My 122S - Page 3

tom-madbiker · Mar 18th, 2011, 07:30

im currently doing an lpg conversion in my amo estate took out the petrol tank and put in a donut tank in the now modded and deepened spare wheel well can get 94 lite torroidal tank in and 26 litres of petrol with no loss of space in the back

Rick269 · Sep 16th, 2011, 10:15

Well, it's been a while so I thought I'd revive the thread and tell you what I have found.
Firstly, I found out why the valve clearances were marked as 0.014". Because it won't get any more clearance than that. Why? Because whoever built the engine must have realised they stuffed up the cam and have fitted 5mm longer pushrods!! 5 out of the 8 were 205mm, the rest were 200mm.
Maybe it's a standard cam, reground to 'D' specs, I don't know. I have a set of standard pushrods coming but I think I'll be up for a new cam if it's that bad.

Secondly, the modified 'F' head I have needs to be fixed before I'm willing to use it again. The valve springs are WAY too big, so big that the rockers touch on the retainer and stop the valve from closing. I managed to relieve the rockers enough to use it but the springs sit taller above the head and put too much strain on the rocker arm. I found out the hard way as one of the rocker bolts snapped under the strain and all the others I found were stretched and almost ready to break.

So for now, I've fitted the old 'B' head and have modified the extractors so my modified supercharger manifold will fit. Next job is to make an adaptor plate for the big single SU and convert to a cable accelerator, I have one from a 240 which I'm hoping will do the job.

Derek UK · Sep 16th, 2011, 13:43

If the springs sit too high the valves must be too long as well. This would give you your clearance problem rather than the pushrods, even if those are mismatched. I haven't a standard one to hand that I can measure but I'm sure someone has. Rocker mount bolts are thin and weak. The long length from head to thread mean they twist like a torsion bar before breaking. 20 ft/lbs max for these.
The valve spring seats, on the head, might have be machined to suit the larger springs so you might not easily be able to use standard ones again.
Good luck with it.

Rick269 · Sep 16th, 2011, 13:59

Hi Derek,

The problem with the valve clearance was with the standard B20B head as well as the 'E' head. The plaque that came with the engine says the clearance is to be 0.014" for both intake and exhaust.
Yes, I initially thought the valves might be longer too, but looking at them I'm pretty sure they are standard size fuel injected ones. I think the valve seats have been cut into the chamber deeper, maybe to lower the compression ratio as the head has been skimmed a lot. The spring seats have been cut to the larger spring diameter too.
I think I'll strip the head down and do some measuring to see if I can resurrect it.

Derek UK · Sep 16th, 2011, 20:36

Be realistic about this head. Seats maybe deep beacause they have been recut after recession due to no lead and running too small clearances. I don't know of any cams that run at 14 thou clearance and that may have caused the problem. D cam is 20-22 thou.
From your description I think I'd consider using the tuning funds on another head.

Rick269 · Sep 16th, 2011, 22:34

Just to clarify, as I think you may have misread what am saying. Here is a pic of the engine plate where you can see the valve clearance specified by the engine builder.

This is of course with the old 'B' head. When I fitted the 'E' head, I had the same clearance problem and I only found out about the longer pushrods while trying to work out why the rocker bolts broke.

As I could not get any clearance greater than 0.014" (rocker adjusters bottomed out on some cylinders) and because the pushrods were longer on some cylinders, that makes me think the cam has been ground incorrectly with the lobe radius too short, and they chose to use longer pushrods to make up for it. Or, someone stuffed up when they rebuilt the motor and put someone else's longer pushrods in, didn't pick up on it/were too lazy to change them, then just engraved the plaque 0.014" so anyone doing the clearances in the future would do them to that spec and be none the wiser ie. me. It strikes me as a pretty dodgy way to go about things though.

In short, I have another set of standard pushrods coming and I've gone back to the low comp. 'B' head as the 'E' head has too many other problems to worry about. I need the low comp head for the supercharger anyway.

Thanks for the help so far though.

tsetse1986 · Sep 17th, 2011, 20:39

What a beauty! Hope mine turns out as well as this.

Tim

Derek UK · Sep 18th, 2011, 00:38

Sorry Rick, I have to apologise for saying that the valve clearances for the D cam are 20-22 thou. That is wrong and I was getting it mixed with an earlier correction I made re the C cam. D cam as fitted to the ES as standard has clearances specified as 16-18 thou, warm or cold. Even that is more than the 14 thou on your plate. I can't see why VTC would want to regrind a cam when the standard D cam has always been readily available and not expensive compared to aftermarket offerings. If VTC are still around, maybe have a chat with them.

tom-madbiker · Sep 18th, 2011, 10:19

what are the clearances for a k cam i set mine to 20 - 22 thou and my ignition timing is about 20 at idle set by driving and seeing if it pinks having one or two issues with the gas too anyone know about setting an omvl r90 e vaporiser

jimbo1593 · Sep 18th, 2011, 11:18

91 RON....if i was going to run any sort of boost i would be wanting the highest octane i could put in it. Over here in the UK our standard is 95 and premium is 99. What are the rting like in the US?

Sep 18th, 2011, 10:19	#29
tom-madbiker Master Member Last Online: Apr 14th, 2020 21:20 Join Date: May 2010 Location: chesham	what are the clearances for a k cam i set mine to 20 - 22 thou and my ignition timing is about 20 at idle set by driving and seeing if it pinks having one or two issues with the gas too anyone know about setting an omvl r90 e vaporiser Last edited by tom-madbiker; Sep 18th, 2011 at 10:23.

