General Torque figure for Scat H beams - VW Forum - VZi, Europe's largest VW, community and sales
 
Machine 7, high quality air-cooled  restoration and performance parts

     
 

Go Back   VW Forum - VZi, Europe's largest VW, community and sales > Tech Forums > Aircooled Mechanical Tech

Aircooled Mechanical Tech A Q & A Forum devoted to Aircooled Mechanical Issues. Got a problem? Then ask in here. Please, no 'For Sale' or 'Want To Buy' ads, plugs for your 'business', links to 'for sale' ads or Ebay links to your (or your mate's) auction (use the VZi 'Classifieds' section) - this also includes thinly veiled 'What's My Car Worth?' threads and "Who Can Sell Me A . . ." posts.

Machine 7, high quality air-cooled  restoration and performance parts
Reply Post New Thread
 
Thread Tools Display Modes
Old 15-01-2020, 11:46 AM   #1
farmer rob
Chat Slapper

Trading feedback: (2)
 
Join Date: Nov 2010
Location: northants
Posts: 234
Default Torque figure for Scat H beams

Hi guys, could someone confirm the torque figure for a set of Scat H beams with 3/8" ARP 2000 rod bolts, Heritage site say's 48lbs/ft. Just wanted to check!

Many thanks Rob
farmer rob is offline   Reply With Quote
Old 15-01-2020, 04:12 PM   #2
HOT 1200
Seasoned Chat Slut

Trading feedback: (0)
 
Join Date: May 2004
Location: Sunrise Coast, Norfolk
Posts: 1,787
Default

We use the same bolts on our race engine.....
Here's what I do, never had a rod bolt failure

Assemble the rods (Dont put them on the crank) and just run the bolts by hand in to the rods, 'feeling' for any tight spots...if they spin in by hand and bottom out on the collar of the nut, you are good to go....
Fit your bearings checking they are the right size, the tab snugs into the lug of the caps and push down at either end of the bearing NOT in the middle (doing this pushes the bearing out of round)
Remember to align each bearing number so cap matchs the rod...and numbers always face up (do not align any logos unless instructed to do so) This is because the rods are 'offset' for the power stroke...for quiet/smooth operation.
Now I suspect they came with a little packet of lube....
I ditch the lube and use a good thread lock (this will act as a lube but also the rod bolts stay put - a bit of insurance)
(That's only what I do....you may want to use the lube, your call)

Torque them up in stages.....7ft...15....25...35......45 and then the final step upto 48........make sure you use a soft hammer between each torque stage tap sides and back of the rod cap (doing this removes stress from the rod cap) and rotate the rod 360deg between each torque.....STOP if the rod goes tight on the crank...back things off and check whats going on.
Once all torqued up...let them rest and check your rod side to side endfloat.

These rod bolts can take much more torque but at 48ft pounds locked in, they are not going anywhere....exceed this and they are stretched to near there max and could let go under severe conditions......so no point in stressing the bolt (and the cap) right up to its limits.....
Go with what the makers suggest, for example CB H beam rods with ARP 2000 bolts only torque to 29ft (remember the rod bolt AND the cap have to be able to withstand the higher torque specs so do not get carried away)

Again, this is only what I do and to date we have never broken the race car bottom end..........
__________________
Anyone can make a big engine go fast!
But only a few know how to make a lil engine go faster!
1192cc 20.4 sec 1/4 mile on single solex 28 !

Last edited by HOT 1200; 16-01-2020 at 02:50 PM..
HOT 1200 is offline   Reply With Quote
Old 15-01-2020, 07:56 PM   #3
farmer rob
Chat Slapper

Trading feedback: (2)
 
Join Date: Nov 2010
Location: northants
Posts: 234
Default

Thank you for your very detailed reply. I have got new old stock without fitting instructions or lube but I think I am all good now.

