Piston Installation and Combustion chamber counter bore

Engine, fuel system, cooling system, heating, carburetors, exhaust, transmission, wheels, and other items related to the moving the car.

Moderator: Dan Szwarc

User avatar
JeremyHoward
Newbie
Posts: 16
Joined: Wed Dec 30, 2009 12:17 am
Location: Portland Oregon
Contact:

Piston Installation and Combustion chamber counter bore

Post by JeremyHoward »

Hi All.

My 1964 Mel 430 is at the machine shop and looks like it may need bored over about .060 to clean up the cylinders.
Were having custom pistons made with the factory wedge design to come close to the factory specs of the 1963-1965 piston design. My machinist has a preferred custom piston manufacturer he is working with.

I will be using proper for 1964 4 bbl heads which have a very small combustion chamber build in (more like valve reliefs).
It appears that MELs have a factory overbore at the top of the cylinder (the combustion chamber).
Is this referred to as a counter bore?

What’s the purpose of this counter bore and is it necessary?

My suspicion is that the counter bore is there to accommodate piston instillation using a ring compressor that slid down into the larger diameter counter bore above and perpendicular to the cylinder?

If I’m not mistaken most blocks with the deck perpendicular to the cylinder use a ring compressor that sits square and flush with the deck during piston instillation. The ring compressor doesn’t go into the cylinder on most engines. Is this correct?

Anyways, my machinist is worried about counterboring the top of the cylinder (combustion chamber) because were already pushing the limits of the cylinder size by going about .060 over.

I’ve searched on here and on the MEL engine forum and see some recommendations for ring compressors.

I also see some recommending taking advantage of the deck angle and using fingers or a plastic tool to finesse the pistons and rings in without a ring compressor.

If the “finger method” is used does the cylinder top (combustion chamber) overbore become unnecessary?

I’m hoping yes as it would solve a lot of problems. Of course, this is assuming the over bore of about .060 will eliminate the counter bore at the top of the cylinder (combustion chamber).

The “finger method” may not work if there is a counter bore which would prohibit the rings from advancing further down the narrower cylinder. The rings would expand above the cylinder bore and get hung up.

Also of note: Considering were having custom pistons made we will factor the absence of a counterbore in the combustion chamber into the piston design for the purpose of achieving the desired compression ratio.

Another honorable mention is that our over bore will be around .060 because we will find rings that are the closest size or slightly over our minimum bore needed and we will have the pistons made to accommodate the rings we find. It may even be a metric size ring. Then we will bore to the diameter which will accommodate the off the shelf rings.

FYI: our goal compression ratio will be 9.5/1

Considering the deck angle is like a chevy 409, I found this YouTube video on chevy 409 piston instillation using fingers without a ring compressor.

https://www.youtube.com/watch?v=YAg8fIWXlr4

If someone with more experience on the matter could weigh in, I would greatly appreciate it.
So: Is the counter bore necessary if not using a ring compressor for piston installation?

Thank You!
Jeremy Howard
Jeremy Howard, Portland Oregon, 1964 Convertible
1Bad55Chevy
Dedicated Enthusiast
Posts: 689
Joined: Sun Aug 28, 2022 2:41 pm
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by 1Bad55Chevy »

Call this guy
https://barnetthighperformance.com/430- ... ebuilding/

He builds these MEL motors stock to insane strokers making over 600 hp, I am pretty sure he could answer all of that for you.

I have never built a MEL so I am of no help sorry.
55 Chevy 2 dr/ht pro street 427
71 Lincoln Mark iii
2004 Dodge Ram 1500 Rumble Bee #1168 of 4000
User avatar
TonyC
TLFer for Life
Posts: 10690
Joined: Thu Apr 15, 2004 1:01 am
Location: San Antonio, Texas
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by TonyC »

Your suspicions are correct, Jeremy. The combustion-chamber area is meant to make installation of ringed pistons easier. See the visual aid below on how to fit the compressor, as well as what type of compressor to use.

Boring to .060" over is pushing the limits of MEL cylinders, though they are capable of such an overbore. Usually, .030" is more practical, which was what I went with on mine.Unless the cylinders are so scored that .030 won't smooth them out, I'd recommend .030", just to maintain the engine's durability.
Attachments
Band Ring Compressor, fitted in MEL Cylinder
Band Ring Compressor, fitted in MEL Cylinder
"Don't believe everything you read on the Internet, just because there is a picture with a quote next to it." (Abraham Lincoln, 1866)
"Question Authority!"

1966 Continental Sedan, affectionately known as "Frankenstein" until body restoration is done (to be renamed "General Sherman" on that event)
User avatar
JeremyHoward
Newbie
Posts: 16
Joined: Wed Dec 30, 2009 12:17 am
Location: Portland Oregon
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by JeremyHoward »

Thank you Tony C for the response.
Boring to .060 is out of necessity due to rust pitting.

I will plan on:
Not counterboring & Installing the Pistons without a ring compressor.

