Putting a different engine in a kit

[MrBuick]

Can I get some examples (preferably with pictures) of how you bash a motor into a kit that it wasn't intended for? Specifically, I'm going to be putting different motors in a few projects...the first one being a 454 from a '70 Chevelle going into a '66 Chevy Stepside Truck. The other is the motor from the 2013 (I think) Boss 302 into a '70 Boss 302.  Admittedly, I still need to buy the Chevy Truck and the new Mustang, so MAYBE they'll just drop in, but in the more likely even that engine mounts need to be scratch built, I'd like to see some examples. 

[Ace-Garageguy]

This is one of those areas where it's exactly like swapping an engine in a real vehicle, only smaller. Proceed logically, one step at a time.

First thing to determine is whether the engine/gearbox you plan to use will physically fit in the engine bay. Get an idea of how the original engine sits in the car, and then mock up the new one in a very closely similar position...especially as far as level or the angle it's installed at.

Firewalls sometimes need to be modified, as do trans tunnels and inner fenders. Occasionally you'll need to slightly relocate the radiator. In reality you usually DON'T modify suspension to accommodate engine swaps, and it's not often necessary on models either. It's also sometimes necessary to alter a frame crossmember or an oil pan to get the engine in place at a reasonable height and setback.

There are various ways to mock up engine placements. I'll usually use scrap or strip styrene, sometimes just rubber-cemented in place. You want your mockup to be accurate and even side to side, and sturdy enough to allow you to work on it while you make engine mounts. When you do the mockup, you need to leave space in the vicinity of the engine and trans mounts to measure and fit.

Again just like real, look at where the original mounts are on the frame and where the mounting points are on the engine. The object is to simply connect the points...engine mount to frame mount, etc. Sometimes it's more expedient to make the trans mount first, and sometimes it works better to make the engine mounts first.

Make your new mounts and glue them to the chassis, using the mocked-up engine in place as a jig. Use rubber cement on the engine-end of the mounts to hold them in place while they set up.

Once the joints to the chassis are good and hard, remove the engine and remove whatever you used to mock the whole thing up, then fill joints (if necessary), primer and paint as usual.

You'll also have to deal with exhaust system (manifolds or headers) clearance AFTER you get the mounts, but you need to think ahead a couple of moves while you're designing your mounts. Steering boxes, racks and linkage can also be things that will need to be moved slightly. 

Every engine swap is different, but these are the general guidelines.

Sometimes you get lucky and the new engine pretty much drops in like it's made for it. This MAY be the case when you go to put the big-block Chebby in the older truck. GM to GM swaps in that era are usually pretty easy in 1:1.

 

Edited June 5, 2016 by Ace-Garageguy

[CometMan]

Colby, these are from when I built a totally stock Revell '49 Merc wagon, it was from the California Wheels series, didn't include a stock engine or exhaust. I took the flathead and exhaust from the AMT '49 Merc coupe as well as various other bits and pieces from the AMT kit that either weren't included in the Revell kit, or were just nicer parts. Everything went together like they were one big 2-in1 kit! Hope this helps!

[Ace-Garageguy]

Here's one example. I had to build mounts to hang an old Pontiac in this little dragster. The white vertical pieces are webs that connect the upper and lower frame rails and provide mounting points at the right height for mounts that represent square tube.

NOTE: This type of car also used plate-style mounts that were bolted to the front of the block, often under the timing cover. The plate design became pretty much standard after a while, and this car does use a plate rear mount that would be bolted between the bellhousing and the rear of the block. 

Though this is a rail dragster, I used exactly the same steps as outlined above to get the engine and mounts in precisely the correct location.

The top view shows the actual mounts that the engine sits on, beveled to fit the block in the location of the real mounts on this engine.

 

Edited June 6, 2016 by Ace-Garageguy

[Ace-Garageguy]

Another example. Comparing the locations of the engine mounts to the old frame mounts.

Here's the engine mocked-up in the right location relative to other mechanical components. The piece of angle stock just ahead of the engine is for mockup purposes only. You'll also see I had to remove a big piece of the trans tunnel to clear this big 6-speed gearbox.

I later decided I wanted to use a 426 Hemi rather than the smallblock Chebby (shown earlier) mated to the big 6-speed. Here, the firewall has been marked to allow the engine to clear it the way I want. The headers are also mocked-up, as are the upper suspension control arms I'm using.

REMEMBER: That big chunk of angle in front of the engine is only for holding it in position while I make the real mounts. It will be removed when they're done.

Semi-complete trans tunnel and firewall...

Now that the engine is where it needs to be, all that remains is to fabricate the actual mounts that go on the frame and pick up the mount points on the block. You simply cut-to-fit strip stock, working carefully and accurately. Then look at how the trans mount needs to be designed to work with both the trans AND the frame.

The slightly bowed piece of round stock is the trans mount / crossmember I made to hang the gearbox in a set of '32 Ford rails. Mounts like this can work on late-model cars just as well.

 

 

 

Edited June 5, 2016 by Ace-Garageguy

[MrBuick]

That's very helpful already! I've done a few engine swaps in 1:1 cars, but 1 was a literal drop in situation with a different set of engine mounts, and the other was an installation kit, so the only thinking required was whether the impact was in forward or reverse . I think I need to order some square rod...seems like that may be the easiest thing to use.

[afx]

Here is an example from a Cobra/Ace build I am currently working on.  The modified chassis in on the right.  You can see I had to remove one cross member, reposition the transmission support and fabricate new motor mounts.

Edited June 6, 2016 by afx

[Jantrix]

the first one being a 454 from a '70 Chevelle going into a '66 Chevy Stepside Truck.

Also, be aware of the scales your working with. If the 454 is from the Revell/Monogram kit, it is likely 1/24 where the truck is 1/25. The scales are very close, but they can still cause fitment issues, particularly in the transmission area.