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Spitfire Crank Journal Size for Spitfires

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UmmYeahOk

UmmYeahOk

Jedi Warrior
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So the machinists has my block and my crank, and swears that the mains are .010 under, but when I called the 3rd party that I gave these things to, their engine guy who spoke with the machine shop kept referring to my GT6 crank/block as a "spitfire" crank/block even though I kept correcting him several times.

Since Im sick and tired of calling them to see what they THINK the original specs were, I was wondering if someone could tell me what the size would be if it were a 4 cylinder spitfire. The only thing I can find is one thread where the owner speaks of 2.31 mains and 1.875 rods
https://speedtalk.com/forum/viewtopic.php?f=1&t=6898

If this is true, it would explain EVERYTHING. But I need to know for sure before I start calling again.
 
I can say that those figures you quoted appear correct for a stock 1500 crank. As I understand it the late 1300 might be the same as that and the early 1300 was smaller. I'm not sure about the 1147.

I pulled out my factory manual for my Mk1 GT6. It says the standard main bearing journal will be 2.001/2.0005 and the rod journals will be 1.8755/1.875

You'll note the main journals are quite a bit different. That may explain the problem you had with the first block/crank.
 
dklawson said:
I can say that those figures you quoted appear correct for a stock 1500 crank. As I understand it the late 1300 might be the same as that and the early 1300 was smaller. I'm not sure about the 1147.

I pulled out my factory manual for my Mk1 GT6. It says the standard main bearing journal will be 2.001/2.0005 and the rod journals will be 1.8755/1.875

You'll note the main journals are quite a bit different. That may explain the problem you had with the first block/crank.
Click to expand...

Thanks. Actually my replacement crank/block is 2.00. Im guessing that pre KC5000 engines had 2" mains, and post KC5000 engines had 2.30 mains. For them to say the stock 2.30 is truly .010 under, that would mean they assumed that whatever they were looking at was 2.31 without measuring first. But they wont tell me that. All I can get from them it its .010 even after sending it back.

The tag on the crank had "triumph" written on it, not "triumph gt6" or "triumph spitfire" Just "triumph." The question is who is responsible for assuming that it was a spitfire crank.
 
Ok now I need to know if post KC5000 GT6 engines have the same size journals as the vitesse, TR6 and others. I can't even find where I got 2.30. All I know is the haynes says 2" which are pre KC5000. My husband found this:
https://www.tr-register.co.uk/forums/index.php?showtopic=6146

Are the cranks the same in TR6es vitesses and other 6 cylinder triumphs? I found this link which claims they are.
https://www.teglerizer.com/triumphstuff/spit_and_gt6_specs.htm

also found this:

https://www.british-cars.net/mg-midget-sp...22103913152.htm

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]In 1968 Triumph became part of BLMC who were intent on cost saving such that in 1970 a major revision was made to the engine with the release of the Spitfire MkIV. It is this revision that would become the Achilles Heel of the later engines. The change centred primarily around the crankshaft. In order to rationalise machining operations the journal diameters were increased to the same size as those on the 6-cylinder engine (as fitted to the Vitesse, GT6 and TR5/6). Journal diameters increased from 2.0005ā€ - 2.0010ā€ to 2.3115ā€ - 2.2120ā€ (main bearing journals) and from 1.625ā€ - 1.6255ā€ to 1.875ā€ - 1.8755ā€ (crankpin journals). In doing so this made the crankshaft heavier with larger diameter but narrower bearings. Thus the later 1296cc crankshafts have more bearing drag than the early ā€˜small bearingā€™ cranks and, with the increased weight, take more power to accelerate.[/QUOTE]

I have no idea what my 1967 post KC5000 crank dimensions are supposed to be. All I know is it's not 2" and their "engine guy" who kept refering it to a spitfire kept saying that they're 10 under and the bearings are wrong, and the machinist can get me the correct bearings. 1) would Victoria British sell me bad bearings? They were backordered and came out of Israel. And how will new bearings prove anything if all four main caps are broken?

-------EDIT--------
I read that County/King bearrings are made in Israel, and that VB often uses them as a supplier. I also heard VERY bad things about them but nothing explaining why I shouldn't use them. Just a bunch of "they're crap don't buy." Could the machinis be right and my bearring are wrong? Seems like this would be common enough for me to find people stating the same issues.
 
was this same issue discussed months ago? I would get my block and crank and go somewhere else if the guy doesnt know the difference between a 4 and 6 cylinder engine what makes you think he can read mics!
 
Call me at the shop tommorow (I'm a t home now), and I'll give you all the specs straight out of the vandervell bearing book. 864-370-3000

Cranksahft jouranls
Rod and main housing bores
Std. rod and main bearing shell thickness

That will give you everything you need to spec clearnce to the machinist.

