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#1
10-03-2009, 12:12 AM
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600 HP Engine Mounts
I have a 1967 firebird that will mostly be driven on the street. It has 585 HP, TKO 5 speed, and 275 rear tires. I would like to stay away from solid engine mounts. What options do I have and will Mity Mounts handle the horse power? This car will get a lot of street miles.
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#2
10-03-2009, 01:08 AM
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IMO Good luck with anything but a solid mount at least on the drivers side.
Or use rubber mounts, none of new ones are worth a $%#^ anymore and use a chain from frame to headbolt or front of head on drivers side with about a 1/4" or less slack in it. Another option are the poly mounts, Ive never used them on motor but I hear they are good. I have poly mounts on the trans on two cars and they seem ok. Resistant to oil which kills rubber. Stock replacement rubber mounts for motor and trans are mostly from India and China and the rubber rips out easily. I believe the mitymounts are ordinary rubber mounts with the lock tab bent up which you can do yourself if you look at them you'll see what I mean. I did that on my 63 which has the same mounts as early Birds and its been good for many years with only 400hp and only seldom driven so your results may vary with more power and miles. Sounds like you have a FUN ride there! |
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#3
10-03-2009, 02:38 AM
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MIDPLATE MIDPLATE MIDPLATE !!!! No kidding. And I don't like solid side engine mounts as it's been proven to stress the number 2 and 3 mains.
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#4
10-03-2009, 03:39 AM
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have the rubber ones with 530 hp no problem not even without a chain ore anything..
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#5
10-03-2009, 06:48 AM
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I had rubber ones with the Jim Hand mod done to the LH mount, and I used front "Elephant Ears". No issues.
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Darin '64 Bonneville Wagon (sold) 69 Lemans-All motor (sold) 9.81 @ 136.39MPH |
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#6
10-03-2009, 08:02 AM
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The three options that I have experience with...
It sounds like you want a mount that allows some engine movement and lasts without breaking frequently, I suggest you try the NAPA mounts, they are a factory style, and have two stops built-in and yhey cost the least of my three options, but they do allow the most movement…
The mity mounts are a good option, however they do allow some movement. The left side of my engine was lifting slightly with mity mounts installed, but they never broke...I forget what they cost, I think they were over $100... Right now I'm using solid mounts, and a urethane trans mount, with no problems, after 636 passes the engine still does not move at all, which is what I wanted... I don’t think the the A-body mounts will work in a F body so the clever Jim Hand trick is not an option… The pic with three mounts, shows two well used mounts on the left that never failed because of the two-stop design, the one to the righ only has one stop...
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1969 Firebird, Tx3-455/468 machined by CVMS E-heads by Dave Wilcox/Comp Cams 300B-6 flat solid 850DP on E-85 by Eric Niefert/T2 1" plastic spacer T-400/PTC 4000/390's/30x9 Hoosier radial slicks,#3400 1.38 60' 6.32 @ 108 MPH at Northeast Dragway NC 5/23/15 (9th pass on new engine) https://m.youtube.com/watch?v=ePCu2v...ature=youtu.be 1.37 60' 6.26 @ 109 half track, 9.86 @ 136 1/4 mile, #3350 11/26/16 at Richmond Dragway (125th pass on new engine) |
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#7
10-03-2009, 08:20 AM
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I was probably just lucky but i had stock type mounts in my ventura and ran 9.11 with 1.33 60fts with no chain.Greg
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#8
10-03-2009, 10:04 AM
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To: John5670 / Pontiac Gregg
Solid motor mounts kill main bearings. I just use the factory motor mounts and add a chain
to the front of the drivers side of the motor, with about 1/16" slack. This way the motor can be all happy on the factory mounts and when you get on the gas, the chain keeps the motor from tearing out the mount. Works GREAT !! I have one on better 1/2's 1973 Ventura, 428 RA4,Pump gas, 648 horse @ sea level, 572 horse ( actual dyno #'s!!) where we live ( Longmont, Colorado, 5050' elevation) Pontiac Gregg
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Greg Merrick |
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#9
10-03-2009, 10:33 AM
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I've been using the Mity Mounts in my '67 Firebird for a while now. I have around 435 rwhp N/A and use 150 shot on top of that at the track. Have used them with TKO-600 manual trans, TH-400 and currently a 4L80E. No problems yet. Before that, I used standard rubber mounts with a torque strap. I actually broke the off-shore plain rubber passenger side mount after a few years, how I don't know (aggressive downshifting maybe??).
http://www.mitymounts.com/index.htm .
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  1967 Firebird ragtop, 464, Weiand 8-71, ported 6H heads, Hyd roller, 4L80E, paddle shifter, Moser 9", Cal-Tracs, Vintage Air, Corbeau seats, 13"/12" disk brakes, Hydraboost, electric cutouts and M&H drag radials. 
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#10
10-03-2009, 11:36 AM
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I run the stock mounts with a chain to the drivers side head with very little slack. I replaced the mounts about 15 years ago. They may be better than the mounts that are made today, mabe not, I don't know. I'm near 750 hp running in the 9.50's without any problems yet. A front and midplate would be better though if you have the time to do it.
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Come take a ride http://www.youtube.com/watch?v=P7Y8Awfk2I0 2008, 2013, 2015, 2016, 2019 Central Il Dragway Mod track champion and 2015 IHRA Div 5 Mod champion 2024 Chief of the Pontiacs 
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#11
10-03-2009, 12:18 PM
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FYI another thread about securing the engine in the chassis without using solid mounts:
http://forums.maxperformanceinc.com/...t=engine+chain
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Brad Yost 1973 T/A (SOLD) 2005 GTO 1984 Grand Prix 100% Pontiacs in my driveway!!! What's in your driveway? If you don't take some of the RACETRACK home with you, Ya got cheated    
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#12
10-03-2009, 12:39 PM
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Ran good factory mounts for years (10+) with a chain on the drivers side head pushing 1000hp and seeing lots of street miles.
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The secret to happiness is not getting what you want but rather, wanting what you have. |
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