carb spacer

[xt falcon]

a while ago someone said that to get the best out of a 600cfm holley was to use a 2inch spacer that spun the carb 90deg in rotation so that the primary side of the carb was close to the motor. i was wondering is this true and if so where would i get such a spacer.
thanks Aaron

 

[xctasy]

The answer depends on if you drive your car hard around corners or want to shut the bonnet!

On an XT, the carby spacer will just fit...the hold down bolt and choke horn are the issue. I've seen people put ADM 34 Webers on 250 2V's, and just mount an XW Phase I hood scoop on the right hand side. Perhaps you could do that on the left side of your XT?

AlloyDave has a similar under bonnet set up to you, and may have done a little work in this area, he could tell you about the space issues with a 465 Holley. Sometimes two people can sort out some of the issues better than one guy going it alone!

Personally, I think that a cammed alloyhead could do with a little more intake runner room if you have a big carb. Lots of show cars ands some drag cars run the carb the wa you decribe.

Cornering is a matter of worry, though. I think you'd need to foam fill the bowls, run a stand pipe and a facet scavange pump and mechanical fuel pump with restrictor jet like suggested in David Vizards Modifiying Ford SOHC engines book. (yes xe, do go on). That way it'd never flood. Try 600 bucks!

Ching ching. My 2.2 cents, plus GST!

 

[alloydave]

HEY XT , i think if your going to use a 2 inch spacer you might have to think about the scoop idea.Ive put a 2 barrell 500 holley on in place of my 465 for the moment .the carb adapter im using is almost 2" thick and its
to high .ive had to take out some of the rib on my bonnet to clear the air cleaner stud and my bonnet sits slighty high at the back just for a bit of clearance at the moment.The 4 barrell manifold i have is a redline 4 barrel. One idea to get your carby the way you need would be to get your manifold machined .get a shop to cut the top off then weld a new plate on the top with the bolt pattern in the correct direction then get in there with a dremel and clean it all up.You may need to look at the throttle linkage then as it may hit the intake runners .If your running an auto therewill be big probs on the kickdown side of things.Has your holley got centre or side hung float bowls?...maybe jet extension tubes could help?

cheers dave

 

[xt falcon]

ok thanks for the replys. it is not an auto so no kick down cabels. alloydave i don't know if my holley has center hung flost bowls or side mounted. i would have to pull it apart to see or is there another way? also what are jet extension tubes? and xecute what does foam filling the bowls require doing and also can you please tell me what a stand pipe and facet scavange pump are? thanks Aaron

 

[alloydave]

Aaron , you should be able to see if the float is centre hung by the location of the needle valve .Normally the if needle valve adjusting nut
is off to side the of the bowl its side hung ,and in the middle of bowl its a centre hung.Jet extension tubes fit on your jets ,they put the pick up of your jets to the centre of the float bowl.Basically this will ensure pickup of fuel when the fuel travels from side to side ,or front to back depending on the way your carb is mounted .Normally used in circle track apllication when gravity can take fuel away from the jets.Havent had much to do on the foam side of things ill let XECUTE run you thru that.
Looks like it might be time for a bit of panel beating on that dent on the strut tower

cheers dave

 

[xctasy]

It's a pleasure to baffle you with more BS. Here goes...

Here is a description for a floatless scavanged fuel bowl on a carb.The system employs two fuel pumps.

Fuel Pump One delivers fuel to the float bowl, where it is prevented from sloshing around by having fuel tank filler foam inside. A stand pipe in the float bowl has its top edge at the fuel level. Fuel rising above this level pours down the standpip and is drawn back into the fuel tank by a second electric pump. This system is very simple yet XTremely effective. (According to David Vizard, an offroad Baja racer with an OHC Pinto engine in the back could be stood on its nose and the engine would still run as if the car were horizontal. Fuel slosh was reduced to a point that the engine would run under any jolting and bouncing conditions that the driver could endure. Carburation was clean and precise despite racing conditions so violent that the driver suffered nose-bleed s and bloodshot eyes )

To make the system as effective as possible, there are a few points to note.

1. An electic pump far beyond the flow rate of the input mechanical fuel pump on the engine. This is a bowl to tank scavange pump. It prevents flooding as long as it flows more thn the input.

2. The incomming jet, located where the needle and seat valve used to be, needs to be sized according to a chart supplied with Davids write-up. This ensures the jet is sized to only just provide enough fuel into the bowl at full thottle. This reduces the amount of fuel returned to the tank to the bare minimum. The jet sizes form the chart are recorded here:-

Inlet pump pressure at 3 psi (21 kPa)
SAE
net
at flywheel HP
per float bowl
....................Restrictor jet size (chamfered at 45 deg each end, with 0.010" margin to ensure non-turbulent flow)
50 hp............0.040", 40 thou or 1.0 mm
75 hp............0.048", or 1.22mm
100 hp..........0.055", or 1.40mm
125 hp..........0.062", or 1.58mm
150 hp..........0.069", or 1.75mm
175 hp..........0.073", or 1.85mm
200 hp..........0.079", or 2.00mm

inlet pump pressure at 4 psi (27.5 kPa)
SAE
net
at flywheel HP
per float bowl
....................Restrictor jet size (chamfered at 45 deg each end, with 0.010" margin to ensure non-turbulent flow)
50 hp............0.038", 38 thou or 0.97 mm
75 hp............0.045", or 1.14mm
100 hp..........0.051", or 1.29mm
125 hp..........0.057", or 1.44mm
150 hp..........0.063", or 1.60mm
175 hp..........0.070", or 1.78mm
200 hp..........0.073", or 1.85mm

inlet pump pressure at 5 psi (34.5 kPa)
SAE
net
at flywheel HP
per float bowl
....................Restrictor jet size (chamfered at 45 deg each end, with 0.010" margin to ensure non-turbulent flow)
50 hp............0.034", 34 thou or 0.86 mm
75 hp............0.042", or 1.07mm
100 hp..........0.048", or 1.22mm
125 hp..........0.055", or 1.40mm
150 hp..........0.060", or 1.52mm
175 hp..........0.065", or 1.65mm
200 hp..........0.068", or 1.73mm

inlet pump pressure at 6 psi (41.3 kPa)
SAE
net
at flywheel HP
per float bowl
....................Restrictor jet size (chamfered at 45 deg each end, with 0.010" margin to ensure non-turbulent flow)
50 hp............0.032", 32 thou or 0.81 mm
75 hp............0.040", or 1.02mm
100 hp..........0.046", or 1.17mm
125 hp..........0.051", or 1.29mm
150 hp..........0.058", or 1.47mm
175 hp..........0.061", or 1.55mm
200 hp..........0.066", or 1.68mm


*Scource:How to Modify Ford SOHC Engines (Pinto/Cortina/Capri/Sierra 1.3- 2.0 litre 1970 to 1982) by David Vizard, published 1984 by Fountain Press.

Page 167, Off Roading the Pinto Engine

ISBN 0 86343 9856, Dewy Decimal No 629.2504 Viz

Unkindly Used without Permission

 

[xt falcon]

ok thanks, for now i am just going to put a spacer on and maybe turn the carb a bit later.

Aaron