Joint lines in motor

[Super28]

What is the best way to get rid of the joint lines when you glue two engine halves together.

Working on a 1962 Thunderbird

[slownlow]

If they’re not going to be seen, like the top of the tranny, don’t bother. The rest of the joint lines can be sanded out or if they have a gap then fill them. Fillers can be bondo, thin styrene, thick body superglue with a dash of baking powder after application (it gets hard real quick) or.....There could be a whole category about fillers.

[Ace-Garageguy]

For starters, I usually first remove the "alignment pins", because they're very often OUT of alignment.

Then I "machine" the mating surfaces dead flat by doing a few passes over a sheet of 180 grit sandpaper adhered to a very flat surface.

And THEN, I put the parts together with plenty of liquid cement, being VERY careful to insure the parts line up as well as possible, thus eliminating as much of the gaps as possible.

Let it all dry HARD, overnight, and file what little there is left of misalignment down to nothing, finish with 400 grit paper, and primer.

I almost NEVER have to use any fill doing it this way.   

 

[BigTallDad]

16 minutes ago, Ace-Garageguy said:

Then I "machine" the mating surfaces dead flat by doing a few passes over a sheet of 180 grit sandpaper adhered to a very flat surface.

 

I take a slightly different approach, especially when it comes to oil pans and trannies. I'll actually bevel the jointing edges (where the two parts come together) of the halves before cementing which allows me to have an area large enough to accept (and retain) the filler for future sanding. Most engine castings have the oil pan/tranny with a vertical angle, thus the ridges on the bottom side

[Snake45]

1 hour ago, Ace-Garageguy said:

For starters, I usually first remove the "alignment pins", because they're very often OUT of alignment.

Then I "machine" the mating surfaces dead flat by doing a few passes over a sheet of 180 grit sandpaper adhered to a very flat surface.

And THEN, I put the parts together with plenty of liquid cement, being VERY careful to insure the parts line up as well as possible, thus eliminating as much of the gaps as possible.

Let it all dry HARD, overnight, and file what little there is left of misalignment down to nothing, finish with 400 grit paper, and primer.

I almost NEVER have to use any fill doing it this way.   

 

Exactly what I do except the sandpaper. I rub the halves on a dead-flat 10" fine cut mill file. 

[SfanGoch]

I do essentially what Bill does. After making sure the mating surfaces are flat, I brush methylene chloride on both parts, align them, then brush the solvent along the seam. This neatly welds the halves together, negating the use of any fillers. A quick pass with a medium sanding stick and no more seam.

[StevenGuthmiller]

7 hours ago, Ace-Garageguy said:

For starters, I usually first remove the "alignment pins", because they're very often OUT of alignment.

Then I "machine" the mating surfaces dead flat by doing a few passes over a sheet of 180 grit sandpaper adhered to a very flat surface.

And THEN, I put the parts together with plenty of liquid cement, being VERY careful to insure the parts line up as well as possible, thus eliminating as much of the gaps as possible.

Let it all dry HARD, overnight, and file what little there is left of misalignment down to nothing, finish with 400 grit paper, and primer.

I almost NEVER have to use any fill doing it this way.   

 

This is pretty much exactly my approach.

 

Steve

[D. Battista]

14 hours ago, Ace-Garageguy said:

For starters, I usually first remove the "alignment pins", because they're very often OUT of alignment.

Then I "machine" the mating surfaces dead flat by doing a few passes over a sheet of 180 grit sandpaper adhered to a very flat surface.

And THEN, I put the parts together with plenty of liquid cement, being VERY careful to insure the parts line up as well as possible, thus eliminating as much of the gaps as possible.

Let it all dry HARD, overnight, and file what little there is left of misalignment down to nothing, finish with 400 grit paper, and primer.

I almost NEVER have to use any fill doing it this way.   

 

How I do it also.... and I put a clamp on each end while glue is drying

[jchrisf]

This is how I am going to do it now...

...my question to the experts is, in this day and age when space rockets can land themselves on floating platforms why can't these kits come perfect?

Edited May 13, 2018 by jchrisf

[Ace-Garageguy]

51 minutes ago, jchrisf said:

...my question to the experts is, in this day and age when space rockets can land themselves on floating platforms why can't these kits come perfect?

Because all engineers are not created equal.

The team working on Mr. Musk's self-landing rocket boosters is an order of magnitude better than the divide-by-25-challenged set working on model car tooling.

Edited May 13, 2018 by Ace-Garageguy

[Can-Con]

Also keep in mind a lot of transmissions do have seams on them. Best to do some quick research before eliminating them to see if they should be there or not.

