Geko Posted December 26, 2015 Report Share Posted December 26, 2015 Hola, I've been dragging the feet with my engine grand strip but it's now on. If found a good salvageable head which I'm going to cut grind, groove all over the place. Problem is cyl #4 whose combustion chamber is rust-pitted. I need to give some guidance to my machine shop boys because they always see me coming in with some trepidation. Based on the pictures below, my question is: Shall I ask for a re-cut or go for valve inserts? I'll use inlet and exhaust large valves, 5/16 stem. Thanks and Merry Xmas Quote Link to post Share on other sites
Mark1965TR4aBRG Posted December 26, 2015 Report Share Posted December 26, 2015 (edited) Inserts. Here's my existing head with new inserts and mine was nowhere near as bad as yours looks. Edited December 26, 2015 by Mark1965TR4aBRG Quote Link to post Share on other sites
MRG1965 Posted December 26, 2015 Report Share Posted December 26, 2015 Inserts. Here's my existing head with new inserts and mine was nowhere near as bad as yours looks. Hi Mark, one question, the numbers written on the head, is that the combustion chamber capacity in cubic centre meters? And if so what compession ratio did you end up with. I guess that depends on the bore size you have. I only ask as I got to take the head off mine and while its off I'll get the unleaded seats and raise the CR at the same time depending on what value is currently. Mark Quote Link to post Share on other sites
TriumphV8 Posted December 26, 2015 Report Share Posted December 26, 2015 Why not fitting new valve guides and recut two seats that seem to be the worst for a test? By adding the 3-angle seat cut the valves will drop down a bit anyway. Some like the advantage that the inserts are harder and prevent the seat from getting dimples, others do not like that the head needs maching and the force of the pressed in inserts might support cracks. I personally have my own cutters and like to reuse heads without inserts I would use bigger valves if the seats are spoiled and can not be recutted to suit. Quote Link to post Share on other sites
Geko Posted December 26, 2015 Author Report Share Posted December 26, 2015 (edited) Some like the advantage that the inserts are harder and prevent the seat from getting dimples, others do not like that the head needs maching and the force of the pressed in inserts might support cracks. Yes, that's a bit the dilemma not to mention that I don't like the idea of an errant insert taking a spin in the combustion chamber...another thing that can go wrong. And I do like the idea of a 3 angle cut allowing the valve to recess in addition to improving gas flow. Edited December 26, 2015 by Geko Quote Link to post Share on other sites
TriumphV8 Posted December 26, 2015 Report Share Posted December 26, 2015 (edited) So what about looking a bit at that NEWAY thing? Bought in the USA you can benefit more than we here from the strong GBP that makes the two cutters and a suitable pilot and some smaller parts a 400 GBP expensive worth every penny you spent. Some information can be found here: http://www.oko-saturn.de/en/produkte/verbrauchsmaterial/neway-ventilsitzfraeswerkzeuge/ Edited December 26, 2015 by TriumphV8 Quote Link to post Share on other sites
Mark1965TR4aBRG Posted December 27, 2015 Report Share Posted December 27, 2015 Hi Mark, one question, the numbers written on the head, is that the combustion chamber capacity in cubic centre meters? And if so what compession ratio did you end up with. I guess that depends on the bore size you have. I only ask as I got to take the head off mine and while its off I'll get the unleaded seats and raise the CR at the same time depending on what value is currently. Mark Hello Mark. Yes - it's the chamber capacity in cc's measured with a big pipette thingy and a thick piece of perspex. I'm now running 89mm pistons and compression ratio was just under 10.5:1 I recall being told.. Quote Link to post Share on other sites
MRG1965 Posted December 28, 2015 Report Share Posted December 28, 2015 Hello Mark. Yes - it's the chamber capacity in cc's measured with a big pipette thingy and a thick piece of perspex. I'm now running 89mm pistons and compression ratio was just under 10.5:1 I recall being told.. Thanks Mark Quote Link to post Share on other sites
Geko Posted January 3, 2016 Author Report Share Posted January 3, 2016 As expected the fear could be read in the eyes of my machine shop boys. On the one hand they apprehend the the insert solution as it could weaken the casting while on the other hand they are skeptical as to whether there would be enough material to recut the seats. Some more advice especially from the racing boys appreciated.... Happy new year ! Quote Link to post Share on other sites
Chilliman Posted January 3, 2016 Report Share Posted January 3, 2016 Stef, the head I'm running at present was very similar in terms of damage to yours - I've fitted the largest valves I could get for both inlet & exhaust and had the machine shop fit inserts for both - done 10K plus so far of hard driving including track days and hill climbs without any issues at all - still the same pressure as when built. Hope that helps,....and I see from the latest TRaction you're now a member so welcome! Quote Link to post Share on other sites
TriumphV8 Posted January 5, 2016 Report Share Posted January 5, 2016 Some more advice especially from the racing boys appreciated.... Happy new year ! Happy new year to you! There are many bigger valves on the market. They will repair nearly every spoiled head unless they have already been in use in that head........ Racetorations made a head I could check with a real big exhaust. I made one with 36mm exhaust. Anyway I would bet that the seats could be rescued by establishing the 3 angles seats I would not worry to set them a bit deeper and there is a lot of material that has to be cut away for that job. Can not believe that all that material is already gone in your head! You need a tuning shop that is familiar with that setup. If the valve seat rings can not get out of your head I would only put them into the exhaust! All these modern guys have to deal all day with aluminium heads and think from that rings are a must but they are not in cast heads and normal use! Quote Link to post Share on other sites
stillp Posted January 5, 2016 Report Share Posted January 5, 2016 I've only once used valve seat inserts - fitted by my local highly-respected engineering shop at the time. One fell out on the motorway, wrecking the engine. I know there are many thousands of engines running about on inserts without a problem, but it's a potential failure that can be avoided. As Andreas suggests, if there's enough metal in the head to hold inserts, then there's enough to allow recutting the seats for larger valves. Pete Quote Link to post Share on other sites
Geko Posted January 7, 2016 Author Report Share Posted January 7, 2016 Thank you all for your inputs, we'll go for a re-cut and will try to source bigger valves which is a bit of a mission in itself. The diameter of the inner seats is currently as follows: Inlet: 41 mm / 1,614 in - Moss big inlet valves are 1,605 in Exhaust: 33 mm/ 1,300 in Anyone knowing where i could source non-standard valves with 5/16 stems? Cheers Quote Link to post Share on other sites
iain Posted January 8, 2016 Report Share Posted January 8, 2016 Try Neil Revington.Always gives sensible advise. Just been through this exercise. Quote Link to post Share on other sites
TriumphV8 Posted January 9, 2016 Report Share Posted January 9, 2016 As the TR4 head I prepared had just fresh bronze valve guides with oil seals in place we decided to stay with the metric size inside. I used a Subaru and a Mercedes valve that was cut to length and rehardend. Anyway 33mm inside is not bad, it is perfect for the 36mm valve and that is something that can be bought for that engine. Bastuck has the ZK22TR4R that is not expensive and fits perfect. The inlet is 42mm and stamped ZK21TR4R. It might be worth a try, a bit small but maybe just okay. Would give it a try! Quote Link to post Share on other sites
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