The Dodge Challenger Message Board

I have a 1971 Challenger SE which came stock with a 318 and an automatic. I would like to put a 440 crate motor in it. Any insite would be much appreciated. ie.. steps involved in preparing car for larger engine and torque, cost involved, drawbacks, etc... I really love my car but want a big block. I'm just not sure if it's worth converting my current car to a 440 or finding a challenger which came stock with a big block.

I think original (stock) is always best. But horsepower is better! The 318 is a mild motor by most standards.

Never get rid of the stock stuff though in case you want it to match later on in life.

It is a pretty straightforward swap.

To do it well you should consider fitting a 26 inch radiator and upgrading the brakes and suspension.

The 440 cars had re-enforcement in the four corners of the floorpan called "torque boxes". You can get these from Auto Rust Technicians.

If you will ever run the car up a drag strip or through it around corners a lot fit some chassis connectors. Although these were never fitted to teh stock cars they stiffen the chassis up a lot and make the car feel better on the road. They also prevent stress cracks in the rear quarters if you drag race.

Also the k member will need to be changed small block is different. also if you go from a 904 to a 727 you will have to cut the drive shaft.And get a larger yolk for 727 . and get a sure grip rear end you pick the gear .

Remember to replace the 318's 5/16 fuel line and sending unit with the 3/8 line and sending unit the 440's and 426's required. You wouldn't want that big block to starve. Also, with the trans change and radiator change, the trans cooling lines will be different as well. Do yourself a favor and mount those to the trans/engine/K-frame assembly before it goes up into the car or lay them in before dropping the engine/trans into the car.... it will be less trouble for you.

71 pacecar wrote:Also the k member will need to be changed small block is different. also if you go from a 904 to a 727 you will have to cut the drive shaft.And get a larger yolk for 727 . and get a sure grip rear end you pick the gear .

Not correct, all k members in challengers were the same for V8 models, just need the correct engine mounts. Only a slant 6 to a v8 requires a k member change. Best place for engine mounts would be http://www.engine-swaps.com/

sorry i stand corrected .but HEMI is different but you can modified to work.

Sorry mate. The Hemi will fit on it as well. I think the only difference with the hemi k-frame I am aware of was the addition of a skid plate on the bottom. But many 440s got that too.

sorry i didn't give exact details on the mods i was talking about but thanks and you have to adjust the motor mount position. i know about the skid plate my 440 car was one.

I am very sure no mods are needed to the K-frame at all. The hemi engine mounts for an e-body hook up in the same position as any other V8.

You might be confused with other Mopars. Other mopars do indeed have different k-frames for different engines. But I assure you all V8 k-frames for an e-body are exactly the same.

go on moparts and ask some one who knows i think your wrong mate.

You go ask if you are stressed about it.

I am pretty sure that the only difference with the hemi is the actual engine mount. I know plenty of people that have fitted hemi's in their Challengers. I don't remember any of them changing or modifying the k-member. You just use the correct hemi mounts as far as I know?

If there was a difference I would have come across it sometime in the last 20 years i am pretty sure.

My memory is (and I admit my memory lets my down more and more these days) there are three part numbers used for the front cross member (to give it it's correct term). The slant six version. the V8 version without the skid pan, and the V8 version with the skid pan.

The T/A and AAR is said to have had another part number for it's K-member (maybe Barry can confirm that?) but there is no physical difference.

Hell if i am wrong I will hold my hands up but I am pretty sure I am right.

I say again. This is not true of other mopars. I think E-Bodies are unique in sharing a common V8 k-member. All others had a special K-frame for small block/big block/hemi I think? But i am not very well up on those models.

Uh no hes not, dave as well as i am, correct on this one ALL i repeat ALL, v8 k members for e bodys are the SAME, except for some skid plates. All you need is the CORRECT engine mounts.

Read for more info...
http://www.engine-swaps.com/window_Hemi_Tech_Tips.html

EDIT Beat me to it dave.

Thank you Mr Fire.

Ditto, sans skid plates and mounts as far as I remember.

I would recommend doing a bit of research before buying a crate motor. It may be that the 440's are better than the "magnum small blocks". As for me with my 402/435 crate motor from mopar, it would of been less expensive to fly Dick Landy and his extended family to my home and build the motor from scratch.

Come to think of it, I may of had just enough $$ left over then to hire Elton John for a private concert...

