 3/8" tube you bent up now becomes 1/4"
not so.
the effective inside diameter of the fuel line is the average of all the different sized pipes over the whole length.. if that makes any sense.
having a short part of the line with a smaller diameter won't restrict flow
#9
_SLEDGE_
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Posted 05 February 2012 - 09:14 PM
I'd be investigating the carbaretor a little more closely. I know of a genuine 500bhp 304 powered Torana that recently ran an 11.2@124mph using a standard 5/16" factory fuel line, standard Torana fuel tank,OZRACE mechanical pump & 750HP Holley & it had no fuel issues to my knowledge. My point is, it could me a tuning issue more so than fuel delivery & it might pay to check this out before throwing coin at parts etc it may not need. JMO
Any pointers as to what I should investigate?
Needles? fuel level in the bowl?
#10
_LH SLR 3300_
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Posted 05 February 2012 - 09:35 PM
From memory these carbs are vaccum opertated secondaries, i'd start there checking the linkages aren't worn etc & the diaphragm is working as it should. I think these carbs are very sensative to vaccum changes etc too, i had one that had been internaly modified on a worked 308 & i could never tune it quite right i believe because of this. I'd be finding someone who knows these carbs & if possible getting them to check it out, sorry i can't of more help.
#11
_Mint_
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Posted 05 February 2012 - 09:50 PM
i believe it willhaving a short part of the line with a smaller diameter won't restrict flow
#12
_SLEDGE_
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Posted 05 February 2012 - 09:51 PM
From memory these carbs are vaccum opertated secondaries, i'd start there checking the linkages aren't worn etc & the diaphragm is working as it should. I think these carbs are very sensative to vaccum changes etc too, i had one that had been internaly modified on a worked 308 & i could never tune it quite right i believe because of this. I'd be finding someone who knows these carbs & if possible getting them to check it out, sorry i can't of more help.
They are mechanically operated secondaries, however they do have a vacuum brake which restricts how quickly they open up.. and they seem to open fine so don't think they're the issue.
Definitely sounds like I need to have a closer look at the carb though, or for surge issues in the tank
#13
_SLEDGE_
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Posted 05 February 2012 - 09:57 PM
i believe it will
that small diameter is over a very short distance in comparison with the whole length of the fuel line. and so the restrictive effect it does have will not be noticeable.
One way to show this, is by getting two drinking straws - 1 of them 15cm long and the other just 2-3cm long.. and blow as hard as you can through each.
your lungs will empty much quicker blowing through the shorter straw
#14
_Mint_
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Posted 05 February 2012 - 10:08 PM
Jack..as a quick test you could remove the fuel filter altogether(for a short time) just to see if that makes any difference
i myself have a filter boss that takes a screw on type filter so it's larger capacity an no restriction
still sounds like fuel supply to me now that youve got more horseys where as before it may have just kept up?
i myself have a filter boss that takes a screw on type filter so it's larger capacity an no restriction
still sounds like fuel supply to me now that youve got more horseys where as before it may have just kept up?
Edited by lxssv8, 05 February 2012 - 10:09 PM.
#15
_Liam_
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Posted 05 February 2012 - 10:35 PM
Sounds like your float needle needs to be reset, and tune the carby.
There are Quadraject Tuning books available.
There are Quadraject Tuning books available.
#16
_ljxu1torana_
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Posted 05 February 2012 - 10:37 PM
yeah right doing those times with a mechanical pump and 5/16 fuel line.I'd be investigating the carbaretor a little more closely. I know of a genuine 500bhp 304 powered Torana that recently ran an 11.2@124mph using a standard 5/16" factory fuel line, standard Torana fuel tank,OZRACE mechanical pump & 750HP Holley & it had no fuel issues to my knowledge. My point is, it could me a tuning issue more so than fuel delivery & it might pay to check this out before throwing coin at parts etc it may not need. JMO
#17
fuzzypumper
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Posted 05 February 2012 - 10:45 PM
My Brothers Torrie did the same thing, had a quady (pre Pollution) drive it hard WOT, and it would die like some one switched the ignition off,
yhen could come alive 1-2 sec later.
You couldnt do a successfull 1/4 mile run without it happening.
