Hi John, We will be doing a video on Camshafts soon (most likely a 2 part video 1) What to inspect / change when doing a cam 2) first start up etc. However for now and in answer to your questions below is what I have typed up and send out to customers. With regards to breaking a camshaft in the advice from most camshaft manufactures is to start the engine and hold the revs at approx. 2000 rpm for 20 minutes. However this is not always possible and from our experience the below is what has always worked for us without any issues at all and we are lucky enough to have customers still in contact that bought engines from us in the mid 1990’s if not earlier. Once reason for breaking the cam in is in fact breaking the lifters and push rods in. The camshaft is profiled with a tapper so as to cause the lifters and push rods to rotate in the block. If you just started the engine and let it sit at idle speed for a long length of time then there may be a tendency for the lifters to not rotate correctly and this could lead to premature camshaft / lifter wear. Firstly if you have just changed the cam in your engine and are about to start it for the first time, or better still you have rebuilt your entire engine, then the thought of starting it and holding the revs at 2000 rpm for 20 minutes is very daunting and rightly so. Let’s assume worst case you have a carburetted engine, in this instance you will not have the luxury of an idle valve to stop the engine from stalling if the fuelling or ignition timing is not quite right. In our workshop we will get the engine started and then advance the distributor by hand until it simply sounds about right whilst blipping the throttle to keep it running, a possible tweak to the idle stop screw may also be needed to get the engine to tick over without touching the throttle. Once the engine will rev up freely and will idle we check the water level as the engine may have pumped air out of the system and in turn emptied the header tank. By this time the tappets will have all gone quiet and we are about 2 to 3 minutes into engine first run time. We have not allowed the engine to simply sit at idle as we were blipping the throttle whilst doing these simple basic adjustments. Obviously if your fuelling system is injection and you also have coil packs then this step is not needed as assuming it’s all assembled correctly the engine will start and run without any input from you. Next, as we now have an engine that will rev up and also idle you want to keep blipping the throttle up from idle to around 2000 rpm along with holding the rpm at approx. 2000 for 20 to 30 seconds at a time. After holding for this period at 2000 rpm then let the engine return to idle and do a quick spot check for oil and water leaks, make sure that the header tank is still full of water. Stop worrying about all the smoke form the exhaust manifolds that’s just grease and the odd splash of oil burning off them. Feel the top hose to see if things are coming up to temp yet. As you can already see there is lots that you need to check that you cannot do if the engine is running at 2000 rpm constantly. Add to this if the whole engine is a fresh build then simply holding the revs at 2000 rpm for 20 minutes is one way to head down the slippery slope of glazed bores, and you will be wanting the engine to idle for a few seconds here and there during this time so you can set you mind at ease that there are no knocking or ticking noises. As I mentioned glazed bores don’t worry too much about this but in blipping the throttle up and down the rev range sharply will start to help bed in the piston rings to the bore whereas holding the revs in one place for 20 minutes does not give any load to the pistons. Once you have had the engine running for around 10 minutes the temperature will now have started to raise and we will fit the coolant head tank cap. Still the whole time taking the engine from idle to 2000 rpm and holding 2000 rpm for around 30 seconds each time but then when returning to idle doing our checks making sure that it is still safe to continue running the engine. We will keep doing this until the thermostat opens and the whole coolant circuit is nicely warm. If electric cooling fans are installed you will want to make sure they will cut in and out correctly as well. This whole process normally exceeds the 20 minutes previously mentioned. Once you are happy that you have no leaks, that the cooling system is working correctly (stat opening, fans coming in and out) you can then set about setting the ignition timing up and the mixtures on the carb if applicable to your engine. Next is a final check over and then a road test. For us we normally go for a 10 mile drive when possible using the engine in the mid rev range 1500 to 2500 rpm which again stays in a safe range for a fresh engine build and also avoids long periods of idle. Once this road test is completed we return to the ramp and check again for any leaks or issues and assuming there are none then it’s back to the road for more miles and fine tuning where needed, by this point there is no issue with having the engine idle for any length of time, the cam is broken in and the lifters / push rods are all rotating as they should be. Kind regards, Ian
@@RPIEngineering Thanks Ian.. you are the best.. I thought you guys might do it differently. Thats why I asked. I rebuilt this 4.2 before. I used 30wt breakin oil, I ran it up to 2000 for about 2 or 3 minutes, to make sure I had oil circulating and then down to around 800-900 then up again to 2100 for a couple minutes and basically did what you did. It ran great. ( I am the guy with the broken Balancer that busted my timing chain)..I will get the engine assembled with the parts I bought from you in the last 2 weeks. I had bent valves,, so i replaced all head parts (thank you) and had a 3 angle grind added replaced every other internal bearing and rings etc. This Time I will do it the same way you described and with the new piper torque max cam ( I got from you) I hope to have it running better then it ever did. Thanks again..
