Blue thunder heads

[Heo]

Yes what we call thunder
Is the sound of Tor riding
His chariot over the sky
Slaying gigants with His
Hammer . He is also
The protector of the blacksmits

[TomP]

Art Thor Francis?

He makes some nice stuff.

[XR7]

Hey that is kinda cool Barry. I sure did not know that. I have only known 2 (other) people with that name in my lifetime as well. One was in Norway where I was born, and the other I met in a remote fly in hunting camp, in Alaska, where I lived for 15 years. I have heard it is hard to even be able to talk with Art, he doesn't want to talk with customers, prefers them to go through dealers.

I always heard Thor was the Norse god of thunder. I have a hammer, but don't know how to use it...

Here is another picture, the next one after this will be a dead give-away...

[Chrisss31]

Busy weekend for the forum!!  So.........I'm ready for the answer

[BH107]

Speaking of Blue Thunder heads, I saw a new set for sale on eBay with rockers from one of their distributors.

[FE Jonny]

If you are going max effort why not SOHC? I could never afford it but we have discussed the advantages with cam design and high RPM power. Plus no pushrods offer bigger, straighter ports.

[Nightmist66]

If you are going max effort why not SOHC? I could never afford it but we have discussed the advantages with cam design and high RPM power. Plus no pushrods offer bigger, straighter ports.

Besides the cost as mentioned, another obvious consideration would be real-estate, especially in a shock tower car. Jmo.

And then there's boost or squeeze...........

[TomP]

I'm thinking the wedge might have more power potential than the Cammer just because of camshaft limitations in the SOHC design. The thing the Cammer has going for it is allowance for more stroke.

[machoneman]

I'm thinking the wedge might have more power potential than the Cammer just because of camshaft limitations in the SOHC design. The thing the Cammer has going for it is allowance for more stroke.

Good point on the SOHC's camshaft/rocker lift issues. I'm quite sure Jay has mulled this over a lot. And I do hope someday he comes up with a viable solution for a lot more lift and duration at the valve while still retaining the head's stock integrity, even if it requires all new cams and rockers. I don't remember what Jay said long ago on the max lift he can attain now (under .800?) but I've often wondered what a SOHC  could do in the hp department with more like Pro Stock lifts of 1" or a tad more. JMO!

[XR7]

I've wondered about the max lift available for the SOHC also, not that I'll ever own one but a friend is going through this now. His idea is too raise the cams, lengthen the valves and lengthen the rockers also, thus trying to get more ratio out of the rockers. Then the lobes could be bigger and with the increased ratio, much more lift could be attained. This sounds like all one off stuff, but he (and a head guru) are looking into it.

I think the SOHC rockers are only 1.3 ratio? Max lobe lift is something like .575 or so? I have never heard the exact numbers. .575 x 1.3 would be 747 gross...

I still have more pictures to post on the BT heads and the "mystery" intake I plan on using on Jay's HR adapter, just been real busy lately and away from home, travel, work,  etc.

[jayb]

Miraculously, we have all witnessed one of those rare moments when Tom P has hit the nail on the head!

My big SOHC has a reduced base circle on the cam and still maxes out at about 0.740" lift.  Stock rocker ratio is about 1.3:1.  The lobes look super radical compared to a wedge cam, but the lift just isn't there.  If I wanted to reduce the base circle some more I could increase lift, but to fit the lift the duration would have to increase also, and there would be a much greater tendency for valvetrain instability.  Because of the limits of the valve opening profile on the SOHC I think Tom is correct that a wedge FE may have just a little more peak power potential than an SOHC.

But on the other hand, I think its a lot easier to get to the engine's peak power potential with the SOHC.  Its easier to get the ports to work, and as Tom mentioned without the cam in the normal location you can fit a much bigger stroke into the engine, for more cubes, which will pull harder on the ports. 

I also think to get to 1000 naturally aspirated horsepower, you'd probably spend about the same amount of money with either engine.  JMO - Jay

[machoneman]

Cool Jay! Guess we need to wait until a whole bunch of your other FE projects get cleaned up before this topic can be re-visited.

[XR7]

So Jay, what do you think about raising the cam bore up, and lengthening rockers, valves, etc. Could it work to attain more lift?

[jayb]

I actually did a design and started a machining project to go a different route.  This would be to use smaller diameter rocker shafts, and move the rocker fulcrum closer to the cam.  You could use offset bushings in the existing rocker shaft bores to position the new, smaller diameter shafts inboard towards the cam.  My drawings indicated that I could increase the rocker ratio to 1.5:1 this way.  Still a project I want to tackle, but other stuff has gotten in the way...

[machoneman]

Appreciate the details. Per my shade tree math, your .570 at the cam with the std. 1.3 rockers nets the .741 valve lift. At a 1.5 rocker, you'd net .885 at the valve. Nothing to sneeze at for sure. It would appear then to approach 1.0, you'd need a 1.75 rocker which would net .998 valve lift.

While a 1" lift isn't any magical number, is it really approachable using your technique or is the .885 a true maximum lift with the SOHC, assuming stock head as-cast cam bearing bosses?