My 49 Pontiac is set up for a Pontiac 400, I have been told all pontiac blocks are the same by some people. If this is correct and I get the motor and trans from a 1976 bonneville 455 will all the mounts line up? It is suppose to have the front clip from a camaro or trans am. This was done before i got it. What do you think?
Well..... there is a little more to it than that. There are different mount patterns depending on the year, not the size. However, after looking over your picture, I see large pieces of steel welded to your crossmember. That is not stock, that is something someone did. I can only see the right side...I see a shadow where there was a 3 bolt mount bolted to it.... correct? Answer me and i will help you further. also a front shot showing both mounts would be helpful Steve Barcak www.pontiacheaven.org <DIR>Hosting 11th annual Pontiac Heaven, show, swap, drags, party and all around good time. Saturday April 4, 2009 at Speedworld near Phoenix, Az Also hosting- 7th annual Nostalgia drags, show and swap coming Sunday April 5, 2009 to Speedworld. Phoenix, Az </DIR>
"All the same from the 326 to the 455 " Nope, not true. Steve Barcak www.pontiacheaven.org <DIR>Hosting 11th annual Pontiac Heaven, show, swap, drags, party and all around good time. Saturday April 4, 2009 at Speedworld near Phoenix, Az Also hosting- 7th annual Nostalgia drags, show and swap coming Sunday April 5, 2009 to Speedworld. Phoenix, Az </DIR>
Oil filter mounting and senting units are not all the same. In some cases you'll have to fine the correct one to clear your frame.
They changed motor mounts over the years. Early ones mount off the timing chain cover. Then they went to the side of the block and then early-mid 70's the added more tapped holes in the side of the block. A '76 block will have all the properly tapped holes to mount in an early side mount as well as the later side mount frame/motor mounts.
The bolt pattern on the risers look like the 3 bolt pattern for earlier GTO/LeMans frame mounts. 69 I believe was the last year with the isolator on the engine half of the mount. After that the mounts on the engine are solid and the frame mount has the isolator half.
You should have 3 threaded mounting holes on each side of the block, for different yrs. & aps. Use the late 70's clamshell style mounts so they don't separate under torque. Just make those frame risers stronger than the mounts.
The motor in question, ls the one in the 76 bonneville 4 door, the guy runs derbys and re-uses his same motor just gets new cars. Of coarse I'm on a budget and I can get it almost free, I bought a 1994 dodge shadow about 5 years ago for $50 and he will trade me for it, or $400 for the motor and trans. Should I just go for it and if it does'nt work go from there?
I don't know why they have the motor up so high ( unless the car sits really really Low.) But I would Imagine finding the appropriate year frame side mount for Trans Am or Firebird would be a great start. same on the motor side. I would get both from Ames Performance (or applekrate-and he does kinda have a "direct line" to Ya.
From what I see from the new pics...someone welded up the adaptors and used the 3 bolt syle bracket mount that was used on '64-'72 Tempest, Lemans and GTO with 326, 350, 389 and 400 engines only. they are not real hard to locate. I have a pair here at Pontiac heaven if you need them. This set uses steel mount brackets on the chassis and rubber mounts bolted to the engine. However, double check that your new motor has 5 motor mount holes on each side. If it does, you can buy the frame brackets and new motor mounts for the same application. If you have further questions, you can post or email me. Good luck, Steve Barcak www.pontiacheaven.org <DIR>Hosting 11th annual Pontiac Heaven, show, swap, drags, party and all around good time. Saturday April 4, 2009 at Speedworld near Phoenix, Az Also hosting- 7th annual Nostalgia drags, show and swap coming Sunday April 5, 2009 to Speedworld. Phoenix, Az </DIR>
When you get the motor check and see if it has 5 or 3 holes on the side of the block. I agree with applekrate that is appears to be set up for the 62-72 Tempest-Lemans-GTO mount setup. Starting somewhere in the early 60's there have been basically two motor mount styles on the Pontiac engines. The first style had two bolts just above the oil pan rail to attach the motor mount to the block. This style was used up until 1969. Then starting in 1970 they added three extra mounting holes to the block. These were first used on the Firebirds with a different style mount to allow the engine to set lower in the chassis. From 70 until either 75 or 76 the blocks were drilled for both styles of mount, hence the 5 bolt holes in the side of the block. Then in 76 or 77 they eliminated the early style two bolt holes from the block. If your engine has the 5 bolt holes you should be good to go. If it only has the 3 later style ones you may have to do some refabbing to make it work. HTH
It looks like the factory frame mount holes are still there in one of your pics underneath that plate. You can remove whats on their now and buy some motor mounts for a 70-76 Firebird with a Pontiac v-8 and bolt them directly to the frame. Unless you want your engine to sit up higher than stock anyway. Here's what the factory 4 bolt mount looks like.
