Oil pressure vs volume

[Steve.k]

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Thanks to Kevin Johnson for sending me one of his screen assemblies. Just getting it fabbed in. I’ll get some pics when bolted in. Fit perfectly Kevin!!

[Steve.k]

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All in place with locks.

[Steve.k]

Well borrowed some 1.8 crowers to double check lift. The 1.73 net .748int and .731 ex with zero lash. The 1.8 give .770 int. And .759. The cam is ground for .780 on both. The difference in both shows the difference in valve train geometry and likely difference in rockers themselves. . The bt heads are quite different. Has Anyone else seen this? Also opened up pushrod holes and the screen offered by Kevin. Still debating on cam and vac pump. Thanks.

[Geoff2]

Yes, large lift variation between rockers. Very good chart in D.Vizard's BBC book, where he tested different rockers with interesting results.

[Steve.k]

Geoff im getting variation between intake and exh with same rockers. Never seen that on other Cleveland heads before.

[swampbuggy]

Steve, are you saying that the same two rockers on different cylinders is giving different lift numbers ?? Please expand. Mark H.

[tuffxf]

Geoff im getting variation between intake and exh with same rockers. Never seen that on other Cleveland heads before.

Have you set the push rod and rocker geometry up correctly on both the intake and exhaust for these heads?
Paul

[Steve.k]

Yes. Verified lobe lift. Use same rocker on both valves and do everything identical the exh ends up close to .011 less lift every time. Switch to 1.8 rockers same result.The geometry for both intake and exh must be different somehow. I’ve had another guy tell me head has some unusual quirks. That must be what he was referring to.

[tuffxf]

G,day Steve,
Are you using a shaft or stud rocker? How are you setting up your geometry?
With stock heads i see different stand heights and different length push rods between intake and exhaust to get them set up correctly.
Advertised rocker ratios mean very little,
Those BT heads are an excellent head.
Paul

[Steve.k]

Rockers are on studs yes. I like the head just this little quirk the i can see.

[tuffxf]

I’ve seen difference between intake and ex before with stock heads.
IMO with shaft rockers you have a better chance of getting your geometry correct by being able to change both stand height as well as pushrod length.
Bit of a compromise as you can see with a stud rocker

[Steve.k]

Tuffxf is it the angle of valve that throws it off or stud pad heights?

[tuffxf]

Yes all just geometry :-

[David Redszus]

Slightly tangental to the topic but perhaps useful nonetheless.

Recently viewed a x-y graph comparing oil pressure to engine speed across the full range while on track.
The irregularity of pressure trace was quite surprising. It showed oil pressure behavior never expected.

If your data logger can measure oil pressure, plot the pressure against rpm.
Add cornering and braking G forces in place of rpm.

[dannobee]

Schrick has a dyno that rotates in X and Y axes and can simulate g-forces on various road courses. Obviously limited to 1.0g. We data logged our circle track car and saw a high of 1.8-1.9g on a super late model, depending on tires and setup.