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MOTOR MOUNTS QUESTION

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Old Jan 26, 2014 | 10:28 AM
  #1  
smokintires's Avatar
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From: lewiston idaho
Car: 1984 firebird and a s10
Engine: 406 and a357
Transmission: 400 turbo and a 350 turbo
Axle/Gears: 4.11 and 4.56
MOTOR MOUNTS QUESTION

whats the difference between solid mounts,and a motor plate?and just because im trying to learn here,do you need a mid plate with solid mounts?just wondering
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Old Jan 26, 2014 | 11:03 AM
  #2  
smokintires's Avatar
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From: lewiston idaho
Car: 1984 firebird and a s10
Engine: 406 and a357
Transmission: 400 turbo and a 350 turbo
Axle/Gears: 4.11 and 4.56
Re: MOTOR MOUNTS QUESTION

is there any experts on here?
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Old Jan 26, 2014 | 11:21 AM
  #3  
Barlow8869's Avatar
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From: Mattoon Il.
Car: 1989 IROC-Z / T-Top -1987 GTA
Engine: 305 (LO3) _350 (L98)
Transmission: 700R4 _ 700R4
Axle/Gears: 2.73 L.S. - ???
Re: MOTOR MOUNTS QUESTION

http://www.swracecars.com/store/imag...ledpackage.JPG
one for the front and one for the rear
solid motor mounts just replace the factory mounts, but have no rubber in them
http://s3.amazonaws.com/s3.racingjun...me-mount-G.jpg

and no, you do not need a mid plate with solid mounts
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Old Jan 26, 2014 | 11:30 AM
  #4  
khulsebus's Avatar
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Car: '89 Camaro
Engine: LS1
Transmission: 4L65/70E
Axle/Gears: 9 Inch, 3.70 gears
Re: MOTOR MOUNTS QUESTION

Straight from the NHRA rulebook:

Where an SFI 6.1, 6.3, or 9.1 bellhousing is mandatory, a full, one- piece motor plate is also mandatory at the rear of the engine block. The motor plate must be constructed of steel or 6061-T6, 7075-T6 or 2024-T3 wrought heat-treated aluminum alloy plate, minimum 1/8-inch thick for 6.1 or 9.1 applications, minimum 3/16-inch thick for 6.3 applications. In addition to the fastener requirements noted below, the SFI 6.3 flywheel shield must be fastened to the motor plate with four 1/2-inch-diameter Grade 5 shoulder bolts or high strength steel (or titanium) fasteners and nuts, one in each quadrant. Where an SFI 6.2 bellhousing is mandatory, see Section 2:8 for motor plate and fastener requirements.

Honestly by the time that you need one, you'll probably already have a rule book and know what else you need.
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Old Jan 26, 2014 | 02:08 PM
  #5  
AlkyIROC's Avatar
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From: 51°N 114°W, 3500'
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: MOTOR MOUNTS QUESTION

Solid motor mounts simply replace OEM mounts so the engine is still attached to the car from mounts on the side of the block. With a high torque engine, this can distort the cylinder walls where the mounts are located. The rear weight is still supported by the transmission tailshaft at the trans mount.

A front motor plate bolts to the front of the engine. It uses the lower mount holes in the block beside the balancer as well as going behind the water pump and also use the water pump bolts (dual water pump gaskets required). This moves the water pump away from the block and if you use a belt to drive the water pump, adjustments need to be made to keep all the pulleys in line. As long as you still use a trans mount, nothing else really needs to be replaced however if the trans tailshaft housing ever breaks, the back of the tranny will fall to the ground.

Using a mid plate with the front plate allows the engine to be supported at the front and back. A trans mount should still be used with larger, heavier transmissions. My powerglide is simply bolted to the back of the engine and does not use a trans mount. Solid trans mounts are never recommended as they can break the tailshaft housing.

Using front and rear motor plates allows you to position the engine/tranny exactly where you want in the chassis. Mine is sitting as low as possible and it's pushed back as far as it can go to help redistribute weight in the car. Also when running front and mid plates, the engine/tranny will flex the plates forward and backwards. Braces on both sides of the engine go forward or backward depending on available room and attach to the frame to eliminate this flexing motion.

Where an SFI 6.1, 6.3, or 9.1 bellhousing is mandatory, a full, one- piece motor plate is also mandatory at the rear of the engine block.
That rule is not going to apply to anything running in the bracket classes.
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Old Jan 26, 2014 | 07:15 PM
  #6  
smokintires's Avatar
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Joined: Jan 2014
Posts: 5
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From: lewiston idaho
Car: 1984 firebird and a s10
Engine: 406 and a357
Transmission: 400 turbo and a 350 turbo
Axle/Gears: 4.11 and 4.56
Re: MOTOR MOUNTS QUESTION

thank you very much,now I know
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