Big block motor mounts

Mirada512

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Hey guys what motor mounts are you guys using for the big blocks. I was going to go with C body big block mounts, I heard those work. I also know that engine-swaps.com is also selling them again. Any pros and cons or your thoughts? Thanks!
 

BudW

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One side stock big block engine mount (Right?) is in correct position (front to rear and Left to Right). The other side (Left?) stock big block engine mount is about 1/4 inch different front to rear (but same Left to Right). I have heard from friends that there is almost just enough give in the rubber bushing to accommodate that much difference (but no first hand difference).

I have a few new stock big block engine mounts and my plan is to pushing the rubber insert that distance (1/4 inch, or so) and call it a day. Not sure about using screws like this person did - but screws are hidden so can't say why not. Sense I already have new OE mounts, I don't see a reason why not to use 'em.

Forum link: Big Block C body to F body mounts
FMJ BB_mounts3.jpg


One thing I am not sure about, however, is the small block K-frame mount height is the same for the big block mounts. I suspect they are - but not measured to confirm.


On a different note. The Schumacher SB to BB motor mount conversion requires K-frame modifications - to use their mounts. I don't know if the new company has changed this or not - but here are the "old company" mounting instructions for their SB to BB conversion kits (below).

BudW
 

Duke5A

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Got mine from engine-swaps. Comes with instructions and as Bud says it requires a little work to the driver side motor mount tower. You'll also need to grind down clearance for the oil filter too. Give some thought to a remote filter setup. Mine is right behind the bumper. This will make life a lot easier.

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BudW

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Thank you, @Duke5A
I can re-locate the battery on my Fifth Ave to the trunk - but have a harder time doing so for my station wagon. Having the battery in place can make big block oil changes fun sense the torsion bars are in the way to access from underneath.
I am highly considering doing something exactly like what Duke5a is doing myself for the engine, and placing an external filter for transmission on the other side


On a different note: all Chrysler "spool" style engine mounts for cars are "mostly" the same, from '73 to '89 within each engine family.
Big block spool mounts are the same from '73-78 - except some have an extra nut welded in (see below picture) for some obscure bracket used on a few cars.
Big block mounts are also longer than small block mounts are.

The big blocks had three different part numbers (depending on the year) for each side - but the difference was not the metal mount but the softness of the rubber. After 20+ years of usage, I don't think any one can tell the difference of rubber softness - except when rubber is broken.
This mount, you can see stamping showing White and Green (softness of rubber):
BB Spool.jpg

The other side is "orange" if you couldn't tell (marked by orange paint stripe).

Small block spool mounts came in two rubber grades (police and other). By the way, the hard rubber OE mounts have not been available for decades.
BudW
 

Greg55_99

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One side stock big block engine mount (Right?) is in correct position (front to rear and Left to Right). The other side (Left?) stock big block engine mount is about 1/4 inch different front to rear (but same Left to Right). I have heard from friends that there is almost just enough give in the rubber bushing to accommodate that much difference (but no first hand difference).

I have a few new stock big block engine mounts and my plan is to pushing the rubber insert that distance (1/4 inch, or so) and call it a day. Not sure about using screws like this person did - but screws are hidden so can't say why not. Sense I already have new OE mounts, I don't see a reason why not to use 'em.

Forum link: Big Block C body to F body mounts
View attachment 46357

One thing I am not sure about, however, is the small block K-frame mount height is the same for the big block mounts. I suspect they are - but not measured to confirm.


On a different note. The Schumacher SB to BB motor mount conversion requires K-frame modifications - to use their mounts. I don't know if the new company has changed this or not - but here are the "old company" mounting instructions for their SB to BB conversion kits (below).

BudW


I had to laugh because it's been 42 years since I modified those Big Block mounts to work on my F-body frame. Those are mine and yeah, they worked. Hinckty as they look, they worked. That was all that was available back then and I was broke.

Greg
 

Remow2112

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My first BB install was done with factory mounts on a SB K frame. It works but not perfect. These are my notes I sent to someone who wanted to do it.

Take stock 73 and later BB motor mounts and cut the insert flush to the outer tube. The sleeve that the bolts goes through sticks out both end of the rubber insert, that is what you trim back, I did it with a grinder.

The other thing I had to do was drill some 1/4" holes on the inside (part closest to the block) of the motor mount so it would collapse enough to fit the small block K-frame.

Best way to do it is to get the engine dropped in, Do not tighten down the engine mounts yet, then bolt up the tranny. Then move the tranny into position. You will have to slot the tranny motor mount and pry/push it to the passenger side. Once you bolt up the tranny crossmember you can finish the motor mounts. Leave all the mounts a little loose so it has some adjustment.

