Nick Jones Posted May 28, 2015 Share Posted May 28, 2015 The studs can be troublesome...... though not usually quite as bad as 1850/TR7/Stag as they are all oiled from the top (as it were).I'd have a damn good look for other reasons for the misfire first!Nick Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted May 28, 2015 Share Posted May 28, 2015 Ugh! Horrible, horrible job.M. Quote Link to comment Share on other sites More sharing options...
Toledo Man Posted May 28, 2015 Share Posted May 28, 2015 Nick is right. The first thing to check is the ignition. A few basic checks on the ignition system will help. The head is alloy so it had hardened valve seats. This means that you don't need to worry too much about valve seat recession. Quote Link to comment Share on other sites More sharing options...
Stuart Wilson Posted May 29, 2015 Author Share Posted May 29, 2015 It's just recently had new cap, leads, points, plugs etc. I'll investigate a bit more before looking at pulling the top off.No doubt I'll be back with more questions ;) 8) Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted May 29, 2015 Share Posted May 29, 2015 Check valve clearances & compression test.Nick Quote Link to comment Share on other sites More sharing options...
Stuart Wilson Posted May 29, 2015 Author Share Posted May 29, 2015 compression test done all just about the same, varied from 145 to 160.I'll have an hour or so tonight on it before my busy motorsport filled weekend Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted May 29, 2015 Share Posted May 29, 2015 1/ Does it overheat?2/ Does it overheat?3/ Does it overheat?If none of the above it is unlikely to have head gasket issues. As above, I'd check ignition and fuel pump maybe the carb settings but ignition is the likely culprit. I think the Delco distributer could be a weak point on these cars too. Plug leads and those extension pieces that go down the rocker box used to be the bane of my life when I ran a Sprint 35 odd years ago.Mark Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted May 29, 2015 Share Posted May 29, 2015 Misfire as in running on three all the time or running on three at low rpm/small throttle openings with the 4th chiming in when pushed harder? Which pot is not playing?Nick Quote Link to comment Share on other sites More sharing options...
Toledo Man Posted May 30, 2015 Share Posted May 30, 2015 Mark, the Sprint has a Lucas 44D4 dizzy. It was only the 1850 that had the hateful Delco dizzy. That's why I've got a Sprint dizzy in my 1850. The compression figures are on the limit of "within 10% of each other" so the head might just need retorquing. If your dizzy shaft has some play in it, you will get timing scatter. The only fix is to recondition/replace the dizzy or to fit electronic ignition. There are some poor quality ignition parts out there so don't rule out the new parts. Check your carb mounts. An air leak might affect running. Quote Link to comment Share on other sites More sharing options...
Stuart Wilson Posted June 1, 2015 Share Posted June 1, 2015 Well folks, looks like I've cured it. Before my trip to Ireland in it I had a lot of bits and pieces done to it. Fresh carb mounts, various vacum pipes, plugs, leads, cap, points and basically it was running fine. I'd done about 1000 miles before it started playing up. On friday I changed the plugs and checked the cap and rotor arm, hey presto it is running on all four and going well. I'm putting itdown to a dodgy plug. I'd ruled them out originally as they were effectively new, but I had another set so was no harm trying them.Thank you for all the advice Quote Link to comment Share on other sites More sharing options...
Stuart Wilson Posted June 1, 2015 Author Share Posted June 1, 2015 Well folks, looks like I've cured it. Before my trip to Ireland in it I had a lot of bits and pieces done to it. Fresh carb mounts, various vacum pipes, plugs, leads, cap, points and basically it was running fine. I'd done about 1000 miles before it started playing up. On friday I changed the plugs and checked the cap and rotor arm, hey presto it is running on all four and going well. I'm putting itdown to a dodgy plug. I'd ruled them out originally as they were effectively new, but I had another set so was no harm trying them.Thank you for all the advice Quote Link to comment Share on other sites More sharing options...
RobPearce Posted June 1, 2015 Share Posted June 1, 2015 Never assume new parts are immune to faults! At one point I replaced the plugs on my Toledo, just as a general service item, and within a few weeks it was only running on three cylinders. The ceramic of one of the brand-new plugs had given out, causing a blow-by leak that developed into complete non-function. And they were a reputable brand (albeit bought from Rimmers, IIRC). Quote Link to comment Share on other sites More sharing options...
RobPearce Posted June 1, 2015 Share Posted June 1, 2015 Never assume new parts are immune to faults! At one point I replaced the plugs on my Toledo, just as a general service item, and within a few weeks it was only running on three cylinders. The ceramic of one of the brand-new plugs had given out, causing a blow-by leak that developed into complete non-function. And they were a reputable brand (albeit bought from Rimmers, IIRC). Quote Link to comment Share on other sites More sharing options...
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