Thanks Rob
farmer rob is offline   Reply With Quote
 
Old 15-01-2020, 10:56 PM   #4
ainokea
Chat Slapper

Trading feedback: (0)
 
Join Date: Nov 2012
Location: Honolulu, Hawaii
Posts: 427
Default

The Uni Tech chromoly rods I got from C.B. in 2007 torqued to 45 lbs. Still all good today.
ainokea is offline   Reply With Quote
Old 16-01-2020, 01:19 AM   #5
vw60
Chat Slapper
 
vw60's Avatar

Trading feedback: (0)
 
Join Date: Mar 2011
Location: Pomona Queensland, Australia
Posts: 410
Default

Quote:
Originally Posted by farmer rob View Post
Thank you for your very detailed reply. I have got new old stock without fitting instructions or lube but I think I am all good now.

Thanks Rob
Do not use loctite on the bolts as it is not a lubricant as the lube supplied will achieve the correct clamping force when torqued to the specification, without it you will achieve the torques setting without the clamping force as it is lost in the friction generated when using the loctite, I have done this type of work for years in oil and gas were the coefficient of friction of the lubricant is taken into account in the toque setting, my 2276 with the same rods has been on the road for years. The other method is to measure the bolt stretch, the correct way of doing it. I think that is about .003", that method avoid the influence of the lubricant.
vw60 is offline   Reply With Quote
Old 16-01-2020, 02:45 PM   #6
HOT 1200
Seasoned Chat Slut

Trading feedback: (0)
 
Join Date: May 2004
Location: Sunrise Coast, Norfolk
Posts: 1,787
Default

we used to measure bolt stretch....but once you find out that not every bolt is the exactly the same length in each kit its starts to get a time consuming ball ache with the dial gauge. Go with the instructions or.......experience and whatever works for you.....for me.....35 years of building these little screamers and you tend to have your own unique way of doing things......
The main thing...don't rush.....and make sure you use a good calibrated torque wrench.....unless you are running a turbo or revving to the moon and back..those bolts wont let go......in the 80's we ran with stock rods n bolts.....(balanced) and it all stayed together....the first rod failures appeared when the turbo boys arrived on the scene....and yes it was the rod BOLT that was letting go....not the rod.
__________________
Anyone can make a big engine go fast!
But only a few know how to make a lil engine go faster!
1192cc 20.4 sec 1/4 mile on single solex 28 !
HOT 1200 is offline   Reply With Quote
Old 16-01-2020, 02:51 PM   #7
HOT 1200
Seasoned Chat Slut

Trading feedback: (0)
 
Join Date: May 2004
Location: Sunrise Coast, Norfolk
Posts: 1,787
Default

Quote:
Originally Posted by ainokea View Post
The Uni Tech chromoly rods I got from C.B. in 2007 torqued to 45 lbs. Still all good today.
Sorry I meant to say CB H Beam rods, they torque to 29ft...as the subject was about H beams....
__________________
Anyone can make a big engine go fast!
But only a few know how to make a lil engine go faster!
1192cc 20.4 sec 1/4 mile on single solex 28 !
HOT 1200 is offline   Reply With Quote
Old 16-01-2020, 10:51 PM   #8
farmer rob
Chat Slapper

Trading feedback: (2)
 
Join Date: Nov 2010
Location: northants
Posts: 234
Default

Thanks for all the reply's and help guys

Rob
farmer rob is offline   Reply With Quote
Reply Post New Thread

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 08:51 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.

Disclaimer: For recreational purposes only, some assembly required. Any resemblance to real persons,
living or dead is purely intentional and the site admins are not responsible for direct, indirect,
incidental or consequential ridicule resulting from any defect or failure to perform. No animals
were harmed in the creation of this forum. Colours may fade over time. No other warranty expressed or implied.

volkszone.com

SupportingSupporting Brad's Cancer Foundation

 










 
© Volkszone • Terms and Conditions of use



volkszone.com is an independent Volkswagen enthusiast website owned and operated by VerticalScope Inc. Content on volkszone.com is generated by its users. volkszone.com is not in any way affiliated with Volkswagen AG.