RS Motorsport :: Classic Speed Restored

Hi All,

Just got the new 2 litre in and running. its a pretty basic engine with minor mods but seems to go really well up to about 4200 4300, then develops a rapid power loss or miss.

Engine nuts and bolts.
stock 2 litre crank and rods, flat tops, 0 decked.
ported standard head, mainly in the exhausts. Inlets just done in the short turn and blended seats.
new crow valvesprings and 242 degree .448" cam. set to zero with vernier.
roughly 10:1
pacemaker tri y extractors and 2.25" exhaust (loud!)
ported plenum standard inlet with 2 spacers.
fresh 38dgas carb.
powerspark electronic ignition conversion.
standard fuel supply and pump.

Sierra 5 speed and 3.9 diff.

seems to run a little hot but drives fine and temp does not effect the issue. neither does gear.

base timing 14 degrees and total 34. vac is hooked to advance side only.

I havent done mixtures yet but idles nice with mild burble and pulls super strong from 2500+ till the miss hits (bout 4300).

I am thinking either it is going dead lean up top (fuel pump?) or some kind of ignition issue.

Any thoughts guys?

no one keen to comment?

OK, I'll have a stab.

Maybe your float levels are too low, your spark plug gaps are incorrect or your leads are shagged?

That's all I've got.

Chuff.

When it gets to the miss at around 4 ish does it push through it or is that it, it basically stops there and refuses to go any further?

Usually these things are fuel, ignition or cam timing.

Things to check - float level in DGAS, fuel filter clean and not blocked, cam timing correct.

14 degrees at idle seems a little high. What's idle RPM? If it's running a little hot it could be related to too much advance.

Check those things and report back.

Had the same issue and it ended up being the drive belt being off by one tooth.

Cheers

Matt

Double triple checked cam timing and is set spot on zero.

Will check float level again but doubtful seeing as seems to be rpm not load or gear specific.

Fuel pump and filter are new. Filter is fresh clean.

Thanks for the comments guys. I will let you know if I find anything in the carb.

Nev. Yes basically stops there and wont go any further.

Is the rotor facing the groove in the distributor-body at TDC?

Is 34 degrees total advance enough? Shouldnt it be more like 38 degrees for a Pinto. Did you fit the points conversion yourself and is the distributor in good condition? Also, check your volts or wiring hookup for the electronic ignition as they sometimes wont work properly if the volts drop below 13V

yes I did the conversion myself, rebuilt the dizy so all seemed to work smoothly and as it should when it all went back together.

Havent checked the alignment with the body, but surely thats going to change as the timing is adjusted.

new high output alternator fitted and the voltage gauge says almost 14V. I will check at the coil though as well.

What about your ignition coil itself? Was just reading the manual for my Crane ignition and in the trouble shooting section it mentions internal arcing in the coil as a cause of misfires at high RPM. Not sure if 4300 counts as high or not