Piston size!

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Jens Hansen
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Piston size!

#1 Post by Jens Hansen »

Several years ago my dad and I bought a T5. Think it was on the road somewhere in the states in the mid seventies but not sure.
2 years ago my dad started the body work and hopefully he will finish it soon.
The engine was inside the car when we bought it.
Engine number is: 71787, 1600cc, 616/1 for a T2 1959.
Yesterday evening I got a few things done but I don't know how to see the piston size!
On 1 of the pistons the is "3" stamped and on 3 of the other cylinders there is "2" stamped on each of them.
The cylinders are rusted on the outside but inside they are perfect.
How can I tell what size the pistons are?
Hope someone can help me!
Thanks,
Jens
Jens Hansen

1962 T6 Coupe S90
1960 T5 Coupe Normal
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Brad Ripley
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Re: Piston size!

#2 Post by Brad Ripley »

You say you can see the inside of the cylinders. So, why not measure the bore diameter and then you'll know.

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Jacques Lefriant
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Re: Piston size!

#3 Post by Jacques Lefriant »

that vintage sizes were -1,0,+1 heights were 5,6, usually. you may have to actually measure them with a micrometer and bore gauge.
j
 

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Jens Hansen
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Re: Piston size!

#4 Post by Jens Hansen »

Diameter is 86mm! It's the number on the piston I can't find anywhere. Might have to look at the maestro's book again.
Jens Hansen

1962 T6 Coupe S90
1960 T5 Coupe Normal
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C J Murray
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Re: Piston size!

#5 Post by C J Murray »

That is an aftermarket replacement piston and cylinder.

Regardless of what pistons and cylinders you might have you should measure the bore for size, roundness, and taper and then measure the piston to calculate clearance. The piston rings should get a visual check and measure the gaps. Any markings on used parts are meaningless.
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Jens Hansen
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Re: Piston size!

#6 Post by Jens Hansen »

I'll get some new piston rings after I have checked the cylinders and pistons.
Thanks for the replies.
Jens Hansen

1962 T6 Coupe S90
1960 T5 Coupe Normal
1960 Morris Minor Conv.

Dick Weiss
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Re: Piston size!

#7 Post by Dick Weiss »

Jen,

If the pistons are OEM Mahle, you should see some stampings on top of the pistons like 82,45 (for 1600cc);
If the stamping is 83,0, it's a 1st oversize, and going further, there's a 2nd oversize; Big bore sets are 85 and 86mm

Also, piston ring gaps should be in the range per the spec book (or shop manual) including the wear limit of the side clearance to the groves.

Finally, there's a difference of piston clearances w/aluminum vs. cast iron cyl's.; Full alum. are 'things of the past".
Late Biral cyls. are similar to cast iron w/cast aluminum fins and full CI cyls. should be matched heights w/in .0004"!

Dick

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Wil Mittelbach
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Re: Piston size!

#8 Post by Wil Mittelbach »

Jens Hansen wrote:I'll get some new piston rings after I have checked the cylinders and pistons.
Thanks for the replies.
Additionally; ensure that the piston ring lands/grooves are not worn beyond ring/land clearance specs to assure a proper ring/piston fitment.

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Jens Hansen
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Re: Piston size!

#9 Post by Jens Hansen »

Just to be sure then I'll get a new set of cylinders and pistons.
Thanks for the help.
Jens Hansen

1962 T6 Coupe S90
1960 T5 Coupe Normal
1960 Morris Minor Conv.

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Jens Hansen
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Re: Piston size!

#10 Post by Jens Hansen »

In the process of installing the piston rings. On the 3rd ring there's a spring.
Should I change that spring at the same time as I install new piston rings or should/can I leave the old spring?
Better be sure to do it right the first time.

Thanks in advance

Jens
Jens Hansen

1962 T6 Coupe S90
1960 T5 Coupe Normal
1960 Morris Minor Conv.

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C J Murray
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Re: Piston size!

#11 Post by C J Murray »

Some oil rings have springs and some do not, depends on design. If the rings are a new set they should be complete to replace all the parts of the old ring set.

You had better post detailed pictures of what you have.
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Re: Piston size!

#12 Post by Helge Tielker »

Berekening Compression ratio 356er.xls
(36 KiB) Downloaded 75 times
a small calculation tool on clearance and compression ratio in Excel
cheers
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Jim Nelson
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Re: Piston size!

#13 Post by Jim Nelson »

There's also an early Kolbenschmidt big bore kit, 85.45mm, that is for non-counterbalanced cranks. Works out to a little over 1697cc.

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Ron LaDow
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Re: Piston size!

#14 Post by Ron LaDow »

jim nelson wrote:There's also an early Kolbenschmidt big bore kit, 85.45mm, that is for non-counterbalanced cranks. Works out to a little over 1697cc.
Pretty sure that was the "industrial" PC set; flat topped, you're be hard put to get more than 7.5:1 out of them.
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Jim Nelson
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Re: Piston size!

#15 Post by Jim Nelson »

Ron LaDow wrote:
jim nelson wrote:There's also an early Kolbenschmidt big bore kit, 85.45mm, that is for non-counterbalanced cranks. Works out to a little over 1697cc.
Pretty sure that was the "industrial" PC set; flat topped, you're be hard put to get more than 7.5:1 out of them.
Beats me, Ron, there isn't a lot of documentation with the box.
IMG_1512.jpg

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