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MG TD TF 1500 - Camshaft character experience
|NTG (www.mgbits.com) offers a camshaft with for me remarkable properties. Its degrees are 52-18-18-52 which makes a pretty large overlap of 36 degrees. Also the announced lobe separation angle of 107 degrees in my opinion would mark its character as not so standard. |
Anybody out here experience with this camshaft: does it deliver at the higher rev's and what about the low rev behavior (rough or still ok).
|Huib, Please contact me off the BBS for flat lifter & roller lifter camshaft information.|
I have this camshaft in my engine since 3 years. I'm very satisfied with it. Idle is very good and top speed also.The lift is not so high as the original.Instead of valve clearance 0,21 Inch I do it with 0,12.
You didn't mention your application, street, high performance or supercharged.
Just a comment... if it is supercharged, which I realize is probably unlikely, avoid a cam with wide overlap. I picked up one of Len's cams for street supercharged with minimal overlap. I should get around to ordering a second one since we have 2 supercharged TDs.
|Len, you have got mail.|
Klaus, if the clearance is decreased from 0.021 to .012, the overlap gets increased above the 38 degrees. I find it remarkable that idle is still very good.
Jim, I can understand that the high inlet pressure at supercharged will blow straight away through the outletvalve during the long overlap.
|Huib there's an article in the archive called "Valve Springs for Roller Lifters" that you should read if considering the roller cam kit. Cheers|
Peter TD 5801
|Huib, oops email@example.com|
|midgetairns has published some info on the variety of standard cams fitted to M.G.'s over the years on pages 25 & 26 of his book "Engines for M.G.'s". I've reprinted the following.|
"XPAG Camshaft Checking.
This is the most important part of the engine in terms of performance and drive-ability, though good cylinder head design does help. As years pass, people modify their cars, or fit replacement items that have been improved by the manufacturer. One problem that often occurs is trying to decide which camshaft your XPAG has fitted, without stripping it down. Many cars have the 0.012" clearance camshaft, but some still have the older 0.019" clearance version. By far the best method I have seen was in the MGCC Safety Fast magazine, sent in by David Clark of Westminster, Vermont, USA. It relies on the fact that only the later cars had 5;45;45;5 cam timing, known as equal-overlap, or split-overlap if you speak American. That is both inlet and exhaust cam have the same timing, but in 'mirror' fashion. The earlier 'T' types had 11;57;52;24, very un-equal. The first pair of numbers read as inlet opens BTDC, closes ABDC, then exhaust opens BBDC and closes ATDC. The XPAG is not a quiet engine anyway, and one to worry about is one with no tappet clatter, as it is better to hear it than not. In today
|Thanks for that, Peter. |
When Neil says:
"At this TDC loosen the locknuts and turn the tappet adjusting screws all the way up and then down again until there is exactly no clearance at the valve."
I am assuming he meant 'valves' for that last word... i.e. you are supposed to adjust BOTH the intake AND exhaust valves for #1 cylinder such that there is no clearance and the valves are fully closed.
|Dunno Kevin. I haven't got an original unknown cam in my TD so I didn't need to go down that road. Just checked the valve timing on my Chet Herbert cam with info provided by the manufacturer (Andrews Products) & I'm relieved to find that it's near enough to spot on. Exhaust is 036" @ TDC & Inlet is .050" @ TDC (Should be .052" which is close enough for me). Sorry I can't answer your query but I'm sure somebody here will. Cheers|
Peter TD 5801
|Chet Herbert has not produced a MG camshaft since about 1962. You do not have a Chet Herbert cam.|
|That's surely in part due to the fact that Chet Herbert is no longer alive. His son Doug now runs the business.|
|Thank you Peter for that interesting overview. Also "David Dubois" presented in the past camshaft info that is published on our famous TTalkinfo (http://www.ttalk.info/TSeriesCams.htm). |
Combining that info and only listing a few, demonstrates my initial question:
Early TD and TC cams: 11-57-52-24 makes overlap 35
Late TD and TF cams: 5-45-45-5 makes overlap 10
Half race cams: 13-59-50-22 makes overlap 35
Full race cams: 32-58-60-30 makes overlap 62
Current offered MOSS standard cam (also Crane 340-0002):
11-51-51-11 makes overlap 22
Current offered NTG cam: 18-52-52-18 makes overlap 36
Only looking at these figures,makes me conclude that the early TD/TC cam and the later Half race cam are kind of lookalike.
And: The late TD shows much less overlap so further away from the full race and half race area into the none race area.
The MOSSstd is between the late TD and half race (so between none-race and half race).
The NTG is between the MOSS and the half race.
Agree/disagree with this reasoning?
So, back again to my initial question: who (else than Klaus) has experience with this NTG camshaft?
This thread was discussed between 24/01/2015 and 26/01/2015
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