FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#21
|
||||
|
||||
So from the discussion it sounds like one set of mounts moves the motor a little more forward? If so does that affect trans mount location?
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#22
|
||||
|
||||
I always frowned at mounting at the pan rail. The extra bolt and relocation of the 455 mount helps but I would think the biggest issue for stock vehicles would be shock loading; ie. hitting large potholes, etc.
This is GM's LT architecture (2014-present). Evidently the General's march toward progress is webbed mounting in line with the bulkheads and centered on the motor. Note these are deep skirt motors; the row of 5 bolts above the pan/block line are cross bolts for the main caps. |
#23
|
|||
|
|||
The 455 frame mtg brackets are moved fwd & line up with the further fwd mtg of the 455 motor mounts. No difference in where the engine is fore/aft in the chassis. Buick did a very similar thing with the slightly fwd mounted cast iron engine to frame pads their 70-72 GS 455 models.
__________________
Buzzards gotta eat... same as worms. |
#24
|
||||
|
||||
Roger I guess I will go look at a block used to my second gens using the same bolt holes on a 455 and a 400!
I guess the forward mount hols vs back ones are just the difference
__________________
Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#25
|
||||
|
||||
To further demonstrate the change, the first picture has the early 2 bolt mount. Notice it straddles he #3, or center main bulkhead.
The second picture shows a 5 bolt dual pattern. The first and third holes are used in the 455 later style mount, along with the raised hole. This puts stress on the #2, and #3 main web bulkheads. It took me awhile to see the thoughts of the engineers, but when you see he blocks from this angle, the engineering change is pretty obvious. You also see the #2, and #4 holes are the early design in contrast. The extra raised stiffening ribs near the late mounts are also very evident.
__________________
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 Last edited by Sirrotica; 05-28-2023 at 12:08 PM. |
The Following User Says Thank You to Sirrotica For This Useful Post: | ||
#26
|
||||
|
||||
Quote:
I just saw this…. https://butlerperformance.com/i-2445...ml%3Fq%3DMount Very little info on Butler’s or Warpath’s site on it, on the surface it appears to do exactly what you/me are looking for?
__________________
costs too much |
#27
|
|||
|
|||
I am still using the 455 big car style motor mounts (Mighty Mounts) on my 73 400 High Port stroker build. Only I have the elephant ears and a mid plate as part of it.
The motor mounts are for location and fore and aft movement. With the elephant ears you can pull the trans and the engine does not drop in the rear when mid plate is removed. Thing was with the OEM 455 mounts only, the engine rocked less then with the Mighty Mounts. Not really a upgrade. |
#28
|
|||
|
|||
Quote:
OTOH, it's a bolt-in solution that requires no engineering, fabricating, or welding. |
#29
|
||||
|
||||
Quote:
|
#30
|
||||
|
||||
No matter what type of stock motor mounts you use, in a hard usage scenario they are going to first stretch, then loose the bond from the steel and then tear, and fail.
I learned years ago that without a hard restraint to limit the engine movement 500 lb ft of torque is going to destroy the rubber no matter who makes the mount. Years ago I devised a turnbuckle restraint that is infinitely adjustable to tune the amount of movement it allows before it puts a hard stop to save the rubber in the mounts. I usually leave 1/8" of movement before the turnbuckle stops the engine then it applies the torque stress to the upper portion of the engine. Having a small bit of adjustable movement, still allows the rubber to soak up vibrations, as it was engineered to do. I've never used any steel mounts in any Pontiac, race car or street car. You're stressing the thin area of the block just above the oil pan rail, way more than the engineers ever designed it for originally. I attach the 3/8" turnbuckle to the frame rail, and attach the other end to the front of the cylinder head. The reason I want the limiting device on the front of the head is the water crossover will transfer the torque stress from the attachment point, through the water crossover, then to the right cylinder head. This takes the bulk of the torque stress from the pan rail area and the main bulkheads. I've seen quite a few grenaded Pontiac engines in race cars that the #3 main web is cracked up to the cam bearings, some caught the cracking before the engine scattered, some didn't. The common denominator was relying on the stock mounts to restrain the engine, sometimes steel mounts, sometimes basic parts store mounts. My advice is if your going to hammer the car hard, don't rely on the either type (2 hole, or 3 hole mount) to limit the engine movement of a car that is raced or just abused on the street. Add slicks to the combination, and everything gets multiplied. Street cars with 6-800 HP aren't uncommon any longer. Of course you can go the motor plate route too, and just disregard the OEM mounts. Tat's my take on the mounts, YMMV........ |
#31
|
|||
|
|||
I stopped getting notifications on this thread and was not aware of the new responses. There is good information in here from everyone - thank you.
I received the Ames 400 mounts last week and they are very nicely made. I do understand the advantage of a clamshell which will positively prevent an engine from becoming unrestrained, but the factory design does include the large interlocking tab that should prevent total separation. For my application - ~425hp on street 235 tires - I will not be stressing things too much. I feel like I can also keep the factory mount and frame attachment tucked as close as possible to the engine which is important since I will be dealing with exhaust, steering shaft, and mechanical clutch linkage all on the driver's side and I need as much space as possible.
__________________
Hoping to finish a project while I'm still able to push the clutch in.... 1963 Tempest Convertible (195-1bbl, 3-speed transaxle. 428 RAIV, 5-speed, IRS planned) Pictures |
Reply |
|
|