MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Camshaft AEG 122

Hi Guys,
What is the common opinion of the Factory "Competition" cam AEG 122? I remember someone saying it is not a good cam but perhaps that was in certain applications?

I know AEG 122 is fairly similar to a standard TC cam as it has only 2 or 3 degrees "wilder" inlet timing and 2 degrees "milder" exhaust timing. Both are much "wilder' in general than the TF cam. (Although the TC has slightly less lift.)

The Factory Tuning Manual suggests that AEG 122 needs a special exhaust system, so I am guessing that this would also apply to the TC cam because they are so similar. (In fact the TC exhaust timing is slightly "wilder" than AEG 122.)

Valve timing. TF / TC / AEG 122 for comparison.

Inlet opens... 5 / 10 / 13
Inlet closes. 46 / 57 / 59

Exhaust opens 45 / 52 / 50
Exhaust closes 5 / 24 / 22

If I ever get to rebuild my road TC engine I thought I should use my NOS AEG 122 in place of the Factory "race" 168551 which has been in it for 52 years. (The car does have a "tuned length" exhaust system.) Just wondering what you guys think.

Bob


R L Schapel

Bob
Going by the specs I have, there would be a decrease of 18 deg on both inlet and exhaust which would bring the power curve down a bit in the rev range--how much I don't know but I'd be expecting a fair bit more lower revs torque from the AEG122 compared to the racer cam but possibly loose a bit up top-maybe

Half race = AEG122 ; 13/59/50/22/8mm/.019",.015" for quietness

Full race = 168551 ; 32/58/60/30/8mm/inlet.012",exhaust.019"

But you'd know that anyway
William Revit

Thanks William. Yes, I agree. But I am curious about how AEG 122 feels in a car compared with the standard TC cam. (Interesting aside is that the "Full Race" 168551 inlet closing is BETWEEN the AEG 122 and std TC cams! They are all within 2 degrees on that statistic!)

The 168551 is a great cam but needs lots of revs to be at its best. It is really quite mild by modern standards for a "full race" cam.
R L Schapel

Bob
Until just recently I've been running a Derrington hot road cam that I bought in 59. This was advertised by Mr. Derrington as requiring an extractor exhaust which I used until it gave up the ghost and I replaced with another extractor system.
I've lost my timing info but I don't think it was a 122. It was an excellent hot road cam with good pull from 3000. Does anyone have any info on this XPAG cam.
I have a grinding master and the cam has another grind left. I replaced it with a roller only to eliminate the wear. I'm not selling as I still might go back to it but would be interested if anyone has numbers on it.
Thanks
Charlie

c mac quarrie

Just curious but can either of you provide the full specs for the the AEG 122 and the 168551 camshafts including lift and cam timing specs?

Are there any visual identifying features on the camshafts themselves. I have seen neither of these cams. Am I to assume by the “168” # that this was some sort of over the counter “service package” cam intended for the MK IIs?

Thanks gentleman

Bill Chasser
TD/c-8151
W A Chasser

Hi Guys,

I have run an AEG122 cam on my TD since 1975, this was with originally a high compression head steel head, then later a Lystall head, big valves, 1 ½" carbs, and extractor manifold, I felt it worked well and greatly enjoyed it. However, like a lot of XPAG's we had the cam follow problems, and twice they eat one lobe. I have now changed to one of Len's performance roller cams and roller rockers. I have one installed in my TF, but as that is more of a concours car it has only done 3000miles, it does not have the extractor manifold but seams to work well.
Point to note about the AEG122 is that the needles are well documented as LS1, but what is less recorded is you use Red springs, not the standard Blue.

Bernie
B W Wood

Bill, the timing for the AEG 122 is in the table above. The numbers on the right (Inlet 13 and 59, Exhaust 50 and 22). Lift is 8.3 mm and valve clearance is .019" (down to .015" for quietness). It was a cam offered by the MG Service department and was called the "Competition" cam, although I think I have heard it called the "Half-Race" cam too.

The 168551 was also offered by the MG Service Department and was called the "Racing" cam. Timing is Inlet 32 and 58, Exhaust 60 and 30. Lift is also 8.3 mm. Valve clearance .012" inlet and .019 exhaust.

