qkingston Posted January 9, 2020 Report Share Posted January 9, 2020 What is the purpose of the blanking bolt at the top rear LHS of the TR4a cylinder head? Can it be used for additional lubrication, does it need to be? Thank you David Quote Link to post Share on other sites
RogerH Posted January 9, 2020 Report Share Posted January 9, 2020 It is there to blank off an oil gallery with a dog leg. It connects to the oil hole in the rear rocker pedestal. If you are brave you can get a kit that will supply more oil, to the rocker shaft possibly at the expense of the crank - don;t go there. Roger Quote Link to post Share on other sites
Motorsport Mickey Posted January 9, 2020 Report Share Posted January 9, 2020 1 hour ago, RogerH said: It is there to blank off an oil gallery with a dog leg. It connects to the oil hole in the rear rocker pedestal. If you are brave you can get a kit that will supply more oil, to the rocker shaft possibly at the expense of the crank - don;t go there. Roger As often the case Roger is correct. The factory decided you don't need an ancillary feed from there, racers over the years have decided not to run a feed from there, DON'T go there, standard is fine. Mick Richards Quote Link to post Share on other sites
qkingston Posted January 9, 2020 Author Report Share Posted January 9, 2020 OK thanks chaps Quote Link to post Share on other sites
Darranh Posted January 10, 2020 Report Share Posted January 10, 2020 Interesting - would you therefore recommend that I remove mine then from my TR4? When I replaced the rocker cover gasket there seemed to be more than ample oil swilling around at the rear of the rockers... Never thought about the effects on the crank... Quote Link to post Share on other sites
silverfox4 Posted January 10, 2020 Report Share Posted January 10, 2020 I would say absolutely yes, but hopefully more experienced minds will chip in Alf Quote Link to post Share on other sites
RogerH Posted January 10, 2020 Report Share Posted January 10, 2020 8 hours ago, Darranh said: Interesting - would you therefore recommend that I remove mine then from my TR4? When I replaced the rocker cover gasket there seemed to be more than ample oil swilling around at the rear of the rockers... Never thought about the effects on the crank... Hi Darran, the oil through the add-on external feed comes from the main gallery in the block. This also feed the crank among other items. If the external feed is not engineered very well then you run the risk of taking too much oil from down below. Probably on many engines you may well get away with it. But!!! how will you know until it is too late. There have been a few(very few) posters on here to say theirs works perfectly (how do you measure perfection) The majority of posters have warned against its use and these include well respected TR racing drivers/engineers. The bottom line is simple - a rocker shaft will take 30,000 miles to wear out prematurely and takes about £50 and 2 hours work. The crank will cost £1000+ and take 2 weeks. Unless you like experimenting then I wouldn't go there. Roger Quote Link to post Share on other sites
Darranh Posted January 10, 2020 Report Share Posted January 10, 2020 Thanks Roger and Alf. I'll add that to my list of jobs to do and totally agree. The car had a new crank in the mid 90s and I don't want to repeat that in my ownership. Was planning on an oil change anyway. Good to learn these things. Darran Quote Link to post Share on other sites
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