55-59 Engine Placement Question - V8 Swap

[Strider]

Hi,

Currently building a 57 GMC truck and having issues with engine placement in terms of the distributor hitting the firewall and potential for the TH350 not going to fit. Pics show issues.

I put in a sbc in the truck using a Trans Dapt motor mount kit. I based the placement of the engine. To determine placement, I bolted a cast bellhousing to the back of the engine, then bolted that down to the stock bellhousing crossmember ( as I was going to use a 5 speed before). Then I leveled the engine intake and bolted the Trans Dapt motor mounts to the frame. Engine fan is sitting 5 inches from rad. Large HEI GM distributor touches firewall with cab bolted back down. TH350 trans that I am now going to use seems that it will be a tight fit under the floor. Pics show this. Trans needs to come up another 2 inches and go forward another 1 inch or so.

Question is, did I make a mistake basing the placement of the engine off the bellhousing crossmember (which is now removed so that the auto trans can go in)?
What distributor should I use?


Trans Dapt mounts



firewall / trans pic





Any thoughts or help would be sincerely appreciated. My "expertise" is 67-72 trucks. I'm still learning on the TF ones!

Cheers! Enjoy your build.

[PDW HOTRODS]

The T-350 is bigger than the stock 3 or 4 speed trans. You need to work on the floor or move the engine. Its not hard to modify the floor. I have a 350 with T-400 in my 56 and did not need to modify the floor, so mine is lower or forward of yours.

[Strider]

Originally Posted by PDW HOTRODS

The T-350 is bigger than the stock 3 or 4 speed trans. You need to work on the floor or move the engine. Its not hard to modify the floor. I have a 350 with T-400 in my 56 and did not need to modify the floor, so mine is lower or forward of yours.

Thanks for the reply. What you're saying is very true as it wouldn't be difficult to move the engine forward and/or drop it down. Just wondering if anyone out there did the same thing by basing the engine location off of the bellhousing crossmember and how it worked out for them.

Anyone else with experience here or the same situation?

[PDW HOTRODS]

I used a Camaro sub and had the engine bolted to the trans I was using when I test fit. I have the engine set back a little from where it set in the Camaro. I had to cut out a little in the subframe for the fuel pump. After adding some metal back in, you can't tell where it was modified.

[_Ogre]

55-59 chevy and gmc trucks came factory with v8 motors, while there are some differences in gmc and chevy frames
the cabs are the same, a sbc and th350 will fit without any floor or firewall modifications
the crank pulley should be very close to the x-member, i suspect your motor is too high
post a pic

truk came with a 350/350 that was poorly installed on the original front motor mounts
with the sheet metal on the truck i was able to fab up these side mounts

[_Ogre]

not sure if the x-members are the same, but just found this in dan in pasadena's build



valve cover to firewall clearance reference



no floor modifications



and a th350 installed with the stock rear x-member (orrieg did this too)



lots of good pics in his build thread
http://67-72chevytrucks.com/vboard/s...=463698&page=5

[Trucknut57]

When I installed my engine, I suspended it on a cherry picker and put the core support, radiator and fan shroud on so I could get the fan to sit in the Shroud without any modifications.

Just a thought.

[Strider]

Thanks for the input Gents!

Can Dan in Pasadena or Truck Nut measure your fan blade to rad clearance for me? I might just be too high in the frame. And like Truck Nut says, I might just re-suspend the engine/trans and redrill.

Is there a recommended distance from fan blade to rad that I should observe?

What distributor should I use? Stock GM HEI or something smaller?

Thanks!

[Trucknut57]

Strider,

Distance from your shroud will be determined by the type of fan you are using.

Mine looks like it sticks out about 1.5" but when the engine is running those fan blades flatten out and are almost even with the shroud.



I made my mounts based off this design:



And the placement on mine turned out pretty good. I had to drill one hole on each side.


Drivers Side,






Pass. Side,



Sorry I don't have any better pictures. But hopefully that will give you an idea how I did it.


I have used the Mallory Unilite distributor since this engine has been in the truck. About 15 years now. I have about an inch between the firewall and distributor. It has the same size cap as the old points style did.

[starterman99]

My 57 was an original v8 truck but I moved my motor and original bell housing mount
2 1/2 inches forward so as to have plenty of firewall clearance with full sized HEI distributor. Moved core support and radiator to the
6 cylinder mounting position and still have to use a spacer on fan to get close enough to radiator.

[Strider]

Originally Posted by starterman99

My 57 was an original v8 truck but I moved my motor and original bell housing mount
2 1/2 inches forward so as to have plenty of firewall clearance with full sized HEI distributor. Moved core support and radiator to the
6 cylinder mounting position and still have to use a spacer on fan to get close enough to radiator.

