Engine and Transmission Tech

Why would you ? Some of us, can't leave well enough alone. For better or worse, we push our journeys. Where would the RV8 be without the 300 Buick aluminum head ? Has anyone run a Rotus V8, yet ? Likely Fred Key will be first. My gripe with these is cost, scarcety and cost of shims/labor to maintain valve lash. Rumor is, a Volvo 4 vale head might work. Biggest problem with putting an I4 head on a V8 is cam sequencing is always wrong, unless you convert to a 180 deg. crank,( fire two cylinders at once). Another option is making custom modular cams. This is much easier if cams are retained by caps, not in one piece housing bores.
Onward, Art.

Quote:

Where would the RV8 be without the 300 Buick aluminum head?

Not sure I follow that one, Art.

Long before aftermarket heads, there was the 64', 300 Buick head. It became the head swap, logical choice for bigger RV8's.

I'm converting a SOHC 2 valve hemi head to fit the RV8/ etc. Coverting the oem cam to modular lobes, is a logical choice. Waterjet labor to cut a lobe profile, needing only finish grind is $11. ea.
Onward, Art.

Quote:

Long before aftermarket heads, there was the 64', 300 Buick head. It became the head swap, logical choice for bigger RV8's.

Right. I have a set. Not convinced that they are much better than the late 4.0/4.6 Rover heads. I also have a set of those.

Well consider this. The only functional difference between a pushrod head and an OHC head is the pushrod. Which is nothing in the world but a long stiff and fairly light weight tube. If a high rev limit is the only goal then *maybe* it's worth eliminating that tube but you are basically talking about the difference between 8,000 and 9,000 rpm and the rest of the engine has to be built to take it. Even with special reinforcements the 215 isn't capable of that for very long.

And the TA heads are state-of-the-art hardware with a thoroughly modern combustion chamber. The ports are large and can be made larger if ordered with CNC porting and then can be made larger still. Add a roller cam, roller lifters, Carbon fiber or titanium pushrods, titanium valves and retainers, beehive springs of the appropriate rate and upwards of 8K has just become a very real possibility. I expect you can even get hollow bucket lifters with a very light weight if you want, may even be available now in ti. The intake runners can go vertical past the port if desired so there is no advantage I am aware of in port design. It does take a bit of cash to buy these heads but really less than you would expend on a custom refit.

By this point there is very little reason to put the cams on top of the heads and you can keep the low center of gravity.

I think the whole OHC/DOHC thing is just a search for bragging rights and reduced manufacturing costs, when the same or better results could have been achieved by refining the earlier architecture. GM has made great progress on that front and there are a great many things they have not incorporated into their designs that we as individuals could make use of.

Jim

Consider what you did not consider. OEMs did not switch only to brag or implement reduced cost. Emissions, fuel economy and simplified 2 valve designs were actively involved. Let's consider your MGB build, Jim. What is valve spring pressure over the top ?
Now x 16, four times per revolution, say 6k. rpm. How many events per minute ? Let's go mild at 300 lbs over the nose. These events happen 24,000 times per minute@ 6k rpm, When you consider the total poundage trying to rip the heads of the decks and split the block, then add about 600 psi+, when ignition happens. When you hear a Nascar motor on a Spintron, all is revealed. I suspect about 90% of Nascar motor failures, start in the valvetrain. The enemy is mass times velocity. The worst partis when the valve slams against the seat with the lowest possible spring pressure. There is good reason why no one uses a modular, push rod cam.
The stresses are simply too high, as described.
Onward, Art.