Here's a quick clearence formula for the roads and mains

Housing bore - bearing shell thickness x 2 - crankshaft journal = clearence

The shop manuals only give you crank jouranl sizes, but call me and I'll give you the whole shooting match. Pretty much all the specs on all these engines have .0005" spec range for journal sizes and housing bores.
 
I had an odd revelation just now in reviewing this topic and factory literature pertinent to same: the Factory Workshop Manual for the GT6/Vitesse 2L is, well, wrong. Not totally wrong, but the spec's it gives for the main and rod bearing and journal sizes are all for the early (as in <KC5000) engines!

By all means, let Hap confirm or contradict the numbers I'm about to give you, as I suspect the Vandervell book will be more reliable here. But here is some main bearing info* for the TR250, which uses the same connecting rods as the >KC5000 GT6 engine (note the stroke is longer, though, on the TR250/6):

Main journal diameter -- 2.4790 to 2.4795 in.
Main bearing wall thickness -- 0.0720 to 0.07225 in.
Main bearing housing diameter -- 2.6250 to 2.6255 in.
Main bearing clearance
-- Manufacturing -- 0.0015 to 0.0025 in.
-- Wear limit -- 0.0031 in.

Edit:

*Data taken from <span style="font-style: italic">Leyland Repair Operation Manual; Triumph TR4 - TR4A - TR250 - TR5 - TR6</span>
 
Ok, here's what I have right out of the bearing book

(Standard Motor Co./Triumph) GT6 Mks I II III
1998cc
2498cc

rod shaft size 1.8750"-1.8755"
rod housing bore 2.0210"-2.0215"
STD. bearing shell thickness .072"

Main shaft size 2.3110"-2.3115"
main housing bore 2.4570"-2.4575"
STD. main bearing shell thickness.072"

Remember if you are measuring bearing shell thickness for clearnece purposes, then it needs to be done with a ball mic, and for the undersize bearings, half the undsize added to each bearing shell from standard thickness, say for example a .010" under size bearing you would add .005" to each bearing thickness, so a .010" under bearing shell would measure .072" + .005" = .077"


FWIW, both the Spitfire 1296 and 1500 large journal engines are exactly the same sizes at the GT6, the earlier small journal 1296 and 1147 engines had smaller numbers.

Hopes this helps.
 
Thanks Hap.

Ok so a 2.30 main IS ACTUALLY .010 off. So the idea that I was given the wrong numbers and a original size bearing was needed instead is incorrect, and the machinist was not at fault after all.

So my question is, what happened? All my broken main caps were numbered and placed in order. I used .010 bearings that should have fit. I know this because I accidentally got them for the smaller crank and it's obvious that those don't fit. These looked like it fits when placed, but when torqued down, the sides get smashed outward while the bottom doesn't get touched at all. Our plastigauge never was flattened or even touched.

The bearings, ordered through VB, came out of Israel, and are not the highly sought out after vandervell. There was no name on the package other than the words "made in Israel" and the VB part number sticker. I have not heard of anything negative about these bearrings other than that they may not last as long as the vandervells. This means that out if all the negative comments no one has said anything about having the same issue as me. Could such an incident occur if installed in the correct order but facing backwards? Could something else have gone wrong? This happened in Feburary so I dont exactly remember everything exactly.

Guess I'll just ask for everything back and have it take up garage space.
 
OK, lots of info there, first thing I would do is cheack the main housing bores, this has to be done with a bore gauge with the main caps torqued down and no bearings installed. Then measure the shaft, then the bearing sheel thickenss, the crank should have good filet radiuses where the edges of the journal rolls back into the crank body, if not, you had crank ground by DA (for the lack of better words) The acutal .010" under main journal spec range would be 2.3010" - 2.3015", a good crank man will hit your numbers +/- .0001" , or least my guys do, Spartan Crankshaft in Spartanburg, SC, all they do is cranks and they are excellent.

Clearence is all follows:

Housing bore - bearing shell thickness x 2 - shaft size

I don't know what clearnces you are aiming for I normally build street engines to .0015" rod and mains.

You mentioned Israel made bearing, King is in Israel, Where you bought your parts probably sells the the King bi metal bearings, and I would prefer the King tri metal bearings I get them from BPNW ( a supporting vendor here) and nice knowledgable guys. OK, without without calling out company names here, I like to order parts from people I can actually ask a question to and they either know or find out for me, not a generic order taker who knows nothing of my car, That why I do business with BPNW, and not where you bought your parts, I also like the fact I have quality choices as well, which you can't get from where you bought, take that for whatever worth you see in it.
 
