Installing replacement pistons

[AnthonyG]

Received new piston assy’s from original builder because original pistons had issues @ 2000 miles. Cylinders look good @ still show original honing pattern but I know I should re-hone them. I see two types of honing tools, deglazing which I think will be fine or full honing tool. With the original honing pattern still evident What r some thoughts/advise?

[Fordestes]

Always hone to assure proper ring seating and use proper honing oil , the left over cross hatch had rings already wearing against it , it is a good idea to start with a freshly honed cylinder, you indicate there was a problem with the first ring /piston assembly so start with the correct cross hatch and proper grit of stone to suit the type of ring material to insure good ring seating, always clean with hot soapy water and wipe with a clean rag to check for left over hone abrasive. for just a re-ring job I use the expandable spring type purchased from an auto supply or the berry bush type , after a re-bore in order to bring cylinders to size clearance ,proper finish, I use a Sunnen A N micro adjustable . be sure to check ring end gap, Piston ring land clearance,depth etc. and piston to cylinder wall clearance, you didn't say why the other pistons failed , if you don't mind what was the failure of the pistons at such low mileage ? this sounds like the pistons may have been installed incorrectly or a number of other contributory factors.

[flatheadmurre]

Since you have a correct size and just want the surface for the rings a flex hone is the easiest way to get the job done correctly,
Brush research flex hone...any ridgid hone or glace breaker needs pressure adjusted right to end up with the right finish.
Just my 2c.

[flatjack9]

A rigid hone will also remove some material and may effect piston fit.

[AnthonyG]

I’ve seen the brush type too. Considered but all seem to use carbide in them. Carbide can cut quickly?

[flatheadmurre]

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The flexhones removes a minimum amount of material to achieve the correct wall finish compared to an oldfashioned ridgid stone.

[AnthonyG]

Opinions on this type? https://www.amazon.com/dp/B002XUL1EE..._9cfmEbEVN9RWR

[flatheadmurre]

If you have cast iron rings...not moly or something exotic like low tension...that brush wil get the job done !

[Ol' Ron]

Just curious, whatwas wrong with the original pistons & rings.

[Fordestes]

That is what I am wondering also , what will stop the new pistons from failing ?

[deuce5wndw]

From your previous thread, I think I would check clearances before reassembly.

[Bored&Stroked]

I believe he had a detonation problem and destroyed some ring lands . . .

[Kurt in NJ]

Ever since I read the replacement ring set instructions that said honing is not necessary if there is no bore damage I don't hone, --- even experimenting with putting used rings from another engine in (used rings with 180k in 200k bores)
I have taken apart recently honed and new rings engines apart for bearing failure due to honing debris

[Ronnie]

Yes all that can be correct in many cases,the cautionary statement exists because the average shade tree fixer either doesn't know what is required to get a acceptable job done or is following 50 years of bad info and practices.


R

[AnthonyG]

Ol’ Ron & Fordestes- As Bored & Stroked said, Builder believes detonation is what caused. From another thread I posted when I removed heads, Offy. alum. & discovered from many who posted there’s an issue with the head design regarding s. plug reach. Short story no plugs made in correct heat correct length. My builder put 437 reach Autolites which were .250” short & not entering the fire chamber causing detonation which cracked land between rings on 4 cast pistons. New pistons r Ross Forged. Offy Heads counter sunk @ 120degree to flush thread condition on plugs as recommended.
Kurt & Ronnieadvice if cyl’s not damaged don’t hone have me wondering now if I should or shouldn’t hone? W only 2000 miles on engine when this happened it still has original honing pattern showing?

[JSeery]

You need to check the piston clearance. Forged pistons normally require more clearance than cast. If you hone the cylinders you need to figure out how to not contaminate the rest of the engine. If it was me, I would pull the crank.

[Ronnie]

Originally Posted by AnthonyG

Ol’ Ron & Fordestes- As Bored & Stroked said, Builder believes detonation is what caused. From another thread I posted when I removed heads, Offy. alum. & discovered from many who posted there’s an issue with the head design regarding s. plug reach. Short story no plugs made in correct heat correct length. My builder put 437 reach Autolites which were .250” short & not entering the fire chamber causing detonation which cracked land between rings on 4 cast pistons. New pistons r Ross Forged. Offy Heads counter sunk @ 120degree to flush thread condition on plugs as recommended.
Kurt & Ronnieadvice if cyl’s not damaged don’t hone have me wondering now if I should or shouldn’t hone? W only 2000 miles on engine when this happened it still has original honing pattern showing?

Yes you should hone it isn't easy to not contaminate the rest of the engine.


My first post explained why the no hone was stated. Not my belief that honing must not be done. I myself haven't seen a current no hone statement regarding any common replacement rings.



R

[tubman]

I don't know if I'd accept the builder's explanation of what went wrong, especially since he was the one who installed the incorrect plugs. He either didn't check them or chose to ignore the obvious mismatch. If the latter, why does he know it's a problem now when he didn't then?

