1963 Tiger Block L6 compression range

[mk30h]

Guys,
What would be considered good compression on a 45 year old 6 cly? I don't know what the original specs would be for this engine 1964 8500. What values would warrant a rebuild on a powerhead transplant? I.e., the cost to rebuild would likely be much higher than picking up another block.

[Capt.Insane-o]

They were usually right around 125. A few years back I did a 1962 1000 with new internals, came out shootin' at 125.

[Mark75H]

Not all gages read the same ... more important that the cylinders are close than high

[mk30h]

I've got similar readings on 1, 2, 4, 5, 6 at about 110
No 3 shows a reading of 90. ie approx 21 % less on average.

I opened the ports and saw pitting below the last ring which extend about 1.5 cm down the side of the piston. (No 3)
others looked good.
I will take a picture of piston and post next week.
Will remove the exhaust and water cover to view other side of cyl.
I have a 68 100 block that I can use if need be (assuming bolt patterns match up), or can rebuild if need be.
Thanks Guys.

[Mark75H]

I would advise leaving the exhaust side cover on. Whatever the gage tells you and you can see from the intake side and spark plug hole are enough.

The bolt patterns are the same, but there may be differences in the water inlet and base gasket. You can usually transfer everything from one mid to another as long as you keep the correct base adapter with the block.

The bolt pattern was the same from 1957 to 71 (72 on 115) but there are many exhaust and water changes

I have seen pictures of a 1250 put on an 800 DR tower


The '68 100 will be a lot more power, it would be my choice

[mk30h]

Thanks for the advice Sam, now to check the compression values on the 100 hp to see what it's readings are. Fun for the weekend.

I didn't realize that you could put the the 62-71 engines on the old DR towers, got a few DR staters kicking around if I want to get creative. Just trying to get ready for my winter project which is revitalizing the old six.
Thanks.:smiletest:

[Mark75H]

60 & 66 ci DR's used a different driveshaft, only the 76ci DR driveshaft fits the newer bigger motors

[Dave S]

The 68 will be a bit of work putting on the 64 lower if you want to keep the old solid covers. Best use the 68 rods and pistons in the 64. Never just use one of them oldies....... they get in bad shape... and ya don't know whats in them or how they have been mis-used. Some of the REAL early ones had bronze reed cages.;) You can use the flat SS exhaust cover from the 800 dock buster.;)

[mk30h]

The 68 will be a bit of work putting on the 64 lower if you want to keep the old solid covers. Best use the 68 rods and pistons in the 64. Never just use one of them oldies....... they get in bad shape... and ya don't know whats in them or how they have been mis-used. Some of the REAL early ones had bronze reed cages.;) You can use the flat SS exhaust cover from the 800 dock buster.;)


Dave, what do you mean "never use just one of them oldies", do you mean just do a complete internal transplant to the 64 tiger block?

I do like the looks of the older external control L6 which 64 was the last year. Thinner shape, and a bit taller- and I do like the ability to hand crank if battery doesn't have enough juice. I suspected the blocks might have different cast in mounts but I hadn't checked yet.
I know that the 69 has an exhaust tube which extends into the lowerunit while the 64 is just an open chamber. Also the shift shaft is different between the engines as is the electrical system- points vs thunderbolt.

Whas there any real internal difference between the 850 and the 1000 or was it mainly just the carbs? Were the reeds different or port sizes?
Thanks
Steve:rolleyes:

[Dave S]

What I meant is I don't like running old motors with out pulling them apart to have a look.:eek: HeeHee big eyes.:rolleyes: The 850 had smaller carbs and smaller reeds. The 68 1000 had better stuff. The rods had better bolts ....longer as to put more meat where the rods are notched. Biger wrist pins. 3 Thinner piston rings that seal better. The rod bearings like to slide more than roll so they are a weak point. Being fussy.;) When ya put the reeds in use the bigest stops that you have. They control the reed better.

[mk30h]

Thanks Dave,
Now I guess my next step will be liberating the powerheads from the midsections for transport to the shop where I will be able to work on them. Fortunately I have full access to a complete well equipped machine shop at a local highschool. Now, I quess I'd better pick up a set of ring compressors. How many will I need for the 6 cly- 3 or more?
Thanks
Steve

[Capt.Insane-o]

6 There are straight and relieved ones, so look in the manual to see what you need.