55 Cheiftain, that is not correct "It looks like the factory frame mount holes are still there in one of your pics underneath that plate. You can remove whats on their now and buy some motor mounts for a 70-76 Firebird with a Pontiac v-8 and bolt them directly to the frame. Unless you want your engine to sit up higher than stock anyway. Here's what the factory 4 bolt mount looks like." '70-'76 Firebird mounts are NOT the same. Steve Barcak www.pontiacheaven.org Hosting 11th annual Pontiac Heaven, show, swap, drags, party and all around good time. Saturday April 4, 2009 at Speedworld near Phoenix, Az Also hosting- 7th annual Nostalgia drags, show and swap coming Sunday April 5, 2009 to Speedworld. Phoenix, Az
I don't understand why it has to be a hard one to figure out. If you are on a budget ask him for the frame mounts too. Hack them crap risers off there and put the frame mounts on. If thats a mid 70's Poncho f body clip it should be full of bolt holes for different mounts. If not just set the engine where you want it and drill new holes. A running 455 is worth what you want to give, be it the car or the cash. The clip has the small sway bar so its not a Trans Am or Z28 but Camaro or Firebird. Not that that matter at all with what you want. If you get it done and it seems to have body sway you can upgrade to a Trans Am sway bars. It's thicker. You will have to get the frame bushings for the bar from Just Suspension. They make a bracket with the mounting holes in the right place to use a bigger bar on a non T/A ~Z28 frame.
Thanks for the correction, One thing I do know is I don't know everything. My point was to get the factory engine mount setup for the subframe thats on the car instead of using the welded plates.
Looking at the pictures it seems that those "mount extensions" are there to keep the engine level. Look at the transmission crossmember and you'll see what I am talking about. It would appear that the sub-frame install was done low in the old frame which necessitated those crazy brackets. Without them, the engine would be in a very nose-down position which would bring its own bag of troubles.
Guys, please don't misinterpet me. I am not trying to be a 'know it all'. I am sure everyone here wants to help solve the issue and is sharing what they know is right...or think they know is right. I have about 450 old Pontiacs here including just about every model from 1955-1981 so I have this 'reference library' of real cars to look at. I took the time today to walk my yard, take pics, resize them and share them here for all of you. This thread is not about Pontiac motor mount interchange but, how to solve this problem so I will stick to that. As you said, you have a Firebird sub frame. What someone did was build steel mounts, or plates on your chasiss. Whether they knew what they were doing or not is up to question and we to not need to judge that. Firebird motor mounts and chassis brackets are the same from 701/2 though 1974. that includes 350, 400 and 455. Then the mounts were redesigned for 1975 and stayed that way through 1981 including- 301, 350, 400, 455. First, here are pics of a 70 1/2 through 74 Firebird chassis and their proper mounts............ Look at them closely.. Note- they use a stamped steel bracket that bolts to the frame. then a rubber mount bolts to the engine with 3 bolts.... Steve Barcak www.pontiacheaven.org <DIR>Hosting 11th annual Pontiac Heaven, show, swap, drags, party and all around good time. Saturday April 4, 2009 at Speedworld near Phoenix, Az Also hosting- 7th annual Nostalgia drags, show and swap coming Sunday April 5, 2009 to Speedworld. Phoenix, Az </DIR>
Here is the style mounts for 1975-1981 Firebirds with Pontiac V-8 engines. Starting in 1975, the mount style was changed to what is known as a 'corporate' style mount. This made it easier for those on the assembly line to fit engines from different divisions into different chassis. The rubber portion was moved to the chassis and the engine itself used a simple stamped steel bracket. Steve Barcak www.pontiacheaven.org <DIR>Hosting 11th annual Pontiac Heaven, show, swap, drags, party and all around good time. Saturday April 4, 2009 at Speedworld near Phoenix, Az Also hosting- 7th annual Nostalgia drags, show and swap coming Sunday April 5, 2009 to Speedworld. Phoenix, Az </DIR>
Now, with this information and pics on firebird mounts behind us...back to your quesiton... You asked in the first post...." If this is correct and I get the motor and trans from a 1976 bonneville 455 will all the mounts line up?" The direct answer is- I don't know and no one else here can answer you either. the reason is because you have something that someone fabbed up and none of us can be 100% sure. There is no reason to elevate the engine mounts... as the prior person did...as far as fitting to the chassis. you now know this because you can see the factory mounts are bolted directly to the crossmember and do not need the 'extensions ( for lack of a better word)' that your car has. My guess is due to the type of car your chassis is fitted to that someone simply wanted the motor to sit much higher than the stock location. Nothing wrong with that if that is what you like or want. Now that you know what the stock mounts look like you can make your own choice. I would suggest that whatever motor you end up getting to also make sure you get the engine mounts and brackets. Both the part that bolts to the engine block and to the frame of the donor car. With those parts, you can fit the motor in and the elevated height or the stock height. I hope this is helpful to you. Steve Barcak www.pontiacheave.org <DIR>Hosting 11th annual Pontiac Heaven, show, swap, drags, party and all around good time. Saturday April 4, 2009 at Speedworld near Phoenix, Az Also hosting- 7th annual Nostalgia drags, show and swap coming Sunday April 5, 2009 to Speedworld. Phoenix, Az </DIR>
Very helpful thank you for the pictures and all the info. Is there any advantage to running the motor higher or should I cut them off and go right to the frame like in the pictures?
my guess is they fabbed those mounts up because of clearance issues after it was installed in the 49' i would not worry because the stock mounts are in the location they are for clearance in said stock application of the subframe. get everything level and go to town. keep the pic's coming.
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