Clevo120Y

No worries Gerg, I have one word for you that explains the down size in fuel jet, EFFICIENCY!! Your carb is now more efficient and your engine requires less fuel to make the same power, the booster signal will be cleaner etc etc. this is why when people say that if you have more airflow you have to add more fuel but it isn't always the case, an efficient motor will use less fuel for more power and that's in the forefront of my mind when I do my little experiments.

No worries Gerg, I have one word for you that explains the down size in fuel jet, EFFICIENCY!! Your carb is now more efficient and your engine requires less fuel to make the same power, the booster signal will be cleaner etc etc. this is why when people say that if you have more airflow you have to add more fuel but it isn't always the case, an efficient motor will use less fuel for more power and that's in the forefront of my mind when I do my little experiments.

No worries Gerg, I have one word for you that explains the down size in fuel jet, EFFICIENCY!! Your carb is now more efficient and your engine requires less fuel to make the same power, the booster signal will be cleaner etc etc. this is why when people say that if you have more airflow you have to add more fuel but it isn't always the case, an efficient motor will use less fuel for more power and that's in the forefront of my mind when I do my little experiments.

This mod was inspired by Stumper's thread on Street Stock Speedway and the carby mods he's done. When i had my 4011 Holley apart the other day, I noticed that the barrels had some pretty rough casting marks and misalignment between the top and bottom halves of the Venturi.

Might not show there but it's like they took the safe approach with their mouldings and made the top half slightly narrower than the bottom (so there's no chance of any ledge jutting out) with a distinct inward ridge all round. I looked at the finish and all i could see was turbulence and restriction, yet on my little 302 it probably wouldn't make any difference, or so i thought. Regardless, i just couldn't help myself...
 
Anyway about 10 min with my little Dremel and this is the result:

 
So i slapped it all back together and did notice a smoother transfer to main circuit but was a little doughy up top compared to before. I figured that more air was flowing around the booster instead of through it, so less fuel was being pulled out and needed more jet to compensate... So i thought (again). Chucked in some 70s up from 67s and it went worse!
 
Yesterday i chucked in some 64s and was slightly better, so today i thought I'd go way down to 61s and blow me down, it's going pretty good! Maybe the extra flow is giving more velocity and more booster signal, so it draws fuel harder. Hard to tell what's the go in this hot humid weather but it's fine for now.
 
What I'm trying to say is that messing with fiddly things like carbies can be trouble and can give you the opposite result to what you expect, but if you're keen to learn then this is the only way.
 
And thanks Stumper for showing what can be done with a bit of man-shed engineering

Thanks for the help fellas, my fuel pump is pumping fine but I found the smallest piece of crap in the carby needle today. Pulled the jets and venturies out and they were spotless but a piece of crap the size of a piece of glitter was hiding in the needle & seat so carb was prob flooding causing it to run like crap. Went for a test drive, thrashing it on petrol and it seems to be fine now

be wary of pumps on ebay guys
 
have heard very bad stories of guys who have bought what they thought were genuine bosch 044's and they only lasted 3 months

In the video he is setting preload by pitch of the thread. If you know the thread pitch is, for example, m10x1.25, then you know 1 full turn is 1.25mm, which will give you your preload. remember the fulcrum when setting preload this way is the valve stem and the effort is the rocker nut. The amount of preload will be affected by the rocker ratio. If the ratio is 1:1 and you move the point of effort (the rocker nut) downward 1mm then the load (preload in this case) will move down 2mm.

If you want to set up preload properly, install the rocker to zero lash like in the video, then stop. Get a metal rule and place it across the top of the head, where the rocker cover gasket usually sits, so that it sits against the pushrods. Get a paint pen/white texter and mark roughly this position with a fat line. Then use the rule again, at zero lash and mark a line on the pushrod with a sharp scribe. 
Then tighten the rocker down. Again use the rule to mark a second line on the pushrod. The distance between these 2 lines is your preload. Typical preload is .020-.060" or 0.5-1.5mm

 

Will do, I was just looking at a manifold and I think I will knock something up, it will have 3 webber mounts so an adaptor to a strommy would be needed.

I'm considering the idea, I might look at putting something together just to see if it can be done properly hmmmm brain is going now hahaha

I'm considering the idea, I might look at putting something together just to see if it can be done properly hmmmm brain is going now hahaha

I'm considering the idea, I might look at putting something together just to see if it can be done properly hmmmm brain is going now hahaha

I'm considering the idea, I might look at putting something together just to see if it can be done properly hmmmm brain is going now hahaha

I understand that different bit bro for sure. But you need to use a good set of carbs that meter well yet flow enough to work. I mean my engine has around 1600cfm of air potential thru the carbs so would 3 pissy strommys really work ?