The cams were listed in the "SPECIAL TUNING for MG midget ENGINES type XPAG/TF-1250 and type XPEG-1466 (As fitted to Series TF and TF 1500 cars". I will scan the page and put it into this thread. The image I have attached now, is of four cams to show the difference in profile (and the similarity between AEG 122 and the TC cam).

I have seen AEG 122 stamped on a cam, but my NOS AEG 122 has no identifying marking. I have seen several 168551 cams but none of them have had identifying marks. I have seen many TC cams and they have all had the two "rings" machined in the back face as in the photo, but I haven't seen that identification officially documented anywhere. Note the Wolseley 4/44 cam is the same as TF.

Sorry Charlie, I know nothing about non-MG Factory cams.

Bob






R L Schapel

Bill, I have attached the image of the page in the TF "Special Tuning Manual".

Thanks Bernie, That is the sort of information I am after. Did you get any comparison with an early TD cam? Interesting that you had cam follower problems. Touchwood, I have not had such problems yet, but have heard it is common. Perhaps it is because I have never bought any new valve springs? I run the same old springs and occasionally grind the small chips out of the follower faces on the side of my bench grinder wheel. The latter sounds crude, but I do it carefully, checking with a "square". Being hand-held, it is impossible to get them dead flat, but a radius is desirable anyway! I don't recommend my method, but it seems to work for me. The followers have fairly deep (chilled) hardening.



R L Schapel

I did see the post above. I meant to say if there was an advertised lift @ .050 for the purpose of degreeing in the cam. Or whether you found a particular cam timing advance/ retard that worked best. I have no idea what cam was installed in dads car and I didn’t degree it to find out. My roller cam I’ve played with quite a bit to find its sweet spot with my NA 1366 performance engine.

Thanks for posting the comparison sheet.

Bill Chasser
TD/c-8151

W A Chasser

Their are " Experts" that claim that the checking clearance, for duration, of MG OEM cams is .021" !
I hope that someone can confirm if this is correct or not, and what the duration @ .050" lifter rise is.
Len Fanelli
Len Fanelli

It's a good point you make Len with the .050" lift measurement
Although the AEG 122 cam and the std TC cam appear very similar , I suspect that the 122 cam has a much more aggressive opening rate which the .050" measurement could indicate , A check further on say at .100" would also be interesting
William Revit

Ugh. I meant duration not lift at .050 Thanks Len
W A Chasser

"The (AEG 122) camshaft may be described as semi-racing and some feeling of lost power at the lower revs. may be felt, but the free-running of the engine at the higher revs. in top and the intermediate gears should compensate for this. But be reasonable when using the revs. available, as, due to the design of the camshaft, the valve crash-point is not loudly audible, and the maximum revs. could be considerably exceeded. A good driver is aware of this point of uselessly over-revving his engine (with resulting expensive noises) and drives on the rev. counter with due respect."

Special Tuning handbook, 1954, p. 9.

Tom Lange
MGT Repair
t lange

Does anyone have a web link to "SPECIAL TUNING for MG MIDGET ENGINES type XPAG/TF-1250 and type XPEG-1466 (As fitted to Series TF and TF 1500 cars" that Bob and Tom mentioned?

I was going to post the link as an aid to this thread. But I can't find the link. I downloaded and saved a PDF color version and a black & white version of document in July 2014. (This is why I always save every MG manual and document on the web to a PDF document that remains when the link is broken or lost.)

Thanks,

Lonnie
TF7211
LM Cook

Hi Lonnie,

If you wish, I could scan each double page of the TF version of the document and send it to your email address. It would be when I get a chance during the next few days. Let me know if this would help.

Willy,
The image I posted does not show visible difference in profile / opening rate of AEG 122. But I am aware that "visual" differences are not clear with regard to cam profiles. I don't have the AEG 122 in an engine and would have to learn new skills to do the tech calibration you guys are talking about.

Bob
R L Schapel

Len' I've heard of the .021" checking clearance before and believe it was a figure quoted from the 'factory' as it eliminates quietening ramps etc
My guess is that it was the way they did it back then whereas the .050" measurement for aftermarket cams is more the norm nowadays
I'm still searching, I've seen it somewhere but can't get my hands on it--------yet
William Revit

Bob if you could send me a scan of the Tuning document, I’ll add it to my library as well. I have the earlier TD timing pamphlet. Just interested in any changes or additions for comparison. You can send it to the email link above. Thanks in advance.

