So far SM420 in stock location with 66 Chevy V8 bell with 55 clutch fork to factory rear engine mount. Pass side truck manifold does not clear the frame or rear engine crossmember. Heads hit firewall on both sides. Either move engine forward about 2 inch or modify firewall is the hold up for moving forward now.
Found lots of info on this swap but none using factory trans in this body style.
How much clearance between engine and radiator---should be lots. You would have to relocate trans shift tower hole and custom bend shift lever, neither a biggy. Modify clutch release rod to throw out arm, side mount engine with adapters to use old style motor mounts and fab brackets to run the two inches back to the mount holes on the factory cross member. Don't remove cross member if you are using leaf springs. I believe this would be easier than making or buying a recessed firewall. You will love the LS power and fuel mileage.
I've got a good 4 to 6 inches between fan and rad. So moving 2 inches forward we be plenty in the rear without getting to close to rad.
Leaning towards a small mod to each side of firewall. Only need about the size of a pack of cigarettes on each side. And since I have a bunch of holes to fill on the firewall anyway, it wont add much time to the project. Plus everything else can stay as it was from factory.
I just like to have options.
If I was to move engine forward I would just move rear crossmember forward a few inches.
Already using side mounts on the engine that are not attached to the frame yet.
I had to dent the firewall a little to clear the coil bracket but i have mine bolted to the stock 3 speed with enclosed drive in my 3/4ton. So its back pretty far. Plenty of room in between the rad but it just sits a little too low to use the stock mechanical fan because it sits way down on the lower half of the rad.
Use a piece of the tub from an inexpensive stamped steel wheelbarrow to modify the firewall, and don't get involved in relocating the bellhousing. It's a quick, simple way to create some clearance at the rear of the engine, and it doesn't seriously compromise foot room inside the cab. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Literally just a few well placed hammer blows right where the corners of the valve covers sit is all mine needed. I didn’t have to cut anything. And thats with the motor bolted to the stock trans and stock driveshaft so its basically in its original position as far as setback.
I don't like the hammer blows idea, it just look half assed. Also if your fan is to low I would guess your engine is also to low in the front. with the engine sitting at the correct height (same crank centerline) as stock it would need a lot more than just a little dent on the pass side. since as the engine drops in the front the heads move forward. I can see interference with the lower bolt and bracket that holds batt box.
I can see where you could get some curves from a wheelbarrow, but it would be just as easy to cut the curved bulge at each corner off and flip them inside out, or lop off the corner and just replace it with a flat piece.
If you're determined to reject advice that's offered by people who have "been there- - -done that", why bother to ask? Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
because its ALWAYS good to have other views. I thought that was the reason for a discussion forum. I'm not saying that the advice is bad, I just stated why I didnt want to go that route on my project. I didnt say it wouldnt work, it just doesnt work for me in this case
Well the fan location on a LS engine (waterpump centerline) is indeed lower than the original straight 6 so thats why the fan was to low. I had a electric fan from my previous car builds so i slapped that on without skipping a beat. They work better anyways. If I didn’t use the stock driveshaft I wouldn’t have had to dent or touch the firewall in any way. But i set the motor basically against stock bellhousing location. If it was 3/4” foward it would be fine. I also offset it to the pass side at least a full inch. Most v8’s are in these trucks. Has no effect on anything anyways. Im curious why you would want to cut the stock firewall though and not make a dent that nobody would notice. And the dent is actually easily reversed from other side if you sold it or changed setups. Your also gonna run into issues with the stock brake pedal and if you use column shift that stuff too.
Heres mine. Actually fits great. Im used to jamming these in import cars so it was a nice change of pace to have so much free real estate under the hood.
the pics I posted are with it bolted to a factory V8 bell housing and the original sm420. it took a full 2 inches of forward movement to clear the firewall. So I am still undecided on the move engine or modify firewall question. after looking at the factory manuals, I'm thinking the V8 rear crossmember is different than the 6cyl one.
anyone have a pic of an original one? All I have is factory drawings of it.
the pics I posted are with it bolted to a factory V8 bell housing and the original sm420. it took a full 2 inches of forward movement to clear the firewall. So I am still undecided on the move engine or modify firewall question
Mines bolted to a late 60’s era v8 truck bellhousing. Only one i had at the time was the one with the bigger hole for the bearing retainer so i got a nice little adapter shim from novak.
my bell is the 64 to 67 type that fits the sm420 directly.
the chevy bell bolted right up. but the factory parts manual for gmc shows both a v8 crossmember and a 6cyl crossmember. from drawings it looks like the V8 one mounts the tranny a little lower in the frame. keep in mind my manual is a GMC one and gmc used pontiac v8 which is A LOT bigger than a small block chevy.
Used individual side motor mounts. engine 2 inches forward from factory. 4L80e fixed yoke tranny. used lsx mount adapters with pass side cut to clear a/c pump and drivers side not modded. pass side mount 2 holes back from the drivers side one. drivers side forward as far as possible to gain steering box clearance. So far so good.
Lookin good! Did you move the steering box out? Did you try test fitting a manifold in there yet?
truck manifolds wont work, they are to wide and pass side exits straight towards the rear crossmember. if you shaved head to manifold at a slight angle to roll the bottom towards the block and wernt using the rear crossmember and moved steering box you could use the truck ones.
Looks like the GTO or Camaro ones would work ok. but the block hugger headers give the most clearance and only $80 a set shipped is way cheaper
I would have kept the original 4sp but it just kept having one fit issue after another. So I already had the 4L80e that the 14 bolt came from. only thing I had to get was a flywheel to replace the 4L65e one. It should cruise nice with 3.73 gears and overdrive with lockup converter.
Yea that thing will be a beautiful cruiser. Only reason i kept the old trans was I actually wanted to keep the 3 speed column shift. Its one thing i just had to have. I just enjoy the old feel of driving it like that. I spent a lot of time making it all work like factory. It will be even better when i put the overdrive setup in it. Until then cruising with the 4.10’s i put in it is totally tolerable.
