Getting back on the road

[sdibbers]

Time for an update after the race season. I wanted to balance the conrods fully as they’ve never been done properly. I also wanted to ceramic coat the piston crowns and moly coat the skirts. On top of those bits there was a tick that started when the engine had warmed up. Sounded like a tappet but was lower in the engine. So new small end bushes are on the list.

I pulled the head and sump, and took out the piston/rods. Bearings are in good condition, but I have new main and big end bearings to fit that I’ve had moly coated too.

Unfortunately I’ve found the tick. I say unfortunately because two of the gudgeon pins are partially seized and they have become loose in the pistons. Hence the noise. Oh well, at least I found it before things went bang.

 

[cobraboy]

I just got my Alfa bottom end back from being balanced, crank, pulley, flywheel and clutch. I sorted the rods and pistons, I enjoy doing it, but it can be a challenge weighing rods. I got the pistons cock on and the rods within a couple of tenths of a gram.
The accepted procedure for the Alfa is to fit new liners and pistons when things get worn, I am hoping my rattle is piston slap, I've changed everything else !
Looks like it's a rebore and new pistons for you. Can you get Hypereutectic pistons for the Rover, they come with coated skirts usually, I put some in a 289, the clearance was virtually zero, was scary running that one in.

I will call you in a day or so, I may have something to ask you.

Mark

 

[sdibbers]

@cobraboy the bores are in excellent condition still. No barrelling or ovaling going on. You can even see the cross hatching on them all.

New pistons certainly with the gudgeon pins rotating in them, explains the ticking.

As for coating, I’ll be getting the crowns ceramic coating to reduce hotspots and moly dry film coating on the skirts of the new pistons. I am interested as to why the pistons failed as they did, very odd.

I’ve had the main and big end bearing shells dry lube coated too. Good insurance for next year.

 

[sdibbers]

Measured the bores and they have no wear whatsoever on any of them. So just a light hone before the rebuild I think. Good news.

 

[sdibbers]

Pistons and gudgean pins now within 0.5 grams of each other. Rods are the same with the small ends the same. The total weight of each rod/piston/pin is spot on. Next will be ceramic and moly coating the pistons.

Progress is happening, slowly.

 

[cobraboy]

Just done the same with the Alfa internals and got a full balance job on the crank assy. It is very satisfying winter work.
Alfa had first start today on new engine, only ran it enough to set timing and balance carbs, when the roads clean up I will make it work to bed in the rings.

Will your Moly coating allow you to run tighter tolerances ?

 

[sdibbers]

Will your Moly coating allow you to run tighter tolerances ?

It’s more to reduce friction between the skirts and cylinder walls. The ceramic to reduce hotspots on the crowns.

 

[sdibbers]

Just done the same with the Alfa internals and got a full balance job on the crank assy. It is very satisfying winter work.

I agree, I really enjoyed just taking the time with each component. Dialling it in, reducing stress risers, setting up for the next stage. There’s no hurry this end, the highest temps this whole week have been -7°C lowest was -20°. So the garage feels artic.

 

[sdibbers]

Found some time today to start the coating process. First off, the ceramic coating on the crowns.

I'm using Cerakote's Piston Coat V-136, oven cure. Their instructions are quite precise on prep.

First I cleaned the pistons with acetone to thoroughly degrease them. Then I masked them ready for media blasting. I'm also going to dry film lube coat the skirts so masked for both crown and skirt blasting.


After using the specified 100 mesh aluminium oxide blast media, I de-masked, washed them in hot soapy water followed by another wipe down with acetone.

Now wearing nitrile gloves (don't want any contaminants affecting the surfaces) I masked and sprayed the ceramic coating. Let it air dry for 15 mins before de-masking and putting in the oven for an hour at 300 deg F, that's 150 deg C for those watching in colour.



Next steps tomorrow is to do the dry film lubricant coating. Similar process according to the instructions.

 

[sdibbers]

Today was slick day. After remasking and degreasing the pistons. I sprayed them with Cerakote p-109 dry film lubricant coating.

After flashing off I demasked and baked for an hour at 300°f. They came out great!


Once done I assembled the rods and pistons. They’re ready to be refitted.