Cylinder head rebuild - running in procedure?

[McBreadhead]

About to finish the cylinder head rebuild on my Stage 4 xflow engine and need to know the running in procedure. I will be running same forged pistons with new rings, big end bearings, oil pump, valves and guides. Car runs on twin 40DCOE carbs.

 

I will be taking car to rolling road but wonder if after only 20 miles running taking car up to max revs (7250rpm) will be too much too soon.

 

What is the precived wisdom of blatchat on this? 😶‍🌫️ Do I need more road miles first and at what revs?

[Peter Carmichael]

It will be too much too soon. You need the rings and bores to become intimate without blowing a load of combustion gas past the rings and glazing the bores.

 

It is just the rings and bores you give a damn about.

 

More road miles. No labouring. Light throttle. Revs up to 3500-4000.

[Mcalvert]

Hope thsy don't mind my posting this but when Vulcan rebuilt my Xflow a while back, these were the running instructions provided.

 

The Name in performance Engines.

We recommend the following procedures with new Vulcan Engines.

We Recommend Valvoline racing 20/50 Oil in all of our Engines

At 500 miles: Change oil and filter, check tappet

clearances, check head torque

 

At 1500 miles: Change oil. At this point the engine

should be fully run in

 

After this period, we recommend the oil is changed every 3000 miles and that general services are every 6000 miles.

 

Starting the engine and running in:

 

1) Spin the engine over without the plugs in until some oil pressure is obtained.

 

2) When the engine has been started do not allow it to idle. Ideally it should be run at 2000 rpm for 20 minutes. after which set the idle between 750 and 1000 rpm.

At This point the Tappets will need to be checked & adjusted as per sheet when cold.

3) When the engine is running, do not allow it to get hot. Remember that a new engine produces a lot more heat than an old one. If the engine is running hot, check your radiator. In some instances it will be necessary to increase the number of radiator cores. We also recommend having a header tank as part of your cooling system.

 

4) 0 - 500 miles: Max: RPM in gears 4000

top 4500

500 - 1000 miles: Max: RPM in gears 4500

top 5000

1000 - 1500 miles: Max: RPM in gears 5000

top 5500

 

5) Ensure that the mixture and ignition settings are correct otherwise serious engine failure will result.

 

6) The engine must not be ‘rolling road tested’ @ full RPM until it has done at least 3000 miles.

7) You can get the Engine Tuned on a rolling road with a Max RPM of 4500 from new but don’t leave the car at the rolling road with out you being there.

 

[McBreadhead]

I am not altering the carb set up or timing thus assuming I can just plonk the head back on and get running without a RR session then?

 

However I am fitting a fuel pressure regulator (FilterKing) but assuming I set the correct pressure with a guage this should have no effect on carb set up/tuning or am I wrong?

 

I've already paid for 2 RR sessions so want to avoid another if possible but if I read the advice correct I need to do some low rev road miles before I head to the RR? However 3,000 miles is a year's running - surely this is overkill!? I was thinking 500 road miles then RR.

[Sheds Moderator]

You can RR the car at lower engine speeds without damage. Watch out though, if you have reworked the head the engine will breathe better at high revs and this will mean you need more fuel at the top end, which may mean a rejet. You don't want it lean at the top end as this can cause damage.

 

Having said this your RR operator can advise, I bet he can get it pretty damn close for the whole range without going past 4500 rpm in testing, once you have the first bit of running in done. He'll probably just leave it a tad rich.

[Mick Day]

There is of course the other theory in how to get the rings aquainted with the bores. That is to drive the car ASAP after 1st starting using the whole rev range; just don't let the engine labour. It's said that the opportunity is lost if one treats the engine too gently in the 1st few miles. Also use the cheapest mineral oil possible (correct grade/ACEA/API classification) & change after a few hundred miles. My new engine was run in on the RR.