Gear drive on S2 with 109 style front cover and pump?

[turbocliff]

Wondering if guys have had success with running gear drives on an on center motor with 109 style front covers? I have a whites racing stock style front cover with their oil pump... and have just broken my first timing chain, and hopefully my last. (really dodged a bullet the pistons and valves did not cause any damage to each other, and so far no evidence that they even met at all). The chain broke at about 6000rpm on a chassis dyno at 32psi.... talk about scaring the $HIT out of me....

Its back together with another timing chain already, but I want to start planning on changes over the winter. The belt drive is an option I guess, but looks like I'd have to change too much other stuff along with it-

 

[forcefed3.8's]

The idler gear will hit the cover. Minor cutting and welding, and it will work. I have a gear drive set up I wanted to run, but heard of harmonics problems because of them.

What kind of chain were you running? Were you oiling the chain? What is the cam thrust set at?

 

[turbobitt]

Been running one for years with no issues. Just make sure it's the large single bolt style idler gear.

Allan G.

 

[turbocliff]

forcefed - The old chain I "think" was a cloyes double roller, and I just replaced with a PRO GEAR double roller, however close inspection of the two chains side by side yeilds no difference at all, they look exactly the same (except one is broken obviously). I do not have a seperate oil feed into the top of the front cover specifically for timing chain / distributor gear oiling, however all signs indicate oiling is not an issue even on the cam/distributor gears, etc. As far as cam thrust, not sure, I'd have to ask the engine builder.

Allen - Thanks for the pic, that looks simple enough. Do you mind sharing what brand or part number gear drive set you are using?

Thank you both-

Cliff

 

[forcefed3.8's]

From what I have gathered, the later Milidon gear drive is the one to get.
I have wondered why the Buick V6 has a problem with timing chains breaking. A friend of mine has a BBC with over 900lbs open pressure springs and has never broken a chain. This is a weekly driven street car too. On my new stage 2, I have a small hole drilled in the passenger side cam oil galley plug to spray the chain. I am using a used chain (I call it broken in, prestretched. Makes me feel better.) that fits snug in this engine, the theory being it is only going to stretch so far. When they fit loose, they break. Also cam thrust is set to .005 or less. I am running a solid roller with 298 closed, 596 open springs.

 

[turbocliff]

Yea I wonder why they break often in the buick v6s myself. From what I understand is that a number of peeps with heavy springs and spinning the motor hard (over 7K) tend to have failure when they let out of the throttle at the top of a pass... mine broke on its way up in RPM... broke at 6000 and 32psi we intended it spin it to 7400ish. However, only a few pulls before that we got out of the throttle at about 6000rpm due to tire spin on the dyno at 38psi... might have "stretched" it on that pull...

I also have a solid roller and spring rates are right around yours-

 

[turbobitt]

forcefed - The old chain I "think" was a cloyes double roller, and I just replaced with a PRO GEAR double roller, however close inspection of the two chains side by side yeilds no difference at all, they look exactly the same (except one is broken obviously). I do not have a seperate oil feed into the top of the front cover specifically for timing chain / distributor gear oiling, however all signs indicate oiling is not an issue even on the cam/distributor gears, etc. As far as cam thrust, not sure, I'd have to ask the engine builder.

Allen - Thanks for the pic, that looks simple enough. Do you mind sharing what brand or part number gear drive set you are using?

Thank you both-

Cliff

I don't have the part number but it is a Milodon gear drive. Been driving this on the street and never had any issues with the idler bolt coming loose. Some people stake or weld them. Mine was retained with loctite 680 and staked. Been over 8500 rpm with this motor.

 

[turbocliff]

I don't have the part number but it is a Milodon gear drive. Been driving this on the street and never had any issues with the idler bolt coming loose. Some people stake or weld them. Mine was retained with loctite 680 and staked. Been over 8500 rpm with this motor.

Ok thanks-

 

[Tweeked6]

Cliff,

I set up my own front cover and gear drive and have had no issues yet. Stock front cover, 0016 block though. I love it. I am going to check it over the winter, but so far I think is a good thing. Glad to hear nothing was damaged for you.

 

[2GNS4ME]

Cliff,

Steal one from Prasad I know he has a couple. I have one on my stage II motor been going back and forth about keeping it. I know I wouldn't push it nearly as much as you would

though
Denny

 

[DR BOOST]

Cliff,

Steal one from Prasad I know he has a couple. I have one on my stage II motor been going back and forth about keeping it. I know I wouldn't push it nearly as much as you would

though
Denny

thanks for sharing.

 

[WIKEDV6]

Cliff,

Steal one from Prasad I know he has a couple. I have one on my stage II motor been going back and forth about keeping it. I know I wouldn't push it nearly as much as you would

though
Denny

Denny, you want Fries with that?
Prasad

 

[turbocliff]

Wickedv6 is my top supplier of replacement T-Tops

 

[49-blues]

I have a stage2 front cover and a complete milodon gear drive set up -$250. shipped

 

[Alky V6]

I've been running a milodon with a modified stock front cover on an on-center over 6 years now. The same one. I don't know where the harmonics concern comes from. My setup is completely quiet. I would imagine there is a higher chance of harmonics caused from a loose timing chain slapping back and forth due to the spacing of the valve events with the V6.

 

[turbocliff]

I'll likely be switching to the gear drive behind the stock style front cover when the motor comes out for a freshen up after the season is over. In the meantime, I replaced the chain with another and have my fingers crossed that it doesnt come apart again. Probably be fine since I'll only see maybe 10-15 more passes this year.

Went out on saturday to race with the local 275 radial guys... didnt push it just wanted to make a few hits and make sure everything was working correctly. Everything went very well.

 

[Mike E]

I figured this would be the best place to add this. I modified a stock cover today. The milodon instructions only show two small spots that need to be cut, but in reality their not easy to weld up. So, you have to cut out a big section and make a large patch like turbo bitt shows above. I couldn't find a way to get enough clearance in the area next to the bolt hole without covering up the bolt, so I made a new bolt boss and extended it out. Lots of work.

 

[turbobitt]

I had to do the same with the bolt boss. Added a tube spacer and welded around it.

 

[turbocliff]

Good info guys, thanks for the pics and explination. Still havent decided totally to go this route, decision time will be over the winter while its apart for a freshen up.