Please tell/show us how you break in your camshafts
Hi John,
We will be doing a video on Camshafts soon (most likely a 2 part video 1) What to inspect / change when doing a cam 2) first start up etc. However for now and in answer to your questions below is what I have typed up and send out to customers.
With regards to breaking a camshaft in the advice from most camshaft manufactures is to start the engine and hold the revs at approx. 2000 rpm for 20 minutes. However this is not always possible and from our experience the below is what has always worked for us without any issues at all and we are lucky enough to have customers still in contact that bought engines from us in the mid 1990’s if not earlier. Once reason for breaking the cam in is in fact breaking the lifters and push rods in. The camshaft is profiled with a tapper so as to cause the lifters and push rods to rotate in the block. If you just started the engine and let it sit at idle speed for a long length of time then there may be a tendency for the lifters to not rotate correctly and this could lead to premature camshaft / lifter wear.
Firstly if you have just changed the cam in your engine and are about to start it for the first time, or better still you have rebuilt your entire engine, then the thought of starting it and holding the revs at 2000 rpm for 20 minutes is very daunting and rightly so. Let’s assume worst case you have a carburetted engine, in this instance you will not have the luxury of an idle valve to stop the engine from stalling if the fuelling or ignition timing is not quite right. In our workshop we will get the engine started and then advance the distributor by hand until it simply sounds about right whilst blipping the throttle to keep it running, a possible tweak to the idle stop screw may also be needed to get the engine to tick over without touching the throttle. Once the engine will rev up freely and will idle we check the water level as the engine may have pumped air out of the system and in turn emptied the header tank.
By this time the tappets will have all gone quiet and we are about 2 to 3 minutes into engine first run time. We have not allowed the engine to simply sit at idle as we were blipping the throttle whilst doing these simple basic adjustments. Obviously if your fuelling system is injection and you also have coil packs then this step is not needed as assuming it’s all assembled correctly the engine will start and run without any input from you.
Next, as we now have an engine that will rev up and also idle you want to keep blipping the throttle up from idle to around 2000 rpm along with holding the rpm at approx. 2000 for 20 to 30 seconds at a time. After holding for this period at 2000 rpm then let the engine return to idle and do a quick spot check for oil and water leaks, make sure that the header tank is still full of water. Stop worrying about all the smoke form the exhaust manifolds that’s just grease and the odd splash of oil burning off them. Feel the top hose to see if things are coming up to temp yet. As you can already see there is lots that you need to check that you cannot do if the engine is running at 2000 rpm constantly. Add to this if the whole engine is a fresh build then simply holding the revs at 2000 rpm for 20 minutes is one way to head down the slippery slope of glazed bores, and you will be wanting the engine to idle for a few seconds here and there during this time so you can set you mind at ease that there are no knocking or ticking noises. As I mentioned glazed bores don’t worry too much about this but in blipping the throttle up and down the rev range sharply will start to help bed in the piston rings to the bore whereas holding the revs in one place for 20 minutes does not give any load to the pistons.
Once you have had the engine running for around 10 minutes the temperature will now have started to raise and we will fit the coolant head tank cap. Still the whole time taking the engine from idle to 2000 rpm and holding 2000 rpm for around 30 seconds each time but then when returning to idle doing our checks making sure that it is still safe to continue running the engine. We will keep doing this until the thermostat opens and the whole coolant circuit is nicely warm. If electric cooling fans are installed you will want to make sure they will cut in and out correctly as well. This whole process normally exceeds the 20 minutes previously mentioned.
Once you are happy that you have no leaks, that the cooling system is working correctly (stat opening, fans coming in and out) you can then set about setting the ignition timing up and the mixtures on the carb if applicable to your engine. Next is a final check over and then a road test. For us we normally go for a 10 mile drive when possible using the engine in the mid rev range 1500 to 2500 rpm which again stays in a safe range for a fresh engine build and also avoids long periods of idle. Once this road test is completed we return to the ramp and check again for any leaks or issues and assuming there are none then it’s back to the road for more miles and fine tuning where needed, by this point there is no issue with having the engine idle for any length of time, the cam is broken in and the lifters / push rods are all rotating as they should be.
Kind regards,
Ian
@@RPIEngineering Thanks Ian.. you are the best.. I thought you guys might do it differently. Thats why I asked. I rebuilt this 4.2 before. I used 30wt breakin oil, I ran it up to 2000 for about 2 or 3 minutes, to make sure I had oil circulating and then down to around 800-900 then up again to 2100 for a couple minutes and basically did what you did. It ran great. ( I am the guy with the broken Balancer that busted my timing chain)..I will get the engine assembled with the parts I bought from you in the last 2 weeks. I had bent valves,, so i replaced all head parts (thank you) and had a 3 angle grind added replaced every other internal bearing and rings etc. This Time I will do it the same way you described and with the new piper torque max cam ( I got from you) I hope to have it running better then it ever did. Thanks again..