My creation.... it lives!!!
Discussion
Well, it was a long slog, but by buggery was it worth it. The 390 is back in action, and I'm starting to realise just how far the engine must've deteriorated even though it would still pull like a train etc. etc.
To recap, it's had a rebore and new pistons, with valve pockets cut out to cope with the high-lift cam. (The piston & rod assemblies were weighed and found to be within 2 grams of each other!)
Crank was reground, and all new shells fitted. The oil pump was rebuilt with an uprated relief valve spring.
Heads were stripped & decoked.
Various ancillaries were refurbed; some bits were painted or powder-coated.
Once rebuilt, the oil system was primed using a drill on the pump shaft, then the engine was spun on the starter with the plugs out for a while to align everything and get the oil moving. Apart from having plumbed the fuel pressure reg backwards (doh!) the car started first time and idles beautifully, which it's never done while I've had it!
First few miles have been a revelation. It's almost a different car. Power deliver seems to be different, insofar as the torque starts lower down and is not so peaky (though I haven't had more than about 4500 RPM up yet!). The temperature is more stable, there's upwards of 3 bar oil pressure and the whole drive is smoother and more comfortable.
Just need to fine-tune the ignition and fuelling now and then get down to some serious running-in!
With luck I'll be down at the Chatsworth meet on 9th June, so if anyone wants to se what a brand new V8 sounds like, you know where to come!
W. (well chuffed!)
To recap, it's had a rebore and new pistons, with valve pockets cut out to cope with the high-lift cam. (The piston & rod assemblies were weighed and found to be within 2 grams of each other!)
Crank was reground, and all new shells fitted. The oil pump was rebuilt with an uprated relief valve spring.
Heads were stripped & decoked.
Various ancillaries were refurbed; some bits were painted or powder-coated.
Once rebuilt, the oil system was primed using a drill on the pump shaft, then the engine was spun on the starter with the plugs out for a while to align everything and get the oil moving. Apart from having plumbed the fuel pressure reg backwards (doh!) the car started first time and idles beautifully, which it's never done while I've had it!
First few miles have been a revelation. It's almost a different car. Power deliver seems to be different, insofar as the torque starts lower down and is not so peaky (though I haven't had more than about 4500 RPM up yet!). The temperature is more stable, there's upwards of 3 bar oil pressure and the whole drive is smoother and more comfortable.
Just need to fine-tune the ignition and fuelling now and then get down to some serious running-in!
With luck I'll be down at the Chatsworth meet on 9th June, so if anyone wants to se what a brand new V8 sounds like, you know where to come!
W. (well chuffed!)
Right then, a quick update:
A pool of coolant kept forming on the top rear of the inlet manifold gasket. Testing with the coolant system pressure tester revealed a very slight weep from the top hose at the thermostat housing. Then one of the hoses to the header tank developed a pin-prick leak, which was resolved temporarily by shortening and rerouting said hose. At the moment, the coolant is staying where it should, and the tester says 1 Bar for a good while after stopping the motor. Temp is stable at 88 degrees, but seems to go a bit high initially as the 'stat opens. I have an 82 degree stat so may try that as a fix. I've got new hoses to fit to the rear of the water pump also. Oddly, the oil is staying clean, although I didn't manage to get every drop of the old black stuff out of the cooler pipework, so I'm not sure whether the oil 'stat is stuck or whether the oil just isn't hot enough to need to go through the cooler. I've been experimenting with ignition timing and mixture settings, but the best compromise I can hit still leaves me with 3.7% CO, which seems rather high. I can change the power delivery of the engine quite dramatically with these adjustments, which suggests they work OK. Of course the ECU could be kaput, or maybe Mr. Previous-Owner arsed around and I haven't hit the correct settings yet. Haven't used more than 5000 RPM (once!) yet, mostly 4000-4500 through the gears, max speed 105 so far, no glaring engine troubles. After 1000 miles I'll drop the sump and do a quick bearing shell check.
I have a new ECU temp sensor to fit, and a few wiring improvements to make. The PAS is still weeping oil from the pinion seal; I've lived with it for almost 2 years so I guess a bit longer won't hurt! I had the rack apart and I think the problem is due to pitting on the pinion shaft, so even a new seal will leak.
The gearshift action has improved due to my ad hoc copper bushes, and the output shaft seal no longer dribbles onto the exhaust.
Ee, it's amazing what you can find wrong when you go looking.....;-)
W.