There are some red flags here for me, anyway.

[Tim Ayers]

deleted comment

[AnthonyG]

Tubman, I don’t know what was in the builders mind but am skeptical also. Remembering before any dis-assy, always adjusting for what I thought were timing issues. Since dis-assy & the long discussion on Offy head issues & seeing the dark condition of tops of pistons & remembering also no matter what plugs I used to use they’d all be dark on removal. Even had Charlie NY set up carbs on his test engine & still had plug issues. So on removing heads & seeing plug reach so short, & long post/thread on Offy heads seemed to make sense. Be that as it may I gotta re-assemble.
I don’t want to pull the crank. Plans were going to b:
Wrap exposed crank bearing surfaces with clean flannel to protect while honing
Hone w brush style lightly to just break potential glaze
Clean bores w terrycloth soaked w kerosene then flush wipe again w brake cleaner.
Final clean w clean terrycloth till clean.
Remove flannel from crank flush wipe w brake cleaner crank surfaces w terry cloth till clean
Check piston to cyl clearance, JSeery said forged s/b greater than cast pistons, how much???
Verify compression ring gaps
Reassemble
Comments?

[tubman]

You're doing it yourself? I already feel better. The only thing I would add is that if you run into anything you're not absolutely sure of, come on here and ask. The piston clearance question is a good example.

[JSeery]

Originally Posted by AnthonyG

Check piston to cyl clearance, JSeery said forged s/b greater than cast pistons, how much???

I would check with Manufacture on their specifications for the pistons you have. It was my understanding that the original pistons were cast and the replacements were Forged, is that correct? Cast and Forged pistons expand differently and forged normally require increased clearance over cast. However I built a 460 with forged pistons that specified fairly tight clearances. So the only real correct answer is to check with the manufacture.

Here is an example of a Ross Piston box. Did your new pistons come with instructions?

[flatjack9]

Concerning cleaning: soap and hot water is the only way to really clean the bores. Wipe with lint free towel and blow dry.

[AnthonyG]

Correct, builder used cast, he’s giving me Ross Forged.

[AnthonyG]

Thx flatjack9, sounds like in addition to what I described? Also would ur suggestion b to do same to crank surfaces? Also are we talking like a dish detergent soap?

[Tim Ayers]

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Originally Posted by AnthonyG

Correct, builder used cast, he’s giving me Ross Forged.

Anthony:

Have you opened them up or looked at the label to see if they are cast or metric rings?

The difference will also determine the type of honing that needs to be done as well.

[AnthonyG]

Haven’t received yet.

[JSeery]

"there's a common misconception that forged pistons always require greater skirt-to-wall clearances. This isn't always true because clearances depend on the type of alloy used in the piston, the design of the piston itself and the profile of the piston. The coefficient of thermal expansion for some forged alloys is actually not much different than that of an ordinary cast piston."

Hopefully the required information will be included with the pistons.

[Tim Ayers]

Originally Posted by AnthonyG

Haven’t received yet.

I'd hold off on buying a hone and doing any honing until you determine what type of rings these pistons come with.

[Bored&Stroked]

Originally Posted by Tim Ayers

I'd hold off on buying a hone and doing any honing until you determine what type of rings these pistons come with.

As well as what are the recommended piston to cylinder wall clearances that Ross recommends. Keep in mind, that unless you have a good quality cylinder dial-bore gauge, it is not easy to measure the true bore diameters. Also, you need to know WHERE to measure the piston.

If these are Ross "stocking pistons", then they are not made to your bore - you must make sure your bores are "made to the piston" (may need to be power honed - in a machine).

However, if you're ordering them from Ross, they will make the piston diameters exactly WHAT you need (your specific bore size) - for a mere $40 more than a stocking piston. I'd sure get my ducks in a row before I ordered pistons from Ross.

Lastly - don't just throw the rings on the pistons and install them - you need to validate that the end-gaps are correct, you may need to "file to fit". If the gaps are not correct, this is another way to cause a broken ring land on a piston.

[A bones]

Originally Posted by flatjack9

Concerning cleaning: soap and hot water is the only way to really clean the bores. Wipe with lint free towel and blow dry.

Excellent point, when I saw the mention of terry cloth, I pictured debris lint left behind. Years back, a trans specialist cautioned me about rags leaving lint behind.

Since then I have used Scott C-Fold paper towels for internals. I buy cases at the big box stores they cost less and are much more durable than Bounty. They really do a job.

By the way Keith Black swore by Tide.

[Ol' Ron]

I use Egge Pistons in most of my builds and never had a problem with them. Defamation, is usually caused by excessive ignition timing. However a low oct. ifuel, in a hi compression can cause this as well. It hard to get that much compression in a flathead. The spark plug doesn't enter the picture here, the worst thing would be if it hit the ex valve. I don't like using Ross pistons in a street engine, due to the excessive piston clearance. This can lead to pil commission in a low time engine. A street engine needs a tight piston.

