really bad takeoff in 1st gear.

[Mustardxf 29]

Hey guys I took my xf for its first drive with the new motor today, everything was great apart from taking off. 
 

There seems to be a major flat spot somewhere when trying to take off, I really need to get the revs up and once the clutch is out its hard to keep the revs up. Once its moving its fine and shifting into 2nd is so much better.

Its running a 600 vac secondaries Holley which I think might have something to do with it,  don't know the jetting size!
Its a 4 speed single rail with the standard 2.77 diff, I thought the gearing of the diff might have something to do with it as well.
Motor has 10.5:1 comp with a large cam.

Any help is appreiciated and If you have run a 600 on a crossflow before how did you have it setup i.e. jet sizes etc.

[wagoon 2,429]

Cant help with details but the people that can will need to know specific details like

Actual cam details? Unfortunately "big cam" doesnt mean much

What exhaust are you running? Thats extractors and pipe size

What size airfilter are you using?

What fuel pump are you using?

What is the rear tyre size?

Is clutch new and what?

What is your ignition setup?

Im sure I have missed something but the fella will correct

[PRO250 1,506]

64 jets will be a good place to start. pump shooter size and how its setup will also play a big part in the flatspot it has

What is the static timing set at? this will also play a very big part maybe advance the timing up 4 or 6 degrees and see if its better (do not boot it like this you will damage the engine) your only seeing if it is a dissy issue over a carby problem don't load or rev the engine past say 2000rpm your just seeing if its better or not and if the dissy needs a tweak

The gears is another issue but how big is the cam? over 250@50 would be considered "large" if its a 230@50 it should be able to pull the gears althow not as well as say a set of 3.5 gears

 

[Mustardxf 29]

The cam is a cam tech custom grind, unfortunately I didn't receive the cam information when I got the engine I know it has .577 lift. I believe it is more then 250@50, I told the engine builder I would be running 3.45s so he could get the right set up. 

No pipe on it but Its got Pacemaker extractor 6-2-1 2.5inch and its got about a 2 foot pipe on it as well, think 2.5inch.

Standard Mechanical pump 

225/60/15

 

New upgraded clutch, heavy duty 

 

MSD street fire box, Blaster 3 coil, 9mm street fire leads, Vac advanced dizzy 

 

the Pump size is a 25 

3 degrees is the static timing, advances to 35, the timing was done buy a speedway guru who runs methanol crossflows 





 

[gerg 10,871]

3 degrees is really, really retarded especially for a cammed motor like this. I'd start with at least 10 and go from there. Some have run 30 locked with big cams, crank no worries.

 

What kind of single rail are you running? There were at least 3 different gearsets available for Fords. Carby 6 had the shortest 1st gear, then Efi/302, then some 351s had some really wacky tall 1st gear like 2.6 or something.

 

Tall diff gears and a heavy car need a big pump shot. Maybe go up a squirter size, particularly if it is a cammy motor with poor low-speed vac signal.

 

Go over the basics like pump cam adjustment (must squirt instantly you touch the throttle) and float level (if adjustable). I'd think that raising it a tad would help bring the fuel on a bit sooner if that's what it needs.

 

Is it a stock, unmodified Holley?600 is a big carby for a 250, so it might be a headache to dial it in. Not impossible though.

[Mustardxf 29]

was pinging on 6 degrees.

 

carbied 6 single rail 

 

Ive adjusted the pump lever so it squirts instantly, and float levels are right. I have a 31 squirter here that I'll try tomorrow

 

stock 600

[gerg 10,871]

31 might drown it but one way to find out i guess.

 

Pinging on only 6 degrees base means your curve must be wrong. 35 total sounds like too much to me. 30 sounds more like it, with an initial of say 12. This means your dizzy curve needs graphing back so there's only 18 deg of mech advance as opposed to the 32 it has now. Could you try plugging in the vac advance to full manifold vac instead of ported (only for diagnosis sake)?

 

My 302 clevo has the equivalent of about 20 when cranking and idles beautifully on about 35. All- in it takes 45. I have MSD programmable though. Cam is smaller than yours (in lift anyway) and my comp is probably only a bee's dick more than stock, but crossies are more sensitive to timing, all other things being equal.

[Mustardxf 29]

ahh alright, Ill play around with the carb and gearing to see if that helps, And then it doesn't Ill get the dizzy and timing looked at!

[Outback Jack 6,352]

Hey Colonel Mustard,

Just finished an xf with msd and 600 holley.

Works but as stated above 600 holley is too big.

