67-69 Dart swap questions

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Map63Vette

Map63Vette

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Hi all, I've always wanted to do a Mopar build and now that I have some extra money I've finally started looking for a car to start with. I primarily want a drag car that I could drive on the street, though gas mileage and comfort isn't necessarily hugely important to me in my young age, but I would like to be able to drive the car to the track and back and to car shows. I've been looking around and decided on trying to find a 68-69 Dart since they're nice and small and not too bad to pick up price-wise compared to Cudas and Challengers and they still look nice. In the long run I am really considering a 5.7 or (preferrably) a 6.1 swap. I intend to use a full junk pull engine complete with harness and computer to keep cost down if I can find one for a resonable price (seen them for around $3000-4000 or so on Ebay). I think I may have found a good starter car, but I had a few questions I wanted to try to condense the answers to in one thread. I've found some of this information scattered around in the forums, but it would be really nice to have it all in one spot.

The car in question is a 67 318 4 speed with an 8 1/4 rear end. This is where my questions begin. Firstly, I know I need a small block K frame for the new hemi swap, but I also know that they made conversion mounts for putting a big block in a slant 6 car. I'm fairly sure the car I'm looking at was originally a 270 (according to a dash badge, forgot to get the VIN to double check), but is it possible that someone could have put a 318 in with the slant 6 k frame (in other words do they make slant 6 to small block conversion mounts or is a new k frame required?) If I do need a new k frame, is there any place that sells original or cheap k frames? I don't necessary want to dish out $1000+ for an AlterKation or similar since I don't really need all the suspension upgrades for drag racing (for the time being at least).

The next question is whether or not it is possible to use the old 4 speed for a new hemi. I thought I read somewhere on the forums that it was possible with a 340 bellhousing and some minor trimming of the input shaft while still using the original trans mount, but can anyone confirm this? Also, I assume the 318 bellhousing would be the same as a 340 (both smallblocks), but is this right?

Next, how long could I expect the rear end to last? Ideally I would put an 8 3/4 in it, but if what's in it will hold out for a while it would be convenient to keep in it so I could work on getting some money back, lol.

Lastly, the likely end result of this all will be a blown hemi. That being said, what sort of boost can I put down a stock 5.7 or 6.1 and still expect to be driving it regularly without replacing all of the internals? I thought I read somewhere on the forums that 10 psi in a 5.7 will be fun for a few passes, but that I may not be driving it home after one of them... I'm aiming for something in the 11's in terms of 1/4 mile times, but it would be awesome if I could dip into the tens without just throwing money at the engine.

Thanks for any help you all can provide. Looking forward to any help I can get to help convince me to get the ball rolling =P.
 
The 5.7 and 6.1 Hemis will fit Small block mopar bell housing. If you are going with a 727 behind one of these new engines you will need a spacer to push the trans back so the converter does not damage the pump.
 
Must have v8 k frame, good on the 4 speed, 8.25 will last...but an 8.75 will hold up when the boost comes down the road, go with a forged set up and keep the compression no higher than 9.5 to 1 and enjoy.
 
5.7 hemi said:
Must have v8 k frame, good on the 4 speed, 8.25 will last...but an 8.75 will hold up when the boost comes down the road, go with a forged set up and keep the compression no higher than 9.5 to 1 and enjoy.
Click to expand...

So is it possible that the car could have a slant 6 k frame in it with conversion mounts for the 318 or can the 318 only be in there with the right k frame? I got VIN earlier and checked it and the car was originally a slant 6, so something has been done to it, just not sure what all has been changed.
 
5.7 hemi said:
Must have v8 k frame, good on the 4 speed, 8.25 will last...but an 8.75 will hold up when the boost comes down the road, go with a forged set up and keep the compression no higher than 9.5 to 1 and enjoy.
Click to expand...
I agree must have v8 k frame . What engine did it have when you looked at it? If it had a 318 then it has had a k member swop, which is good for you ,it will save you alot of work. Also check torsion bars, you will need the BB bars for the weight and torque. Yes I would up grade to 8 3/4 rear end or if your not worried about keeping it Mopar find a good Fd 9". Personally i would keep it Mopar , maybe even think about a Dana.:thumbup:
 
belmateo said:
The 5.7 and 6.1 Hemis will fit Small block mopar bell housing. If you are going with a 727 behind one of these new engines you will need a spacer to push the trans back so the converter does not damage the pump.
Click to expand...