Hoping this will work.
Thank You!
Jeremy Howard, Portland Oregon, 1964 Convertible
User avatar
Lee
Addicted to Lincolns
Posts: 1019
Joined: Wed Jan 25, 2023 7:15 am
Location: Patriot, Indiana
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by Lee »

Jeremy, may I ask from where your machinist is sourcing the pistons?
1930 A Coupe
1941 LC Coupe
1968 XR-7 (my great-grandfather’s)
1962 LC Sedan (owned 35 years & driven 100k+ myself)
frasern
Addicted to Lincolns
Posts: 1272
Joined: Sun Oct 16, 2016 2:09 pm
Location: North Battleford, Saskatchewan
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by frasern »

Forgive me for changing the question, Have you considered sleeving one cylinder?
I ask this because that was once the cheapest way to rebuild my 462. It was seized, so one cylinder was badly pitted, but the other bores were still okay, and in 1990ish, no oversize pistons were available for MELs, that I could find. Standard pistons were available, but expensive and very hard to get, Before making the call, I found a parts car with a rebuilt engine, +030, so I went that way, as the whole car cost less than the pistons would have.
+060 pistons may be hard to get for that engine, they are rare for any engine, but we have more options today, thankfully.
Fraser Noble, Western Canada
'62 and '67 LCC.
User avatar
TonyC
TLFer for Life
Posts: 10690
Joined: Thu Apr 15, 2004 1:01 am
Location: San Antonio, Texas
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by TonyC »

Actually, from my own sourcing experience, pistons are not the issue. When I needed pistons (and I seriously did), both Performance Direct and Egge offered pistons up to that oversize...though I suspect the latter no longer does. For me, two years ago, rings were the most difficult things to get. Every piston supplier, to include Usual Suspects like LincolnLand, said they could provide pistons but not rings, due to shortages afflicting the whole auto industry at the time. Even the machine shop that machined my core admitted they could not get rings for any of their engine projects.

Not sure if that shortage is ongoing now, but it's something to prepare oneself for, I think.

---Tony
"Don't believe everything you read on the Internet, just because there is a picture with a quote next to it." (Abraham Lincoln, 1866)
"Question Authority!"

1966 Continental Sedan, affectionately known as "Frankenstein" until body restoration is done (to be renamed "General Sherman" on that event)
User avatar
JeremyHoward
Newbie
Posts: 16
Joined: Wed Dec 30, 2009 12:17 am
Location: Portland Oregon
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by JeremyHoward »

Based on my discussion with my Machinist we are trying to avoid sleeving any cylinders for a variety of reasons.
I will inquire about where he is having the pistons custom made.

And a big No to any off the shelf pistons for a 430.
No one makes them with the proper factory wedge design.
They make what I would call crowned pistons which are a reasonable alternative considering the cost of custom pistons and many vendors will sell flat top pistons which are a big no-no.

There are many discussions on here related to MEL piston design as well as the MEL engine forum.
462 MELs you can get proper factory style wedge shape from Egge.
430s you cannot get proper wedge style only flat top and crown designs.

1958-1962 430s use a small wedge piston. The heads are flat with no valve relief which is a factor with piston design.
The 1963-1965 430s have a valve relief build in to the heads which increase the combustion chamber volume and as such have a different piston with a larger wedge design.

I'll let you know how things go with the piston installation.

Thanks guys!
Jeremy Howard, Portland Oregon, 1964 Convertible
User avatar
TonyC
TLFer for Life
Posts: 10690
Joined: Thu Apr 15, 2004 1:01 am
Location: San Antonio, Texas
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by TonyC »

Right...sorry :oops: , I forgot about the piston crown design used in '63-thru-'65. That was a different design, and I remember none of the piston sources offered those particular pistons. I was thinking purely based on my 462.

Howz about rings? Have you any news on ring availability?

---Tony
"Don't believe everything you read on the Internet, just because there is a picture with a quote next to it." (Abraham Lincoln, 1866)
"Question Authority!"

1966 Continental Sedan, affectionately known as "Frankenstein" until body restoration is done (to be renamed "General Sherman" on that event)
frasern
Addicted to Lincolns
Posts: 1272
Joined: Sun Oct 16, 2016 2:09 pm
Location: North Battleford, Saskatchewan
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by frasern »

It sounds like you have done the research, I was not aware replacement pistons were such a poor match. My '62 has 190,000 miles (I think) on it, and the engine was rebuilt at some point. It needs a refresh again, and I haven't decided which way to proceed, but probably leaning towards a 462, just because I have a good one.
My 430 has .010 under bearings, and they are worn, I was able to confirm '62 pistons with a borescope through a sparkplug hole, but I also found a casting flaw in the block. If pistons are a concern, That pushes me more in the 462 direction.

