1uz/2uz/3uz & 1uz vvti conrods - offset or not ???

[ed_ma61]

i seem to be a building pile of heresay evidence to suggest (potentially) that the early 1uz rods (the 'beefier' ones) may not be offset, whilst the later 2uz, 3uz(?) and 1uz vvti rods (the pissy weak looking ones) have an offset bigend from rod centreline of around 0.060"-0.070" (1.6mm-1.8mm)...

now its a forgone conclusion that the bore centrelines across this engine series remains constant. its also generally concluded that the crank journals are the same, utilising the same pin dia and big end width...

...its therefore interesting that people have run clearly non offset rods like the eagle rods, without issue, in early 1uzfes. its also interesting that speaking to argo today, that their rods for the early 1uz are also non offset (unless you call 0.004" an offset!) and on top of that zuffen stated he couldnt 'see' and offset on the argos he eyeballed...

however, the 1uz vvti and the 2uz clearly NEED offset rods for the rods to line up with the bore centre-lines, and thus for the loads to run down the true axis of the rod.

does this mean: that the early 1uz DOES have offset rods but noone has ever noticed? that the early 1uz has different bore/crank journal alignment thus meaning a zero offset rod aligns striaght? is the bore spacing different to the later 1uz's and other later families? does the early 1uz just endure with slightly off centre rod alignment?

I have no idea! ive only got access to a 2uz and a 1uzfe vvti. Ive never held a non vvti early 1uz rod in my hand or seen a decent picture! can someone confirm one way or another with absolute certainty?

I'd love some clarification of this as its driving me nuts. Id love to take advantage of rods etc designed for the early 1uz in my vvti engine, but am starting to get paranoid about this potentially weird incompatability!

lol...

thanks guys
ed

PICS:

1uz vvti rod:


2uz rod (and pauter 2uz rod)

 

[cribbj]

Ed, here's a page from the Lexus TIS for the early 1UZ motor. While it doesn't specifically mention the offset, it does make reference to orienting the rods correctly so the "outer marks" are in their correct positions.

Maybe by virtue of having a beefier big ends and beams, the earlier rods inherently have offset that isn't as visible as the later rods? Perhaps with the later rods, the offset is more apparent because the sections of the beam & big end are thinner? Just posing possibilities here....

John

 

[ed_ma61]

yup - they're offset then. quite clearly...

ok so whos run the eagle rods? were they offset ground on the bigend thrust face? what pistons did you/they run with the rods? did you/they manage to capture the offset with this machning? was the side-side gudgeon pin clearance measured once installed?

maybe ive got it all ass-backwards? are the eagles themselves perhaps offset rods?

very curious as to all this...

as for argo stating their offset was 0.004" - maybe its a simple mistake? im awaiting a reply from sean at argo offering further clarification

cheers
ed

 

[cribbj]

Here's another page where Lexus calls out the opposing cylinders offset of 21mm. It would be interesting to put two stock rods together, with the outer marks oriented correctly, and see what the C/C distances are between the wrist (gudgeon) pin ends. Knowing Lexus/Toyota's penchant for precision, I'll bet it's 21mm.

John

 

[ed_ma61]

ill measure it now...

as for the eagle H beam rods - they ARE offset...

so, im guessing argo quoted me the wrong number, and zuffen didnt look closely enough at the ones he got

cheers
ed

 

[ed_ma61]

i measured it at 21.6mm but allow an error factor of x2 beers

 

[cribbj]

Sounds like an offset of a 0.6mm RCH is in there too....

Whose rods are those in the photos, from left to right?

Eagle - Late OEM - Early OEM?

 

[Lextreme II]

I called my engine builder yesterday. The Eagle or the after market Chevy rods are .060" offset. Looks they are Eagle, OEM and CAT rod

 

[Pro]

great - now i'm confused.

can we please keep eagle out of this? i'm under the inmpression that the GB this relates to is for ARGO, so can we PELASE keep it ARGO only?

argo have quoted 4thou (less than 0.1mm)? that's barely an offset at all, when you consider ed_ has measured 21.6 mm...

WTF is the go here?

 

[ed_ma61]

oh thank god, pasted below is ARGO's reply

Ed:

Sorry for the confusion...Perhaps I misread the chart when giving you the
measurement. In any event, I have RE-Checked on that rod....The Left and
Right cylinder bank on that block is offset by .825". Which means the
Conrod offset is one half of that...(.4125" on both sides)...the difference
between .4125" and my second measure of .4875 is to account for the gap on
the crank journal. (give you a net offset of .075 per rod.)

I hope this clarifies...let me know if you have any questions.

Regards

Sean Grady
Argo Engineering & Marine
Argo Conrods

 

[cribbj]

great - now i'm confused.

can we please keep eagle out of this? i'm under the inmpression that the GB this relates to is for ARGO, so can we PELASE keep it ARGO only?

argo have quoted 4thou (less than 0.1mm)? that's barely an offset at all, when you consider ed_ has measured 21.6 mm...

WTF is the go here?

Mistakes were made with the original numbers. Sean admitted he misread a table for the rods.

Added to this, we're talking about and mixing totally different measurements and taking the numbers out of context.

I'll have a go at trying to explain this without making things more confusing.

The UZ's opposing cylinders are offset from each other by 21mm or 0.827 inches. This means the wrist pins and beams of the rods for opposing cylinders have to have this same offset in order to be perfectly centered in the cylinders, so as not to generate an unbalanced rotational couple (fancy name for a bad vibration).

The big ends do not provide all of this offset, so the beam and wrist pin end must be offset from the big end. This is what we're referring to as the "net rod offset". Here's how you can find/prove it:

Stack two OEM rods together, as they would be mounted on the crank journal, and measure the center to center distance between the big ends, you'll find they're not quite 21mm. Now measure the center to center distance between the wrist pin ends, and it's 21mm (the offset between cylinders). Now find the difference between these measurements. This is the "net" rod offset (or actually double the net rod offset, because we're measuring across two rods.)

Where things got confused, the initial measurements quoted by Argo by way of Ed "looked" like they were supposed to be the net rod offset, but Sean (Argo) had misread a table.

The 2nd set of measurements, where he's talking about the .4125" are where he's explaining (his way) the same thing I just did above. Easy to understand if you have two rods in front of you; difficult if you're trying to explain with words.

Toyota could have avoided all this by making the big ends of these rods wide enough to provide all the offset necessary, however that would have made the rods heavier, the journals wider, then we wouldn't have had mains as beefy as we do, etc. All in all, a very clever solution, and very typical of Toyota!

John

 

[bango]

We must thanks ed and cribbj for making these things clear,things u learn from true forums guru's....ed ,are u sure you wern't fighting at the gates of Troy? Your persistance for the truth is amazing..cheers

 

[Zuffen]

Whilst not the clearest of photos this shows the offset quite clearly.

I was rushing around with too many things to do in the last day before my trip and should have taken the time to have a decent look.

 

[ed_ma61]

cha-CHING !!

thanks for the pic, rod

ed

 

[bango]

Good to see you back Rod,with all bods waiting for the rods to be shod ...err..