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engine starting problem.. SU's

Started by _draglc_ , Apr 10 2006 09:00 PM

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13 replies to this topic

#1 _draglc_

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Posted 10 April 2006 - 09:00 PM

Ok, ive posted about this before, but the problem is still here...

engine specs:

202 + 40thou, flat top pistons, blue rods, nitrous cam .238 & .248 @ .50, 1.6 inlet & 1.5 outlet ratio roller rockers, big $$ 186 YT head big valves, screw in studs and guideplates, straight cut gears, triple 1.75 HIF SU's, 2.5" exhaust, elec dizzy and splitfire 8.8mm leads, carter electric fuel pump.

Now the problem. I can crank the car over for a minute, before my battery starts to die, but the carbs dont get any fuel. They are the HIF design, with the integrated fuel bowl. I let the carter pump go for 5 seconds, then try to start and it will splutter once, then just turn over for ages, and ages, until it starts to get fuel. But thats usually after my battery dies. If i spray a shitload of 'Start ya bastard' down the pcv into the manifold, itll fire, and run dodgily and eventually get going, though it sounds like its running on 5 cylinders.

The carbs were tuned a month or so ago, but they do need another tune, but i dont think thats the problem. They DO have oil in them, singer sewing machine oil.
The timing is set at 14 degrees advanced, could that be the problem with a high compression engine (10.5-1)? If the engine is warm/hot, it will start instantly. Its only when its dead cold that i have this problem, ie in the mornings, and in the arvo when i try to go home from work.

Can anyone suggest a solution?

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#2 _Herne_

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Posted 10 April 2006 - 10:01 PM

Is your coil the right one for leccy ignition??

Just a thought.

Cheers
Herne

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#3 rodomo

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Posted 10 April 2006 - 10:05 PM

Hit the nitrous button for 1/2 a sec and then crank. Sorta like priming an LPG car. :blink:

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#4 Loui

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Posted 11 April 2006 - 07:00 AM

You got the chokes hooked up??

If not, what I do when its been sitting for a while is open the jet on the bottom of the carb and put a clothes peg on them to stop then closing

It then starts easy, as soon as it start put the pegs off and start as normal.

Dont give it a rev with the chokes open as the needle can get stuck on the top of the open jet and cause all kinds of problems.

Cheers

Loui

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#5 _draglc_

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Posted 11 April 2006 - 08:28 PM

dont all chokes do is open up the butterfly a little? im thinking of hooking up the nitrous and just using the fuel solenoid to get it started.. but im not sure what mr plod would think of that!

A1

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#6 Loui

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Posted 11 April 2006 - 08:46 PM

the chokes pull down the needle seat which allows more fuel in, they may or may not open the butterfly a bit, not sure

Cheers

Loui

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#7 Struggler

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Posted 11 April 2006 - 10:37 PM

The problem lies in the fact that SU's dont have an accel. pump. Next cold start crank the engine with your acc. pedal on the floor for a couple of secs, then let the throttle shut, while still cranking. This draws fuel into the engine.

Give that a go and see how it turns out. It worked on my old Datsun 1200 !!

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#8 _draglc_

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Posted 12 April 2006 - 02:35 PM

this morning i let the fuel pump work for a few seconds, then cranked it, then checked to see if there was any fuel going into the engine, and there was. if i knocked back the timing would that make any difference?

A1

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#9 rodomo

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Posted 12 April 2006 - 03:35 PM

Try drying out the singer oil, this might make the pistons lift better.
Also if it has a big cam it may be low on vacuum at crank. (The fuel is there but not getting sucked into the combustion chambers) Also with the timing at 14 it probably is cranking a little slow. Maybe back it off to 10?

Good luck!

Edited by rodomo, 12 April 2006 - 03:37 PM.

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#10 _draglc_

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Posted 12 April 2006 - 05:38 PM

ive already dropped the timing back a tiny bit, but ill try a little more tomorrow morning. how would i increase vacuum in the manifold? block off breather in the rocker cover?

A1

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#11 _uglybob_

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Posted 12 April 2006 - 07:59 PM

hey its that when you use a vacc. pump? when the cam is so big you dont hav bugger all vaccum?

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#12 rodomo

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Posted 12 April 2006 - 10:40 PM

Vacuum pumps suck and I would'nt use one :tease:

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#13 _revmaniac_

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Posted 17 April 2006 - 08:36 PM

was that MEANT to be a pun rodomo???
i personally would try to get in the habit of holding the acc pedal down when turning the engine off so some fuel gets sucked into the manifold in that last few seconds... either that or "teeing" your fuel line and fitting a soleniod (same as the ones used in duel fuel cars) between the "tee" and the manifold so that before you crank the engine you can let the electric pump prime the system then a short press of a button would open the solenoid and spray a bit of feul into the manifold...
hope you get her sorted