Discussion
Some of you may remember I had my cams go several years back and I set about fixing myself using a rebuilt head from rnd
(and lots of free guidance from Dave). Head is fine. But my bottom went rattly last summer
I suppose the rule of thumb "do the top, do the bottom" is further confirmed.
Anyway, the bottom end had started to sound kind of "hollow" and at cold idle there was a definite but quiet chakety-chakety-chakety noise.
Thought it was the gearbox input shaft at first, tried to ignore it, then one day...proper noisey raspy, football rattle type noise at idle
that would start as suddenly as it stopped. 100m up the road confirmed it was time to garage it and call Dave !
Removed the engine myself (not mucking about this time...and since the head work, I have built myself some full tipping ramps so can get the car 1/2m in the air)
Stripping engine down showed lots of wear on the main bearing shells. Not scored so much as just plain worn out (esp at the edges). Big end bearings not great either.
Also brought back to focus the fact that the original rods and pistons meant the crowns sat down the bore nearly 40thou which was always a bit of a mystery (TVR special parts bin ?? Or reduced compression to avoid detonation ??? Who knows.)
Long story short, I now have a very nicely running motor again with new H-beam rods, some funky JE pistons with coated skirts and offset pins, billet crank, 4-bolt main conversion and a few other new bits of course ! Compression ratio around 11.5 (by calc and some measurements). Reviewing the old setup I had 9.6:1 !!
All now carefully run in and heading fast to 1000 miles. Sounding great and feels far more perky ! Short block was done by Dave...all the other work was me. For me personally, as a keen "hobbyist" builder, this arrangement works just fine. This is not a thread designed to spark the "usual" row. Please ! But happy to share my experiences during the rebuild if anyone wants to try the same DIY approach.
(and lots of free guidance from Dave). Head is fine. But my bottom went rattly last summer
I suppose the rule of thumb "do the top, do the bottom" is further confirmed.
Anyway, the bottom end had started to sound kind of "hollow" and at cold idle there was a definite but quiet chakety-chakety-chakety noise.
Thought it was the gearbox input shaft at first, tried to ignore it, then one day...proper noisey raspy, football rattle type noise at idle
that would start as suddenly as it stopped. 100m up the road confirmed it was time to garage it and call Dave !
Removed the engine myself (not mucking about this time...and since the head work, I have built myself some full tipping ramps so can get the car 1/2m in the air)
Stripping engine down showed lots of wear on the main bearing shells. Not scored so much as just plain worn out (esp at the edges). Big end bearings not great either.
Also brought back to focus the fact that the original rods and pistons meant the crowns sat down the bore nearly 40thou which was always a bit of a mystery (TVR special parts bin ?? Or reduced compression to avoid detonation ??? Who knows.)
Long story short, I now have a very nicely running motor again with new H-beam rods, some funky JE pistons with coated skirts and offset pins, billet crank, 4-bolt main conversion and a few other new bits of course ! Compression ratio around 11.5 (by calc and some measurements). Reviewing the old setup I had 9.6:1 !!
All now carefully run in and heading fast to 1000 miles. Sounding great and feels far more perky ! Short block was done by Dave...all the other work was me. For me personally, as a keen "hobbyist" builder, this arrangement works just fine. This is not a thread designed to spark the "usual" row. Please ! But happy to share my experiences during the rebuild if anyone wants to try the same DIY approach.
Great to see someone going for a home build. Couple of questions if I may? Have you gone for a bigger cc? If so was it bored? Stroked? Both? Re lined? Original crank? Were there any mods to the bottom end apart from the four bolt mains? Half time bearing oil feed? Oil pump?
Are the head and cams modified or standard replacements? Are you still running mbe? Could you give an idea of the costs involved? (Pm me that if you prefer)
Sorry for all the questions but I'm looking at building a new engine for mine in the next year or so and I'm trying to get through the secrecy, bullsxxt and scotch mist to get some real world answers instead of the usual 'I took my car to X specialist and really pleased I spent £12k and only have to spend £1k a year getting it serviced for complete peace of mind' stuff.
Andy
Are the head and cams modified or standard replacements? Are you still running mbe? Could you give an idea of the costs involved? (Pm me that if you prefer)
Sorry for all the questions but I'm looking at building a new engine for mine in the next year or so and I'm trying to get through the secrecy, bullsxxt and scotch mist to get some real world answers instead of the usual 'I took my car to X specialist and really pleased I spent £12k and only have to spend £1k a year getting it serviced for complete peace of mind' stuff.
Andy
Hi Andy
Just a bore skim...not stroked and original liners...so "same" capacity nominally
Crank replaced with Billet (just because I could...Dave had one available)
No mods to oil pump, chains etc but I had replaced most of that stuff when I did the head.
The half time bearing was silky smooth like new so I left it well alone
Cams are std profile, supplied by rnd when they did the head some years back. Also uses their finger followers, valves etc. I run a modified cam timing to get a bit more torque lower down (at the expense of top end power figure). I'll dyno it soon to compare it against what it used to do with the wrong compression ratio.
Yes, still using MBE. I think i've reached the limit of "refinement" using it...its good enough now. I'm talking about normal town driving manners really.
For me, self build is what this is all about...partly why I bought the tiv in the first place. Means you can take your time and get everything just right and learn along the way.
yhm
Just a bore skim...not stroked and original liners...so "same" capacity nominally
Crank replaced with Billet (just because I could...Dave had one available)
No mods to oil pump, chains etc but I had replaced most of that stuff when I did the head.
The half time bearing was silky smooth like new so I left it well alone
Cams are std profile, supplied by rnd when they did the head some years back. Also uses their finger followers, valves etc. I run a modified cam timing to get a bit more torque lower down (at the expense of top end power figure). I'll dyno it soon to compare it against what it used to do with the wrong compression ratio.
Yes, still using MBE. I think i've reached the limit of "refinement" using it...its good enough now. I'm talking about normal town driving manners really.
For me, self build is what this is all about...partly why I bought the tiv in the first place. Means you can take your time and get everything just right and learn along the way.
yhm
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