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Spitfire & GT6 Forum

Anyone have experience with Roller Rockers? Adjustment issues

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Dave at OldSchool Avatar
Dave at OldSchool Dave Perry
Battleground, AL, USA   USA
Geoff, While you have the rocker assembly off, pull the spark plugs and crank the motor. You should have a LOT of oil pumping up through the head passage.

IF NOT a LOT of oil pumping throught, note that for building engines that run at high rpm's, it is common practice to put a restrictor in the hole in the block, and it may not be large enough, or be incorrectly done, preventing the oil supply required for lower rpm use.

Dave Perry OldSchool Restorations of North Alabama USA

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spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
In reply to # 1595563 by Dave at OldSchool Geoff, While you have the rocker assembly off, pull the spark plugs and crank the motor. You should have a LOT of oil pumping up through the head passage.

IF NOT a LOT of oil pumping throught, note that for building engines that run at high rpm's, it is common practice to put a restrictor in the hole in the block, and it may not be large enough, or be incorrectly done, preventing the oil supply required for lower rpm use.

Dave Perry OldSchool Restorations of North Alabama USA
Dave,
On a Spitfire engine? With the oil to the rockers running through the flat on the rear cam journal? Remember no valve guide seals on the standard engine. A lot of oil? Not the normal wisdom. Tony M is closer in saying it can take some time before the oil supply shows up.
All the best,
Paul

Dave at OldSchool Avatar
Dave at OldSchool Dave Perry
Battleground, AL, USA   USA
Paul, cranking with the spark plugs out and no restriction by the rocker assembly, there should be a good flow of oil coming through the passage.

I am only addressing the possibility that the engine builder did put a restrictor in the block, since it is simple to check the flow, , while the rocker assembly is already off.

I don't disagree that it takes a bit of time to get oil to the rockers, that is a different issue when I am considering an engine someone (else) built with roller rockers ... what else did they do , expecting higher rpms ?

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spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
Dave,
The pulsed nature of the flow through the flats on the rear camshaft bearing journal is a restriction. Triumph didn't send full flow to the rockers. Consensus is they didn't send enough, leading to excessive rocker shaft wear.
All the best,
Paul

Dave at OldSchool Avatar
Dave at OldSchool Dave Perry
Battleground, AL, USA   USA
yes, Paul, I know that .......... does that countradict my suggestion about checking the flow though the block and head passage ??? NO.
I know the oil flow is metered, but it is still under some pressure . maybe you have never built enough engines to have found a restricted or blocked passage there. While the rocker pedestal is off, it's so easy to check, I don't understand why you don't think he should.
But then, I have only been doing this since the 1950's, so I check most everything that I can when building a motor, especially when servicing one that "someone" else built earlier, that now has problems.

Dave Perry OldSchool Restorations of North Alabama USA

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
I think we are all on the same wavelength.

It would be nice to see how much oil is coming up from the cam.

clshore Carter Shore
Beverly Hills, FL, USA   USA
Oil restrictors are typically fitted to the cam journal bearing supply passages.
Spitfires do not require such on the valvegear supply, and doing so is a surefire formula for problems.
I've built and raced these Spitfire engines for over 50 years …

That said, it will harm nothing to run the test as Dave suggested ... but expect to see a minimal oil flow.
However, if you see zero oil flow, then that is a concern.

For example, if cam bearings have been fitted, without ensuring that the bearing lubrication holes line up with the
oil supply passages, then zero oil will be metered to the valvegear, plus zero oil to the #4 cam bearing as well !!!

When I have seen rocker clearances rapidly increase in service, it has been due to lifter/cam lobe failure and deterioration.
Since this motor has allegedly been freshly rebuilt, I'd e worried about that.

If so, that cam is toast, and at least one lifter.
Plus, any metallic debris can cause 'cascading' failures inside as well.



Edited 2 time(s). Last edit at 2019-02-10 07:43 PM by clshore.

Roy Avatar
Roy roy o
Marietta, GA, USA   USA
Harland-Sharp roller rockers - company said (8/18) they do not need extra oil on Spitfire engines .So that's the way I'm running mine-no extra oil line from main galley . .

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