g) Engine Rebuild (Bottom end)

Now that the top-end is complete, it’s off to the shed to begin the bottom end.  Again, this will just be a standard stock rebuild without any performance adders.

The engine has not run since the mid 90’s but it is in pretty good shape, initial inspection shows minimum wear which is a good sign.

I removed the Fuel Pump, Motor Mounts and the standard complement of brackets.  They were all sand blasted and re-painted.  I left the distributor in-place until I am ready to remove the timing chain so I can mark the timing position.  At this point in the project I removed all 12 lifters (keeping them in order) and placed them with the push rods.

Getting Started – Bottom End
Getting Started – Bottom end 2

Time to flip over the engine and remove the oil pan.  All of the oil was drained but I placed a drip pan with absorbent mats under the engine, it helped out since not all of the coolant was drained out.

Engine flipped 2

Here is a picture of me taking off the oil pan.  Always wear your Safety Glasses.

Doug & oil pan removal
Pan Off
Pan Off 2
Pistons are out.  The center cylinders seem to have more build-up on them and the rings in those cylinders have a lot of carbon build-up.
Time to clean everything up to see where I stand.
I’ve ordered new ARP Head Studs & Connecting Rod Bolts from Summit Racing (best price) but I will need to wait as they are on severe back-order.

Top End, Pistons Out


Botton End, Pistons Out

I have the parts separated.  The rings on Pistons 4 thru 6 were very hard to remove.  I have my hands full cleaning up the pistons, I hope they do not need to be replaced.



Typical Piston

Time to clean up everything and order the new bearings.   I still need to break down the rest of the block.  The crank shaft, timing chain assembly and cam still need to be removed.

Here are two pictures, the first is typical of a piston that was removed.  The rings were stuck in pretty good.  The second picture is of the ring grooves cleaned out.  I used a carbide “cut-off” tool for a lathe.  It cut out all of the old carbon and cleaned up the grooves quite well.  Now I need to replace the wrist bearings.

After a quick cleaning I disassembled the pistons from the piston rods and pressed out the wrist (Gungeon) pin bearings and replaced them with new ones.  They needed to be reamed to size (to fit the gungeon pins).  I then reconditioned the pistons, cleaned them and installed new rings.  After the rings were installed I re-assembled the pistons onto the rods.  They are now ready for re-assembly.

(Piston Pictures Below)

Press in New Bearings

Reamed to Size

New Rings Installed

Ready for Re-Assembly

Next I proceeded to remove the balance of the parts from the block.  Below you can see the Distributor, Timing chain & sprocket along with some oil pump parts and the crank shaft in the lower picture.  I was told not to lay it down (keep it vertical) when it is not being held in the races.

Here is a picture of the stripped down block.  Time to start cleaning it off and prep it for honing & paint.

Here is a picture of some restored parts.  Timing Cover, Timing Pulley and Oil Pan

The next set of pictures should cover the cylinder honing and the finishing of the engine block.  I used a scraper & engine Gunk to clean the outside of the block and a series of brass brushes to clean out all of the oil ways.  The paint is 500 degree engine enamel.  I think that the Red, Silver & Black combination will look great.

I cleaned up the block and put a quick coat of paint on it.  Next I will begin the hone out the cylinders and chase all of the threads.

Painted Block

I make a habit of leaving in the old nuts & bolts, that way when I replace them I have the old one as a reference.

Painted Block

Now that the block is cleaned up and ready to go, it’s time to start reassembling the components.  First the crank shaft goes back in.

Crank shaft installed & torqued.

Once the crank shaft was installed it was time to insert the pistons.  The pointer arrow on the face of the piston faces front and the ring gaps are away from the thrust side of the piston.

Pistons, Bottom End

You can see the new ARP fasteners from Summit Racing

Half way done

Pistons installed & torqued

Time to install the Rear Main Seal.  The housing is aluminum so be careful checking flatness and not stripping out threads.  Be sure to have the brass washer for the top center-most fastener and to add some gasket sealer to the thread as it is assembled.  This fastener protrudes into the Crank Case.  The engine in inverted so the uppermost fastener in on the bottom in this picture

Rear Main Seal

Front Aluminum Bridge Installation took some additional work.  The gasket set came with the gaskets and only one Wood Wedge so I cobbled up a set of Wedges.  Making sure that the aluminum bridge is not damaged and in good condition, it was re-installed.  Proper Alignment is critical to prevent leaks.

Aluminum Bridge

In the next couple of pictures I re-assembled the Cam Shaft, Timing Chain and Oil Pump / Pick Up assembly.  The Cam Shaft does not have bearings (strange) it rides directly against well oiled journals in the cast Iron Block.  A new Timing Chain was also installed.

