All Small Six On a Quest to Figure Out What the Maximum Valve Lift is That You Can Get With a 200 Six

[bubba22349]

Offset FE rocker tip/advice was made here at Ford Six back in 2016, using the David Vizard method of offset bushes. 67straightsix and I talked about it.

See post #41 in this thread


"https://fordsix.com/threads/high-ratio-rocker-arms.74180/page-3"

Hi xctasy and Ford Six members, after re-reading through Xctasy's above post from (https://fordsix.com/threads/ford-inline-six-build-on-engine-gremlins.84399/#post-678763) yesterday this sparked some thoughts and put me onto researching what the Max Valve Lift you could get on any of Ford Small Six's. This research is for a current 200 six build as well as another in the planning on trying to get more total valve lift with a parts combo used on the Ford Small Six Large Log Head's. I am wondering what is the maximum of Camshaft Lobe Lift size is that can fit into the Short Blocks Camshaft Tunnel? The highest lobe that I have found listed for any of the off the shelf Camshaft Grinds seems to be a .330 Camshaft Lobe (this gives you a total Lift is .545 when used with the 1.65 YellaTerra Roller Rocker Arm's) this is with the Clay Smith 292 Solid Lifter Grind has anyone been able to use any thing bigger in a block with a custom ground cam? I would like to see .600 or even more lift.

 

[pmuller9]

If you take a straight edge and run it across two of the cam journals, the absolute maximum cam lobe height is the distance from the straight edge that is resting on the cam journals down to the cam core.
I have seen cams with the heel of the lobe ground even with the cam core.

 

[bubba22349]

Yes I have that Clay Smith S-292-10 Cam its Card is in attachment below.

 

[pmuller9]

Yes I have that Clay Smith S-292-10 Cam its Card is in attachment below.

What do you measure from the OD of the cam journals down to the core between cam lobes?

 

[bubba22349]

I will try and get that info for you tomorrow we have had a lot of snow fall yesterday and today so going to take me awhile to dig out to be able to get down to the shop.

 

[aussie7mains]

Ok, first off its yella terra, an Australia company in Melbourne. If your talking about maximum lift of the valves in the small six, firstly in most poppet valve engines lifting the valve any higher than 25% of its diameter is a waste of time, this is mathematically where the curtain area queals the valve head area. If you look at most flow charts for these valves you will find that flow (actually restriction) improves fairly linearly up to about the 255 mark then flattens off, there exceptions to this. So if we are talking about a 45mm intake valve then least restriction will occur at 11mm lift, going any higher has little benefit. Increasing the lift results in increasing stress on the valve train for two reasons, firstly the valve spring load is increased as more deflection is applied to it, secondly if you are to maintain duration and increase lift the cam lobe acceleration must increase, this places ever higher stress on the whole valve train. So basicaly the objective is to get least flow restriction with the lowest lift at the valve, this is especially true with a pushrod engine. So in conclusion I would NOT consider going any higher than 12mm in one of our old pushrod engines. The best value for work effort is, as always, to be found in decreasing flow restriction to raise BMEP. The old sixes have a cam with a relatively small base circle which does NOT help with cam design, all proper engines have roller cams and followers. Hope this helps for you.