Pre-rebuild info gathering

[Injuhneer]

I am about to rebuild a '96 4.0. So let me state that I am a cheapskate. Well, not really. I just don't like getting soaked for parts because they have a certain name on them.

So I am researching alternative part sources. Bearings are plentiful and cheap so no worries there.

Here are questions I could not find answers for in the service manuals:

1) Are there any exterior markings on the engine to indicate the grade of the installed pistons (assuming OEM motor grade A or B)? I was hoping to avoid the whole disassemble/inspect/measure/order drill.

2) The dimensions of the piston rings. Clearances and gap are listed but not height, depth, or type. Alternately set numbers (Hastings, Mahle/PC, etc) would be nice.

3) Valve dimensions (IN and EX). If there is a like valve in a common part (Toyota, GM, or some such) I'd like to find it.

 

[macgyverizer]

I just finished rebuilding my 4.6l With my lforgue80 and so far so good. I got all my internals from Mark at D&D. I know that the bill adds up quick but it will be worth it. It won't cost you any more than stock parts but you will get much better quality.

 

[ptschram]

Pistons will be labeled on the crown as to grade.

Why are you concerned about valves? It's very rare to have problems with them.

 

[Injuhneer]

I was hoping that the grade was on the block. If not that means borescope time if the crowns are clean enough. I thought that knowing the grade would at least let me order the proper oversize before ordering. I was asking about the dimensions to look for a match elsewhere. The best price I found was ~$225/set. Thought I may do better by finding a match with a higher production volume (read:lower price) ring set.

WRT the valves, just asking. Same idea. They aren't terrible in price but maybe cost could be cut in half with a dimensionally same valve from a higher volume vehicle. This engine does have 180k mi. on it so I am expecting to replace the valves. Seals at a minimum. Possibly lifters too (have one that is tapping on startup).

Just putting my options together. Thanks for the input.

Thx.

 

[Injuhneer]

Ok, it appears that the copy of the workshop manual I had was edited.

In the General Specifications section, subsection Engine 4.0 V8:

Piston rings
Number of compression rings 2
Number of control rings 1
No 1 compression ring Nitrided steel barrel faced
No 2 compression ring Tapered spherical barrel marked ’TOP’
Width of compression rings
1.478 - 1.49 mm / 0.0582 - 0.0587 in
(Top) 1.21 - 1.23 mm / 0.0476 - 0.0484 in
Compression ring gap 0.40-0.65 mm / 0.0157 - 0.0256 in
(Top) 0.3 - 0.5 mm / 0.0118 - 0.0197 in
Oil control ring type Aclonoform
Oil control ring width 3.0 mm / 0.1181 in
Oil control ring rail gap 0.38-1.40 mm / 0.0150 - 0.0551 in

Given these dimensions there are several ring sets out there not designated as Rover rings that can fill the bill for about half the cost. If you are willing to widen the top ring groove to 1.5mm the selection of ring sets increases further.

 

[Injuhneer]

And for 4.0 valves:

Valves
Length: Inlet 116.59 - 117.35 mm / 4.590 - 4.620 in
Exhaust 116.59 - 117.35 mm / 4.590 - 4.620 in
Seat angle: Inlet 46°- 46°25’
Exhaust 46°- 46°25’
Head diameter: Inlet 39.75 - 40.00 mm / 1.565 - 1.575 in
Exhaust 34.227 - 34.48 mm / 1.3475 - 1.3575 in
Stem diameter: Inlet 8.664 - 8.679 mm / 0.3411 - 0.3417 in
Exhaust 8.651 - 8.666 mm / 0.3406 - 0.3412 in
Stem to guide clearance: Inlet 0.025 - 0.066 mm /0.0010 - 0.0026 in
Exhaust 0.038 - 0.078 mm / 0.0015 - 0.0031 in
Valve lift (Inlet and Exhaust) 9.94 mm / 0.3913 in
Valve spring length fitted 40.4 mm (1.59 in) at pressure of 29.5 kg (65 lb)

I am still searching for valve options but will see what turns up.

 

[JohnB]

Don't order s single part until you have the engine on a bench.

 

[Injuhneer]

Don't order s single part until you have the engine on a bench.

Or the spare, right?