SU Carb damper fluid

Tom Donnelly

Tom Donnelly

New member
What damper fluid are you using in your SU's? I remember Katman was tuning piston travel with damper fluid and springs and using a dowel pin shaped needle. What fluid and how much? David? Mike? Keith? Steve? Joe? Ron? :)
 
Hey Tom.....
Glad to see you twisting on your Z!!!!
I've heard so many things about this...... Stormin Norm, uses 3 washers and no oil, no spring in the dampers, Seriously. Runs 12.8 quarter miles with a su, carbed 2.8 litre 240z..... My present car came with no oil at all in dampers, but with springs...ran great for 1 and half weekends til I ground off a cam lobe, and pulled the engine. But ran rich occaisionally, but otherwise made decent power... My present engine, a sunbelt build from 2005 has a fairly thick oil that really restricts piston movement....I'd guess 10w or so. Motorcycle fork oil, castorl oil, mineral oil, engine oil, tranny fluid, brake fluid. I've heard all of these, being the thing to use...... Likely temperature related to optimum vicosity needed..... Check out the videos on ZHOME.com showing the piston doesn't ever open fully.... So don't want'em flopping up and down wide open......

david
 
I think David has pretty much said it - people use oil weights all over the grid.

I was using Marvel Mystery quite a bit (still do from time to time) but my preferred oil is the 20W motorcycle Fork oil that I keep in the trailer. I meter it into the bore accurately with an eyedropper, have to check my notes but on the 260 flat tops seems 2.5mL is about right.
 
I've been using ATF just like the recomendation on the ZTherapy videos. When I got my new motor back from Sam Neave he had taken the fluid out. He swears by the no fluid concept, and it works great on the dyno, but I found that corners needing partial throttle caused it to run rough. WOT- no problem. Putting the ATF back in smoothed out the midrange response.
 
Tom didn't ask me but I'll throw my two cents in anyway :)

DOT5 brake fluid.

I rarely, almost never, run the black car below 5000 feet elevation. I wonder if that makes a difference?
 
David,
Hey! Yep, can't stay away forever. :) Spent some time cleaning out the carbs and fuel lines. That cell foam does make a mess but that's what a big fuel filter is for.
Now I'm hooking up the fire system, re-webbing belts, fixing brakes.... A to-do list 6 pages long. I love it!

Ty, I knew I left somebody out but it was late! Left Paul out too! And others.
Sorry about that.

Thanks for the feedback, I'll give y'all an update when I get done.

Tom
 
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Mike,

Yep, but the Sna Keoil is part of the driver's diet, right? Which fits since thats the most improvable part to a race car.

Tom
 
Ron and Paul win the "most likely not to fake oneself out with funny SU damper oils" award. 20wt, commonly found in the two place they mentioned- motorcycle fork oil and Redline.

I've seen a lot of custom damper tuning and Sna Keoil's in my time, all from people BEHIND me on the grid. Lighter oils and shaved needles, SM needles, and all sorts of other "more gas" concepts just result in a fatter mixture and a slower car. Leaner is meaner, FTW :smilie_pokal: at most tracks.

Now then, if you're spending a LOT of time above 7000 rpm, you may need a bigger jet and the appropriate needle. And I mean based on time at rpm, not the fact that you get 7400 rpm at the dip at the old Road Atlanta. If aluminum from the top of the pistons is showing up on your spark plugs we may need that. Otherwise, the race is won coming off the corners at 4500-5500 rpm, where most Z folks are way too fat with their mixture....

YMMV
 
I wouldn't use that.

Just get some 20w motorcycle fork oil from your local motorcycle shop. Cheap, works well.
 
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