So are you saying that they could possibly be bad bearings after all? That was the "excuse" that they were told. I went into great detail in another thread months ago, so forgive me if I repeat anything you may have heard. The shop I took it to specializes in modern mustang performance, so I dont expect them to know what a GT6 is. All I wanted was a recommendation but they offered to send it to a machinist they use all the time, since all they do is machine work, again, not a triumph specialist. So I assumed this was a generic "excuse" given to place blame somewhere else, but perhaps it could be true?

Didnt realize there was math involved. I come from the plug-and-play generation where everything is supposed to be simple and handed to you :smile: I assumed that if .010 bearings dont fit a 2.30 main, nothing will. Whats a "DA?" Using a micrometer the mains measured:
2.3005
2.300
2.301
2.2995

Using your formula, would the crank need to be turned more? or the housing trimmed? I cant imagine sanding the bearings down. .0015 would be fine, I want this car to be able to be daily driven someday.

The other thing is, with all the main caps cracked, could the main housing bores be measured correctly? Also how many torque lbs? I think the haynes says 50-55ft/lb, but I just wanted to make sure.

Its a shame youre not in texas. If someone in my situation came to your shop, how much would you charge to make and/or line bore new main caps? And if thats not something you do, how much would you think something like that would cost?

Thanks again.
 
OK, it could be your micrometor measurements, if don't use one alot, then your numbers can vary, it's a touchy-feely type thing that take some doing to get use to. If your measurmant are corect, then only one of your journals is in the .010" spec range and the rest runnng for .0005" to .0015" out of range, which is not good, crank work is done in increments of tenths of thousads of inches, so half thousands here or 1 thousands there ain't gonna cut it.

Ok, I heard you mentioned you had broken main caps. I guessing you had to get a replacement set of main caps, correct? OK with that being said, I'm going to throw out a crazy question, did you get the block line bored/honed when you use the the new repalcment main caps ? If you introduced different main caps to a block that did not come on that engine from the factory, then you absolutely have to line bore/hone the block, no ifs, ands or butts, you have to do this. You can't just introduce another main cap to the block, they are machined bolted down in place, and no two would exactly alike from one engine to the next.
 
Hap Waldrop said:
OK, it could be your micrometor measurements, if don't use one alot, then your numbers can vary, it's a touchy-felley time thing that take some doing to et use to. If your measurmant are corect, then only one of your journal is in the .010" spec range and the rest runnng for .0005" to .0015" out of range, which is not good, crank work is done in incrments of tenths of thousads of inches, so half thusands here or 1 thousands there ain't gonna cut it.
Click to expand...

How come only one is in that range? I assume that 2.30 + .010 = 2.31 (the desired spec) right? So the machinist WAS wrong? These are NOT .010? Or are you saying that they are, theres just no room for oil/plastigauge? With what the bearings did, its almost as if there wasnt even room for half the bearing

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Ok, I heard you mentioned you had broken main caps. I guessing you had to get a replacement set of main caps, correct? OK with that being said, I'm going to throw out a crazy question, did you get the block line bored/honed when you use the the new repalcment main caps ? If you introduced different main caps to a block that did not come on that engine from the factory, then you absolutely have to line bore/hone the block, no ifs, ands or butts, you have to do this. YOu can't just intorduce anyoehr main cap to the block, they are machined bolted down in place, and no tow would exactly alike form one engine to the next. [/QUOTE]

I have not yet gotten new main caps. I was lucky enough (thanks to a member here) to find a FREE local engine (pre KC5000). This is one of the reason I have been putting things off (well other than I hate dealing with the poor communication of the shop) If I could prove that the machinist was at fault, then maybe I could get them to correct the problem, including new main caps, for free, or at least refund my money for the crank I cant use. Since this is a numbers matching engine, a 67, and, from what Im told, an extremely rare car, this engines value is priceless, and should be corrected if its their fault. But if its mine, then it will just have to sit somewhere for years, decades, new owner, whatever, in hopes that it will get new line bored main caps someday and go back in the original car.
 
I hate to say this to you, but I think I think it needs to be said, you are looking for someone to blame for this, and so far in what I read here, that you have had to say, you seem to be the one that knows the least about all this, many things you had said, don't lend me to think you know alot about this type of job. I'm not trying to insult you, but thats what I take from all this.

For starters, when a crank is ground it is done to under the standard size, again not insulting you, but just think about it, how could on make some thing bigger by turning it down. Undersize bearings are thicker to accomondate the undersizing of the crank.