I used the new conversion flex plate. You don't need the spacer any more. The 8 1/4 will hold up as long as it's not abused. If you drive it like Ms Daisy a 7 1/4 would hold up. You must use an original sb K frame to use the conversion mounts.:-D
 
Just to add a little more confusion to your build down the road...I saw this new-Hemi killer setup at Mopars At The Strip this year.




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MATS2010095_edited (Small).JPG
 
It's got the 318 in it now, so that helps the pocketbook some. I don't exactly intend to be all that kind to the rear end though, what's the fun of a Mopar unless you drive it like you mean it =P? I figured the 8 3/4 was inevitable, just didn't know if it would last long as is. As it stands the car should run and drive, so I intend to sort of do things as weekend projects until I find a hemi I can drop in it. I assume I need to start looking if I want to find an 8 3/4? We had a 69 Charger a while back that desperately needed one to back up the 440 we built for it, but they were mighty hard to find and awfully expensive for anything with a posi in it. The 4 speed is in it to stay, so what do I need to consider for getting it to fit a new engine? I thought someone said that you had to shorten the input shaft (at least with the Mopar performance clutch and flywheel setup) which is not problem, but do I need to worry about any mounting changes or can I pretty much just pull the old engine and drop the new one in?
 
Unless you get a smoking deal on the 6.1, you can get stock 6.1 power out of a 5.7 for considerably less money though trading the cam & heads which are both easily handled as bolt-ons. The later a-body v8 k-member is preferable by many especially if you are planning on using the TTI motor mounts. In fact, I think it is required for TTI mounts

You should be able to use the stock 5.7/6.1 flex plate but remove the ring from it.

If you want to consider boost, I strongly encourage all of our customers to build a motor that is up to it. The stock blocks are not up to more than about 8 lbs. Some have gone well beyond that but usually kill the motor after only a few runs. I suggest to those who want to build up their motor as they can afford it to start w/ a forged bottom end and a NA cam. We occasionally offer a cam swap program for our customers who progressively upgrade their builds using our products such as now adding heads and a blower. Trade in that Inertia NA cam for an Inertia blower cam. When you go from the NA cam, many take that opportunity to go to some heads that are ready for it.

As part of the 10/30 cuda project, we are working on a stand alone system the would activate the MDS systems on pre-08 Hemis, including adding this feature to the 6.1 blocks :) Imagine running on only 4 cylinders conserving gas when loads are light and at the flip of the switch or automatically kick into the v8 mode whenever you want.

As for 1/4 ET's....try using one of the online ET calculators http://robrobinette.com/et.htm . Using 380 wheel horsepower and ~3300 lbs for the loaded car. ~380 hp is achievable w/ strictly a cam swap on the block and heads stock 5.7 . That shows a 12.19, ( in a perfect world) Either way that is solidly into the 12's. All you did was put a cam in, so you have barely scratched the surface as far as making some hp.
 
Yeah, I figured I would have to do a more thorough job if I wanted to boost the engine later, but I hated to have to pull the block back out to do the internals and really didn't think I would have the money to go all out before I put it in the first time. Ideally I would build up the motor some (like upgrading the bottom end) before I put it in so I could do later upgrades with the block in the car, but didn't want to get way ahead of myself price-wise. I know I would prefer to drop the compression before I drop a blower on it for longevity, but I didn't necessarily want to build the engine for a blower when I didn't plan to have one on it for quite some time since I don't really have the $5000+ for a blower sitting around.
 
