Engine Mounts

[drive.1968]

I am swapping in a L92/LS3 into my 1968 C10. I am doing away with the fan and radiator shroud and installing electric fans. How forward can I move the the LS engine and still have a correct mount up and alignment for the turbo 400 transmission I am using? To me I do have a little bit of room to move forward but 3 inches seems like to much?

Thanks,

[Matt Cramer]

If you're willing to move the crossmember and shift linkage, the answer is, "Until you bang into the fans."

Was this originally a six cylinder? The mounts are in the six cylinder location.

[hellbent72]

You want to push the motor forward as little as possible the least amount of weight at the nose of the truck the better. The best place to place the motor for the best handling would be in the cab with you sitting on the air cleaner..lol

[drive.1968]

Originally Posted by Matt Cramer

If you're willing to move the crossmember and shift linkage, the answer is, "Until you bang into the fans."

Was this originally a six cylinder? The mounts are in the six cylinder location.

No she actually had a 307 with turbo 400

[drive.1968]

Originally Posted by hellbent72

You want to push the motor forward as little as possible the least amount of weight at the nose of the truck the better. The best place to place the motor for the best handling would be in the cab with you sitting on the air cleaner..lol

Is there a better distance to go for when purchasing the engine mount? I worry about it sitting it to close to the firewall or having to remanufacture the headers or the truck. I will be using a set of Headman 1.875 dia long tube headers.

Thanks

[BR3W CITY]

Originally Posted by drive.1968

I will be using a set of Headman 1.875 dia long tube headers.

Thats optimistic Seriously tho, the header thing will end up being the biggest PITA of the swap. Have you seen that header used in truck swaps before? afaik there are only a few true long tube headers that will clear the engine stands and frame. Now if these fit, thats awesome, but just don't be surprised if they don't fit straight away. There are other factors as work besides engine position, including where the steering shaft fits, and what type of tranny you have behind it.

The 4l80e for example has large "ears" which can come very close to the collector pipe.

There are 2 sensors on the back of the engine block, as well as the rear 2 coil packs, which can be an interference issue if the engine is set way back. Also, the engine is supposed to have an amount of downward tilt to the rear (3-4*). With the engine too forward or too aft, this can be trickier because of clearances to the tranny hump or the position of the trans mount.

[crazy longhorn]

A mock up, would be the best way to tell....but my thoughts? If you run the 400 turbo, I would set the trans in in the stock location, with the engine bolted to it & do some measurements. There are many options on mounts/stands , that will fit the variables.I Agree with BRCW CITY, that the headers will be the hardest part to fit. You may find that you need aftermarket (tubular) engine stands, or late model (73-87) style mounts/stands for clearance on the headers? Best of fun...Longhorn

[hellbent72]

Originally Posted by drive.1968

Is there a better distance to go for when purchasing the engine mount? I worry about it sitting it to close to the firewall or having to remanufacture the headers or the truck. I will be using a set of Headman 1.875 dia long tube headers.

Thanks

Even though it takes more time I would mock the ls with a cherry picker to see where you stand clearance wise at the firewall and oil pan clearance at the front crossmember. I would find out which oil pan has the best clearance in the sump area for your app.
A tranny cross member is easy to build so I would find where you want the motor to sit and bolted up and then build a new trans x member.
I really like the look of tubular motor mount stands and ditch the factory one. Take your time and don't rush it and you will save some money. If your like me when I get an idea a rush rush rush and end up spending 3x what it should of cost.lol

[Hart_Rod]

Use the dirty dingo mounts and you wil have 3" of fore and aft movement. Look at my 68 build thread. I have my engine sitting as far back you can go without hitting the firewall. With the same engine mounts and oil pan, I could have moved the whole setup 3" forward.

[crazy longhorn]

Oil pan....the stock truck pan will fit many apps/positions, but it does hang a couple inches below the eng crossmember? I opted for a GMPP hotrod pan kit (basiacally an H-3 hummer pan. You will loose about 1 q capacity, dropping the truck pan, but this pan will fit pretty much any position? Also, @ 150 bones, for the kit (pan,complete, with gasket/pickup tube/O-ring/dipstick tube, & all hardware, including the tray), it was a smoking deal ! Try Summit, Jegs, or Pace performance on the parts? Longhorn

[faribran]

H-3 pan.... Or your local GM dealer. You might be surprised at the price

[68c10airstream]

Hey longhorn, my 5.3 in my 68 c10 with my own motor mount perches puts the truck pan about 1 1/2-2'' below the cross member, and the low sump area is almost rubbing on the cross member, maybe 1/2". Does this sound like where you were at before the hummer pan? I'm about to pull the motor soon and was going to mark the area to be sectioned out and modify the pick up tube, etc. I'm also going to try and put the factory a/c bracket that sits low on the passenger side of the block down low, so i will need to deal with a couple of stand-offs on the side of the pan that the compressor bracket bolts to. Any help is appreciated, thanks in advance, Brian F

[BR3W CITY]

Sounds about right. With the H3 pan, that clearance to the sump will be about the same 1/2-3/4", but the pan will hang about even with the crossmember +/- ~1/2. Depending on the mounts and perches.