I done a little trainig experiment in my shop to prove the "skill" need to make acurate measurments with a micrometer, I put a crankshaft up in the lathe, a easy place to turn and hold to it for measuring. I give the apprentice/student a micrometer, and ask them to measure every journal, rods and mains, ten times and record their findings, the numbers will be all over the place, +/- .0015", I use this as tool to then teach them how to properly read, and use a mic. I have never had a student unfamilar with using mic pass this test initially, ever. Mind you all ts is done on freshly ground cranshaft that is my by measurments at +/- .0001"

Your machinist could be a fault, I'm saying they are not, but thus far you not convince me you know enough about all this to even make that judgement.

Look, I'll say this again, I'm not trying to insult you in anyway, anyone who knows me, knows I call em, the way I see em. Not trying to make you mad, just trying to help you find your problem. I suggest you get a second source (a machinist) to measure your crank.

We all have to learn, but we all need a little help and proper instruction to get there.
 
Just to let you know, this is my car, but my husband was the one who installed the bearings. So you're right, I dont know everything. We did measure it several times with the micrometer. But if we're dealing with thousandths and ten thousandths of an inch. I wouldnt think it would make a big difference. I understand that a .010 bearing would naturally be thicker than an original size bearing.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Pretty much all the specs on all these engines have .0005" spec range for journal sizes and housing bores. [/QUOTE] So the ideal size would be 2.3010"-2.3015" if .010, right? I realize that you can get several different readings from a micrometer, but we did measure several different times and pretty much got 2.30" with the occasional thousandths and ten thousandths difference that was posted. It seems that for all the caps to break like that, there would need to be a much bigger error in measurement than +/- .0015"

Where can I get an affordable ball mic? Because I dont think I will ever get any specs from anyone whos touched my crank unless I get my own engine back and do it myself. And why should they? They could at least lie to me and give me fake specs. This is why we try to do everything ourselves. Anytime we get someone else to touch our cars, they mess things up. Things get broken. I mean I cant even get an oil change without something going wrong. Youd think places that do such things all day long would have it mastered, but no. You know that Ive been to 3 different muffler shops, in 3 different towns, and each one Ive had an issue with? Thankfully the last only required me to rebolt something. But still, it should have lasted 20 miles. Sorry for the rant, but man, we just dont have any lucky with anyone. And when I say we, I mean my whole family tree.
 
Enco Tool should have a ball mic that is not terribly expensive, FWIW I never seen a labled bearing be anyhting but waht it was represented to be in 25 years of building LBC engine for street and race.

Here's my skinny on crank grinding, it's artform, not something any ole machinist can do, most are butchers at it. I seen alot of crappy crank grinding over the years, +/- .005", my crank guy, thats all his does is cranks, will hit my blueprint numbers to +/- .0001". The second issue with crank grinders is if they put a nice filte radiu on the edge of the journal, I seen every chciken crap attempt at doing wrong you could every see, them maing several stop to give the illsuion of a radiu, but al they have to do is dress the wheel proper for a good radius. Every, read that again, every cracked crank I ever magnafluxed was a crank that had been turned by a machinist who did not do a proper filet radius, and that is almost the only palce a crank will crack, they crack ecause of their shotty work.

OK with that being said, you still need to get someone more expereinced than you all to measure the crank, you may be right on the money, but a second opinion will not hurt.
 
you might have to put your block on a palet and ship it off to someone that actually works on British cars, maybe send it to Hap in Greenville SC, or Bob Mason in Rhode Island, Roadster Factory does engine work too, but I am not endorsing anyone, since I have not had an engine rebuild, (yet) Got all my parts now. thats why I will pay the shipping cost and send mine off, and you are right there are very few machinest comming out of school that know what they are doing and the ones that know what they are doing, or knew how to do it are retired or 6 feet under, guys comming out of schools now want to sit behind a computer to work, Sad state of affairs in the good old USA

my 2 cents worth

Hondo
 
Maybe a trip to Kip Motors in the Dallas area would be worth while, aleast Kip could recommend a good machinist, but I'm still not getting the cracked main cap deal, that would take some effort to do, was the crank binding once torqued down with bearings and it was forced to turn over by hand, was the main caps installed in the correct orientation, sorry it's just not all adding up for me, lots of gaps in the info. What was the markings on the bearings? Did I understand it to be all of the main caps or just one?

I don't mean any harm, but I wouldn't touch this job with ten foot pole, these folks are upeset with the machinist who did the work, maybe he is at fault, maybe not. The arse job you can put yourself in is following someoen else's mistake. Plus i got a TR6 motor here now that was fully built by British car shop and never got over 15 psi, I would have never took that job, had it not been I knew the guy's brother and met this guy and he seemed level headed and willing to let me try to fic this motor, all I can hope for is that I find the smoking gun, but after talking to the guy that built, that no idea what the clearence were, I'm sure I'll find the problem.
 
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