Re: shorter pushrods???

[bgthomas@earthlink.net]

Hello Everyone

I continue to work on the TF 1500 engine for the TC which I have fitted with a AEG122 cam and my head is 2.995" (76.07mm) thick. As I went to adjust the valves I discovered that there is no clearance to adjust, even though I had already fully backed out the screw to give maximum clearance when I attached the rocker assy. Since the standard pushrod seems to go solid, my thinking was that I would need a rod about .250" shorter. I figured this would put me about in the middle of the adjustment range of the screw.

I know Moss sells shortened push rods for their cams, but when I called them they could not tell me how much shorter they actually are. Also I understand that some people have fitted spacers under the rocker support bracket, but the impression I had was that it is better to fit shorter rods.

I also looked at Abingdon Spares catalogue. They show shims for the rocker support and they also show a separate "TF" pushrod, which they describe as solid. Does anybody know what difference in lenght there might be as well?? This is the first I had seen any reference to a unique pushrod for the TF.

When I mentioned this need for .250" to a fellow who is very knowledgable about engines, although not about MG's, he could not believe I would need to take that much off the length and was worried about the geometry of the valve being so off that I would end up pushing the valve sideways too much, quickly wearing out the guides.

Any and all enlightenment would be much appreciated.

Thanks again for all your help. It is really great being able to turn to such a knowledgable group when I find myself sitting in the garage staring at the car thinking "now what???"

Bob
TC EXU7388

[Jennifer and Hugh Pite]

Bob, the pushrods from engine # XPAG/TD2/17298 are shorter in length since the adjusting screws are longer in length. This is from page A.32 in the MG MIDGET TD and TF workshop manual. According to the manual, you cannot mix the parts.

Hugh Pite
TC, J2

[Bob and Carolyn Grunau]

Hi Bob, shorter pushrods are available from Crane Cams in Florida. I had to use these pushrods on my race XPEG engined TC as the large cam lobes required them. Crane should be able to give you the exact length. Alternatively you can draw the end off your pushrods and shorten the tube. Then re-install the end. Tig weld the ends to the tubes as required. Easiest if you select pushrods that already have one end loose in the tube, a not uncommon occurrence.

I am surprised that you need shorter pushrods with only 0.027" milled off the head. Has anybody milled anything off the rocker pedestals? This could cause your problem. Or possibly the cam has large lobes?? I have the Crane short pushrod part number somewhere but can't put my hands on it right now. If desperate I can possibly find it.

regards,
Bob Grunau

[Skip Kelsey]

Bob:

The stock cyl. head is 76.75mm thick. 8.6 to 1 is 76.25mm thick,and 9.3 to 1 is 75.50mm thick. so yours is still within specs for the road. The TF pushrod is very slightly shorter than the TC unit, plus the adjusters are longer. This was due to the change from the TC cam with a .308 lift to the TF cam with a .315 lift. I have put TF cams in TC/TD engines before and didnt have the trouble that you are having. Are you using the TF grind, I dont remember? I have been using custom made pushrods made by Smith Bros. up in Bend, Oregon.

Cheers:
Skip Kelsey.........................