Post by scottydugg on Jan 21, 2020 13:51:32 GMT
Progress Update:
The head was sent out for a skim following it's disassembly, I went for a 20thou skim as first and foremost: this is to be a budget swap, so no Vernier pulleys /dyno time; I don't know if I'll go FI or N/A in the future, so this doesn't commit me to either.
IMG_20200116_181105 by Scott Reid, on Flickr
Picture below shows that the head had warped during removal, it'd taken a 5thou skim to get it flat. Black section in the centre show it was banana shaped. 5thou not being that bad according to the machinist he'd had another that needed 17thou before flat prior to mine.
IMG_4156 by Scott Reid, on Flickr
I've continued reading up what I can about the BP4W swap, some of what I've found leads me to believe that straight swapping a BP4W onto a Mk1 block results in a slight drop in power as it reduces compression by a couple of points (-2/3BPH). So for the swap to be effective a skim is required. I can't find any information on what power increase (if any) can be expected but the general feedback is it's a worthwhile swap (improved flow/cam profile).
Some more reading has lead me to use the mk2 Injectors (you already need the mk2 fuel rail due to a different offset to mk1). The mk2 rail operating at a higher pressure than the mk1, 40 psi vs. 60psi, with the mk2's having a better spray pattern. From what I can see the mk1/mk2 fuel pump is the same and only changes at mk2.5. I intend to send the injectors out for cleaning, no point going this far and not. Thoughts on this being airflow will be increased with the swap so increase fuel to match. I did read also that mk1 injectors on a mk2 rail, results in less pressure than on a mk1 rail.
I spent time cleaning up my valves now that the head was back, firstly trying a drill in a bench vice with a brass wire brush, which took some off but not the harder stuff. Eventually evolving into taping the valve stems up and putting them in the drill, attacking with emery paper, this was a far better method (Note: protect the valve stems if using this method). Some of the inlet valves have heavy carbon build up, which is backed up by combustion marks in the head, which suggests these have been sticking open. So I'll be going through the valve shims once the heads back together, following the Car Passion Channel guide (LINK).
IMG_20200117_191934 by Scott Reid, on Flickr
IMG_20200117_213550 by Scott Reid, on Flickr
I've now started lapping the valves on the inlet side, I've found a point on each valve seat that remains shiny when lapped. I've had to use the corear canoe lapping paste initially to get a nice uniform finish before going over again with the fine paste. It's not that bad a job, quite easy to lose a couple hours whilst you listen to a podcast. Although I've now gone and read about lapping and those who are for and against and wish I hadn't…but I'm committed now. At least I have a continual 2mm band round both the seat and valve so it's better than it was.
IMG_20200117_201101 by Scott Reid, on Flickr
Once everything is lapped, it'll be re-installation of the valve assemblies. Not sure what I'm going to do about getting the collets in as I bought the wrong sized valve spring compressor so needed to use a socket for removal. I'll need to butcher another socket to get the collets back in, rather than spend another 30 quid on another compressor!
I'll update again when I'm a bit further along.
The head was sent out for a skim following it's disassembly, I went for a 20thou skim as first and foremost: this is to be a budget swap, so no Vernier pulleys /dyno time; I don't know if I'll go FI or N/A in the future, so this doesn't commit me to either.
IMG_20200116_181105 by Scott Reid, on FlickrPicture below shows that the head had warped during removal, it'd taken a 5thou skim to get it flat. Black section in the centre show it was banana shaped. 5thou not being that bad according to the machinist he'd had another that needed 17thou before flat prior to mine.
IMG_4156 by Scott Reid, on FlickrI've continued reading up what I can about the BP4W swap, some of what I've found leads me to believe that straight swapping a BP4W onto a Mk1 block results in a slight drop in power as it reduces compression by a couple of points (-2/3BPH). So for the swap to be effective a skim is required. I can't find any information on what power increase (if any) can be expected but the general feedback is it's a worthwhile swap (improved flow/cam profile).
Some more reading has lead me to use the mk2 Injectors (you already need the mk2 fuel rail due to a different offset to mk1). The mk2 rail operating at a higher pressure than the mk1, 40 psi vs. 60psi, with the mk2's having a better spray pattern. From what I can see the mk1/mk2 fuel pump is the same and only changes at mk2.5. I intend to send the injectors out for cleaning, no point going this far and not. Thoughts on this being airflow will be increased with the swap so increase fuel to match. I did read also that mk1 injectors on a mk2 rail, results in less pressure than on a mk1 rail.
I spent time cleaning up my valves now that the head was back, firstly trying a drill in a bench vice with a brass wire brush, which took some off but not the harder stuff. Eventually evolving into taping the valve stems up and putting them in the drill, attacking with emery paper, this was a far better method (Note: protect the valve stems if using this method). Some of the inlet valves have heavy carbon build up, which is backed up by combustion marks in the head, which suggests these have been sticking open. So I'll be going through the valve shims once the heads back together, following the Car Passion Channel guide (LINK).
IMG_20200117_191934 by Scott Reid, on FlickrIMG_20200117_213550 by Scott Reid, on FlickrI've now started lapping the valves on the inlet side, I've found a point on each valve seat that remains shiny when lapped. I've had to use the corear canoe lapping paste initially to get a nice uniform finish before going over again with the fine paste. It's not that bad a job, quite easy to lose a couple hours whilst you listen to a podcast. Although I've now gone and read about lapping and those who are for and against and wish I hadn't…but I'm committed now. At least I have a continual 2mm band round both the seat and valve so it's better than it was.
IMG_20200117_201101 by Scott Reid, on FlickrOnce everything is lapped, it'll be re-installation of the valve assemblies. Not sure what I'm going to do about getting the collets in as I bought the wrong sized valve spring compressor so needed to use a socket for removal. I'll need to butcher another socket to get the collets back in, rather than spend another 30 quid on another compressor!
I'll update again when I'm a bit further along.
even with modern 'so called' lead-free valve gear and people rarely use lead replacement supliments )
