Yes.
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| Engine size query? 1071? https://www.ausmini.com/forums/viewtopic.php?f=2&t=68756 |
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| Author: | austinseven [ Tue Feb 08, 2011 6:20 pm ] |
| Post subject: | Engine size query? 1071? |
Hi, I have just aquired a new engine and was wondering any simple ways of identifying what size the engine is. There is no engine number plate on the top the block. I was told that the engine was a 1071. The engine was running a big bore head and it had exposed tappet covers on the side of the block so I assumed it was a 1071. However when I pulled the head off I noticed that it was a small bore block with 20" oversize pistons in it(bore approx 65mm). The block had been pocketed to except the big bore head. Is there any way that a small bore block could be modified to run a 1071 crank if somebody was really motivated to use the crank and didnt have access to a big bore block? If it is a 998 or 1098 crank which is probably the case is there any way to check without pulling the engine apart? Any advice would be greatly appreciated. Thanks, Scott. |
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| Author: | mini_mad_matt [ Tue Feb 08, 2011 6:27 pm ] |
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Seeing as you have the head off, measure the stroke and someone should be able to tell you what crank it sounds like. |
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| Author: | austinseven [ Tue Feb 08, 2011 6:33 pm ] |
| Post subject: | |
Thanks for the reply. Do I measure the stroke by measuring the distance the piston travels up and down the bore? |
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| Author: | jb007 [ Tue Feb 08, 2011 6:41 pm ] |
| Post subject: | |
Yes.
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| Author: | drmini in aust [ Tue Feb 08, 2011 6:52 pm ] |
| Post subject: | |
68.26mm = 850 crank (or a 1071S, but I doubt it in a smallbore block). 76.2mm = 998 crank 83.7mm = 1098 crank. The main bearing bolts on a smallbore block are too close together to fit a 1071 (or 1275) crank, which both have 2" main bearings. All smallbore cranks are 1.75" mains. Most likely you just have a 998 or 1098 with a 1275 head stuck on it. Pretty common mod, ever since 1275s came out. I did mine in 1968. |
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| Author: | austinseven [ Tue Feb 08, 2011 7:04 pm ] |
| Post subject: | |
Thanks for the replys I will check the measurement. One more question. When I pulled the head off I noticed that some of the pushrods looked slightly bent especially number 4 which was very bent. I checked the Valve lift and the clearance on the cutouts on the block and they appear to be fine. Could the Valves have hit the pistons, is this possible? I believe the cam is a 649, but with 328" lift not 315" ground by Kelford cams in CHCH in about 1980 and it is using standard rockers. |
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| Author: | drmini in aust [ Tue Feb 08, 2011 7:07 pm ] |
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More likely it has the wrong valve springs, and they are getting coilbound at full lift. Max valve lift happens when pistons are about 1/2 way down the bore.. so unlikely to hit valves unless really thrashed. |
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| Author: | austinseven [ Tue Feb 08, 2011 7:21 pm ] |
| Post subject: | |
Using my vernier callipers from the top of the block (which the pistons are flush) the measurement comes in at 82mm. Just to double check, Does this measurement confirm that it is an 1100? Thanks Scott |
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| Author: | drmini in aust [ Tue Feb 08, 2011 8:12 pm ] |
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Allowing for measurement errors it's more than likely a 1098. 1132 actually, with +.020" pistons. |
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| Author: | mini_mad_matt [ Tue Feb 08, 2011 8:17 pm ] |
| Post subject: | |
If you think the pushrods look bent, find a smooth, flat surface (bench, concrete floor etc) and roll the pushrod across it and you should be able to tell more clearly then just looking at it wether its bent as you will see it wobble. |
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| Author: | austinseven [ Tue Feb 08, 2011 8:36 pm ] |
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Thanks for all the advice Scott |
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| Author: | graham in aus [ Wed Feb 09, 2011 11:48 am ] |
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This motor sounds like some sort of a Mini Se7en racing cast off! They still race Mini Se7en in NZ I believe!
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| Author: | austinseven [ Wed Feb 09, 2011 4:46 pm ] |
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The engine was built to use as a race engine in about 1980. The owner didnt end up using it and it has been sitting around for 30 years. I got it started the other day and it sounded really good. However when I took the car for a drive the engine dropped down to 3 cylinders. Valve number 4 was stuck half open and I pulled the rocker cover off and noticed that it had far to much valve clearance so I pulled the head off to discover the pushrod was badly bent. I am just trying a few things to see if I can fix the problem as it sounded like the engine would be a bit of fun. I will check if the valve springs are binding and I am going to use some plastercine to see if the valves may be touching the pistons. I know that they probably shouldnt be but all of the pistons has been relieved or ground on the exhaust side so whoever built the engine thought that the valves could hit. Is the exhaust valve more likely to hit the piston than the inlet valve? I ask this because only the exhaust side of the pistons have been groundand not the inlet. |
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| Author: | drmini in aust [ Wed Feb 09, 2011 6:19 pm ] |
| Post subject: | |
The inlets won't hit the block, as they clear the bore. But the exhausts overhang, more so on a 1275 head as the valve centres are greater. `Notching the block' as yours has is a recognized procedure when fitting a 1275 head and a hi-lift cam, to a smallbore block. [edit] Maybe a valve was stuck in its guide after standing 30 years, that can bend a pushrod... 
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| Author: | 9/61 [ Thu Feb 10, 2011 12:24 pm ] |
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drmini in aust wrote: Allowing for measurement errors it's more than likely a 1098.
1132 actually, with +.020" pistons. 1114 +.020" Pistons 1132 +.040" Pistons just nit picking |
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