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21 Jun 2009, 06:47 (Ref:2487293) | #1 | ||
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Join Date: Jun 2009
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Running in a engine (MGC modified)
I have a engine being completed and need some advice on running in.
Its highly modified Forged CP pistons, forged rods , roller rockers , triple 45's etc, all balanced etc. Now apart from running good quality mineral oil to start with what else can i do to get it ready for full throttle runs. I have read Puma racing txt and its seems a fair way to do things. |
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21 Jun 2009, 08:00 (Ref:2487327) | #2 | ||
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If you have a flat tappet cam not a roller cam with roller followers (not rockers)then the cam is the most important bit to initially run in, read on some of the yank sites as they have plenty of info. A lot recommend removing one set of valve springs if using duals and adding a zinc additive to the oil for the initial run in period. Also it seems a lot advocate initially running the engine for 20 minutes at no less than 2000 rpm the argument being the higher revs splash lubes the camshaft, whether this relates to v8s only I dont know but I would say just take particular care with the flat tappet cam. As most road cars now have roller cams I think this is probably the reason plus tighter build tolerances that breaking in does not seem to be a prerequisit so much these days as it was in the past.
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21 Jun 2009, 08:22 (Ref:2487338) | #3 | |
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I'd add that bores and rings need to be run in.
I've been told by the various engine builders I have used over the years that this can only occur properly if there is load on the engine, so the car must be driven on the road or on a rolling road, or the engine run in on a dyno. On a Porsche engine from the same era as yours I was advised to use a 30 monograde mineral oil for the running in period, though on a '68 Ford engine I was advised to use Valvoline Racing 20/50. I was told that the engine needs some load, but not full load, using a range of engine speeds, not just a constant speed, and with a top rev limit of, say, 4000 rpm initially which you gradualy edge up to your red line over the equivalent of about 600-1000 road miles. Then change oil, filter, re-torque the head and check clearances etc etc and you should be good to go. |
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21 Jun 2009, 08:31 (Ref:2487342) | #4 | ||
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IMHO if you gap the rings correctly and fine hone the bores then they bed in very fast. In many cases what do you do? Its usually just impractical to run in a race engine unless you have a wad of cash and if you are paying a builder he should dyno it for you. Thats why I would concerntrate on that camshaft. This reminds me years ago some mate of mine bought a 4 cylinder Ford Kent from a 'professional' builder and it was so tight he had to tow it around the yard to start it, any race engine built like that will never bed in properly. I am building a 5800cc Chevy at the moment and have just dropped the crank in and the amount of torque required to turn it is so low its unmeasurable and thats how it should be. It won't be till I bolt the heads on and lash the valves will it be hard to turn such is the pressure the valve springs excert on the camshaft.
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21 Jun 2009, 15:44 (Ref:2487619) | #5 | ||
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Quote:
Maybe you can do it in a lap of Brands - I don't know for sure - but I have always followed my engine builders recommendations: Andy Prill in the case of the Porsche 912 engine, Tim Swadkin in the case of the Ford x-flow engine, Guy Croft in the case of my Lancia engine. I don't know what would have happened if I hadn't followed their advice, I can only say that following their advice did work. For what it's worth, I have also been told that the first 30 seconds of running will decide whether your cam will live or die, so I always use the correct cam lube. |
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22 Jun 2009, 00:09 (Ref:2487945) | #6 | ||
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It is bad form to quote yourself but, this is what I have posted on another forum:
"Re: running in a piston engine Postby Notso Swift » 26 May 2009 10:01 "TwinTurbo wrote:Not running the rings in is sometimes a sign of incorrect honing, but more often due to the use of incorrect running in oil and procedures. Use 100% mineral oil, no additives, no synthetic. I use the basic Castrol GTX, cheap and readily available. Run the engine till it gets warm, let it cool, change the oil fiter and top up the oil. Then I run it in, road or track, with load, no babying around, no constant throttle, up and down hills is good. Check the leak down after a hour of running, if OK, then drain the oil, change the oil filter and fill with Castrol Edge. Cheers Gary" Notso Swift Wrote: That is the most important thing, none of this 50's bull about 1000 km gently, no more than half throttle and what not. You need to make sure the cyl pressure forces the rings into the bores, that means open the throttle. But make sure every thing is hot enough first, cold oil and water is an obvious no-no Do Three 1/2 Throttle runs from 40% - 60% of your engine's max rpm Do Three 3/4 Throttle dyno runs from 40% - 80% of your engine's max rpm Do Three Full Throttle dyno runs from 30% - 100% of your engine's max rpm You will not have any oil smoke and the rings will be done, between each group of runs you should let it cool a little to stablise the temps. Now maybe my last couple of race motors haven't lasted long enough to wear out, ](*,) but I have never have a ring problem, blow by, anything and leak down has always been excelent :wink:" In short this is pretty much exactly what a manufacturer does when the pull it off the line, the car goes straight to a rolling road and they open it up... they do it for a good reason, the rings need it! Oh and high zinc is a must for cams, you can buy additive packs. Pro's have noticed that as Zinc has been reduced over the past 10 years in oil there are more cam failures on street cars, co-incidence....? , the oil companies still say they the zinc is no longer needed because of the new tech, but... ask your mechanic what he is noticing |
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22 Jun 2009, 07:07 (Ref:2488056) | #7 | ||
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BMC engines always seem to bed in better by using "the old school" method.2000 rpm for 20min's using a plain,ordinary 20/50,Comma oil is about the most basic you can get.Then of course you change the filtre,and oil.Motul seem's to suit these engines very well.
