ITTony

I am running a Collari .21 7 port in an 1/8 buggy and am having some odd issues I'm hoping someone can help me with. I just started in Nitro this year and have only ran 1/8 scale for a couple of months and am loving it.

Problem - When I come out of a long straight and hit the brakes it dies instantly. I have had two other people besides myself help with tuning and nothing seems to help. It runs great throughout the rest of the track, it only happens after a long staright run, I say long but it's just long enough to top out and then I'm on the brakes again. I have tried different fuels, different nitro content, glow plugs include everything form Odonnel hot/medium/cold, OS R5, LC3 but still nothing seems to help. I can run it for a while and let it idle and it idles great for long periods. I'm hoping it's a simple tuning issue.

Any thoughts?? Any help appreciated!

Davidka

iTrader: (86)

I'm betting your clutch is hanging up a shoe and it's only happening there because you are going from top RPM to on the brakes.

o.s. power

iTrader: (14)

check that and you might be a little lean on the high speed needle.

always stick with a cold plug in a 21 motor, I use the odonnell 99 to great success along with odonnell 20% fuel.

E2

It could also be that your top end needle is on the lean side and you are getting to an overheat condition.

ITTony

Thanks for the replies. I replaced the clutch to hopefully eleminate the clutch shoe hanging problem, but will still double check it to be sure. I will also richen the HSN a little to see if that helps as well. Oddly enough when I temp it, it never seems to be over 230, but that doesn't mean it couldn't be topping that on the straight away with full throttle.

Thanks again!

Davidka

iTrader: (86)

Lean top is a possibility but I still think this is mechanical. I have a B7 too (love that thing) and it runs great with a cold plug but if you run 20% you can easily get away with a warmer plug (McCoy MC-59 or something like that) and get better idle and resistance to tuning errors. A cold plug becomes necessary with 30% fuel so that you don't get detonation at higher engine speeds.
What kind of clutch setup are you using?

230 is about right for these. I go more like 250 but don't tune anything until it is fully warmed up. Collaris take FOREVER to warm up, much longer than any other engine I've seen and then they like to run warm. Don't get hung up on trying to get down to 210 like other guys.

ITTony

Using a GS factory 3-shoe clutch, what do you recommend?

I too love the engine, it screams down the straight. I'm using Sidewinder 30% now with the OS R5 plug, I tried a hotter plug initialy but they kept burning up on me about every three tanks or so.

Davidka

iTrader: (86)

I think an R5 is a pretty hot plug but that is not the real problem. OS plugs are short reach. You need a long reach plug in that engine which is just about everybody else's plugs. I have great luck with McCoy MC-9 cold plugs and O'Donnell OD99 plugs.

sedanaddict

one other possibility is to make sure you aren't using the radio sub trim to set the idle. the idle screw must set the idle or when you hit the brakes the venturi will close until it hits the set screw which if it is too low will stall the engine.

ITTony

Thanks for the reply sedanaddict, but if I hold the tires off the ground punch it and hit the brakes it seems okay, so I wouldn't think it would be the trim.

SpeedBump57

Tony, David gave you great advice! One other thing though the B3 & B7 were both shimed for 30% nitro.

dremelboy

its the collari

best bet is a novarossi based motor or even an O.S motor

best of luck

Scottmisfits

iTrader: (7)

Check the inside of the clutch bell. Look for any scraping marks from anything. The 3 pins on the flywheel could be hitting it. Make sure everything is shimmed properly.

You said only at the end of the straight? It's not anytime you hit the brakes?

ITTony

Good to know SpeedBump, didn't have a clue about the shims and I was running 20% for the first few tanks.

Right, only at the end of the straight, everywhere else on the track is fine, brakes and all. I will take a look at the clutch bell tonight when I strip it down.

What type of flywheel/clutch would you recommend? I was thinking about a Werks adjustable clutch with carbon shoes...any opinions?

Davidka

iTrader: (86)

I have heard that the only critical thing about the Werks clutch is cleaning all of the components off to get any assembly oil off of them and then using blue locktite on the adjusting nut. The base setting most start with is carbon shoes, gold spring, adjuster nut tightened so that there is one thread showing. The shoes are supposed to last 4+ gallons on those things.