Time to install the front Cam Plate.  The kit came with two gaskets, a thin one and a thick one.  The book says to use the thinner one but does not say why.  I think the thicker one would put the timing chain out of alignment.  After the plate was installed I inserted and secured the cam shaft.  In retrospect I did not need to install all of the fasteners at this point as most of them will need to come out to install the timing cover………Live & Learn.

Front Timing Plate

Now it’s time to align the timing and install the timing chain.  Basically, all of the alignment dots need to be aligned (pointing at each other) when you are at TDC.

Timing Chain Aligned

Next comes the installation of the Timing Cover.  Goop Up the gasket and position the timing chain tensioner and pop it on.  Secure all of the fasteners being careful not to strip out the threads in the three positions where the aluminum brackets are.

Timing Cover

Now I can install the Harmonic Balancer (timing pulley) and components.  The spacer bushing goes first (lube it well).

Bushing Installed

Balancer Installed

Fan Blade Mount Installed

Now it is off the completing the oil pan installation.  Rotate the engine and prepare.

Oil Pick-up & Pump

At this point I can button up the bottom end and install the oil pan

Be sure that all of the seams running over the aluminum bridges are smooth.  I used a liberal amount of gasket seal as well.

Oil Pan Installed

The Bottom End in now all assembled (less the Distributor).  I will finish the Engine in the “Top-End” section as it will require adjusting the valves.



Just after the first start (see Youtube, “TR6 1974 First start”) the motor seized up.  I went from complete excitement to total depression in 5 mins.  The problem was not that bad but I did pull the motor back out to have a look.

I had made a mistake when I replaced the thrust bearings, I put the rear bearing in facing the wrong way, fortunately it was not that difficult to repair and the motor went back in and was running well within a week.

CIMG8084Rear Thrust Bearing Spun.    CIMG8085


Simple problem to fix, It could have been much worse.


After re-assembling the new Thrust bearings you should check the crank shaft back-lash, .006″ to .008″ is perfect.  If you have to much play you will need to purchase oversized bearings.

Published on November 7, 2009 at 11:28 pm  Comments (6)  

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  1. Hello, Doug. I was given your website by my nephew, Jason, when I inquired about the whereabouts of my old TR. With the care and detail you are obviously placing into her restoration, you may want to research her history with me as it is a colorful one. You will also discover some inaccuracies possibly relayed to you by Jason- eg., this car was lovingly owned and garaged by me in Florida for 21 years, and was regularly driven and maintained until Hurricane Ivan in 2004. Everything including all Lucas worked perfectly. The car was a victim of that hurricane and we should talk about that- I believe I can even round up some photos of my garage sitting on the poor TR! By the way, the rear springs were actually previously replaced with race (HD) in the late 90’s and the rubber spacer fix was to correct the inevitable bump steer issue which usually occurs unless the front springs are also race stiff.All the running gear was loose and working and the damaged steering box mount occured during loading on a trailer to bring the car to Jason in CT.I have lots more interesting conversation for you about your car and would love to see her again next time we are in CT. We live part-time in Winsted, have two TR3’s and a ’59 Turner race car at present. I may even have some memorabilia from the TR6 somewhere (?). Best regards, Tom

  2. That block looks good in red.

  3. Hey Doug I’m currently undergoing pretty much what you did on a 1976 TR6. I have couple of questions though, what clearances did you get for your main bearings and connecting rod bearings? I can’t seem to find specs. Thanks in advance!

    • Hey Fabian:

      If you don’t already have one, you should purchase the “Big Blue Book”. (The Complete Official Triumph TR6 & TR250 1967 – 1976)

      Page 104: Connecting Rod bearings:
      The connecting rod side clearance for all engines should be between 0.0086″ & 0.0125″. If you check the rod bearings with plastigage, the clearance should be between 0.001″ & 0.0027″

      Page 110: Main Bearings – Set
      Measurements should be taken at two locations for each journal (90 degrees apart from each other) If there is a difference of more than 0.002″ in between any of these measurements the crankshaft should be replaced or reconditioned. Undersize bearings are available.

      Main Journal Caps Diameter: 2.3110″ – 2.3315″
      Crank Pins Diameter: 1.8750″ – 1.8755″

      Note: The actual Bearing Clearance was not listed. If you are between the 1.8750 & 1.8755 (and round), the standard bearings would be OK.

  4. In the picture of the alignment of the timing chain components I note that the timing chain master link is facing with the open end of the connector in the direction of rotation. I just replaced my timing chain and gears and the timing chain manufacturer was pretty emphatic that the closed end of this clip should face in the direction of rotation. They gave some pretty dire warnings if this was not followed. This will require the clip to face inward on my engine to comply with the stated requirement. Any comment?

    • Phil: Good catch, I actually reversed it when I noticed it. The picture was taken prior to setting it right. I will need to update the picture, Thanks for the catch

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