55.2-59 move engine forward question

[jmlloar]

Trying to swap in an LM7 5.3 into my 55.2 GMC.
Used factory V8 bell and am having clearance issues between heads and firewall.

My question is has anyone moved the factory rear manual trans crossmember forward? and if so did you have any issues with shifter location?

[Katrina/10]

That would be really difficult to do, lots of rivets in it. I don't know if its ever been done.

[jmlloar]

Rivits are not hard to remove.
Replace them with fine thread grade 8 bolts to reinstall.

Probably end up modding firewall, but looking at all possibilities before hand.

[56hotrodred]

Your right rivets are not that hard to remove. I had to shift my engine around to get some room on firewall when using 350 ramjet engine and 700R4 transmission.

But I used aftermarket transmission support and the Dirty Dingo engine mounts that allow to shift things around.

It was also real close between water pump and radiator even with using short water pump. I did figure it out and went with Vintage Air Front Runner system and 2 Spaal electric fans and it all worked out so far. That however is a speedy way to go. Glad I bought those parts when I was still working for a living. Now being retire I have more time than money.

If needed I can still clock my distributor to gain a bit more room but I think I will be okay.

Its called the "ripple effect" make one change and 2 or 3 other related issues pop up!!!

[joedoh]

depending on your firewall clearance, you can dimple it for the head. on my trucks (ADs) I usually need a 1-2" diameter dimple just on the passenger side (the passenger head is further back than the drivers). its not a "show quality" modification, but think of all the extra work you wont need to do, moving motor and trans mounts, moving the shifter, and the extra space you lose at the rad.

just a counterpoint, do what you like

[jmlloar]

is your rad support in the 6cyl or 8cyl location?
I have tons of room between rad support and waterpump.
plus with mine being a GMC instead of Chevy I have even more room than Chevy guys.

[jmlloar]

Originally Posted by joedoh

depending on your firewall clearance, you can dimple it for the head. on my trucks (ADs) I usually need a 1-2" diameter dimple just on the passenger side (the passenger head is further back than the drivers). its not a "show quality" modification, but think of all the extra work you wont need to do, moving motor and trans mounts, moving the shifter, and the extra space you lose at the rad.

just a counterpoint, do what you like

I have tons of rad space.
probably do the dimple, but if so I will cut and fold it to look like factory design. All I need is to fold in the inner corner of the bulge close to the engine. Can probably lop corners off and turn inside out then weld back into place.

Only need about 2 inches in and about a 2inch by 2inch section. Pass side won't even affect batt box location.

[starterman99]

My 57 chevy was original V8 truck. I moved the bell housing mount xmember forward and put the radiator support in the 6 cyl position and am running a Muncie 4 speed. Still had to modify the floor shifter to come up in front of bench seat. Had to extend the clutch linkage but nothing too difficult about it.

[jmlloar]

Originally Posted by starterman99

My 57 chevy was original V8 truck. I moved the bell housing mount xmember forward and put the radiator support in the 6 cyl position and am running a Muncie 4 speed. Still had to modify the floor shifter to come up in front of bench seat. Had to extend the clutch linkage but nothing too difficult about it.

this was along the lines I was thinking. Only issue with mine is it is a 4sp SM420 so shifter is already under the dash.

How far did you move yours? I know mine would be different but just looking for ideas.

[starterman99]

about 2 1/2 inches forward

[Clarance J]

Originally Posted by jmlloar

this was along the lines I was thinking. Only issue with mine is it is a 4sp SM420 so shifter is already under the dash.

How far did you move yours? I know mine would be different but just looking for ideas.

Hello jmllor. Maybe you could fab your own shifter. Instead of looking for a shifter that will fit, fab one that will work no matter where the shifter base is. You make it fit any where you like it best. I made mine using 3/8 steel plate.

Earl

[jmlloar]

I can't do that. the sm420 is a top loader

[jmlloar]

thought about swapping trans but park brake is on it. Havent been lucky enough to find another with same type setup. need one from a 70's or 80's med truck with 5 speed with over or a SM 465 with brake on it.