Back to the rings, I have heard of working them in without a compressor, also heard of using an adaptor (torque plate), milled ad an angle, (expensive). I would be wary of twisting them in, as that could upset the ring spacing. It may be possible to install 4 from the bottom?
Fraser Noble, Western Canada
'62 and '67 LCC.
User avatar
Lee
Addicted to Lincolns
Posts: 1019
Joined: Wed Jan 25, 2023 7:15 am
Location: Patriot, Indiana
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by Lee »

Fraser, I may be mistaken, but isn’t the bellhousing pattern different between 430 and 462’s?

Edit: I have now read that 462’s have a dual pattern PCA/C-6. I trust that is true…because the possibility of that swap is also on my own radar.
1930 A Coupe
1941 LC Coupe
1968 XR-7 (my great-grandfather’s)
1962 LC Sedan (owned 35 years & driven 100k+ myself)
frasern
Addicted to Lincolns
Posts: 1272
Joined: Sun Oct 16, 2016 2:09 pm
Location: North Battleford, Saskatchewan
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by frasern »

That was what I thought too, until this forum set me straight. Some people have done it here, and shown posts. Going a little off topic, 460 also has a dual pattern, my '68 has the same transmission as my '67, however, I think the Mark III uses the more symmetric pattern, on the same engine.
Fraser Noble, Western Canada
'62 and '67 LCC.
User avatar
TonyC
TLFer for Life
Posts: 10690
Joined: Thu Apr 15, 2004 1:01 am
Location: San Antonio, Texas
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by TonyC »

Would make sense to have two bellhousing patterns on 460 blocks, being that there were two different shells of C-6 transmission by '68. The Mark version is definitely different, not just in its bellhousing pattern, either.

Anyway, I too have heard and abide the story that the 462 had two bellhousing patterns built into it, to accommodate the first C-6 shell and the old PCA Cruise-O-Matic mated to 430s. Story behind that was that the 462 was seen by Ford as a service replacement for any 430s that bought the farm (could also be why they had so many surplus 462s in that warehouse, which they had to exhaust before they could start using the 460s). On my engine, I counted 12 threaded holes in the bellhousing area; however, my C-6 uses only 8 of those holes. The other 4, I would think, have to be placed there to align with bolt holes in the PCA.

If you do end up going with a swap, Jeremy, the 462 is your best bet. It's the only other engine in existence that can fit into your car's bay without mods having to be done to the unit structure, which would compromise your car's integrity...to say nothing about the chain-reaction swapping of every other component of the drive train that a dissimilar engine would precipitate.

---Tony
"Don't believe everything you read on the Internet, just because there is a picture with a quote next to it." (Abraham Lincoln, 1866)
"Question Authority!"

1966 Continental Sedan, affectionately known as "Frankenstein" until body restoration is done (to be renamed "General Sherman" on that event)
User avatar
JeremyHoward
Newbie
Posts: 16
Joined: Wed Dec 30, 2009 12:17 am
Location: Portland Oregon
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by JeremyHoward »

I do feel strongly that a 462 would be a great option and the proper piston design is available from Egge. I mentioned wanting to share the piston manufacturer with the group but my Machinest was hesitant to tell me. I'll get it out of him sooner or later. LOL I think he wants to keep him all to himself. LOL
As far as ring availability. Considering were going with a custom piston manufactured to our specs (based on the factory design) we found an off the shelf ring that was as close to the necissary bore size or just slightly over. Then we bored to match the ring size and are ordering the custom pistons to match the off the shelf rings and custom bore size.
After talking with the machinest some more. He feels confidant that we can use the deck angle to our advantage and probably use a ring compressor still but it will neither go all the way inside a counter bore nore be flush with the block. It may go into the cylinder bore on the high side slightly and then finesse the rings in the rest of the way by hand. Im planning on asking the Machinest if I can assist him in the lower end assembly. Of course I'll bribe his team with doughnuts a couple times before I ask him.

After I pay for all of this I will likely wish I had gone with a 462. One of my reasons for going with the 430 is because My heads were near perfect and I paid top dollar to have them powder coated with some special ceramic coating. They look beautiful and I wanted to use them. I am considering using an oil fill tube from a 462 that mounts where the fuel pump push rod access plug goes. I think it will look good and It will be nice to eleminate the stock oil fill tube. Not sure on that though.
Jeremy Howard, Portland Oregon, 1964 Convertible
User avatar
JeremyHoward
Newbie
Posts: 16
Joined: Wed Dec 30, 2009 12:17 am
Location: Portland Oregon
Contact:

Re: Piston Installation and Combustion chamber counter bore

Post by JeremyHoward »

By the way. the over bore has been done and it's about .075 over!
Yowsa!
this will be the last over bore for this block.
Were also going to design the piston to give us a 9.5:1 compression ratio. ( factory was 10.1:1 or 10:1 depending on where you look)
Of course that involves measuring the combuston chamber which will be challanging but possible. I told him were going this far, might as well not skimp on the combustion chamber measurment.
It's only money right?
Jeremy Howard, Portland Oregon, 1964 Convertible
Post Reply

Who is online

Users browsing this forum: No registered users and 0 guests