[crazy longhorn]

Originally Posted by 68c10airstream

Hey longhorn, my 5.3 in my 68 c10 with my own motor mount perches puts the truck pan about 1 1/2-2'' below the cross member, and the low sump area is almost rubbing on the cross member, maybe 1/2". Does this sound like where you were at before the hummer pan? I'm about to pull the motor soon and was going to mark the area to be sectioned out and modify the pick up tube, etc. I'm also going to try and put the factory a/c bracket that sits low on the passenger side of the block down low, so i will need to deal with a couple of stand-offs on the side of the pan that the compressor bracket bolts to. Any help is appreciated, thanks in advance, Brian F

The tightest spot on my pan is up front, over the cross member (aprox. 3/4"). The engine was set in 1 " forward , from I 6 spot using the original 6 cyl stands. Clearance is good @ the rear of the pan, I could easily move the engine position 3" forward without issues? I do have a set of urethane mounts (which are a bit taller than the stock rubber pcs), & running a set of mount spacers tween the mount & block plates. If you have issues with clearance up front, I don't think that the H-3 pan will help, as it looks to be the same as the truck pan in that area. (more like a height issue)? Just a thought....rather than mod the pan,I have opted to mod the cross member on some swaps? Longhorn

[Hart_Rod]

Here's a good thread on engine mounts and LS oil pans:

http://67-72chevytrucks.com/vboard/s...d.php?t=272174

[drive.1968]

WOW!!! Thanks for the comments. This is the first thread that has responded to any of my questions. I guess I had chosen poorly before…

As for what I am reading the LS engines sit far lower that the Gen 1 engines whereas the 1/3 and 2/4 exhaust header tubes must make a quick turn and travel for a few inches before turning down and heading towards the collector without impacting with frame rails and the motor mounts? As well the oil pan must sit close the crank to clear the cross member which in turn pushed the pan reservoir below the cross member. However, with the cam I am installing and the rework of the heads I am using an aftermarket high volume oil pump would really like to use the aftermarket oil pan to gain an extra qt of oil.

I have seen some pictures of long tube headers used with a LS engine in a C10 pickup but have never been able to get a part number or manufacturer of the for mentioned headers.

BR3W CITY you are saying that the only thing I need to worry about on the clearance between the firewall and the engine is the O2 sensors and crazy longhorn you are saying that I should use the later model engine mounts to help with clearance issues. hellbent72 you are saying that you have much better luck with tubular mounts. However, which motor mount holes should I use? The front set or the back set? I know that moving the engine forward to the front set of motor mount holes made a big difference to the big block we used in one of my friends trucks. My mounts were set in the front holes from the factory; I always had clearance between the distributer and the firewall. I know that the LS does not have to deal with the distributer. Is there a preference for the LS engines?

Hart_Rod you are saying that the dirty dingo mounts worked better for you. Are they the single short fine thread bolt from rubber to mount or do they use the long std thread bolt through the rubber type?

So what if I extend the motor mounts up? Would that fix some of the header problems and for sure help the pan issues as well as keep the 3-4 tilt to the rear. Apparently, there will be plenty of room between the turbo 400 and the firewall with having trouble keeping the 3-4 tilt on the LS engine mount up.

These are just guess-to-mations. Please correct me if any of these ideas will cause problems or have been tried before and failed.

Thank you for all the help

[69trk]

I used the front holes in the frame with tubular mounts and dirty dingo sliders.. works great.. only problem with the sliders you can't use the ac compressor in the stock location. But you can buy a bracket and move the compressor up... The sliders are awesome, due to i didn't have to do anything to the driveshaft..

[BR3W CITY]

Originally Posted by drive.1968

WOW!!! Thanks for the comments. This is the first thread that has responded to any of my questions. I guess I had chosen poorly before…

I find that hard to believe, especially on this forum...for the main reason that I post on 95% on questions in this section. Did you post your other questions here in "LSX"?

Originally Posted by drive.1968

As for what I am reading the LS engines sit far lower that the Gen 1 engines whereas the 1/3 and 2/4 exhaust header tubes must make a quick turn and travel for a few inches before turning down and heading towards the collector without impacting with frame rails and the motor mounts? As well the oil pan must sit close the crank to clear the cross member which in turn pushed the pan reservoir below the cross member. However, with the cam I am installing and the rework of the heads I am using an aftermarket high volume oil pump would really like to use the aftermarket oil pan to gain an extra qt of oil.

