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     back to Pauls' Triumph home pageWhitey's Engine Rebuild  
   The Cylinders  

   Whitey - 1975 Spitfire Specific Tasks and Procedures

Transmission    The vibration    second rebuild    Clutch    O/D    driveshaft 
Special Update Whitey finally gets it's 6 cylinder engine, Fuel injected at that!
Section #2 - Whitey's Spit6 conversion Process                     F.I home page


    Well putting Whitey's' engine back together has been a real learning experience. I'm the type that likes to understand exactly how stuff works. Diving into a project I've never tackled before does not scare me. After all, If I really screw it up, I can always go back and let someone who DOES know what they're doing, do it right. And in the meantime.... I've at least learned, what it is I'm paying someone else to do for me. 

     Although not totally flying blind here (I have done this kind of stuff to smaller engines,... 2 stroke motorcycles, lawnmowers, etc.) I figured how hard could it be.  Well it's not. Trust yourself. Read everything you can find. Take your time.  Hey..this philosophy worked when I tackled the O/D tranny rebuild in Whitey and it turned out fine.

     First things first. Measure everything, TWICE. I picked up a bore gauge (on EBay of course) so I could see what the bores were like. Were they straight?  ...need an over bore? What?

    Measuring the bores I found cylinder #3 (that actually had the low  compression) was amazingly in better condition than cylinders #2, & #4, that still had good compression.


75w_boregaugeboxed.jpg (11271 bytes)

75w_boregaugeread1.jpg (29712 bytes)

  Each graduation on the gauge is 0.0005". I used dial calipers to set a 'zero' on the gauge at 2.9000".  In the photo above left, the bottom of the bore still measured 2.900+/-0001".  Above right shows a cylinder reading near the top of the bore at 0.0012". So it's actually reading 2.9011".


   75w_cyl_sketch.jpg (2779 bytes)


   The Drawing at the left, is the positions in the bore where measurements were taken with the bore gauge. The letter measure 'concentricity, the numbers, the depth in the cylinder. I wanted to know if the cylinders were warped, and how 'oversized' they might be. I needed to know if I needed a bore and hone , or could get away with honing the cylinders and just installing new rings, etc etc.

The dimensions in the following tables are 2.900" minus what's in the
table. That means the cylinder is 'oversize' by that amount

First measurements of the cylinders after initial piston removal.

Cyl #1 A B C D
1 .0010 .0005 .0007  
2 .0002 .0002 .0003  
3 .0005 .0005 .0005  
4 0 0 0  
Cyl #2 A B C D
1 .0012 .0010 .0007  
2 .0010 .0012 .0002  
3 .0012 .0012 .0005  
4 0 0 0  
Cyl #3 A B C D
1 .0032 .0015 .0018  
2 .0032 .0015 .0015  
3 .0032 .0014 .0020  
4 0 0 0  
Cyl #4 A B C D
1 .0035 .0015 .0025  
2 .0035 .0010 0  
3 .0030 .0010 .0005  
4 0 0 0  


               rear 75w_honed_cyls1.jpg (14174 bytes) front of block

      After honing, cylinders #1 (at the right) and #2 are looking good and are only at 2.902" worst case (0.002" over stock diameter) Something else to notice is the 'chaff' from the original block casting in the water passage between the left two cylinders in the above picture. I'm going to break out the rest of it to open up the full little triangle. This should allow a greater cooling water flow and will match the opening in the head. I'm going to do this in all the water passages.

front of block  75w_honed_cyls2.jpg (17754 bytes)  rear     

     At the top of the #1 cylinder (upper left) you can just make out a small dark line about 3/8" below the top of the cylinder. Although I can't feel it with a fingernail, or see it on the bore gauge, I think I'll hone it just a bit more. The lines at the bottoms of the cylinders are at the original 2.9" even. 

    75w_honed_4streek.jpg (16433 bytes)

      After initial honing of the cylinders to break the glaze on the walls and flatten them a bit, I noticed a problem. In the #4 cylinder. There was a very visible vertical 'groove' up the front face (towards the front of the engine). I could just barely feel it with my finger nail, and to the best of my abilities, the bore gauge said it was roughly 0.0007" deep. Much more visibly identifiable, than measurable because of the honing striations.  After further honing this 'groove' has now almost completely disappeared.

After honing the cylinders (three times), I'm leaving it at these dimensions. (Plus I'm getting better at using the bore gauge)

Cyl #1 A B C D
1 .0005 .0003 .0009 .0006
2 .0005 .0002 .0006 .0006
3 .0005 .0002 .0008 .0003
4 0 0 0 .0002
Cyl #2 A B C D
1 .0015 .0009 .0015 .0010
2 .0015 .0006 .0012 .0006
3 .0010 .0005 .0013 .0006
4 0 0 0 0
Cyl #3 A B C D
1 .0035 .0021 .0020 .0012
2 .0034 .0021 .0012 .0009
3 .0034 .0021 .0012 .0005
4 0 0 0 0
Cyl #4 A B C D
1 .0033 .0022 .0019 .0015
2 .0030 .0021 .0012 .0012
3 .0030 .0020 .0012 .0010
4 0 0 0 0

    So if you look closely at the two tables, (ignoring my lack of skill reading the bore gauge the first time) The second table by comparison, shows the cylinders to much more concentric. Using a glaze busting three leg stone hone in a power drill, barely removed  0.0005" from the walls of the cylinders.

... update 11/20/21...

     I found a clean, simple way to mask off the cylinders. I always use a thin coat 3M's Copper Spray gasket dressing and use to tediously  tape off the inside top edges of the cylinders.

   A much easier way... simply fold in half, lengthwise, a piece of printer paper, roll it up and stick the tube in the cylinder. Then stuff a paper towel or two in the cylinder to fill it out. Then you can spray away without contaminating the cylinder walls.


75w_papercylinders.jpg (8191 bytes)
The cylinder block after copper coating

    Both  surfaces of the gasket as well as the deck and head surface get a coating. The idea is to add metal particles to the seal area, not cover or soak the gasket in copper color. I've never had a gasket ever leak or blow. (YMMV)


75w_papercylinders2.jpg (9027 bytes)
And the head with masking still in place and a copper coat

75w_withrockergear2.jpg (20541 bytes)
The head back in place with the intake exhaust manifold area 'copper' coated.
Yep... it's back to black again as well.

75w_rebuildrunning1x2.jpg (26152 bytes)

       After a ton of cleanup, polishing, and sealing, all the ancillaries are back on.    Starting it up for the first time I suggest the following procedure.

1- Manually spin up the oil pressure via the distributor tower.
2- With no sparkplugs installed, and no electrics to the points or coil, turn it over with the starter to get up oil pressure, and re-fill the carbs with gas.
3- Install the sparkplugs, and hook up the coil etc.

   Well I'll see what it's like in the morning. I let it run at 2-2.5krpm for about 30 minutes, while I messed with the carb balance and checked the engine for leaks. I took it out for the 'suggested' 8-10,
30-50mph accelerations to  seat the rings.

   Now I've heard run it at 2krpm for 1 hour, then drive, and other camps say, drive the break in cycle driving right away, while avoiding long cruises for the seating period. So what do you do?  I did a bit of both.   :-)


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