Can get it to run but will always be rich.

Start with your timing.

You need to get motor to sit at 30 degrees advance timing.

Then the msd is actually a retard device, it retards a lot at low revs and less at high revs.

 

Idle timing on graph starts at 10-12 degrees and goes up roughly 2 degrees every 500rpm. That will give you a basic curve.

Do that before playing with carb.

Personally I would go 350 holley if you cant get it to run right with a lumpy cam.

Curve info supplied to me by ando76.

If you have questions can ask Ashxf too, that's who I fitted MSD for.

 

Takes more than just replacing jets to get 600 flowing less fuel.

You will need to do a vac test so u ou can work out what power valve you need as well and which spring in vac secondary it needs to be.

 

Jack.

[gerg 10,871]

And I'll add that you'll struggle to even get the secondaries open on an engine that size. Might start opening at around 4000 even with the lightest spring, by which time everything else is topping out. A lot of blokes running a 4-barrel on their crossy use double pumpers.

[Mustardxf 29]

Yeah starting to think Ill run a different setup for the carb, any recommendations on carb sizes, brands etc?

[slydog 7,873]

600 will be fine but I would suggest a TFI dizzy conversion first and throw that POS electronic thing to hell.What is the cyl head? 10.5 comp with 250 cam is perfect IMO.Just needs to be tuned right.Time for a dyno tune with blinders on and forget about what on the car and tune the bad running out of it.

 

2.77 gears and a rail and it will NEVER go well btw. Them gears are waaaaaaaaaaaaaaaay to high. Even 3.23's will be too high for that combo.

[Mustardxf 29]

Yeah Been thinking about going TFI, the head is a c2 flows 350hp.

yeah I have a 3.45 el xr6 diff Im getting for it so thats not a problem.

[slydog 7,873]

Hows the chamber look though,that could be your detonation issue right there. If its has a wide lobe sep it will help make it a rattler too. 

 

3.45's are good but if you can I'd even go 3.7's or 3.9's TBH as a 250 camshaft is a fair chunk of stick.

[Mustardxf 29]

50 cc chambers, I have pictures of the whole head if needed, its a solid cam as well. 

Yeah Ill try the 3.45's and see how they go.

a 31 squiter was to big, I put the25 back in and it was way better.

as stupid as this may sound I think the throttle cable my of had something to do with this shitty throttle response, I was playing around with it last night and just fired it up to test the squirts, much better on take off and was even spinning the tyres with a little bit of brake, it wouldn't of done that yesterday.

[slydog 7,873]

Yes need to SEE the chambers as that can tell you straight away.

 

Squirters would be around 29 to 31 if it were mine too but the size of the PV has abit to do with it as well as the jetting.

 

No that isn't stupid at all,happens more than many admit too. 

[Mustardxf 29]

 

[slydog 7,873]

OK now the common thought for these cyl heads in performance applications is to lay the back of the chambers down especially over the exhaust side.The sharp point has been removed which is very good but the chambers could be suffering from quench area perhaps creating a rattle down low.

 

Swapping gearing and going to a TFI WILL help and may even take the issue away. They do look good and very well prepped TBH over all and hopefully a solid ignition system can solve alot of the issues.

[Mustardxf 29]

Cheers for the help sly(Y) 

will find a TFI dizzy for it and will change the gears to 3.45's 

 

heres a clearer image 

[wagoon 2,429]

Looks to be a nice bit of work that has gone on there like Sly said. The only thing I have seen done extra is in the pic on the top leftish side the sharp edge removed by laying it back a bit on an angle. From my understanding this sharp point is where heat builds in the metal and causes pinging due to fuel igniting on the hot metal instead of the spark plug igniting it.

Definitely sounds like a fun engine you have there and hope you can get a handle on it and give it a good go. Plus we will need a vid of the car running when you get the chance.

[Mustardxf 29]

Here is a couple videos 

 

[slydog 7,873]

Looks pretty tidy bruz.Good luck with the tune but it sounds like it will be alot of fun when going.

 

Cyl head doe's look like some one has spent some real time on it and it will be a good thing.

[Mustardxf 29]

Yeah pretty clean old boat, yeah once the tune and diff gears are sorted should get up a boogy.

 

The lad that did the head was happy with himself and the engine builder was extremely happy with it as well. Now it has the slydog approval (Y)

[slydog 7,873]

Oh keep my name out of it or it will catch "annoy the hell out of you disease" and never go right ! 

[Mustardxf 29]

HAHAHAH, With my luck it probably already as that disease