How To Repair An Older Hac On A Snowmobile
670 Summit High Altitude Compensator HAC
- Thread starter Broz
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I know many are in favor of removing the HAC when it fails and jetting similar a model with out HAC. That may be the all-time in nigh cases, but I wanted to share something here I learned by reading on another Snowmobile forum.
Y'all can indeed actually recalibrate your HAC pod, if the diapram is good, and it is quite elementary. Start let me back up.
Symptoms:
The sled was super lazy and rich through the entire rpm range. Tiptop rpm we could get was about 7200.
Specs and Jetting:
1996 Ski Doo 670 Summit with fresh elevation stop.
K-10 Interruption
Jaws twin pipes
Air box gutted (shelf completely removed)
Mains: P 370 M 360
#75 pilot jets
Stock 7DPI 1 clip in #3 notch
Distance and Temps:
Plug reading were taken at 4200 ft. and 12 degrees F and still safely on the rich side a scrap.
40 mile test ride later recalibration was from 4000 ft to 6500 ft and temps in the teens F.
So hither is what nosotros did.
ane: Remove the HAC pod from the air box and take it into a heated area at room temperature (threescore ~70* F.) Nosotros were at 4200 Ft. Alt.
2: Make clean all the blue sealer compleely from the plug (screw) on the back of the pod and remove the screw and the O-ring that seals it. clean and grease the O-band place it on the screw and set aside.
3: Apply a light suction or light air pressure to the hole to clinch the diaphram is skilful and will hold a vacuum and does not leak.
4: If all is good, I put a few (3~4) drops of "Power Service" diesel fuel conditioner in each side of the diaphram. (both sides, back where plug was removed, and front end into the center vacuum tube) This volition lubricate things, condition old prophylactic diaphram a bit, disapate moisture and aid against feezing up.
5: At present apply lite air pressure to the back pigsty where plug was removed. (yeah,, blow on it) If you become fuel conditioner in your oral fissure spit repeatedly till sense of taste is gone.
six: While applying pressure a pocket-sized contumely pin will slightly protrude through the front end centre vacuum tube. Get a hold of this brass pin with your fingernail and agree it while y'all supplant the rear plug and greased O-band.
5: Then carefully loosen the plug, slowly letting air out till y'all see the contumely pin going back into the tube then stop information technology by screwing in the plug. Now measure from the tiptop of the tube to down in the tube to the tip of the brass pin. When y'all take hold of it at five mm tighten the screw securely. If yous miss it you tin can have a re-do. Actually all the info we tin can find says 3mm to 7mm. I chose 5mm considering information technology was middle spec. But if you are a piddling either side I think you would be practiced to get.
half dozen: If you have fourth dimension permit the pod set over night and re-measure to assure information technology is non leaking. Or reinstall it and re-measure in a few days just to be sure the pod is air tight inside.
This took our 96 Tiptop 670 from a lazy fatty dog that would only plow 7200 rpm to a screaming machine that easily runs to 8200 rpm in a blink.
We have 50 miles on it now and all is notwithstanding proficient. We have merely been to 6500 feet Alt. Simply she ran the same at that place equally she did at 4000.
Hope this helps someone as information technology did united states of america. Here is a pic of my son and the 670 after recalibration at 6500 feet.
Jeff
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I asunder my HAC (96 670 summit running a 98 HO motor) and plugged the large line going to the hac and and then vented the remaining hac lines to temper.
I have iii vaccum ports on this block. Ane goes to the fuel pump. Ane I accept plugged. With the HAC asunder the motor wants to bog and load upwardly unless I open ane of the vaccum ports to atmosphere...
Tin can anyone help with suggest on this?
I have the manuals and can't find the routing for the crankcase vaccum ports/vents on either the 96 or the 98...
Season is almost gone here - just a few more weeks left and I really want to get out into the hills.
Source: https://www.snowandmud.com/threads/670-summit-high-altitude-compensator-hac.41125/
Posted by: reeddrempan1965.blogspot.com
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