Missing top end power 124 Spider on 44 IDF

[Abarthnorway - Remi L]

Hi Guy!


Just built and installed a 2 liter block in a very nice 74 Spider:

10:1+ pistons
130 TC head - 36 mm parallel intake - 34 mm exhaust + valve + guide + seat mods
44 IDF - 36 chokes, F16, 145 mains, 180 air
Inlet cam billet - 10.45 true lift, 280 degrees, 2.5 lift TDC - timed 110
Exhaust cam 1608 - used but still OK I suppose (9.3 lift on lobes) - timed 110
Exhaust manifold 4-2 cast iron into 2-1 secondary pipes - (standard 1800 sport) - 2 " free flow system from manifold and back

The head was earlier used on a very worn low compression 1800 block with 40 IDF- 34 chokes and a milder C&B inlet cam. This engine revved happily to 7000 rpm with this setup.

With the new block/inlet cam/carbs I would expect the topend to have similar characteristics, but this engine seems to loose its response at approx 6500.

Any pointers??

Thanks


Best regards

Remi Lovhoiden




Timed camshafts




Engine on its way into the engine bay - the increased height of engine made numerous smaller problems.....




Everything in place - inlet tracts well used Pipercross items - filter system will soon be fitted




Head combustion chamber

[Guy Croft]

Given your back-to-back comparison it could easily be the ex cam that's now holding her back.

I'd try a billet ex cam with around 10mm FL actual and 2.5mm LATDC, aiming for better ram-charge and purging at higher rpm.

GC

[Abarthnorway - Remi L]

Hi Guy!


Thanks for the advice - will have to test/adjust the car a bit more to rule out other "pitfalls". Will try to optimise what is already in place, and from that make a decision.

Keep up the good work.


Best regards

Remi Lovhoiden

[ace124]

Remi,

Make sure you check ignition timing also if you have not after tuning carbs etc. I had a similar prob before i re did the timing after my rebuild. Now the car pulls right thru redline and above.

Good luck.
Let us know how you went.

[Abarthnorway - Remi L]

Hi all!


Problems disappeared as the ignition/carbs were exactly balanced/tuned.

With these spot on engine runs strong from as low as 2000 to 6500 +

Anyway thanks for inputs!:-)


Best regards

Remi Lovhoiden

[Guy Croft]

Remi!

Problems disappeared as the ignition/carbs were exactly balanced/tuned

You should not be driving it unless - the ignition/carbs were exactly balanced/tuned!

All readers please note!

GC