Belive me theres not many who have tubbed 4 linked and fitted a 5500 stall to a 6cyl powered anything so I know about the want to be different.

What do you guys think of using a manifold like an aussie speed or something in that shape. Cut of the single carby mount and area under the carby. The cut the outside of the runner for 1&6  leaving the top and bottom untouched down to around were 2&5 runners. Then make a new section just like the carby mounting section that was cut out but so that it mounts the 3 carbies. I would envisage the carbies would be mounted fairly high so that you could have enough volume under the carbies for all three carbies and to allow for tapering to the outside runners for smoother air flow. Sorry for the really basic drawing but hopefully you get the idea. Clearly the drawing isn't to scale as the carbies would take up a lot more room but do you think this might be plausible. I know the weight of the carbies may be an issue.

 

cross weights will be the most important thing and to actually know where the car is at will be equally important. 
 
Even with all the adjustments I had on offer to me with my modified - most of my fine tuning on the scales was done with tyre pressures and sizes.  I know 'race rubber' reacts way quicker to air pressure changes than radials, but there are still solid gains to be had by scaling any race car - if you know how to interpret the data and make changes to suit.  that is the complex bit - but oh so rewarding when you get it right. 
 
don't forget the scales also tell you left, right and rear percentage - all critical data - especially for a car that has to go around both ways.   

There is the problem - bloody GM shit not mixing well with ford. Bahahahahaha. Nah agreed - idler pulley required on the back side of the belt to stop flexing.

Feel free to ring me when you are at the scales. don't forget to take a pile of different size tyres and the tyre pressure gauge that you use at the track. Oh this is going to be good....

We are finally getting the car scaled and suspension setup in the next 2 weeks, thank god for that haha

Yeah you get nights like that - everyone wants to be 'the man'.  That's how is was the first meeting up here last year when I got fenced, which wrote off the car.  Dead set you think they are racing for sheep stations some times. 
 
Ok well with some more seat time I'm sure Wombat will feel the difference in the car.  Good luck. 

Good Onya Stumpers, good to see ya keeping the only flying Wombat in Australia going. Rubbin is Racin......
 
Jack.

Good to see ya still kickin along Stumpers. keep those Perth boys on their toes.........
 
jack.

$4 at the bearing shop for a 2" a section pulley and 2 seconds on the lathe to bore the centre out to 9/16 then a longer 9/16unf centre bolt from the bolt shop (maybe another $4) job done. 
 
As to the cars looking like junk - a wise man once said "They all look good with the chequer" and I'm sure both are not that far away from a couple of solid feature wins once the drivers get a bit more seat time.
 
Fletchers Q1 XF has only recently started to look reasonable - it used to look like junk and was lucky to finish a meeting with a panel still on it - but damn its fast.

Cheers Ando, the only problem with this "race team" is that Wolfy owns the local wreckers so the car is put together with wrecker parts lol so yeah 25 spline axels, some sort of ribbed belt setup on the front hahaha, the guy is a great bloke but he won't spend money if he has something in the junk pile ☺️

Yeah mate and she has more to give, he wasn't even pushing it, Wolfy said he didn't give it more than 70% throttle as he is still getting used to it. When you listen to the vid the other drivers are flogging theirs and the old boy is hardly on it hahaha. The blue car in front and the White one that came third (Wolfy ran second in that race and right up the arse of the blue one) they both are BIG $$$ cars from Perth that came down to have a run because the state titles are at the Albany track this year and the XF ran with them no worries and faster down the straights than both of them, the XF actually posted the fastest lap time in that race, Wolfy just isn't stringing enough of them together yet to be dominant.
Anyway the night went like this, heat 1 the car didn't make it out as it snapped an axel in the pits lol so heat 2 is the vid above and ran 2nd, heat 3 he ran 3rd behind the 2 Perth cars, he got back in the pits and said it was loosing power in the corners, found the reason, his pit crew were too busy celebrating how the car went in the last heat they didn't put any fuel in it so the car was sucking air in the corners hahaha I try to make my engines efficient but they can't run on air alone

Here is a vid of last night, just a short one of the first few laps, the new engine flies and I was pumped to see it in person, a great result for the first stage of the tune with more development to come on this one. I will tell more of last nights run later tonight. Enjoy