Now everything should be where it is going to sit. Go to Home Depot and buy a bag or 2 of (I think they were 3/4" flat washers) washers. Put a bunch together in a vice and cut a wedge out of the bottom so they are slotted. Now put as many as you need in the front and back of each motor mount to pad it out so when you tighten down the bolt you don't crush the ears on the K-frame mount.

Tighten it all down and you are good.

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This is a write up I did.
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Here is the deal. I did this for a mostly drag race car.
1. I have manual steering (Don't know if PS will clear.)
2. Used factory late model BB spool motor mounts.
3. The tranny mount (not the cross member) needs a little modifications.
4. Hedman Hedders 78030 work great in a Volare.
5. I put in a cheap 26" aluminum radiator with the upper and lower ports matching a BB.
6. Milodon 30931 oil pan
7. I am using manual brakes. You can stick with PB but you will need to find a different power booster that will clear the valve cover. An A-body one might work.

Details:
Using the stock motor mounts will put the engine about a 1/2 further forward then using the Schumacher conversion mounts and a little taller. What I did was got a set of beat BB motor mounts and drilled some 1/4" holes through the rubber on the engine side of each mount. (They sit just a little wide and you need some extra give. I also trimmed the extra rubber and metal off the front and back of the motor mounts making them flush to the spool insert front and back. If you don't do that when you get it in the K frame mounts it tweaks the engine so it sits crooked in the engine bay. You will need to buy a bunch of flat washer and cut slots out of the bottom. When you trim the spool ends it leaves a gap on the K-frame mount and you have to fill the gap before you tighten down or you will never get them tight. I did that with cheap washers.

The only mod I did on my K frame was on the passenger side at the front of the motor mount. There is a long thin v fin towards the front of the car. I took a grinder and cut it off because the engine block hits it.


The tranny mount has 2 slots. You need to cut them open on the end that goes to the front of the car. You will then be able to have enough adjustment to get it connected to the 727 tranny. If you weld you can extend the slots.

I used the headers listed above. There are 2 styles of BB headers (that I have seen) this version will not work, Hooker Headers 5209HKR. It has the 5 tube cross over and the 7 sticks out. The 7 will not clearing the steering.

You cannot use a small starter or modern starter. It will hit the header tube. They sell expensive indexable style starters that will work. I just bought a old style 440 starter (It has a longer motor and a little more torque) For those that will ask. I did try banging some clearance in a headers tube to fit the small style starter. I got the tube to half the original diameter and gave up. Not worth it to loose that much flow in 1 tube. I have not had an issue with heat saturation yet.

For a drive shaft I went and found one out of a 70 station wagon and had it shortened. I would not recommend using the small diameter drive shaft. I have a mild 400 and it feels radically different launch then my 375hp 360.

I also chose to cut part of the fender well out on the passenger side to make it easier to get to the #6 spark plug. All the rest are easy. If you don't want to go that route you can drill a 1.5" hole in front of the #6 and get to it that way. The plug wire will still be a pain.

Oil pans: I started with a 699 (this is a number stamped in to the bottom of the pan ... Follow this link for an oil pan breakdown: Oil Pans) But the one I had did not have any baffles. After talking to a friend that has been racing BB Mopar for 20 years I switched to the Milodon listed above. He said that with a good launch and no baffles ( i am not exactly clear on what he considers a good launch :) His cars runs in the mid 10's.) you will starve the bottom bearings. He then warned me that it could still be done with a baffled stock oil pan so I chickened out and ponied up some cash. Back to oil pan options.

Mopar pans 699, 971, and 187 should fit fine. 971 is best just due to the extra room from the front of the pan to where the sump starts and you can still buy one from Mopar 5007807.
These are all 5 quart pans and if you are just street driving. I would just find a used stock pan and go for it. Most generic aftermarket oil pans are elongated 187 pans. Using a 187 or 699 might require a little trimming on the lip on the back of the k frame where the sump sits.

Do not try to put the engine and tranny in together. The engine hits the firewall and prevents the oil pans from clearing the k frame. I tried!

I also chained down the driver side of the engine since I beat up on the motor mounts quite a bit.

There is no reason that this could not be done with a 440 but the extra 1/2" a side is going to make the passenger side even tighter fit.

If you have your act together there is not reason that you couldn't put a BB in your F or a normal weekend. But they will be long days.

Dan...
 

Oldiron440

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The motor is offset to the passenger side about 2", when swapping the big block and TF start with new motor and transmission mounts, you can locat offset and front to back with the transmission mount so you need to have it correct.
 
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