William I would also be interested in more info on the .021 vs the .050 timing cam timing specs
W A Chasser

Bob
I had missed seeing your pic of the 4 cams
The woosly cam and the racer are obviously different
The 122 appears to have more lift than the TC which in itself will give increased lift throughout the range given the duration is almost equal to the TC -so the starting point is almost equal but the valve opens quicker/ further to give it the performance boost
Given the duration and start points are very similar to a TC cam then it 'should' have the same low down power as the TC but rev a bit free'r because of the extra lift etc.
Earlier you mentioned the similar inlet valve closing points between the 1/2 and full race cams although there is a substantial difference in duration
My take on this is that it's done to prevent port robbing because of the siamese port/manifold arrangement and has basically the same effect that a scatter patern cam has on wilder grinds ie. shuts the inlet valve off early to prevent the other cylinder on that port from nicking it's load
William Revit

Bob looking at the pic showing all four cams it’s clear to me that the “168” cam can be identified by its ring pattern (well maybe)? If you look closely the rings on the end of the journal are obliterated nearest to the centering point vs the other three cams.

Bill Chasser
TD/c-8151
W A Chasser

Len
Might be a A?B series thing
Got the following off Paul Walbrum's thing--
Don't know if it covers T types though---

Camshafts can be identified by the opening and closing points of the valves, in conjunction with the amount of lift that the cam has. The actual valve opening and closing points are in an area of the cam action known (surprise surprise) as the opening or closing ramps (resp) or just ramps. This area is one where the cam is lifting very slowly so as to avoid hammering the valves, but the slow action makes precise measuring of the opening and closing points relatively vague. For this reason, cam timings are usually specified at a nominal “timing clearance” which at a lift clear of the ramps and which is significantly greater than the normal tappet running clearance.

A common and popular timing clearance for after market camshafts is 0.050″. However, as BMC specified their cam timing at a lift of 0.016″ off the base circle of the cam lobe, that is the relavant figure to use for MG engines. At the valve end this translates to .023″ on the std B series rockers, .021″ on std A series rockers.
William Revit

> Bob - Thanks for the offer to scan the "Special Tuning" document, but I don't need the document. I'm looking for the link where I downloaded it.

> Bill - I'll send the PDF to you in a few minutes, plus a few similar docs.

Lonnie
TF7211
LM Cook

A tangent which I find curious. Note the colour of the metal between the lobes. The 158551 and ARG122 are silver. It is a NOS AEG122 and the 168551 is almost new (apart from the chewed oil pump drive) so the photo could be misleading. However, I have noticed that all 168551s seem to have that silver look. I remember about 45 years ago cleaning some cams in kero and then hosing them off. The TC cams showed traces of new rust on the white rag (especially if left wet for a while) but the 168551 did not show any rust. Perhaps the special cams were made of different material?



R L Schapel

Another angle showing the lobes for those interested. I assume that the centre recess on AEG122 is not an identification mark (unless others have similar recesses).


R L Schapel

Bob I misidentified my description of the journal end of the 122 cam as being the 168551 cam in my last post
W A Chasser

Jnteresting observation with the material colour Bob
Years ago I had a genuine factory 770 race cam for my MGB and it also was a lighter coloured material and fully machined, and smaller in shaft diameter as your 2 cams appear to be--also if I held it upright by the end and gave it a little tap with something hard it would ring like a steel crank does but a std MGB cam has nowhere near the same ringing result---definatley better, harder material
William Revit

Thank you William regarding checking clearance.
For a reference here is the timing card of the full race flat lifter cam that I stock. Developed to beat the B &G 102 cam with help from the late Dave Generous, Chase Knight ( Crane Cams) Manley Ford & Steve Konsin.
disregard the 1.27: 1 rocker ratio.


Len Fanelli

Here is a photo of the cam lobes for the 242 242 08 @ .050" lifter rise. BTW the copper coated cams are heat treated to a depth of about .120" VS if I remember correctly about .020-.030" for a non copper coated cam


Len Fanelli

Good looking cam Len, it certainly gets some action going nice and early so must hold a nice amount of lift for a long period
I ran a cam in my midget with 300 ex and 320 in. adv. duration, it was a monster,but strangely easy to drive, I've been looking for the card for the .050" specs
I'll post it here when I find it
Cheers
willy
William Revit

This thread was discussed between 10/02/2020 and 20/02/2020

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.