Wreck to Race.

[Jarred]

I know what it is now! found out straight from the horses mouth! (so to speak)

It's great. Never would have thought of it though!

[AUC-05L]

im gonna have a punt and say a thermos.....(spelling??)

keep up the good work.

[GoLfMan]

i recon it was a pretty successful day out, more of a test and tune for the new motor than full out racing but ill let Pete fill us in on it

[Peter Jones]

Great Fun. Thanks to every one who turned up to help out or just to ay hello.

I learnt some stuff about tuning Dellortos today.

A Summary.

First Run
All seemed to be working well.
Experienced loss of power after about 2 laps and retired.
Temps were high but still OK
No fault found in pits.

Second Run.
Seemed a little down.
Red flag after on lap due to an MX5 taking an off road excursion.
Restart Race.
Three Laps in and the car dropped more power and was way too hot.

Third run.
All seems OK after cool down.
Idles a little rough.
Take it out anyway.

Poor Power
Pull it off field after warmup lap.


Diagnosis time.
Suspect Lean condition
Pipe white.
At this stage cooling it doesn't fix idle, it's worse than before.
Now I'm thinking I've burnt a valve and I'm ready to call it a day and go and watch some racing as the car can still be driven home.

Let it cool a bit and pull the plugs just to confirm the lean condition.
Two plugs were stuffed in a way that only pictures can describe.
Well at least the head doesn't have to come off. I packed a spare set of plugs too!

Now to fix the mixture issue. The collective wisdom of the pit crew - Josh figured that the main jets were probably 1.4mm being 140s so I jumped in car and headed to Bunnings (just accross the road) and grabbed a pin vice and 1.5mm and 1.59mm drill bits and upsized the main jets to 150 right there in our field workshop (tent)

Back together again and back out with ot missing a round

Round 4
Better but now the bigger jets are causing fuel starvation as the pump can't keep up.
Actually finish the race! Woo Hoo!

Pit side the pipe still looks a bit light and the plugs look a bit too clean so we drill it to 159.

Round 5
Better again.
Fuel starvation still an issue of course.
5500 rpm and it simply runs out of petrol - New pump required.
Another Red flag finished the race 1 lap early.

All in all a great day, there's still a lot more tuning required, but there's potential there.

The carbs make fantastic race car noises.

I think my best time of the day was a relatively slow 1.52 but once I've got it running right I'm sure it will do a lot better.

Now for the spark plug of doom pics. I didn't think you could burn ceramic......

[Peter Jones]

[Peter Jones]

A few more just for fun.

[Preen59]

Nice work, Pete! Good to see you figured out your problems.

Those plugs are pretty bad but that's why you have spark plugs.. So you can burn them out before you burn a piston! (Unfortunately not always the case!!)

Atleast you went forward progress wise..

[ontarv]

nice
good job on the plugs
cutting it pretty fine though

[Jarred]

HAHAHAH

bugger about those plugs!

Sounds like Josh was right for once, the jets were too small!

I think a high volume low pressure pump, would be the go. Unless you ran the twin pump/twin lines. even then the HVLPump would probably be best. apparently.

It' does sound great though!

[Peter Jones]

I'm still not quite sure about the fueling rate of the the monoblock pump. It should flow 30 gph @ 3.5psi.

As always I went for un-ambiguous overkill in the search for a solution.

First I mounted up a fuel pressure guage. I may or not leave it there, it's only for tuning puposes.

The little facet style pump measuered in at 3psi.

So I fitted up a Carter rotary vane pump capable of 72 gph @ 18psi !

It took a bit to get the air out of the system, when I did the pressure came up to 6 psi which I've since been told is the ideal pressure for the Dellortos. A quick flow check had it fill a 5L jerry can in only a couple of minutes. Theoretically @ 72 gph that pump should empty a Golf tank in 6 minutes. (Probably need 1/2" lines to do it though). That should do the trick I think.

A story is nothing without pics.





There's not many places you can put a pump this big!









Pete