Sorry for the lack of photos in this next bit but there's still some catching up to do before we get the next batch...
After the 2018 Nats, having sorted the valve covers, starter, timing etc there was still one remaining doubt – was the trans working ok? What made us wonder was that we’d lost the firm shifts that we previously had. Even under light throttle, we used to get a little chirp on occasions, on the 1-2 change, but now the change from 1-2 and 2-3 were almost imperceptible. We asked Dave Bishop if there could be something up with the Shift Kit after the rebuild but as he said, the shift kit is in the valve body and he didn’t touch that.
After talking to various friends and MMA members we started to get the idea that the converter that Koffel sourced for us, from TCI, was probably a bit too ‘loose’. Up to this point we hadn’t really looked into converter choice – stall, size etc – we just trusted Koffel & TCI to choose the right one given the engine spec and our intended use. At Brooklands last May, we mentioned the symptoms to RPM’s Martin Saville and he agreed to take a look to see if there was anything other than the converter causing the sloppy shifts and what felt like the trans slipping.
The majority of people reading this will probably know this all sounds like a loose converter but as we hadn’t had a loose converter before now, and weren’t aware of the symptom, so we were keen to see if anything else was up.
We continued to use the car tho and while we were waiting for Martin to have room for us, the next problem reared its ugly head…
Whist road-testing the fitting of a new brake line that Stu had made and fitted for the rear brakes, he noticed a loud ticking noise coming from the engine; the kind you hope is just a leaking exhaust gasket. Unfortunately it wasn’t a gasket. So off with the driver-side valve cover to investigate.
We then noticed that the No.3 exhaust push rod had come away from under the rocker arm. Could have been a lot worse, but it was a lot worse than we expected after 1500 miles on a new engine.
Pics:
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Having reported this back to Koffel, they suggested it was most likely caused by over-revving. Unlikely in this case, especially as this was on a test drive around town, so probably occurred at no more than 2500rpm. Alternatively, they said, it could have been the lifter top not returning to let the push-rod drop.
They did offer a resetting procedure, so, assuming it was just the lifter sticking, we reassembled and readjusted all the rockers on both sides. With the valve covers back on we started ‘er up and the noise, thankfully had gone. Being the cautious types we are tho, we mentioned this to Martin at RPM and concocted a plan to get him to check the trans, this lifter issue and a few other things we felt someone of his calibre would be better off looking at for us; not least of which was a rear main seal leak!
Eventually we got to take the car down to RPM in March this year. One good thing about the pandemic/lockdown situation was that Martin wasn’t as rushed as he would normally have been, with a queue of customers waiting to get their cars done in time for various events, so he was able to take his time a bit more than he otherwise would.
Priority tho was to check the trans line pressure, shift kit operation etc and establish what stall speed our converter is. But as soon as Martin drove the car he could tell the stall was too high for our intended use and was most likely the cause of the soft shifts and also the high underhood temps we’d experienced in traffic.
Martin’s estimate was that the stall was 3000rpm.
Around this time I remembered I did get a photo of the converter in its box when it was shipped with the engine, so once I found that and looked up the number, we knew it was actually 3800-4000!
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I checked with TCI and they were still happy that was the correct converter for us! Curiously, I also asked Hughes, as they seemed to be a favourite amongst a few MMA people I asked and they also recommended something around 3000.
Recommendations from everyone else tho were more in the 2000-2500 region so we opted for a Hughes 24-25HD (2500) converter which I ordered from Summit last week and it arrived at the start of this week.