Thanks Starterman,

From your pics I see the difference in the shroud you have and the one in the post before you. Yours is factory then, right? The one above is aftermarket I assume.

So you had to move your engine forward in order to have the fan blades fully or mostly inside of the shroud, right?

Your truck looks great. Good to know about the distributor too.

I could move my engine down and forward easily enough I suppose. What's a couple more holes in the frame, right? I just like the current position of where the fan sits in relation to the rad - not the distance from it, but the fact that it looks centered in the rad.

[Strider]

Originally Posted by starterman99

My 57 was an original v8 truck but I moved my motor and original bell housing mount
2 1/2 inches forward so as to have plenty of firewall clearance with full sized HEI distributor. Moved core support and radiator to the
6 cylinder mounting position and still have to use a spacer on fan to get close enough to radiator.

What is the 6 cylinder mounting position for the rad for these trucks? My truck was a 6 cylinder so I suppose the rad wall and rad are in this position on my truck?

[Strider]

Originally Posted by Trucknut57

Strider,

Distance from your shroud will be determined by the type of fan you are using.

Mine looks like it sticks out about 1.5" but when the engine is running those fan blades flatten out and are almost even with the shroud.



I made my mounts based off this design:


And the placement on mine turned out pretty good. I had to drill one hole on each side.


Drivers Side,






Pass. Side,



Sorry I don't have any better pictures. But hopefully that will give you an idea how I did it.


I have used the Mallory Unilite distributor since this engine has been in the truck. About 15 years now. I have about an inch between the firewall and distributor. It has the same size cap as the old points style did.

Thanks again Trucknut,

Your truck is great too. I like the mounts you made for the engine. There is nothing wrong with the TransDapt ones I used and there are several options for engine mounts for these trucks which is great. I see several people have used crossmember style mount which would likely add strength to the frame.

I'm assuming using a manual trans with the engine based off the bellhousing mount is a non-issue and only becomes an issue when an automatic is used.
Perhaps the autos are more robust in size thus requiring the engine moved forward / down from the original bellhousing position.
Any thoughts on this?

[Strider]

Originally Posted by _Ogre

not sure if the x-members are the same, but just found this in dan in pasadena's build



valve cover to firewall clearance reference



no floor modifications



and a th350 installed with the stock rear x-member (orrieg did this too)



lots of good pics in his build thread
http://67-72chevytrucks.com/vboard/s...=463698&page=5

Does anyone know what Dan in Pasadena used for engine mounts? I can see in the last pic that he still has the bellhousing crossmember in the frame and the TH350 still fits. Anyone know what kind of tailshaft crossmember that is?

[starterman99]

Originally Posted by Strider

What is the 6 cylinder mounting position for the rad for these trucks? My truck was a 6 cylinder so I suppose the rad wall and rad are in this position on my truck?

On original V8 trucks the radiator support is about 5'' closer to the firewall. In the previous pictures you can see the hole in the inner fender about even with the shroud where the radiator support was bolted originaly.

[Strider]

Originally Posted by starterman99

On original V8 trucks the radiator support is about 5'' closer to the firewall. In the previous pictures you can see the hole in the inner fender about even with the shroud where the radiator support was bolted originaly.

Are there corresponding mounts on the frame for the rad wall to bolt to then?

[Strider]

Originally Posted by Strider

Are there corresponding mounts on the frame for the rad wall to bolt to then?

Or is the rad itself spaced from the rad wall on factory V8 trucks?

[starterman99]

Originally Posted by Strider

Or is the rad itself spaced from the rad wall on factory V8 trucks?

The mounting brackets on frame are moved and radiator wall or support is moved then it has a sheet metal filler pnael on top to cover the gap that is from hood latch to radiator. The radiator is not spaced from rad wall.

[OrrieG]

Here are the FAM drawings of the factory v8 mounts and radiator tin. Also a photo of my mounts and valve cover and HEI clearance. I placed my engine by installing the block, transmission and transfer case in place with the front drive line connected (expensive to modify). I then raised the assembly so that the carb base was level, which gives the engine, trans etc. a 4 degree down angle, and the TH350 pan cleared the original rear cross member and trans bellhousing did not hit the bottom of the cab. I also dropped in a point dist to check clearance. Front mounts were fabbed from 1/2" steel plate using one existing crossmember hole and another drilled. Rear transfer/transmission mount from the 74 donor was used with extensions to bolt to the side of the frame. I went with the front mounts to avoid clearance issues with the exhaust and steering. I kept the radiator in the stock 6 cylinder place and found a fan shroud that works (70 Mustang of all things). This was all done in 1985 before the internet based on a local truck that had a similar conversion.