A pool of coolant kept forming on the top rear of the inlet manifold gasket. Testing with the coolant system pressure tester revealed a very slight weep from the top hose at the thermostat housing. Then one of the hoses to the header tank developed a pin-prick leak, which was resolved temporarily by shortening and rerouting said hose. At the moment, the coolant is staying where it should, and the tester says 1 Bar for a good while after stopping the motor. Temp is stable at 88 degrees, but seems to go a bit high initially as the 'stat opens. I have an 82 degree stat so may try that as a fix. I've got new hoses to fit to the rear of the water pump also. Oddly, the oil is staying clean, although I didn't manage to get every drop of the old black stuff out of the cooler pipework, so I'm not sure whether the oil 'stat is stuck or whether the oil just isn't hot enough to need to go through the cooler. I've been experimenting with ignition timing and mixture settings, but the best compromise I can hit still leaves me with 3.7% CO, which seems rather high. I can change the power delivery of the engine quite dramatically with these adjustments, which suggests they work OK. Of course the ECU could be kaput, or maybe Mr. Previous-Owner arsed around and I haven't hit the correct settings yet. Haven't used more than 5000 RPM (once!) yet, mostly 4000-4500 through the gears, max speed 105 so far, no glaring engine troubles. After 1000 miles I'll drop the sump and do a quick bearing shell check.
I have a new ECU temp sensor to fit, and a few wiring improvements to make. The PAS is still weeping oil from the pinion seal; I've lived with it for almost 2 years so I guess a bit longer won't hurt! I had the rack apart and I think the problem is due to pitting on the pinion shaft, so even a new seal will leak.
The gearshift action has improved due to my ad hoc copper bushes, and the output shaft seal no longer dribbles onto the exhaust.
Ee, it's amazing what you can find wrong when you go looking.....;-)
W.
Wedgie .. are you having trouble getting the mixture right.. operhaps run out of adjustment on the mixture screw on the flapper value unit ?
If so - you can take the black top of of the air flow meter - inside you will see a wheeled toothed thingie
(sorry cannot think of a better way to describe it..)
- there is a metalic trye spring that keeps this setting and stops it moving - if you lever if off of the toothed wheel you can turn the wheel either way.
You should then see big co2 swings when you try it one way then the other.
Sorry I cannot say which way to try it but I would suggest you put a mark on the wheel before you start experimenting.
Rev.
If so - you can take the black top of of the air flow meter - inside you will see a wheeled toothed thingie
(sorry cannot think of a better way to describe it..)
- there is a metalic trye spring that keeps this setting and stops it moving - if you lever if off of the toothed wheel you can turn the wheel either way.
You should then see big co2 swings when you try it one way then the other.
Sorry I cannot say which way to try it but I would suggest you put a mark on the wheel before you start experimenting.
Rev.
Yes, initially it does seem that the mixture is the problem, although I have yet to determine the ideal idle ignition advance anyway! I've seen figures as high as 28 degrees BTDC suggested, but the scale is onle graduated to +/-10 degrees, and the manuals I have say 8 degrees BTDC. If I give it plenty of advance then the idle speed goes up; then I correct the idle speed but can run out of adjustment there, car won't start or idles roughly. So not sure what course to take on that. At the mo I have about 10 degrees BTDC, idle speed 800-900 RPM, idle CO 3.7, rises under acceleration, leans off on cruise. It still seems to be using a lot of fuel, but 'a lot' may be 'normal'.....!
Done about 100 miles tonight, can't fault the power delivery; no stalling when coming back to idle after high-speed running; no overheating; is it as good as it will get?
I know about the adjustment on the flap meter; I also know that it's best left alone! One thing about being a service engineer: you learn to not fix what ain't broken! :-)
One thing has occurred: I haven't cleaned the K&N filter since the rebuild, maybe that's a contributory factor.
W.
Done about 100 miles tonight, can't fault the power delivery; no stalling when coming back to idle after high-speed running; no overheating; is it as good as it will get?
I know about the adjustment on the flap meter; I also know that it's best left alone! One thing about being a service engineer: you learn to not fix what ain't broken! :-)
One thing has occurred: I haven't cleaned the K&N filter since the rebuild, maybe that's a contributory factor.
W.
Yes, initially it does seem that the mixture is the problem, although I have yet to determine the ideal idle ignition advance anyway! I've seen figures as high as 28 degrees BTDC suggested, but the scale is onle graduated to +/-10 degrees, and the manuals I have say 8 degrees BTDC. If I give it plenty of advance then the idle speed goes up; then I correct the idle speed but can run out of adjustment there, car won't start or idles roughly. So not sure what course to take on that. At the mo I have about 10 degrees BTDC, idle speed 800-900 RPM, idle CO 3.7, rises under acceleration, leans off on cruise. It still seems to be using a lot of fuel, but 'a lot' may be 'normal'.....!
Done about 100 miles tonight, can't fault the power delivery; no stalling when coming back to idle after high-speed running; no overheating; is it as good as it will get?
I know about the adjustment on the flap meter; I also know that it's best left alone! One thing about being a service engineer: you learn to not fix what ain't broken! :-)
One thing has occurred: I haven't cleaned the K&N filter since the rebuild, maybe that's a contributory factor.
W.
Done about 100 miles tonight, can't fault the power delivery; no stalling when coming back to idle after high-speed running; no overheating; is it as good as it will get?
I know about the adjustment on the flap meter; I also know that it's best left alone! One thing about being a service engineer: you learn to not fix what ain't broken! :-)
One thing has occurred: I haven't cleaned the K&N filter since the rebuild, maybe that's a contributory factor.
W.
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