4.6 engine information

Correct re kero - catches fire on exit from a pipe if rate is too high. One of Bernoulli's formulae covers the observation of the reduction in cross section of a fluid flow as its velocity increases - think of the vertical flow of water from a tap as it accelerates under gravity. Apparently this involves the speed of sound in the fluid, and this leads to the effect that the reduction in sectional area is inverted if the fluid exceeds the speed of sound, and the area increases again. Hence the gas turbine - the working fluid (air basically)must be accelerated from below speed of sound to above, so that it expands and produces thrust. This involves a lot of work in supersonic craft to reduce the speed of the air in the intakes to below the speed of sound before it hits the turbines.
 
I did it, so I think it is. Hey, I have a lathe so I have to use it for something.

Des Hammell states enough oil gets to the rockers to swamp them (bad) and by inserting a rocker feed restrictor increases pressure for the crankshaft by 5psi. That was good enough for me.
My engine runs at a constant 60psi when above idle.

I made these:
1618040602602.png
Put them there and I've not seen them since:
1618040633829.png

Here the thread on building the engine using Hammill's oil modifications.
Overhauling a knackered engine.

I did the other oil mods too, like reducing the feeds in the camshaft bearings and altered the main bearing shells.

Got to love building engines....
G.
 
Thanks G
I had not read your engine build thread before, excellent. I think I will start saving up for some roller rockers :)
 
quattro said:
Hmmm... they do look rather purposeful don't they :)

Shame V8 Tuner is not available at the moment. Are they still in business?
Click to expand...
Hmmm yes. With a clattery valve train in the P6 I think I will look around for some.
Sadly I read somewhere that the owner of V8T had passed away, please excuse me if I am wrong.
 
I'll quote what Des Hammill advices: "...1/4UNC or 6mm course thread. Fit a grub screw - which has a 0.035-0.040in/0.75 -1.0mm diameter hole drill through the centre." he goes on to give Caution! The grub screws must be screwed into the holes so they are below the block's deck.

Get yourself a copy of the book, it's a good read, and impresses people when placed on view in the background, when on a video call. :cool:
 
I think I may end up doing a refurb on stock rockers. Availability, price, need for headroom, bang for buck questionable all add up to them not being viable.
 
Whats the opoinion on using a nylon 1/4-20 plug (drilled) to reduce oil flow to the rockers? Have plenty of such screws, obviously easy to drill. The head shouldnt get hot enough to melt nylon should it?
 
Hi, It depends on the grade of nylon. Although the oil feed hole is pretty close to the combustion chamber. Try one of the stick on temperature strips to see what temp range it's going to be.

Colin
 
I was actually going to fit the nylon slugs at the top end of the drilling, just under the rocker pedestal. That way I can remove them easily if necessary. Doubt it will get any hotter than coolant there?
 
^^^ He's right ya know. Before fitting a 19 row cooler I regularly saw oil temps of 110 c when pushing hard. With cooler and an inline oil stat I now see the oil temps in line with the coolant at @ 85 c and a useful boost in hot oil pressure of around 10 psi.
 
I ordered Harland Sharp roller rockers direct from manufacturer, shipped to UK and including customs was only a few hundred quid from memory. Edit, was $515 in 2018, £370 approx.
S11601 was the part number, I don’t think they list them for sale anymore but can still be ordered.
They fit standard size shafts.
Jim
 
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Got a couple of 1/4-UNC grub screws 1/4" long. Bugger to drill as noted above, but got it done with only breaking one bit, and probably blunting another. 1/16" hole will be 1/9 of the area of the original 3/16" hole. Tapped the heads at the front pedestal position, both go in below the surface.
 
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