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22 Jun 2009, 08:15 (Ref:2488089) | #8 | ||
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I raced Mini's for 15 years, so it is not a technology thing
For older cars I would suggest Penrite oil from experience, I know some places in the UK stock it, can't comment on Motul for older cars but it is excellent |
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Contrary to popular opinion, I do have mechanical sympathy, I always feel sorry for the cars I drive. |
22 Jun 2009, 08:21 (Ref:2488094) | #9 | ||
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I've used it in my B for several years,its the only oil that is capable of slowing the ware on the cam scew gear,tried just about everything else.
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Living the dream,Chief instruktor and racing on the worlds best circuits-The Nordschleife and Spa.Getting to drive the worlds best cars-someone has to do it, so glad its me. |
22 Jun 2009, 14:04 (Ref:2488335) | #10 | ||
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For some reason some engines take to a gentle running in, but personally I've found that if an engine is going to be thrashed round a track then it doesn't want to be pampered for a start. If the engine has been built by a competent engine builder with the correct tolerances then a drive round a track for half an hour under load short shifting and left foot braking along the straights normally works OK.
As for camshafts they can be a problem and as said will either clap out in the first 5 minutes or go on with no trouble. I have always preferred to use a well used cam with new followers than a new one, and will run a new one in on inner springs obviously at low revs and not necessarily on my race engine but in a road engine for a couple of days. Of course as you can whip the type of engine that I use out of an Anglia or Escort very quickly its not a problem. |
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1 Jul 2009, 09:55 (Ref:2494366) | #11 | ||
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Running in nearly done
Thanks guys it seems to be very much a black art for older engines, never ming well done 300 miles in a mix first 100 up to 3000 rpm with load ie higher gears, and up and down the rev band within 3000rpm. Next went to the track and did a number of laps building up the revs to 5000 in short bursts. I stopped there as the plugs were showing I was running rich on nearly all cylinders. Before the rebuild the plugs were showing all fine.
So it must be back to the dyno and a weber man to sort before going further. I don't really know what I'm doing with the webers and as there are three its even more daunting, I tried the idle mixture but it did nothing, all the carbs are taking the same air flow. The only other thing that bothers me is the tappet clearance the book says normal 16thou, the original builder says 22inl 24exh , this is on a 315 cam anybody got any info on this, the new roller rockers seem fin I do have one noisy one i believe from a low rpm noise (i hope). I asked xrn but they did not supply the cam niether did Piper they list a 320, xrn say 16thou for there's . I have a peter burgass fast road head which seems to be the only thing left for me to play with , agian any ideas on who can better it, I was going to go to CNC heads and see what they can do. Apart from that i can't wait to get her to 7000rpm , even with act cans to keep the noise down to <100 db from 108. If any body has infor on tuning the C would be grateful |
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1 Jul 2009, 10:04 (Ref:2494371) | #12 | ||
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I would have thought PB to be your best bet,he doe's know his way around BMC engines.I think that 22thou sounds right,is it a Kent cam?In the mean time,I would not worry too much about the mixture,far better than it leaning out at higher rpm!
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Living the dream,Chief instruktor and racing on the worlds best circuits-The Nordschleife and Spa.Getting to drive the worlds best cars-someone has to do it, so glad its me. |
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