BIG Bore 260

[0neoffive]

Back Again

Close to 30 years ago, I had a telephone conversation with John Vermeesch of Ford regarding the then oft-quoted belief that 260 blocks with three freeze plugs per side were really underbored 289s with enough wall thickness to safely bore to 4 inches. He explained that block molds were made up of several segments that could be, and were often, mixed randomly so that certain visible features did not necessarily indicate a given set of physical characteristics. It would seem that this variability could also apply to any numbers cast into the blocks.

My apologies to the much more experienced members of this valuable forum if I misquoted or misunderstood -- I'll claim a senior moment!

Jim

All of which brings me back to the old Guru's barnyard method; if a skinny #2 pencil will pass between the cylinder castings, you ain't gonna bore it to a 289.

 

[steven]

All of which brings me back to the old Guru's barnyard method; if a skinny #2 pencil will pass between the cylinder castings, you ain't gonna bore it to a 289.

You got it right

How many hours to try and prove 260 blocks can be 289. If thats the case Ford would not have cast 289 blocks and a lot of hours could be put to other research this topic is reached its end

 

[spmdr]

As some may have noticed, this thread is not in the "Stock" Tiger category.

The reason for that is I am not suggesting ANYONE bore their Tiger 260 engine to 4.000.

So if there is a miss understanding in that regard, Yes, end of story.


I have spent a majority of my Tiger History playing with NON-stock Tigers,

And also, Non-street cars.

But I just happen to have a Tiger that is mostly a Street Tiger.

And I just happen to have Tons of 260 Tiger engines.

So what is the limit I can push the performance of a 260, practically?

In that regard, Bore size is a starting point.

Some have been there, done that, (I have been doing other things).

Most, I have seen, have just shelved their 260s....

The rest are running their 260s.


Also, there is the lingering issue of "over heating" and the seemingly mysterious causes.

Cylinder wall thickness is a factor, little seems to be known the degree (pun fully intended).


Feel free to excuse me for attempting to use this forum for what I think is it's intended purpose.


This is more of a Beginning, .... at least for me.

 

[michael-king]

Dan,

Your question was clear and the intent to try and ascertain information was/is worthwhile.

Anyone who misread your intent wasnt really payimg attention to the questions context... And the topic can close when you feel you've got the information you need.

BTW got to update/ discuss with you some alpine performance engine info...

 

[Warren]

If you ask me.

Trying to get 272 RWHP like you did for D. Leonard fits in the modified section.
I think I still have a handle on the definitions since I did 98% of the move from old cluster ___k that was the old forum format of everything in G.T. D.

Oh and I don't mind the mini paragraphs either. It's good to have content

How many 260s in a ton , sounds like a future Tigers United quiz question

 

[spmdr]

Just for the record, I have built some "smaller" small block Fords for vintage racing.

The engine currently in my Black Tiger (Vintage Race, semi retired), has a 275 CI engine,

I think pulled 285 RWHP (around 7000 rpm), back a lot of years ago.:------

And I built a 260 CI Vintage Race engine that I have not had on any Dyno, but expect would likely pull north of 270 RWHP @ 7200 rpm.


But my future is likely more Street use, at least regarding Tigers.


My guess on the 260/Ton number, how about 4.5?

 

[0neoffive]

Cam Spec

Hey Dan:
What cam specs are you using for a 7000 RPM 260? I have a steel sleeved block here with a 331 crankshaft & short rods we want to experiment with.
Girdled bottom or large caps?

 

[spmdr]

As far as cams, I have not played with very many.

I have been more concerned with reliability than max HP.

In the world of strict Vintage Racing (period correct) the Ford "Le Mans" C7FE-6250-A is very good.

That is the cam in the 275 ci engine.

We also have to run with Stock Ford Rocker Arms, so with them, the Comp Cams Drag Race cam 31-640-5

pushes the limits of the Rocker Arms about as far as we have gone.


With the smaller engines, bottom end strength has not been a problem, with no Girdles or Steel caps (but with bigger Rods and careful with cranks).

Bigger engines with Big compression is another matter.

 

[spmdr]

The real question with this thread is:

Does anyone have proof of the existence of an extra thick cylinder wall 260 Block?

I have not seen one (yet).

My limited measuring of Blocks suggests the late 260 (3 freeze plug)

has a thicker cylinder wall than a typical 289 Block.

My nominal numbers for STD Bore Blocks are:

289 .125 cylinder wall thickness

260 .155


Research continues.

Has anyone seen other numbers?