Damn right. I can run tighter piston to valve clearance than a belt and much tighter than a chain.
Until I see some sign of “harmonics” transfer from the gear drive I’ll keep using them.
Here’s a fun one for the books.
I was watching a video of some dude at Reher-Morrison assembling a BBC.
When he got to timing the cam, he blows the belt drive so hard…use your imagination.
Then, then the dude says “besides the nasty harmonics the gear drives cause, the idler gear forces the cam gear UP and INTO the top of the cam bearings”!
I said WTF? That makes zero sense.
Being the prick I am, and knowing I don’t know everything I pick up the phone and call RM.
I get a dude on the phone and I ask him about the harmonics. He says oh yeah, we’ve tested them when engines come in with them and they make (insert some absurd hp gain) more on the belt drive every time.
So I say on bracket engines? He says we’ve tested them on everything but a Pro Stock engine.
Surely they’d have some actual dyno sheets to prove it. You’d think they’d keep copies so when morons like me call they could shut us up.
I ask for dyno sheets. He says we don’t keep stuff like that! Got it.
Then he says “you know, if you search the web you’ll find tons of testing done on all the gear drives.
I say I’ve looked and the ONLY tests I’ve found are chains and belts against dual idler GD’s. So how about you google it up right quick and send me a link.
He actually starts looking. 10 minutes later he says I can’t find anything but the dual idler stuff. But it’s in SAE papers and everyone know that.
Short story is neither that dude or anyone else has shown me an SAE paper or any other technical paper has ever been produced to prove the claim.
Then told him what the dude said about the idler gear forcing the cam up into the the top of the cam bearing.
He says oh yeah, we’ve seen that too.
So I ask him were these flat tappet engines that had it happen. He says oh hell no. We don’t build those ever.
So I said how the hell does the gear drive have enough force to overcome the downward pressure of valve springs that probably have no less that 320 on the seat and 850 over the nose as that’s a lot of load.
His answer was I don’t know how it works but I know it happens.
This jack *** had zero proof of either claim yet he pumps out that bullshit like it’s fact.
I’m open to reading or even buying ANY study from SAE, NACA or any other competent testing that proves the harmonics claims.
Yet I never get them. I called out a guy on speedtalk about it and he posted a link to (IIRC) a test by Roush that used a dual idler gear drive but not a three gear fixed idler drive.
The other claim the RM dude made about the gear forcing the cam up is so farcical I’d believe the cow jumped over the moon and the dish corn holed the spoon before I bought that ****.
Now that I’m on full prick I’ll also say that as smart as David Reher is he is one arrogant dude.
I watched him at a seminar (I saw it on the web but, not live) and when he was asked about rod length he said it doesn’t matter and then he said Smokey was wrong about using the longest rod that fits and that he didn’t know what he didn’t know.
If Reher was correct in that he would NEVER build an engine where the oil ring goes around the wrist pin. EVER.
He could easily make the rod .100 or even .200 shorter and not do it. But he does.
And he’s doing exactly what Smokey said to do back in ‘78 or whatever year it was he wrote the book.
For him to even privately make that claim while doing exactly what he says doesn’t matter is hypocritical.
Making a public statement like that is beyond arrogant.
So I stand by the gear drive as the most effective, cheapest way to drive a cam there is. And the most accurate.
It’s only drawback is you can’t change cam timing on the dyno nearly as fast as a belt drive. Other than that the GD wins hands down.