Installing replacement pistons

[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?