I would recommend getting a high quality custom motor, balanced and dyno tuned to your satisfaction. It may seem a bit pricey up front, but unless your are quite handy like Dave is, you may end up spending the cost of the motor again in repairs and tuning. The Mopar crate motor's have a 90 day warrantee...

Good luck!

I would find a machinest to take your 318 and make it as bad as you want it. Jeff Spears in Midland, TX will do it for about 8,000 and it will run 10's in the quarter mile. He is turning my 440 into a 500 with 680 horses. 8k sounds expensive, but I am sure it will be cheaper and easier in the long run.

To run 10s with a 318 you need a power band in the 7000 - 8000 rpm range. You would need something like a 4000-5000 rpm stall speed converter amd very low axle gears. You would also need to take some weight out of the car.

Not a very streetable combination.

True, it wouldn't be a very good street/strip combo. Never the less, there is still a lot of power you can push out of a 318, without having to make it a race only car. It depends on what he wants his car to do. If he wants the power of a stock 440, then I say build you a hopped up 318 that can still be driven on the street as well. It just seems easier to me. But if he wants to build a 500+hp car, then I would start with a 440.

I would take Dave's input over mine any day. He seems to know a lot about Challengers. Dave, I will be asking you a lot of questions in the future. I plan to do a lot to my Challenger, and I will need your two cents, or a dollars worth if you have the time.

Yeah no problem.

The age old question of "Do I spend my money building my 318 or do I spend less money to get more power and better drivablilty by starting with a 340/360 or big block" has been argued over many times by many people.

The general agreement is if you want a slightly hotter daily driver and don't want to set the world on fire there is nothing wrong with building the 318.

But if you want good power the best and cheapest way forward is to start with a bigger capacity engine.

Torque is equal to the amount of air and fuel you burn. That is were the energy comes from. So the bigger the engine the more torque you make before you even start hopping it up.

Horsepower has to do with torque multiplied by rpm. The higher the rpm you make the torque the more HP you will have.

But in general you don't want to rev over 6000-6500rpm without spending a big pile of money on the bottom end of the engine and machining it very "loose". So for most people that is a limiting factor. Engines like that have a very short life no matter how much you spend on them. American V8s are just too heavy to spend all day at 18000rpm like a 1000hp 3000cc Formula One engine.

Much better to make as much torque at lower rpms as you can and the engine will live a long long time like that and still perform well. This is what American V8s are best at because of their large capacity.

I found a pics of a hemi k member out of a hemi car . hope this shows were the motor mount part is different on a hemi k member . hope this clears up some of the dispute over them. Have a great holiday season merry xmass.

Still don't believe us do you. If you have a v8 k member in your e body, you can put ANY v8 offered at the time the car was made, including the hemi, just by getting the correct engine mounts, no k member swaps needed.

I am not sure about all the facts about the different k-members. I have found two links that do tell that there really IS a difference between a Hemi k-member and a regular V8 k-member. Or am I wrong?


http://www.engine-swaps.com/frames/fram ... r-ID1.html (at the very bottom)

http://www.engine-swaps.com/frames/fram ... r-ID3.html (at the very bottom)

i am sure you can you use a v/8 k member for a hemi .my point is that there is a differnce in apperance not just the skid plate .

71 pacecar wrote:i am sure you can you use a v/8 k member for a hemi .my point is that there is a differnce in apperance not just the skid plate .

I see what you mean. Thanks!

Thanks Christer finaly someone agrees that there is a difference and I don't know what I am talking about, not to make it seem like i'm bragging but I have being around these cars all my life, and I have a couple of friends with real HEMI cars .
Thanks again Christer .

Your original argument was that the hemi was different and had to modify the k member to put one in, which is incorrect. But you are also correct that a original hemi k member is different from a v8 member, but you dont need to swap any k members unless you are going from a slant 6 to an v8 or vise versa. Im done arguing about it, nothing productive is being done.

spitfire9137 wrote:Your original argument was that the hemi was different and had to modify the k member to put one in, which is incorrect. But you are also correct that a original hemi k member is different from a v8 member, but you dont need to swap any k members unless you are going from a slant 6 to an v8 or vise versa. Im done arguing about it, nothing productive is being done.

Maybe the two scans (From Chrysler Performance Upgrades by Frank Adkins) below is the productive kind of infomation you are searching for, guys?
Wadda ya say?

71 pacecar wrote:I found a pics of a hemi k member out of a hemi car .

That dosen't look like a e-body k-member at all to me. There are too many differences. The steering box mount etc.

Thanks for posting those scans Christer. The important bit is this bit which confirms my position on this subject.