

| Subject: | Fwd: Boston Bob on Connecting Rod Bolts |
| From: | David Beierl |
| Date: | Mon, 6 Sep 2010 21:05:00 -0400 |
>Date: Mon, 4 Sep 2006 10:50:11 -0400 >Reply-To: ROBERT DONALDS <donalds1@VERIZON.NET> >Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com> >From: ROBERT DONALDS <donalds1@VERIZON.NET> >Subject: Re: Connecting Rod Bolts >Comments: To: Evan Mac Donald <macdonald1987@SBCGLOBAL.NET> >To: vanagon@GERRY.VANAGON.COM > >Evan >1.9 and 2.1 rods are the same casting and are interchangeable with the >exception of the bolt. The longer stroke 2.1 cranks in combination with the >1.9 rod bolts can but do not always hit the camshaft >The 2.1 rod bolt work well for 150K and I have seen these stretch to yield >bolts reused with failing. >2.1 rods distort over time by this I mean the big end is no longer round. >The cap shifts and the big end gets smaller opposite the parting line. >Another way to say that is if you draw a line down the rod from the small >end threw the beam of the rod threw the big end the circle is smaller at >that point. So just replacing the bolts is not the cure for the 2.1 rod >problem. The big end needs to be resized to do this I have a cap grinder it >trims a few thousandths off of the mating surfaces of both the rod and cap. >After deburing the hole and installing new non stretch to yield bolts and >reassembling the rod I torque the nuts and resize the big end with a sunnen >rod hone. Machine shops have spec books to provide dimensions for the >finished size. >I take the next step and that is to install rod bearings torque and measure >difference between the size of the ID of the big end with the bearing in >place The size of the rod journal this is clearance to the crankshaft. The >difference influences the warm oil pressure. >used rods with the 150K measure as much as .004ths bearing clearance this is >enough make oil light come on at an idle. My engines have a rod bearing >clearance of .0015ths. and I can say that because I have invested in the >right equipment to properly measure clearances and restore dementions. > >you CANT just replace the bolts unless you only want 6k out of the engine > >my rebuilt rods are $140 exchange with news bolts ready to install >Rebuilding is about restoring clearances >assembling is about adding parts >at Boston engine you get more than parts > >Bob Donalds >Boston Engine > >all rights reserved > > >----- Original Message ----- >From: "Evan Mac Donald" <macdonald1987@SBCGLOBAL.NET> >To: <vanagon@GERRY.VANAGON.COM> >Sent: Monday, September 04, 2006 8:51 AM >Subject: Connecting Rod Bolts > > >>I have heard that the bolts for 2.1 l con rods are not the greatest, and >>should be replaced on a rebuild with 1.9 l bolts. I don't have any 1.9 l >>engines around I could steal them out of, and would also worry about >>re-using "tired" bolts in an upgraded rebuild, anyway. >> Does any body have any suggestions? I haven't had much luck on my own, >>but I also have no idea what other bolts may be a usable substitute.
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