Mitsubishi 2.6 Reassembly Puzzle

I am re-building a Mitsubishi 2.6 L engine (Caravan 84). After
installing the main bearings and finding all appeared well – the crank
turned without effort, I started to install rod bearings, trying #1
and #3 pistons. The rotational resistance torque increased by over 100
ft.lb with rod bearing #1 tightened to spec (34 ft.lb) and that of #3
to 55 ft.lb with rod bearing tightenened to spec. This was without any
rings installed so that the increased rotational resistance is only
due to the bearing. The diameter of the crankshaft and the clearance
as measured with Pastigauge (deformable plastic gauge) are:

Piston Diam(in) Clearance(Thou) Clearance Spec (Thou)
(Haynes)

1 2.057 .001 .0008 to .0028
2 2.056
3 2.056 .00125
4 2.056

What am I doing wrong? Thanks for any light you can shed.

Notes
1. The crankshaft was ground to .030 (main and rod)
2. The main bearings are labelled .030
3. The rod bearings are labelled .75 (I assume mm, the equivalent of
..030
thou)
4. The bearing shells are located correctly with the tabs in the
slots.
5. The Plastigauge was used properly, w/o oil film.
6. The bearing were coated with oil for the turning test

 

Is there a better forum for this - I'm not sure that this vehicle is
not considered an antique.

 

NOt necessarily an antique just not worth the effort you're putting into
this engine. NOt being a smartass or anything the Mitsushitti isn't worht
the powder to blow it up.
Larry

 

However, it seems like his question (Should he see significantly
increased resistance to turning with the bearing caps tightened with
properly gapped bearings, and if not, what could be the cause?) is
generic enough that someone could answer his question.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

87 Caravan Mitsu 2.6 - 240,000 miles on it before I retired it and never a
problem in all that time.

 

One of the very few!!!, normally about 6 heads gaskets, 2 heads, 2
carburetors, and 3 set of chains and guides. not to mention anything about
the balance shaft/ bearings.

 

Do you mean it actually needs powder toblow it up????

 

Actually, if the oil is changed regularly the chains CAN go 200,000Km
ANd the balance shafts too - but you can't run the "A" schedule.

If the head gasket is done right, it only needs one. The chokes on the
carbs were a joke, and they liked dropping welsch plugs - so some guys
put on Toyota carbs. Others put on Holley-Webers.
If, when you have one apart, you do all the stuff mitsushitty SHOULD
have done re: oil clearances, chamfered oil passages etc, a properly
rebuilt Mitsu 2.6 CAN be a pretty good engine. From the factory? Like
any Mitsu Junk, you pays your money and takes your chances.