4600 piston question

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Hair Bear
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4600 piston question

Post by Hair Bear »

In the process of rebuilding a 4600 engine and the new pistons won't fit. Ok, take it as read that we got the wrong ones. Question is, they fit the bore perfectly, but at TDC the crown is 2+ mm above the block face so what would they be for? I believe the difference between a 41 and 46 engine is the bore, the stroke being identical- or have I got that wrong? The block on this tractor has 'T7' cast into the lh side of it.
Any advice please???
If it's green or red, leave it in the shed...

John b
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Re: 4600 piston question

Post by John b »

You are correct about the bore and stroke and my 4100 block has T7stamped on the l/h side so i think that's just the casting stamp. I think the 5000 has the same size bore but an extra cylinder, not sure if the pistons are different though
My biggest fear is that when i die my wife will sell my tractors for what i told her they cost

Hair Bear
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Re: 4600 piston question

Post by Hair Bear »

Thanks John. We'll have to take one out and give it a measure from crown to wrist pin and see where we go next. Crank and con rods are original so it can only be the pistons somehow.
If it's green or red, leave it in the shed...

shepp
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Re: 4600 piston question

Post by shepp »

Well 4.4 inch bore pistons were used in the Pre force and Force 4000 and 4600 tractors with a 4.4 inch stroke crankshaft. However a 4.4 inch bore piston was also used in the 5000 Force and earlier 6600 tractors and also special 4.4 inch pistons in the 7000 turbocharged engine all with a 4.2 inch stroke crankshaft. That might be where your problem lies.
When the 6600 "Power Plus" engine was introduced around 1978 the crankshaft was changed to a 4.4 inch stroke and the 4.4 inch bore pistons used in that engine then were probably the same as the ones used in the 4600 (and 4000) engine. The 7600 turbo engine also went onto 4.4 inch stroke but the 4.4 inch pistons were specials for the turbo engine. You might have the pistons meant for the 5000 Force and early 6600 engines with the 4.2 inch stroke crankshaft. Ford claimed in their advertising that con rods were a standard size and interchangeable for all normally aspirated engines, so if that is the case there must be 2 different types of 4.4 inch bore pistons, one type for the 4.4 inch crankshaft stroke engines and one for the 4.2 inch stroke crankshaft engines. You might have mistakenly bought the ones for the 4.2 inch stroke engine instead of the ones for the 4.4 inch stroke engine which are the right ones for the 4600. In fact I am virtually certain this is what the issue is, you have the pistons for the Force 5000 and early 6600 engines.

Incidentally there will also be 2 types of 4.2 inch bore pistons. The 3000 Pre-Force, the 3000 Force, and the 5000 Pre-Force all had a 4.2 inch bore piston with a 4.2 inch stroke crankshaft. However the 2000 Pre-Force and 2000 Force had a 4.2 inch bore piston with a 3.8 inch stroke crankshaft.
1946 E27N, 1952 Major Diesel, 1959 Power Major, 1962 Dexta, 1962 Super Dexta, 1963 Super Dexta NP, 1964 Super Major NP, 1965 Super Dexta 3000, 1966 Major 4000, 1967 3000 PF, 1994 5640,plus Basildon built NH.

Hair Bear
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Re: 4600 piston question

Post by Hair Bear »

Nice one!
I was aware of the bore difference in some but I just could not find any reference to a stroke issue which is what this clearly is.
It's a friends machine and I've not been back to it recently but when I do I'll let you know how we get on.
Thanks.
If it's green or red, leave it in the shed...

shepp
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Re: 4600 piston question

Post by shepp »

The distance between the centre line of the gudgeon pin and the top of the piston crown is one tenth of an inch greater on the 4.4 inch bore pistons used in the Force 5000 and early 6600 engines (which had a 4.2 inch stroke crankshaft) than it is on the 4.4 inch bore pistons used in the Pre Force and Force 4000 and 4600 and 6600 Power Plus engines (all of which had a 4.4 inch stroke crankshaft). One tenth of an inch is about 2.5 mm which is what you say your pistons are proud of the block by.
1946 E27N, 1952 Major Diesel, 1959 Power Major, 1962 Dexta, 1962 Super Dexta, 1963 Super Dexta NP, 1964 Super Major NP, 1965 Super Dexta 3000, 1966 Major 4000, 1967 3000 PF, 1994 5640,plus Basildon built NH.

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