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Author
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Topic: lean jets or wrong thermostat?
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chips67
Gearhead Posts: 262
From: louisville, ky, usa
Registered: Jul 2001
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posted 09-27-2001 10:32 PM
   
made several changes to the car this year. aluminum heads, huge griffin radiator, rr's, cam, and put in a 160 thermostat. i thought i had my jetting down pat but last night at the track was wierd. my first run the car was hot as it gets (just drove there) and the ambient tempurature was abot 70. the car busted off a pass with 87mph! the highest mph ever. as the night went on the air got colder and the car had time to sit with the hood up. the car bounced all in the 86 mph range but never went 87 again despite the temps almost reaching 50. i started thinking jets are too lean, but then i noticed the mph wasnt steadily dropping, even with better et's...it was all over the 86's. this totally blows the cold air induction theory but what about the thermostat? you know how aluminum heads have issues with retaining heat. im running a 160 stat with straight water. all last year the car ran better the cooler the motor/air temp. could the 160 stat be killing some hp? i have a 180 ready to go. what do you guys think? also, i bumped the timing about 2 degrees and saw a very slight gain (2 hundreths) in et with my consistent crappy 1.89 60 ft., does this mean i go back to square one with my jetting? ------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.
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70coupe
Journeyman Posts: 92
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 09-27-2001 10:43 PM
What was the humidity? My cleveland hates humidity. You can give it warm temps but nothing slows my car down like humidity. Usually when the temps get down to 50 like you said, dew sets in. This is just my guess.
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chips67
Gearhead Posts: 262
From: louisville, ky, usa
Registered: Jul 2001
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posted 09-27-2001 10:46 PM
70, it was low humidity, probably lowest its been all year. does this info help?------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.
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n2oMike
Gearhead Posts: 317
From: Spencer, WV
Registered: Jan 2001
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posted 09-28-2001 06:41 AM
My vote is for more jet. My car needed a few more sizes when it had a 650DP.------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
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chips67
Gearhead Posts: 262
From: louisville, ky, usa
Registered: Jul 2001
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posted 09-28-2001 03:43 PM
mike, it came with 67/73's and after some track time it seemed to like the 69/75's i have in it now. the air temp was about 10-15 degrees warmer last month on average, which is when i did the job. mike wouldnt mph been progressively worse as air temp dropped? hang on, just took another look at slips. it did go progressively worse until the last run when it came up slightly. the last run was when i advanced my timing by 2 degrees. ok, already changed thermostat to a 180....going to change jets now. ------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.
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n2oMike
Gearhead Posts: 317
From: Spencer, WV
Registered: Jan 2001
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posted 09-28-2001 03:56 PM
My car ran best with the engine dead cold and even larger jets than that. I'd yank that 180 degree thermostat immedietly. At the track I would remove the thermostat and use one of those Moroso electric motors to drive the waterpump. This would allow the engine to get stone cold between rounds. If you want that last little bit, you can dump ice onto the intake.  Synthetic oil is a GOOD idea when operating at these cold operating temperatures. Regular oil is still pretty thick until it gets warmed up, and won't flow properly. I've had good luck with Mobil 1 15W-50. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
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kid vishus
Gearhead Posts: 1223
From: a bad scene from "children of the corn"
Registered: Oct 2000
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posted 09-28-2001 08:34 PM
My opnion pn the oil, if you're going to run synthetic cold, run something around 5w-30.I am running syntec 5w-30 in my race motor. I would run something even lighter if they offered it. I know Royal Purple makes a 5w-20 (I have run before and really liked),and a 0w-10. But unfortunatley, my finances cant support oil that costs that much right now.
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chips67
Gearhead Posts: 262
From: louisville, ky, usa
Registered: Jul 2001
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posted 09-28-2001 10:32 PM
mike, you are dead on! the car ran like crap with the 180 stat. i mean it dropped 2 tenths and 2 mph right off the bat. i guess whatever i gained on the jets and snubbers i lost with the thermostat and then some. it really fell on its face. started to pick up as the car cooled between rounds till i gained back a tenth and almost 1 mph but then the shifter wouldnt go into 3rd! what a bad night! all my friends there, dad, couldnt even post an 8.0 much less a 7. i got my 60 ft times down to 1.80 by 5000 on the 2-step and feathering the clutch out a bit on launch but that pass was crapped out with the shifter hanging up in 2-3 again. i had this problem before and its usually the crappy little rod clips getting loose. i just hope it isnt the rings in the trans thats supposed to slow the gears down when you clutch and shift. the cherry on top is that 2 times in the burnout box tonight i had one wheel burnouts....just lovely. what else can go wrong. ------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.
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