[Art Anderson]

20 hours ago, Ace-Garageguy said:

For starters, I usually first remove the "alignment pins", because they're very often OUT of alignment.

Then I "machine" the mating surfaces dead flat by doing a few passes over a sheet of 180 grit sandpaper adhered to a very flat surface.

And THEN, I put the parts together with plenty of liquid cement, being VERY careful to insure the parts line up as well as possible, thus eliminating as much of the gaps as possible.

Let it all dry HARD, overnight, and file what little there is left of misalignment down to nothing, finish with 400 grit paper, and primer.

I almost NEVER have to use any fill doing it this way.   

 

Even better:  Use a bit more liquid cement, squeeze the two halves of the engine block (oil pan too if part of the halves of the block in the kit) tightly together, enough to "squeeze" out a "bead" of plastic--let dry for a couple of days, sand smooth!  That has worked for me, every time I've tried it, for now decades!

Art

[Art Anderson]

3 hours ago, Can-Con said:

Also keep in mind a lot of transmissions do have seams on them. Best to do some quick research before eliminating them to see if they should be there or not.

Steve, GOOD point!

[Snake45]

4 hours ago, Can-Con said:

Also keep in mind a lot of transmissions do have seams on them. Best to do some quick research before eliminating them to see if they should be there or not.

I've noticed that many manual transmission cases seem to have mold/casting lines that have been somewhat crudely ground off. So you don't want a glue seam there, but you don't want it perfectly smoothed down like airplane fuselage halves, either. 

[Force]

On 2018-05-12 at 11:40 PM, Ace-Garageguy said:

For starters, I usually first remove the "alignment pins", because they're very often OUT of alignment.

Then I "machine" the mating surfaces dead flat by doing a few passes over a sheet of 180 grit sandpaper adhered to a very flat surface.

And THEN, I put the parts together with plenty of liquid cement, being VERY careful to insure the parts line up as well as possible, thus eliminating as much of the gaps as possible.

Let it all dry HARD, overnight, and file what little there is left of misalignment down to nothing, finish with 400 grit paper, and primer.

I almost NEVER have to use any fill doing it this way.   

 

I do it exactly the same way...read the tip in a magazine in the late 70's-early 80's.

[NOBLNG]

On ‎5‎/‎13‎/‎2018 at 10:08 AM, Can-Con said:

Also keep in mind a lot of transmissions do have seams on them. Best to do some quick research before eliminating them to see if they should be there or not.

Same with "cast iron" exhaust manifolds, I leave the  mould lines on them.

[Snake45]

10 hours ago, NOBLNG said:

Same with "cast iron" exhaust manifolds, I leave the  mould lines on them.

And also many parts such as tie rods and stabilizer bars, which are forgings. 

[Ace-Garageguy]

1 hour ago, Snake45 said:

And also many parts such as tie rods and stabilizer bars, which are forgings. 

I must live on a different planet.

Just about every fairly recent tie rod I've ever seen (if you're talking about steering linkage) has been fabricated from seamless drawn tube (preferably) or welded tube, or fully-finished bar-stock (forged and rolled or ground). Occasionally you'll see an older tie-rod that's an obvious forging, but the tool lines are usually very minimal. Something like this is a forging, but it's also machined and finished afterwards, and exhibits almost no, if any, residual marks from the forging process.

Below is a typical assembly, made up of internally threaded tube, and forged ends. Again, the ends will have been finish-machined, rolled and/or ground after forging, and will not have a pronounced line.

 

Some of the tie-rod ends may exhibit a forge line though,  

as well as Pitman arms, steering arms, and idler arms.

Same goes for stabilizer bars (if you mean "sway bars" or anti-roll bars). Round bar stock in most production applications, tubing in very high-performance or racing. Though the bar stock may be "forged", you never see a residual line from the forging dies.http://www.kdkforging.com/stabilizer_bars.php

Late-model Corvette suspension control arms are aluminum forgings, starting with the C4, and similar designs appear on other makes as well.

NOTE: Some offshore-produced "forged" replacement arms are actually cast, and have been known to produce disastrous results. I had a client bring me a set for his 2002 Dodge truck. I refused to install them. He got all huffy, saying I was trying to sell him my marked up parts. He "KNEW" all about parts and metals and his were "just as good". I showed him the door. 6 months later, one broke and totaled the truck.

BOTTOM LINE TO EVERYONE: On your real vehicle, or if you're wanting to make your model parts look correct, do the research. Look at photos, and find out if parts are supposed to be cast or forged or fabricated or whatever.

Or don't.  

Edited May 15, 2018 by Ace-Garageguy