Duromax 440 build-reving it up!

[slonomo]

Your build looks good! Can't wait to see the end product.

On my Vegas 440/460 I sheared 3 timing key's. Did the lapping procedure on the 2nd and 3rd. Used an impact to tighten the flywheel down as tight as she would go. Went to straight key after that, no issues.

I agree with the 35# valve springs from Vegas Carts with my Isky race cam and chromoly pushrods no issues.

[Notsoezgo]

Originally Posted by raydhd

One other note since you are using an advance key BE SURE to do the lapping procedure with the flywheel installation. I didn't know they still did the advance keys with the big block clone. One other note there are BIG flow gains by opening the valve pockets below the valve seat . Just be SURE to protect the seat while doing this.

Yes I plan to lap the flywheel to the crank, if I go with the valve upgrades Shepard mentioned I could use the original valves to protect the seats while porting

[Notsoezgo]

Originally Posted by slonomo

Your build looks good! Can't wait to see the end product.

On my Vegas 440/460 I sheared 3 timing key's. Did the lapping procedure on the 2nd and 3rd. Used an impact to tighten the flywheel down as tight as she would go. Went to straight key after that, no issues.

I agree with the 35# valve springs from Vegas Carts with my Isky race cam and chromoly pushrods no issues.

If the timing key is problematic I'll just go straight key. Do you know if anyone sells an adjustable timing bracket like VC used to?

[raydhd]

An easier way would have been to use the ARC billet flywheel with adjustable timing. Something else you might want to add to your list is the autolite AR3910X racing spark plug. It adds noticeable power for very little $'s. Another note is Jody Powell from ARC racing installation videos on youtube for the connecting rod and billet flywheel. He is absolutely against using an impact gun on aluminum billet flywheels. Best case it tough to get off, worst case it warps the softer aluminum flywheel. This from the guy that represents the company that makes the unit and has built 1000's of clone engines.

[sho305]

I have the smaller advance key in mine never had an issue, I lapped it in when installing. The larger key is thinner in the middle, you have to make sure you advance the flywheel against the key correctly when installing. The keys give more advance in the 390 than they do in the gx200 due to larger diameter wheel. I would also cut the head I did .050 a lot of people do .100. I now put the long rod Vegas rod in and had to cut the dish off the piston that likely made it higher compression its a flat top now and all the way to deck height so used the thick gasket instead of the thin one. I run regular fuel you can cut more if you run premium.

Port the bowl by seats, smooth off the valve guide boss they stick way out and mine had big cutter marks around them.

I'm all about scooter carbs or mikuni etc. I ran a scooter CV 32mm and it ran awesome but top end was weak. I modded the spring it was better. Now put a 30mm slide on and it has more top end, it works nice other than at times it will bog on the bottom end but its due to my clutch catching once in a while at low rpm. Both were pumper carbs. The stock carbs can work ok but they never work right, they are too lean top end and too rich midrange. The off idle is another problem area. I'd guess the stock springs are 20-25# or something they will float at 4400 give or take.

The cheater cam is the same lift as stock, its made from the same core. It has way more duration. If you run 1.3 rockers it comes out similar to a performance cam in lift and duration. Anyway with same lift it is nice to the valvetrain compared to perf cams. I ran 5200 with the stock cam and other mods, it goes higher with the cheater cam no problem, more power too. I gained at least 5mph on top I have not wound it out again to check exactly how much. It did 38 stock at 5200, 42 with cam, now its faster with slide carb but I never go that fast anyway. You might lost a little top end with 1:1 rockers but when I put them on I didn't see a big difference it was minimal and those were stamped ones so hard to say.

[raydhd]

Jody Powell from ARC says that with the engines he builds he doesn't use a key at all. That the key is a set up guide and properly installing the billet flywheel it isn't needed. There is a straight up key in my Omega with an adjustable coil bracket. Call me conservative on timing keys.

[Notsoezgo]

Originally Posted by raydhd

Jody Powell from ARC says that with the engines he builds he doesn't use a key at all. That the key is a set up guide and properly installing the billet flywheel it isn't needed. There is a straight up key in my Omega with an adjustable coil bracket. Call me conservative on timing keys.

I have only found one adjustable bracket so far at pfmparts.com

[raydhd]

For the big block clones the only 2 I was aware of that did timing with the bracket was the no longer produced Raceseng unit that is on my Omega and the VC unit you mention. BUT ARC sell several billet flywheels where the timing is altered with an adjustable hub. That PFM unit looks a lot like the VC unit. Shepard had installed the VC unit so maybe he can add his knowledge here.

[slonomo]

Any updates?

[Notsoezgo]

Originally Posted by slonomo

Any updates?

Now that you mention it yes!