JohnC Posted October 8, 2017 Report Share Posted October 8, 2017 (edited) Hi Steve, What was the end result? What work did the crank need? Cheers, John Edited October 8, 2017 by JohnC Quote Link to post Share on other sites
astontr6 Posted October 8, 2017 Report Share Posted October 8, 2017 Could possibly be small end bush material, circlip retaining the gudgeon pin broken causing scoring on your #2 cyl and the subsequent low compression therein??? Just a thought, but as other have already suggested, it may be wise to remove the cyl head or at the very least a boro-scope inspection down the spark plug holes. Regards, Richard. +1 for Richard Small end bushes caused by a dry start! But also check crank shaft thrust washers? Bruce. Quote Link to post Share on other sites
villa.1 Posted October 8, 2017 Author Report Share Posted October 8, 2017 Big end bearing was the issue, I assumed due to a dry start or blockage etc..? I had everything out in bits and the crank was going to need yet another regrind so i decided to bite the bullet and spend some cash on improving the bottom end. Racetorations supplied a new steel crank, lightened conrods, new cam, flywheel..etc... On re-assembly it was obvious all was not right as the crank was very tight could not easily be turned by hand so they checked it with a blank shaft of the correct diameter which had the same issue revealing my underlying problem was the block was very slightly warped/twisted. This was perhaps due to a previous overheating episode before my time. So all apart again and the block was line boared plus installed cam bearings. Also had Racetorations fit their bottom end brace kit, which will further strengthen the bottom end. I plan to get it set up on rolling road next month and will let you know how she does. FIngers Crossed! Steve. Quote Link to post Share on other sites
astontr6 Posted October 9, 2017 Report Share Posted October 9, 2017 Big end bearing was the issue, I assumed due to a dry start or blockage etc..? I had everything out in bits and the crank was going to need yet another regrind so i decided to bite the bullet and spend some cash on improving the bottom end. Racetorations supplied a new steel crank, lightened conrods, new cam, flywheel..etc... On re-assembly it was obvious all was not right as the crank was very tight could not easily be turned by hand so they checked it with a blank shaft of the correct diameter which had the same issue revealing my underlying problem was the block was very slightly warped/twisted. This was perhaps due to a previous overheating episode before my time. So all apart again and the block was line boared plus installed cam bearings. Also had Racetorations fit their bottom end brace kit, which will further strengthen the bottom end. I plan to get it set up on rolling road next month and will let you know how she does. FIngers Crossed! Steve. Steve! Have the bore centres been checked for accuracy of past boring, a long with the flatness of the top of the block face? Also has the blanking plugs in the block oil gallery been removed and a rifle cleaning rod with a bronze brush been pushed through from one end to the other, as sludge collects in the gallery? Bruce. Quote Link to post Share on other sites
Jamiezt190 Posted October 9, 2017 Report Share Posted October 9, 2017 Have you put the right sump on - cranks bottoming out? Happened to me once ! Quote Link to post Share on other sites
TRTOM2498PI Posted February 2, 2018 Report Share Posted February 2, 2018 Hi Steve, How did you get on with the engine build ? Cheers. Quote Link to post Share on other sites
AtRo Racing Posted October 11, 2019 Report Share Posted October 11, 2019 My GT6 does the same thing. When in the car if I slowly rev it and hold it at 4000 Rpms then I hear a chatter dead center in front of the dash board that I believe it is rocker chatter caused by the rocker shaft and the rockers being worn. The engine sounds like it has hit a rev limiter who it does not have. Looking into the ROCKER SHAFT AND BRONZE BUSHED ROCKER SET FROM MOSS THAT IS HONED TO .002” CLEARANCE. It most defiantly is not coming from the lover end of the engine. Robbie Quote Link to post Share on other sites
AtRo Racing Posted October 11, 2019 Report Share Posted October 11, 2019 My GT6 does the same thing. When in the car if I slowly rev it and hold it at 4000 Rpms then I hear a chatter dead center in front of the dash board that I believe it is rocker chatter caused by the rocker shaft and the rockers being worn. The engine sounds like it has hit a rev limiter who it does not have. Looking into the ROCKER SHAFT AND BRONZE BUSHED ROCKER SET FROM MOSS THAT IS HONED TO .002” CLEARANCE. It most defiantly is not coming from the lover end of the engine. Robbie Quote Link to post Share on other sites
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