11 replies to this topic

[n00b]

Hi all, slowly doing this engine rebuild, I bought the engine in bits (block, head and a million bits) Which way does the bottom half of the con rod go? Im thinking it goes like the one in picture 1.Thanks! ERic

Pic 1 -  DSC00024.JPG   770.7K   9 downloads

Pic 2 -  DSC00025.JPG   647.88K   7 downloads

[Ethel]

Hi all, slowly doing this engine rebuild, I bought the engine in bits (block, head and a million bits) Which way does the bottom half of the con rod go? Im thinking it goes like the one in picture 1.Thanks! ERic

Pic 1 -  DSC00024.JPG   770.7K   9 downloads

Pic 2 -  DSC00025.JPG   647.88K   7 downloads

Don't quite see what you're getting at it should only go one way to line the shell bearings up.

Were the rods assembled so you know which caps go with which rods, very likely they're stamped so you know which belong together and to which cylinder.

It would be worth getting the bores and bearings measured to make sure they are still within the working tolerances.

[Sprocket]

The tangs of the bearings go on the same side

[JetBLICK]

pic two. Those little notches both go on the same side. That said tho, you want to be careful if you've been jumbling and swapping the end caps, its not really good practice.

[n00b]

ok thanks for a quick reply, my first engine rebuild, so it wont be 100% up to your standards....We live and learn! Eric

[Sprocket]

you want to be careful if you've been jumbling and swapping the end caps, its not really good practice.

Its not good practice?Its not a practice at all!! it just wont work!! Dont do it!!

[JetBLICK]

U can get em honed tho cant u.... tho, then u'd need specially made bearings... Yea... just dont do it

[n00b]

ok.. sorry...

[Sprocket]

U can get em honed tho cant u.... tho, then u'd need specially made bearings... Yea... just dont do it

Honing the big ends entails having aproximately 1 or 2 thou machined off the cap, the boring bar is then aligned with the half in the rod, thus on removing metal from the cap only. This will bring them all back into alignment. Its not cheap!

You can usualy see, with a good eye, which cap goes with which rod, the hone marks on the rods journals will match, there is also usualy a fairly rough cut on the thrust faces of the big end, again these marks should line up perfectly.

You need a good eye though

Edited by Mini Sprocket, 23 September 2007 - 06:50 PM.

[n00b]

ok thank you!

[sixwheeler]

If the caps on the con rods have been mixed-up then have a good look and see if there was any identifying marks so that you can match them back up.

Failing that then see if you can get them measured (you will need a dial gauge where the legs stick out at 90 degrees) to see if you can match them up that way.

Failing that, then when you come to rebuild the engine, BEFORE you put the pistons into the bore, put the new shells into place and bolt the rods onto the crank (make sure that you tighten the nuts/bolts) - so they are hanging out of the bottom of the engine - and check that they all move freely around the journal. If you find a tight one then move the caps around until they are all moving freely. Bit hit and miss and not entirely recommended....

The conrod and the cap come as a matched pair as they are line bored during manufacure - hence the reason for not mixing them up!

[n00b]

Thank you for your help! And by the way i wasnt the one who mixed them up! The guy i baught the engine from had already stripped the engine and thus just thrown them into a box without marking them Rhubarbs! Thanks ERic