Friday, 8 March 2019

Another Trip to Northampton Motorsports

Having fitted the Newman camshafts it was recommended that to finalise the timing the car should be run on a rolling road and the camshafts advanced/retarded using the Vernier pulleys until the best fit performance achieved followed by a remap of the ignition timing and fuelling.

Adge as if he could come along for the ride so arrived just before 6am and we headed off arriving just before 9am.  Troy strapped down the car and we removed the bonnet to give easy access to the Verniers.  After the first run there was clearly something wrong, the engine wasn't pulling well over 4,500 rpm and by 6,300 rpm it seemed like it was only running on 3 cylinders.  We then spent 3 hours checking the camshaft installation, adjusting the camshaft timing, checking the cylinders compression, pistons for valve contact, etc.  By backing off the fuel map over 5,000 rpm it stopped the misfire but whilst there was a power and torque improvement below 4,500 rpm this was dwarfed by the reduction above.  We even removed the exhaust to see if it was restricting the flow with no improvement.  Eventually we found the best compromise that would allow the car to be driven and stopped having run out of time on the rolling road, any further investigation requiring measurement of the camshafts and more strip-down of the engine.

I contacted David and Richard Newman and they were very helpful, firstly they'd supplied hundreds of sets of the cams so were confident in the design, and secondly they'd happily take the cams back for examination and measurement and would report back; luckily I still had a record of all the shimming changes and all the parts to go back to the original cams.  Whilst driving home from work I had the thought that perhaps the over fuelling might be the opposite, ie a lack of air, Troy had checked the throttle bodies to confirm that the butterflies were fully open at max throttle pedal so it was clutching at straws (I really didn't want to swap the cams over again, and potentially again).

I fully opened the butterflies and did a thorough examination of each of the TBs, Cylinder 3 looked okay, Cylinder 2 again looked okay but there seemed to be a small amount of gasket melted and slightly flowed into the port, Cylinders 1 & 4 appeared to have significant amounts of gasket partially blocking the ports.  I removed the TBs and confirmed this, the middle 2 cylinders appeared to have got hotter than the outer and the material was missing where as the outers being cooler the gasket had melted and flowed into the port.

I'd fitted the gasket principally to stop heat transfer to the Inlet Air Temperature but it obviously wasn't up to the job, the consensus was to use the original Ford gasket so I ordered one from Burtons.

I also took the opportunity to fit the Raceline sump, do an oil change and put the mapping back to the original NMS map.  Once this was completed the car appeared to be running well, I also took the opportunity to re-setup the DigiDash and Freewheel finding that the oil pressure sensor had failed so I fitted a remote sensor.

A few weeks later I headed back to NMS, this time the cam timing and mapping was straight forward and there was a good increase in power (20 bhp) and torque (15 lb ft) from 2600 rpm from both the cams and exhaust changes since the original mapping.

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