[Bored&Stroked]

Anthony G: I saw earlier that you were planning on leaving the crank in and trying to 'mask' around it. I highly recommend that you pull the engine apart such that you don't contaminate the bearings or get other crap in someplace you don't quite see. I know it is a pain, but given that it is a relatively new engine, probably a 2 - 4 hour job to pull everything else out of it. This way you can get the block correctly honed for your pistons (correct cylinder wall clearances and hone finish) and can wash the block with hot soap and water - to truly get it ready for reassembly. The clearances for your pistons should be about .004 (but check with Ross to make sure).

Also, if they have the piston bore size you need with the newer 1.5, 1.5, 3.0 mm metric ring pack (even if you need to spend a bit more money), I highly recommend these rings over the older 'Grant style' rings that we all used to us. They are usually 'file to fit' rings - so they all need to have the ring gaps manually checked/filed for every piston.

I usually run a hose directly from my hot-water heater and usually use blue Dawn soap.

Take a few extra hours - to make ALL the time/money you've spent on this project - the best investment it can be.

[AnthonyG]

THX 4 all the good tips!

[john in illinois]

I have found that most of the detonation I have experienced is due to running too lean. Flatheads will run ok with a lean mixture, but still get damaged. JWL book has a good section on jetting. Might be good to compare to make sure that is not your problem, after you repair the engine.

John

[AnthonyG]

What’s the best Plastiguage to use on 8BA 3.312 bore 8 piston assembly?

[JSeery]

Are you asking for checking the rod and main bearing? If so, the piston size shouldn't have anything to do with it. You select Plastigauge based on the clearance range you are wanting to check. It is cheap, so why not get an assortment of several ranges.

[AnthonyG]

J, sorry about that, giving bore size just habit describing engine. Was interested in best Mfgr., but beings u mentioned clearance rod journals r 2.1185 & looking for a chart showing what Rod clearance s/b? Looking on Vanpelt w/o success so far?

[JSeery]

I thought there was just one manufacture of Plastigauge (it's a band name) but not positive. They come in green, blue & red size range.

[AnthonyG]

There’s about 4 or 5 listed on Amazon, I’ll just pick one. All come with both Red & Green.
Clearance chart for rod bearings on line?

[JSeery]

I have some 59a numbers, I don't mess with 8ba. From the Repair Manual Ford, Mercury & Truck V8 Engines 1937 to 1947 these are maximum ware limits.

Bore out of round .003
Bore taper .006
Piston to cylinder 6-10 lb pull .005 w/.5 feeler gauge
Rod bearings .005
Piston ring end gap .035

[JSeery]

Originally Posted by AnthonyG

There’s about 4 or 5 listed on Amazon, I’ll just pick one. All come with both Red & Green.
Clearance chart for rod bearings on line?

See what you mean, I have always used the one(s) with Plastigauge trademark on them.

[flatjack9]

You'll want the green and you'll want around 1 to 2 thou clearance.

[Bored&Stroked]

On the rods, I like to have about .015 to .002 or so - more on a race engine. On the mains, about .002 to .0025.

What type of rod bearings are you running - full-floaters or late style (49-53) tanged bearings? It is really hard to use Plastigauge with floaters - these types of bearings need to be "fitted" to the rods and crank - I can't see PlastiGauge being of much value to the full-floater process. Also, since you need clearances on BOTH sides of the full-floater bearings, plastigauge really can't tell you enough.

[AnthonyG]

Tanged type. Read an article on crank mains & rod bearing clearance. It was interesting. Indicated best rule of thumb is, .00075”-.001 per inch of diameter of journal is a good gauge! Then adjust for more oil pressure lean to .00075” for more HP lean more to .001”. Made sense. As my 8BA has the Merc 4” stroke crank, a 3/4” isky cam, Domed forged pistons & oversized valves I think I’ll do the .001 per in of diameter. So 2.1185 journal X .001=.0021185 or rounded .002” which is within range of what Flatjack9 & Bored&Stroked indicate.
Thx for the help guys!!

[AnthonyG]

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New Forged Ross Pistons installed! New gaskets & rest of assembly tomorrow. S/B running again this week. Thx for all the help & tips!

[Phil Gillespie]

Originally Posted by AnthonyG

New Forged Ross Pistons installed! New gaskets & rest of assembly tomorrow. S/B running again this week. Thx for all the help & tips!

All the best. It will be a good feeling to fire it up again.
question: did you hone bores or just refit new pistons?
Phil NZ

[AnthonyG]

Just refitted new pistons, went w new rod bearings. Rods bearing races were line honed. With only 2000 miles on since rebuild original honing cross hatch still visible & could feel in cylinders with finger nail, was obvious engine hadn’t broken in yet. No ridge line either. Advise from several on FB & original builder was the risk of honing greater than the reward on this new an engine.