A few things to check:
Remove the fuel filter in the front section of the Quaddie( this is sometimes forgotten and often blocked)
Make sure your float level is high enough ( rochester bowls are small volume ).
Try another carby all together.
Fuel hose kinks.
In his case it was the filter in front of carb and kinked fuel hose at tank ( diff tunnel).
yhen could come alive 1-2 sec later.
You couldnt do a successfull 1/4 mile run without it happening.
A few things to check:
Remove the fuel filter in the front section of the Quaddie( this is sometimes forgotten and often blocked)
Make sure your float level is high enough ( rochester bowls are small volume ).
Try another carby all together.
Fuel hose kinks.
In his case it was the filter in front of carb and kinked fuel hose at tank ( diff tunnel).
#18
EunUCh
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Posted 05 February 2012 - 10:57 PM
Has any one ever measured the ammount of fuel that a stok fuel pump will flow?Plds /hr
and then dun the numbers on how much fuel is required/HP
Dont be ripped off by the big numbrs.454 chev used a quady. and the flaps on top of carb do not open
to "full",they are vac. operated and it is adjustable.
and then dun the numbers on how much fuel is required/HP
Dont be ripped off by the big numbrs.454 chev used a quady. and the flaps on top of carb do not open
to "full",they are vac. operated and it is adjustable.
#19
_Quagmire_
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Posted 05 February 2012 - 11:05 PM
it may also be "flooding"
take the carby in for a tune if you don't have the knowledge..
take the carby in for a tune if you don't have the knowledge..
#20
_Liam_
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Posted 05 February 2012 - 11:15 PM
That's what my Holley used to do. Broken float.
#21
_LH SLR 3300_
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Posted 06 February 2012 - 03:23 AM
yeah right doing those times with a mechanical pump and 5/16 fuel line.
Forty or more people witnessed it at the GMH-Torana forum drag day at WSID last october.Brown LX hatch built by Hercules Competition Engines. I know the owner of the car & i know the car & it also ran that time with a manual trans & 3.7 geared diff.
#22
_oldjohnno_
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Posted 06 February 2012 - 05:47 AM
I'd be investigating the carbaretor a little more closely. I know of a genuine 500bhp 304 powered Torana that recently ran an 11.2@124mph using a standard 5/16" factory fuel line, standard Torana fuel tank,OZRACE mechanical pump & 750HP Holley & it had no fuel issues to my knowledge. My point is, it could me a tuning issue more so than fuel delivery & it might pay to check this out before throwing coin at parts etc it may not need. JMO
Agreed, you don't necessarily need a monster fuel line. The first thing I'd be looking at is the little filter in the carbs inlet fitting (if it's still there), as fuzzypumper suggested. If that checked OK then you could temporarily tee in a pressure gauge just to verify that the pressure was remaining high enough at full throttle.
The quaddies use a spring loaded flap in the secondaries and if the spring tension is set too low they will bog, just like a vac. secondary Holley with a too-weak spring. You get a big hesitation for a second or so before it runs normally.
#23
Struggler
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Posted 06 February 2012 - 08:17 AM
Checking the weezy filter and float level first is good advice.
This is a common problem with a Q jet and mechanical fuel pump. The Q jet bowl isn't big enough and the pump isn't good enough !
The mech. pump will work fine with a Holley as they have a larger fuel capacity. I use a Pierburg electric pump with my Q jet and have no starvation issues.
This is a common problem with a Q jet and mechanical fuel pump. The Q jet bowl isn't big enough and the pump isn't good enough !
The mech. pump will work fine with a Holley as they have a larger fuel capacity. I use a Pierburg electric pump with my Q jet and have no starvation issues.
#24
Peter UC
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Posted 06 February 2012 - 11:29 AM
If you read the specs on the car LH SLR 3300 mentioned, you will see that it does not have a standard mech pump, but one made from OZRACE, that pump will cope easily.
#25
View GaragePosted 06 February 2012 - 06:16 PM
Its normally as simple as that (and quite common), a fuel pump upgrade does wonders (referring to the original poster's comment about having a mechanical pump here)This is a common problem with a Q jet and mechanical fuel pump. The Q jet bowl isn't big enough and the pump isn't good enough !
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