And I wonder why i hard time setting the timing...

-
70aarcuda

70aarcuda

Master Hoader of SBM
Legendary Member
Joined
Jan 16, 2005
Messages
16,639
Reaction score
5,968
Location
las vegas
Last week I changed valve spring on my 71 Demon cause it looked like it might have lost a mph or 2 in trap speed...Today I after rounding up the tools finally, I installed and adjusted the rockers.

After getting that done, I was going to change out the MP race distributors, as I have an old cast iron one in and changing it out for a newer aluminum one that was shooting duck last year due to a bad pick up coil. Which was swapped out for a new one .

Well..I set the damper to #1 TDC to swap out distributor since both are MP race distributors they are actually somewhat different..the tach drives are in difference places..but anyway..I notice that the rotor is pointing over where #8 would be. So I get small screw driver..inset in #1 plug hole...piston is down in the bore...WTF... I turn the engine over by hand check went the piston is TDC...I look at the balancer and no where #1 on it..

Fricking SFI Summit balancer had slipped..a good 90 degrees...And I wonder why went I put a timing light on it last summer I could not set the timing...So I spend the a few hours today swapping out balancers, and then had to readjust the rockers again...since I use the MP chart...

http://www.summitracing.com/parts/SUM-C4278/

replaced with one I got in a deal last year...

http://www.summitracing.com/parts/SUM-B64278/

yeah same brand...but cost twice as much...

So tomorrow I should be able to finish swapping out distributors and getting the timing set...the old balancer was probably 3 yrs old....
 
Thanks for sharing, I was looking in the catalogue at them just the other day. I was thinking why the heck is the one so much cheaper, now we know why?????????
 
yeah..i was wondering also....and reading the description at the bottom of the page...the cheaper one is spin tested up to 12k and the expensive one is spin tested to 18k...

they do look different...the expensive was made Australia
 
There is no damn excuse in this day and age why ANY balancer should slip.....................
 
well f*ck. i have that same unit on mine....its brand new, havent even started the engine yet for cam break in....i have a few weeks before i can start it....
 
That would have sucked if that thing came apart. A customer had one come apart on him while going down the track, took out the fan and radiator. Good thing you caught it.
 
You realize that the first link you post is an SFI unit for an externally balanced 360 and the second link you posted is an SFI internally balanced unit. Maybe that was the whole problem.
 
Glad to hear I'm not the only one having damper issues; I had my builder install an SFI inertia ring damper by Professional Products. damn thing slipped the ring after 5 pulls on the dyno and 50 passes, stroker started vibrating, replaced it with a ATI super damper....Although the PP damper was $260 it is MADE IN CHINA.....never again:banghead:....its a boat anchor now!
 
After my last fiasco with a balancer eating a customer's engine I mark every new balancer so I can check for slippage.
 
1970Duster said:
You realize that the first link you post is an SFI unit for an externally balanced 360 and the second link you posted is an SFI internally balanced unit. Maybe that was the whole problem.
Click to expand...

And you may realize that the second balancer has a bolt on weight! It works for either application.
 
1970Duster said:
You realize that the first link you post is an SFI unit for an externally balanced 360 and the second link you posted is an SFI internally balanced unit. Maybe that was the whole problem.
Click to expand...


NO..that was not the problem...as said..they both use a bolt on weight ..so the balancer can go both ways...

beside the weight does not bolt on to the outer ring which is what slipped....it bolts onto the hub of the balancer..


Engine Balance External, 15.02 oz. imbalance
Safety Rating SFI 18.1
Degree Markings Yes
Degree Marking Range 60 BTDC to 0 TDC
Outside Diameter (in) 7.000 in.
Harmonic Balancer Material Steel
Harmonic Balancer Construction Elastomer
Harmonic Balancer Finish Natural clearcoated
Mounting Hardware Included No
Quantity Sold individually.
Notes Weight is 12.26 lbs. Bolt-in counterweight is removable for internally balanced applications.
 
Nice69 said:
Glad to hear I'm not the only one having damper issues; I had my builder install an SFI inertia ring damper by Professional Products. damn thing slipped the ring after 5 pulls on the dyno and 50 passes, stroker started vibrating, replaced it with a ATI super damper....Although the PP damper was $260 it is MADE IN CHINA.....never again:banghead:....its a boat anchor now!
Click to expand...
Hey Dave,hope the ATI Super dampner helps you out.When I had my stroker built,the ATI super dampner was recommended.Pricey,but is rebuildable.Hope you get your problems figured out Tony.After watching your vid lastnight,you edging on the 10,s :cheers:
 
pettybludart said:
Hey Dave,hope the ATI Super dampner helps you out.When I had my stroker built,the ATI super dampner was recommended.Pricey,but is rebuildable.Hope you get your problems figured out Tony.After watching your vid lastnight,you edging on the 10,s :cheers:
Click to expand...

I mentioned this in a thread way back, but I got my Super Damper as a 'blem' item for under $200 direct from ATI. I expected it to look a little shabby cosmetically but I still have no idea why they rejected it.

Just thought I'd mention it again for those who think the ATI stuff is out of their price range.
 
pettybludart said:
Hey Dave,hope the ATI Super dampner helps you out.When I had my stroker built,the ATI super dampner was recommended.Pricey,but is rebuildable.Hope you get your problems figured out ]

Got it on there Scott it was a major PIA, had to get it honed to fit the eagle crank snout, and find a longer crank bolt, then warm up the hub in the oven....pullies were no problem, it sure is a quality piece......Also ordered the mono's, strut rods & shocks, should be in next week:cheers:
Click to expand...
 
well..left the old distributor in..put the plugs, wires and cap back on..fired engine this afternoon for a few minutes...looks like I only got 25 degree of total time...will double check tomorrow....went i can run it a little longer....while no one is home...

this engine (suppose to be spare) came out of our 71 dart and was run in the 71 demon at MATS 2011, I never checked the balancer since the engine was assemble a few years ago, so somewhere it start to slip...I changed distributors at MATS 2011 due to a bad pick up coil, so I would guess that since then the timing has been off......I remember last summer at Top Gun Raceway, I checked the valves one morning there and checked the timing and now i remember the timing looked funny and I had a hard time see the marks...i just commented to myself dont every buy another chrome balancer cause it was a pain to see the timing marks..

anyway...I think I found out why the car is down a couple mph...and now i have new valve springs too...LOL
 
And I have been chasing a small hesitation at launch also since Top Gun...I switched out squirters and played with pump shot...

Dont have that problem now with transbrake in car....
 
You must log in or register to reply here.
-

Back
Top