Full Throttle Hesitation :(
Posted: Tue Oct 02, 2012 1:47 pm
Hi all,
After a couple of days reading through the archives here I am not satisfied I've found any pointers as to my problem.
And I'm pretty sure someone here must have experienced and cure this.
My engine is recently rebuilt. And probably for the first time ever has good compression on all cyliners.
Engine is at approx 10 degrees static.
On Dell'Ortos.
Lumenition Optronic Ignition.
All valve clearances withing range except on exhaust 1 thou over and one inlet 2 thou over. (Will be reshimming in another couple of hundred miles)
My problem:
I get either hesitation at 4000 rpm starting a 100 to 200 before 4000 and ending about the same after.
If I back off even the smallest amount from full throttle the hesitation does not occur.
Eg.
Accellerate at full throttle to 3500 (no hesitation), stay on full throttle and at 4000 +/- 100 or so - hesitation, above that hesitation gone again.
Accellerate at full throttle to 3500 (no hesitation), back off full throttle at 3500 and then back on at 4200 or so - NO hesitation etc.
Same problem exists at 12 degrees static. (Onlly difference was less responsiveness)
So am beginning to wonder if it's not timing but something else.
I know that I rejetted idle on the Dell'Ortos leaner before this rebuild.
There was no hesitation at any part of the rev range at that stage. But then I had less compression.
Any pointers where to start??
Thanks in advance,
Peter
After a couple of days reading through the archives here I am not satisfied I've found any pointers as to my problem.
And I'm pretty sure someone here must have experienced and cure this.
My engine is recently rebuilt. And probably for the first time ever has good compression on all cyliners.
Engine is at approx 10 degrees static.
On Dell'Ortos.
Lumenition Optronic Ignition.
All valve clearances withing range except on exhaust 1 thou over and one inlet 2 thou over. (Will be reshimming in another couple of hundred miles)
My problem:
I get either hesitation at 4000 rpm starting a 100 to 200 before 4000 and ending about the same after.
If I back off even the smallest amount from full throttle the hesitation does not occur.
Eg.
Accellerate at full throttle to 3500 (no hesitation), stay on full throttle and at 4000 +/- 100 or so - hesitation, above that hesitation gone again.
Accellerate at full throttle to 3500 (no hesitation), back off full throttle at 3500 and then back on at 4200 or so - NO hesitation etc.
Same problem exists at 12 degrees static. (Onlly difference was less responsiveness)
So am beginning to wonder if it's not timing but something else.
I know that I rejetted idle on the Dell'Ortos leaner before this rebuild.
There was no hesitation at any part of the rev range at that stage. But then I had less compression.
Any pointers where to start??
Thanks in advance,
Peter