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MG TD TF 1500 - Grose Jets Question

I just changed the needle valves to grose jets on my TF in the carb floats. When I did, I adjusted the fork lever to 7/16" (rather than 3/8" as is in the manual), as per a suggestion from a previous thread. Since the change, I have had difficulty getting the fuel pump to stop ticking. I did get fuel coming through the overflow tubes, so I put neoprene washers on top of the floats which would have made a 1/8" adjustment - so now the total measurement of the fork is 9/16". The ticking subsided but did not go away although the overflow did stop. This seemed to help, and the TF runs really well. However, I am still getting a tick from the fuel pump about every four seconds, yet I don't see any gasoline leaks. I be befuddled. Any thoughts?

Safety? Fast?
Scott Ashworth - '54 TF 1250
S. R. Ashworth

where exactly are you putting the neoprene washers? if the pump is ticking fuel is moving somewhere; back through the pump, a fitting or through the carbs.
tm peterson

Scott
Strange that, as I fitted grose jets to my TF a couple of months ago and experienced the opposite effect. With the lever arms set at 3/8" fuel flow was cut of too soon, especially the rear carb, and the car suffered some rough running. I had to reduce the lever gap to just under 7/16" to cure the problem. Are the ambient temperatures in your neck of the woods very high at the moment? My pump runs for some time every morning before the first start of the day due to loss of fuel through evaporation during the warm nights.
John 54 TF 5924
John James

TMP,
I have 1/8" thick by about 1" diameter washers that I put on top of the floats. They are very light, so I don't think I'm holding the floats down. The thinking was that if this would cause the grose jets to shut off sooner, I would bend the forks down to beyond the 7/16".

John,
I'm confused by your post: "With the lever arms set at 3/8" fuel flow was cut of too soon, especially the rear carb, and the car suffered some rough running. I had to reduce the lever gap to just under 7/16" to cure the problem."
Doesn't increasing the gap (from 3/8" (.375) to 7/16" (.4375)) have the opposite effect of shutting off the grose jet sooner? At least that's the misapprehension under which I am laboring. The lower the forks are down into the bowl, the sooner the grose jet, or needle valve, would shut off fuel as the float raises.

Thanks.

Safety? Fast?
Scott Ashworth - '54 TF 1250
S. R. Ashworth

Somebody's missing something. The washers that are used with Grose Jets are small, thin, fiber washers that go around the Grose Jet body threads and vary its seating height by the washer's thickness. You generally use either none or one, rarely two. The washers should have been in the package with the Grose Jets.
Bud Krueger

bud, i see what scott is saying..he put a spacer washer on top of each float...sort of like a shim..to see what effect that would have. if successful he would then remove the washers from the top of the floats..and make the required bend to adjust the arm to the same location as provided by the "shim" washer. scott as the other posters have stated..the only time my pump runs s on initial power up and then is quite until i start up and the engine starts burning the gas. if yours continues to run with just the key on...fuel is moving somewhere. in my limited experience the float level doesn't have to move too much to effect the engine operation, but it can vary quite a bit and the grose jets will still shut off the gas. so no fuel out the over flow. on my car the little bleeder pins got hung up and would not let the float rise so gas kept coming..but i had flow out the over flow so even i could trace that problem. best of luck, tom
tm peterson

Scott
Sorry about that I should have said approx 5/16th with the washers that came with the GJ's left in situ. I also found the ball in one G V was sticking a bit until I cleaned it with petrol.
John
John James

Thanks for everyone's help. I am biting the bullet and moving on to the rebuild of the jets. I hate to do that since it's running well, but I can't accept a fuel leak. Nobody has indicated that the grose jets require a geometry change, so I'll remove my shims and go back to the 7/16" gap per the manual,(since I am not seeing the same effect that John did.)

I did sit and watch the Moss SU rebuild video last night. Apparently I have become oldfartified, because I enjoyed every minute of the tape. It does a nice job of de-mystifying the SU's.

Safety? Fast?
Scott Ashworth - '54 TF 1250
S. R. Ashworth

Scott, the expert in the video, Lawrie Alexander, has a shop in California, British Sportscar Center, http://www.britcars.com/ . Lawrie is a great resource for most any sort of lbc issue.
Bud Krueger

This thread was discussed between 30/06/2005 and 01/07/2005

MG TD TF 1500 index

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