They don't really sit that much lower, its really more where the exhaust ports on the heads end up, compared to the overall profile of the engine. The ls motors don't have dimensions drastically different from their predecessors. The primary issue is correct, the rear-slope that most headers use ends up descending too early, and not giving the tube enough room to clear the frame rails and mounts. The other half of this is that some home-made and home-modified solutions clear the mounts, but then hit the steering shaft. Some have built a header that fits through the shaft.

The res in the pan hangs over due it its size, and also the angle which it sits in the cradle on these trucks. If you want more capacity without more depth, you'd have to modify the pan WIDE like some of older custom Moroso pans (or spend big $$ and convert to dry sump).

Originally Posted by drive.1968

I have seen some pictures of long tube headers used with a LS engine in a C10 pickup but have never been able to get a part number or manufacturer of the for mentioned headers.

Check out Doug Thorley, he makes them.

Originally Posted by drive.1968

BR3W CITY you are saying that the only thing I need to worry about on the clearance between the firewall and the engine is the O2 sensors Is there a preference for the LS engines?

The 02 can be an issue clearing where the firewall becomes the floor. Some headers put the collector too close to the floor, and because of the proper mounting angle for the 02's, it would mean they were mounted right against the floor. Don't want that. I put my engine into the front bolt holes with flipped I6 perches and v8 mounts/adapter plates. I have no clearance issues for the coilpacks, knock sensor, or fuel lines. I could move it back about 1/2" but I like the fit and access it gives.

Originally Posted by drive.1968

So what if I extend the motor mounts up? Would that fix some of the header problems and for sure help the pan issues as well as keep the 3-4 tilt to the rear. Apparently, there will be plenty of room between the turbo 400 and the firewall with having trouble keeping the 3-4 tilt on the LS engine mount up.

Depending on which tranny tunnel you have, the th400/4l80e/6l80e as well as the smaller trannies all will fit, with plenty of room to adjust the angles. Taller motor mounts would make the bellhousing clearance tighter, and make the tailshaft exit at a more extreme angle (well over 4*). This means that the driveshaft and rear end have to be setup to compensate this in the pinion angle, making your job harder...or resulting in vibrations and broken u joints. It would also put the engine higher in the cradle, raising your center of gravity, which is harder to compensate for elsewhere in the truck to maintain handling performance.

[crazy longhorn]

I think I also would try to maintain that 3-4 degree angle (don't raise the nose too high)? As far as stands,my thoughts are that you will have better clearance with the headers tubes, with either the 73 up style stands/mounts, OR aftermarket tubular stands? Still by far, the easiest way to tell, is mock it up, & measure .....see what you need to make all the pcs fit Longhorn

[drive.1968]

[quote=BR3W CITY;6400374]I find that hard to believe, especially on this forum...for the main reason that I post on 95% on questions in this section. Did you post your other questions here in "LSX"?

I was not using this forum at first. I am now and the heck with that other one. This forum is cool, I get to talk to people that are working on what I am working on and get responses.

[drive.1968]

Originally Posted by 69trk

I used the front holes in the frame with tubular mounts and dirty dingo sliders.. works great.. only problem with the sliders you can't use the ac compressor in the stock location. But you can buy a bracket and move the compressor up... The sliders are awesome, due to i didn't have to do anything to the driveshaft..

The drive shaft is another thing for I am planning to put somewhere 550 hp to the ground and I still have the original 2 piece drive shaft. Is there a good way to revise the cross member for the carrier bearing to allow a full drive shaft on a LWB truck?

[BR3W CITY]

I'm glad you've had better luck in this department, and please don't take my little g-check about posting in this section, the wrong way. The only reason I asked is that in this area, we have a few members (myself included) that work really hard to make this the best place for LS swaps on the internet (not just for these trucks). If you weren't getting help, I just wanted to find out why. That being said, welcome to the LS section aka my hood.

Wasted Income posted a pic of his frame/drivetrain in another thread on this page, a few spots down. The general idea is that a LWB truck is just a tad too long to run a 1 piece, unless you can run a VERY expensive custom shaft that is a narrower diameter.

Your best bet on a budget is to have a good shop make you a thicker-wall 2-piece shaft with HD (non grease) u joints. It will weigh a touch more, but usually they are good up to 6-800hp, with the ujoints and collars being the weak point. Otherwise, you're stepping up to an aluminum shaft, or all the way up to the narrowed shafts that are carbon/carbon-aluminum mated ($800+ easily)