NCS_TR3A Posted May 27, 2021 Report Share Posted May 27, 2021 Having got the engine up and running after changing oil seals all around the car, fitting a rear Crank oil seal and working (yet again) on the carbs I seem to have it running the best it has been, plugs the right colour, gunson gas tester reading 3.5 to 4 on CO (possibly still a little high but I always go slightly ritch and plugs look right. The bonus being it no longer leaves a mark on the ground. Keen to record were everything is I decided to do a compression test (probably would have been wise to do this before removing the engine). The numbers look consistent but high. The guage I have is also a Gunson and I've tested it against others and they are the same, doesn't mean both are right but it reduces the chance by the both reading the same. I tested the compression cold first, then I added 5ml of oil and tested each cylinder wet and then finally took the car up to temp and tested hot. These were the results - Cylinder No1. No2. No3. No4. Cold 205. 207. 205. 210. Wet. 245. 237. 242. 247. Hot. 200. 205. 210. 205. Results all in PSI (can only really read the guage in 2.5 increments) The engine is a TR3A engine but it has 87mm liners, and a standard TR4 cam form what I can see. I have no ideal about the top end as I've never had the head off. It does have a high torque starter which I guess may increase the results (fast spin) Do these figures look to high to everyone. Is there a risk from having them too high? I was expecting them to be about 150 - 160, and increase when wet (which they have) but then to read higher hot than cold as well which they didn't. The car seems good, everything is probably were it should be and I guess I have no plans to do anything about this unless someone more wise than me has real concern. I just plan to measure the timing (not done yet, it's about 2 degrees static and doesn't pink, but need to measure dinamic) Thanks as ever Neil Quote Link to post Share on other sites
john.r.davies Posted May 27, 2021 Report Share Posted May 27, 2021 The absolute numbers from a compression gauge are never comparable, gauge to gauge. The instruments are neither precision made nor calibrated. But they are comparable, bore to bore, where a difference of +/- 5psi is very good! So no probs, Neil! Enjoy your new engine! John Quote Link to post Share on other sites
NCS_TR3A Posted May 27, 2021 Author Report Share Posted May 27, 2021 (edited) Thanks John, so nothing to worry about. The engine is not new, it came out to tackle oil leaks giving me something to do at weekends in lockdown as driving it wasnt possible (we'll ethically not at least). Just changed the front crank seal, fitted a rear Crank seal, new timing chain etc. Gearbox seals and diff seals and was just happy it all worked when put back together :). It is certainly time to start using it again. Thanks, Neil Edited May 27, 2021 by NCS_TR3A Quote Link to post Share on other sites
Lebro Posted May 27, 2021 Report Share Posted May 27, 2021 The results are extremely close to mine 87mm, Newman PH1 cam, reworked, & ported head, calculated 9.3:1 CR. The y seem rather higher tha one would expect for that CR, but I get no pinking, so am not concerned. My gauge is also a Gunson one, & I have compared it to another gauge I trust on my compressor. It agreed with it when fed 150 PSI of air. Bob. Quote Link to post Share on other sites
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