Mar 18th, 2011, 07:30	#21
tom-madbiker Master Member Last Online: Apr 14th, 2020 21:20 Join Date: May 2010 Location: chesham	im currently doing an lpg conversion in my amo estate took out the petrol tank and put in a donut tank in the now modded and deepened spare wheel well can get 94 lite torroidal tank in and 26 litres of petrol with no loss of space in the back

Sep 16th, 2011, 10:15	#22
Rick269 Junior Member Last Online: Jul 14th, 2018 06:06 Join Date: Jan 2011 Location: SA	Well, it's been a while so I thought I'd revive the thread and tell you what I have found. Firstly, I found out why the valve clearances were marked as 0.014". Because it won't get any more clearance than that. Why? Because whoever built the engine must have realised they stuffed up the cam and have fitted 5mm longer pushrods!! 5 out of the 8 were 205mm, the rest were 200mm. Maybe it's a standard cam, reground to 'D' specs, I don't know. I have a set of standard pushrods coming but I think I'll be up for a new cam if it's that bad. Secondly, the modified 'F' head I have needs to be fixed before I'm willing to use it again. The valve springs are WAY too big, so big that the rockers touch on the retainer and stop the valve from closing. I managed to relieve the rockers enough to use it but the springs sit taller above the head and put too much strain on the rocker arm. I found out the hard way as one of the rocker bolts snapped under the strain and all the others I found were stretched and almost ready to break. So for now, I've fitted the old 'B' head and have modified the extractors so my modified supercharger manifold will fit. Next job is to make an adaptor plate for the big single SU and convert to a cable accelerator, I have one from a 240 which I'm hoping will do the job.

Sep 16th, 2011, 13:43	#23
Derek UK VOC Member Last Online: Yesterday 18:24 Join Date: Jul 2006 Location: Chatham	If the springs sit too high the valves must be too long as well. This would give you your clearance problem rather than the pushrods, even if those are mismatched. I haven't a standard one to hand that I can measure but I'm sure someone has. Rocker mount bolts are thin and weak. The long length from head to thread mean they twist like a torsion bar before breaking. 20 ft/lbs max for these. The valve spring seats, on the head, might have be machined to suit the larger springs so you might not easily be able to use standard ones again. Good luck with it.

Sep 16th, 2011, 13:59	#24
Rick269 Junior Member Last Online: Jul 14th, 2018 06:06 Join Date: Jan 2011 Location: SA	Hi Derek, The problem with the valve clearance was with the standard B20B head as well as the 'E' head. The plaque that came with the engine says the clearance is to be 0.014" for both intake and exhaust. Yes, I initially thought the valves might be longer too, but looking at them I'm pretty sure they are standard size fuel injected ones. I think the valve seats have been cut into the chamber deeper, maybe to lower the compression ratio as the head has been skimmed a lot. The spring seats have been cut to the larger spring diameter too. I think I'll strip the head down and do some measuring to see if I can resurrect it.

Sep 16th, 2011, 20:36	#25
Derek UK VOC Member Last Online: Yesterday 18:24 Join Date: Jul 2006 Location: Chatham	Be realistic about this head. Seats maybe deep beacause they have been recut after recession due to no lead and running too small clearances. I don't know of any cams that run at 14 thou clearance and that may have caused the problem. D cam is 20-22 thou. From your description I think I'd consider using the tuning funds on another head.

Sep 16th, 2011, 22:34	#26
Rick269 Junior Member Last Online: Jul 14th, 2018 06:06 Join Date: Jan 2011 Location: SA	Just to clarify, as I think you may have misread what am saying. Here is a pic of the engine plate where you can see the valve clearance specified by the engine builder. This is of course with the old 'B' head. When I fitted the 'E' head, I had the same clearance problem and I only found out about the longer pushrods while trying to work out why the rocker bolts broke. As I could not get any clearance greater than 0.014" (rocker adjusters bottomed out on some cylinders) and because the pushrods were longer on some cylinders, that makes me think the cam has been ground incorrectly with the lobe radius too short, and they chose to use longer pushrods to make up for it. Or, someone stuffed up when they rebuilt the motor and put someone else's longer pushrods in, didn't pick up on it/were too lazy to change them, then just engraved the plaque 0.014" so anyone doing the clearances in the future would do them to that spec and be none the wiser ie. me. It strikes me as a pretty dodgy way to go about things though. In short, I have another set of standard pushrods coming and I've gone back to the low comp. 'B' head as the 'E' head has too many other problems to worry about. I need the low comp head for the supercharger anyway. Thanks for the help so far though.

Sep 17th, 2011, 20:39	#27
tsetse1986 Member Last Online: Feb 9th, 2023 18:47 Join Date: Nov 2009 Location: Bristol	What a beauty! Hope mine turns out as well as this. Tim

Sep 18th, 2011, 00:38	#28
Derek UK VOC Member Last Online: Yesterday 18:24 Join Date: Jul 2006 Location: Chatham	Sorry Rick, I have to apologise for saying that the valve clearances for the D cam are 20-22 thou. That is wrong and I was getting it mixed with an earlier correction I made re the C cam. D cam as fitted to the ES as standard has clearances specified as 16-18 thou, warm or cold. Even that is more than the 14 thou on your plate. I can't see why VTC would want to regrind a cam when the standard D cam has always been readily available and not expensive compared to aftermarket offerings. If VTC are still around, maybe have a chat with them.

Sep 18th, 2011, 11:18	#30
jimbo1593 Master Member Last Online: Oct 1st, 2023 14:39 Join Date: Dec 2004 Location: leics	91 RON....if i was going to run any sort of boost i would be wanting the highest octane i could put in it. Over here in the UK our standard is 95 and premium is 99. What are the rting like in the US?

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