[Rickysnickers]

Originally Posted by jmlloar

is your rad support in the 6cyl or 8cyl location?
I have tons of room between rad support and waterpump.
plus with mine being a GMC instead of Chevy I have even more room than Chevy guys.

Interesting. How can you tell which position it's in?

[jmlloar]

Originally Posted by Rickysnickers

Interesting. How can you tell which position it's in?

2 sets of holes on frame and where support attaches to the fenders on chevy. rear ones are v8 front ones are l6

after looking at gmc I am thinking how rad is attached to support moves the rad closer or farther from the engine. could be wrong on gmc

[jmlloar]

lots of room between water pump and rad support before moving. Looks like 2 inches forward is the magic number

[jmlloar]

on a side note, anyone know how thick the rubber cab mounts are? sitting cab up in correct location will help wuth clearance, dont want to buy new mounts till I'm ready to bolt it down.

[dsraven]

shifter suggestion
remove the shift lever fromthe trans and bend it like you need it then install again
or
-lop off the shift lever a couple inches up, enough to come through the floor but low enough so a shifter boot would hide the connection
-remove the shift lever from the trans by pushing downward and turning the formed sheet metal piece at the bottom of the shift lever in the top of the trans
-thread the shifter part that is left
-fab a new shift lever that fits like you want or heat and bend the old one
-use a threaded rod long nut to connect the parts
-drill and thread the rod connector nut on one of the flats in 2 spots so it will accept an allan headed set screw that can be used to keep the parts from vibrating loose. assemble the parts and when you have it where you need it remove the allan screws and carefully drill through the allan screw holes to dimple the 2 shafts, this will give the allan screws a resting spot so they don't screw up the threads on the lever stubs. or simply remove the shifter again and weld the 2 parts together. do not tack weld while still in the trans because the electrical current can pass through the trans bearings and cause small "weld" marks where each roller touches. trans doesn't last long after that

[jmlloar]

A simple bend of the shifter will give me clearance.

was more worried the tower would be to far forward, but with 2 to 2 1/2 inches it will be fine. I will also gain steering to engine mount clearance.

Down side is longer driveshaft and have to lengthen clutch rod.

Wondering if shifter on sm465 is back farther from front of trans than this sm420?
or get an nv4500 , did they even make one with park brake on trans?

[joedoh]

Originally Posted by jmlloar

lots of room between water pump and rad support before moving. Looks like 2 inches forward is the magic number

remember that the rad mounts on the back of the core support, not inside it. I dont want to discourage you but it looks like you will have to run an e-fan right now and it will barely fit, if you move the engine forward another 2" it may not

do you have the rad to put in and check how much room you have?

[jmlloar]

on this one, which I tore down the rad was inside the support. LOTS of room.
The V8 truck might have been behind it ,I dont know but this was a 6cyl truck.
I have 6inchs of space. even with the 5.3L clutch fan and moving forward 2 inches I will still have 2 inches between fan and rad.

[joedoh]

on a 55.2-59 (what you tagged this post as) the rad mounts to the back of the core support, which is where my confusion comes from.

the picture you posted looks like a 1947-1955.1 frame and core support, and its further proved by your comment that the radiator mounts inside the core support, which is absolutely true for a 47-55.1 GMC rad.

you have a 47-55.1 truck, if its a 55 its a 55.1. you can modify an aftermarket rad to mount inside the core support, or you can buy one that mounts inside for those years of trucks.

[dsraven]

55.2-57 gmc had 2 styles of rad support. ones like the earlier chevies, up to 55.1, and some were chevy rad supports like a 55-57. my 57 gmc has the chevy rad support which i think is a Canadian one-off. other gmc's from US that I have seen have the older style rad support. some of the gmc's were converted tochevy front ends because guys thought the grilles looked better from the chevies.

[dsraven]

both my 57 and 58 had the 6 cyl 3 on the tree and both rads were mounted to the rear of the rad support. a different rad support than what is shown above.

[jmlloar]

this truck is an unmolested 55.2 gmc built in pontiac. Its rad was mounted inside the support, not behind it. I've had plenty of the ad series trucks, this is not one of those.