Marty_Cutler Posted January 10, 2008 Share Posted January 10, 2008 Hi all,I am rebuilding my 1925 tourer after breaking a crank. I am setting up the mains and big ends. The shims I have are all 3 thou. What should the clearance be for the mains and big ends. I am doing a crank & rod swap from a spare motor, keeping the same pistons. I have already pressed out and replaced the little and bushes, and am up to the mains on the crank.CheersMarty in Sydney, Oz Link to comment Share on other sites More sharing options...
brian1925tourer Posted January 10, 2008 Share Posted January 10, 2008 better stop there.have you measured the crank bearing areas.could be out of round. may need a grind and new bearings. Link to comment Share on other sites More sharing options...
Marty_Cutler Posted January 11, 2008 Author Share Posted January 11, 2008 Hi Brian,I don't have the funds to have the motor professionally rebuilt. The journals and bearings from my spare motor all look in very good condition, so I have no qualms about swapping them over. A new white metal bearing poured by a professional in Sydney is $250, there are 7 of them. Plus the cost of grinding, etc, etc. I am more than happy to swap these over and get the old girl back on the road again. The only reason the spare motor came off the road was it was smokey, so bottom end is fine. My top end is fine, so swap them around to get a result. This way I keep my original engine number as well.I have set them up so that they are tight to turn by hand, then add 1 shim, so clearance at this should be 1 1/2 thou. I will be checking this with flexi guage, but I need to know if that is enough clearance for white metal bearings.CheersMarty Link to comment Share on other sites More sharing options...
dwollam Posted January 11, 2008 Share Posted January 11, 2008 That's just about the way I did mine. Worked fine for these low rpm engines Link to comment Share on other sites More sharing options...
brian1925tourer Posted January 12, 2008 Share Posted January 12, 2008 i hear where your coming from. i had my motor done by very experienced mechanic in melbourne and it cost me $1800 for grind and bearings. $3200 all up with rebore and pistons. however a very good job that should last. now my book says 1 1/2 thou. but you need 3 thou. so i'm told.you may need some bearing blue to see where bearings are touching. if you do decide to rebore my pistons came from jp pistons in adelaide. i don't have their number but could find it if needed. there's a man called cled davies in bendigo who sells bits too 0419 581 854. happy to give advice. ballarat swap meet coming up soon 23feb? it is huge. heaps old bits. Link to comment Share on other sites More sharing options...
Marty_Cutler Posted January 12, 2008 Author Share Posted January 12, 2008 Hi Brian,My dad had the motor rebuilt by a supposed "expert' in 1990, the car has probably done less than 5000 miles since then. It's got jp pistons, they are fine, the problem was, after dissassembly, that this expert had ground the crank and left no radius in the corners of the big ends. The crank broke right on the front of #1 big end journal. Also, the white metal job that this expert did was starting to break up, so I would rather run with the spare stuff I have, than trust another expert to empty my bank account. I know enough to get myself into, and hopefully, out of trouble. If I have bearing knocks or rumbles when it is back together, then I will defer to the experts, but at this present time I would rather trust my own engineering skills. I will run with 1 1/2 thou after checking it with flexi gauge.CheersMarty Link to comment Share on other sites More sharing options...
brian1925tourer Posted January 13, 2008 Share Posted January 13, 2008 unfortunately there are many people who call themselves experts, and they may build engines everyday, but not this type, so they slap it together most likely even do it heaps cheaper but keep your fingers crossed if it lasts. my expert only deals with this vintage stuff, however only time will tell. there's no reason if your careful that your motor should not give many years service. my crank had .012thou out of round so it was not wise to put it back as is. Link to comment Share on other sites More sharing options...
mrgearhead1 Posted January 13, 2008 Share Posted January 13, 2008 Martythe range for rods and mains is .002 to .0015. you are right about to so called experts. I too got bit. not only did he bore the mains crooked but the center manin was higher then the front and rear. In defence of the chap who had his engine done the good ones will give you names of customers and allow you to call and ask questions. my freind just had his 1911 buick rebiult and it was to top notch job and runs like a champ.by the way I did the bottom end of my 23 screenside 17 years ago and it is still not the road today.cheers Reuel Link to comment Share on other sites More sharing options...
Guest clare30 Posted January 13, 2008 Share Posted January 13, 2008 G'day mate,Try Bob Croft down in Kiama NSW. Link to comment Share on other sites More sharing options...
Marty_Cutler Posted January 18, 2008 Author Share Posted January 18, 2008 Thanks Mr Gearhead1, that confirms my thoughts. Gidday Clare30, I have heard of a bloke down at Kiama through a mate who has Fords A's & T's, if it is the same bloke, he is very knowledgable on Henrys, but from what I've heard, no good on DB's. I really do want to do this myself, apart from the cost factor, the satisfaction of doing the job right is strong. I have the help of several mates who are engineers, mechanics, etc, so now that I know the specs, the rest should be plain sailing. CheersMarty Link to comment Share on other sites More sharing options...
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