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MG MGF Technical - FAO Steve and Tim - cam timing article now online
|Hi chaps - |
Have a look at http://www.mgf.ultimatemg.com/group2/engines/tuning/cam_timing.htm - have I missed anything?
Good reading Rob. :-)
Only thing missing was a subjective and/or measured comment on the results obtained.
|One comment other than the spelling of Steve's surname.....!|
Step 23.5 - turn the engine over a few times by hand by rotating the crank and feel for any resistance. This may be piston/valve contact.
Nice work their Rob this should save me having to help anyone else with their cam timing :o)
|Thanks Paul - we'll have to wait for Steve's thoughts on that :o) Unfortunately, no RR data from before the cam timing change - but hopefully will get some data from Emerald in the next month or two when we all go up to Norfolk in Feb/March.|
Tim - !!! Sorry about the spelling Steve!!!
Good point regarding the advice on turning the engine by hand.
|Corrections made - Tim, what specialist tools did you buy to make the job easier?|
|Rob, Step 19 actual lift at TDC was IN:1.7mm (67 thou) EXH:1.3mm (51 thou).|
Impressions to follow when I get an out-of town run.
With regards to the RR I have not made any other changes since the last session at Emerald.
Good write up Rob.
|Rob Tim's tip was|
Step 3 1st remove the spark plug cover
Step 4 remove those ignition leads etc
Step 5 fully loosen all 13/14 of the cam cover bolts - but do not remove
Step 6 remove the cam cover using the loosened bolts to hold the gasket agains the cover - so that bolts, gasket and cover come off as one unit.
In the existing the leads are the 8mm magnecore leads .
|Thanks Steve - couldn't remember the values we measured - I think that they were on the notes you had :o)|
Thanks for the notes - will correct :o)
Cheers - and happy new year! :o)
|Great article - week before Christmas did something similar on our VVC. Now just add the VVC actuators of which there is little to no information especially if one falls apart! |
Three Dial Indicators – I can only afford one! I like the stands/brackets.
Just a tip – if you are by yourself and need to retime either cam pulley, use pieces of cardboard wedged between the belt and the cover to stop the belt from slipping. I tried an adjustable pulley lock between cam pulleys, even with the engine out it was a pain due the small gap between the pulleys.
Cheers - Happy New Year.
|Top Tip from Dave Andrews:|
When adjusting Cam Timing from a know good position. "Mark the verniers carefully first so it is easy to go back without using the gauges. It might be worth marking both settings so you can easily alter them on the RR day and see the results, if the verniers are marked you don't need the gauges..."
|Dennis, wow! How did you manage with only one gauage? A bit of a fiddle I'd imagine. Two of the gauges in shot are mine (bought at an MGCC Silverstone show a couple of years ago - fairly cheap in fact), and the other is Tim's. I now wish that I'd bought three when I had the chance - oh well - will be on the look out for another show bargain!|
Cam lock tool is Draper's - item 8 here: nhttp://www.draper.co.uk/Pages/Pagesource/p81.pdf - very cheap, and a must have item (must buy one myself - been using Tim's!)
Steve, have added in DVA's handy hint - cheers :o)
|If youve been following one of the other threads you will know that I've been having a little trouble with my daughters TF115. I decided to check that the mechanic that repaired the HGF had set the valve timing correctly. I took the wheel off lined the nick in the crank pulley up with the mark on the plastic belt cover, went to the top and the marks on the cam pulleys didn't line up. I then took the opposite approach and lined the top ones up and then went down to the crank, it was about 5 deg out. Not enough to be a whole tooth. (From memory there are 24 teeth on the crank sprocket ie every 15 deg)I put it down to the lack of precision in the timing marks. (the proper oned are cast onto the oil pump body - probably not that precise either)This all re-enforces what Rob has said.|
I have a question for Rob. Is my daughters cam belt automatically tensioned ? I could see how it was done, but from what I could see it didn't look like the original K series set up. My Rover history stopped abruptly in March 2000.
Ive scanned the valve timing article and have to make a couple of points. The total lift off the clearance circle includes the opening ramp height of 0.075mm, so the total is 8.875 for example. You might see some sink down of the hydraulic tappets (depending on how much air is in them) when you measure them using your method. There is no dwell at full lift on the factory cams.
You can not increase the lift above 8.8 without canging valve spring. LGL100008 to LGL100025 (I'm doing this from memory so please check the numbers). VVC has somthing different again I think.
The 9.5 x 252deg is a pretty good profile, I'm not sure you will get much more performance certainly for road use by going any longer in period.
|>> I have a question for Rob. Is my daughters cam belt automatically tensioned ? <<|
Yes, the 115 definitely has an auto tensioner. In fact, Steve's MGF had an autotensioner, which was something of a surprise given its age.
The TF135 head that I've now got on my engine also had an autotensioner, but I had it drilled and tapped to take the manual tensioner to be compatible with the crank pulley.
I haven't counted the number of teeth on the crank pulley, but there are 48 teeth on the cam pulleys, so 24 would be what one would expect to find.
Thanks for the comments regarding the valve springs - I think we've chatted about this before haven't we? With the 9.5mm TF135 cams fitted on my head, I went with the valve springs already fitted to the TF135 head. But the part number for the up-rated part - LGL100025 - I can't find listed in the electronic parts catalogue anywhere. Is there a chance that this was not actually ever implemented? i.e. was a decision taken to use LGL10008 valve springs with the higher lift camshafts?
I know that you'll find this shocking, but Piper and Kent cams appear to get away with 10mm of lift with their performance cam shafts retaining the '08 valve spring...
|Just a small comment Rob, the inclined angle of the valfes is 23 degrees rather than 15...|
And I usually mark vernier positions with a stanley blade mark between the outer and inner, these are easy to re-align.
|Rob I can't remember how many zero's there are in the spring part no's. Try leaving some out. There should be the same no of digits in both numbers. I know this change was definitly implemented. LGL100008 was designed for a cam of 8.2 mm lift so we pushed it to increase lift to 8.8 mm (as I said previously 8.875 total lift off the clearance circle). There is a tremendous tolorance stack on fitted spring length, so if the standard spring is used at 10 mm lift there is a strong possability of going coil bound. The two springs will have different paint stripes to identify them. I don't know if the 135 head has the same on inlet and exhaust. Thanks for the info on auto tensioning. This will extend belt life no end.|
|Dave, thanks, much appreciated :o) Is the valve inclination the same for the VVC/VHPD heads?|
Paul, I've already tried varying the number of '0's in the part number, but to no avail. Mystifying. With the Powertrain engineers now spread throughout British Industry, what chance is there of finding a definitive answer to this conundrum?
|Rob - have you tried talking to Rimmer bros or Moss|
|Actually, no I hadn't - but good idea: I shall drop them a line to see whether they can help :o)|
This thread was discussed between 31/12/2005 and 05/01/2006
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