Map63Vette said:
It's got the 318 in it now, so that helps the pocketbook some. I don't exactly intend to be all that kind to the rear end though, what's the fun of a Mopar unless you drive it like you mean it =P? I figured the 8 3/4 was inevitable, just didn't know if it would last long as is. As it stands the car should run and drive, so I intend to sort of do things as weekend projects until I find a hemi I can drop in it. I assume I need to start looking if I want to find an 8 3/4? We had a 69 Charger a while back that desperately needed one to back up the 440 we built for it, but they were mighty hard to find and awfully expensive for anything with a posi in it. The 4 speed is in it to stay, so what do I need to consider for getting it to fit a new engine? I thought someone said that you had to shorten the input shaft (at least with the Mopar performance clutch and flywheel setup) which is not problem, but do I need to worry about any mounting changes or can I pretty much just pull the old engine and drop the new one in?
Click to expand...

If Your planning on racing and your eventually going to have a Hemi, I would suggest the Dana. Hemi, Cuda, Challenger and Dart all used the Dana as well as the 440 cars. the 8 3/4 is strong enough but as my dad always said " look at what you need, then go a step higher". In other words people tend to over use their equipment. Just alittle food for thought.
 
Where are you located, I may sell mine....
 
I'm fairly sure the car I'm looking at was originally a 270 (according to a dash badge, forgot to get the VIN to double check), [/QUOTE]

Although alot of 270's had the 225 /6 alot also had the 273, do the K frame mounts look like someone did a modification? It's pretty easy to weld some new mounts in either way, sounds like a great project should really haul *** in a little dart. Has anybody weighed the new hemi's to see how they compare weight wise, esp compared to an alloy headed small block?
 
BLWN1 said:
Where are you located, I may sell mine....
Click to expand...

I'm in Lawrence, KS. I assume you're talking about a rear end? I'm hopefully going to look at the car again with my dad this weekend if the weather holds, so I'd be more than happy to let you know if I end up making the deal.

As for engine weight, I looked around on the next some for myself and the only number I ever seemed to find was something around 485 pounds. They were saying it was something like only 50 pounds more than a slant 6, one of the main reasons I was really leaning toward a new hemi swap. I built a 440 once with my dad and when it was fully assembled I don't think it was going to stay on our 750 pound engine stand for long... Nothing like seeing an engine drooping and wondering which mount bolt might go first.
 
So I've come across a new question, can I expect the stock 833 4 speed to stand up to some new hemi power? I'm really hoping for the 6.1 over the 5.7 and will probably drop a cam in either before I put it in the car, so would the 833 handle 400+ horse or should I look into a rebuild / upgrade?
 
They sat behind 426 hemi's and lasted all day long....you wont have any problems.
 
zigs said:
If Your planning on racing and your eventually going to have a Hemi, I would suggest the Dana. Hemi, Cuda, Challenger and Dart all used the Dana as well as the 440 cars. the 8 3/4 is strong enough but as my dad always said " look at what you need, then go a step higher". In other words people tend to over use their equipment. Just alittle food for thought.
Click to expand...

I don't suppose they make such a thing as a Dana that would drop straight in to the A body that isn't custom made? If not what sort of car would I need to look for to be pulling one from? I also read elsewhere in the drivetrain forum about being able to run a slightly narrower axle because of bigger tires, which would most likely be the case for me in the long run, so I assume the main problem would be spring perch location?
 
Continuing the axle talk, what sort of tires can I fit in a stock setup? Ideally it would be something that I could transfer to a new axle without being too goofy, but I'd like to get the most meat I can under it without changing anything right away. I figure a spring relocation kit will probably be the inevitability. I know I need new tires on it since the old ones look pretty bad, so anything I buy I would like to hold on to so I don't have to trade up later. Would a 10" rim be out of the question without mods or should I keep around an 8"?
 
I agree, 8" will work but you have to take careful measurements and get the backspacing right or you will have nothing but problems. FYI I measure three times then ask someone else to measure it again, LOL
 
Haha, good advice. I actually managed to find the exact thread I was thinking of in my head on the forums (max tire size you can fit in a stock a body fender), go figure someone else had the exact same question, lol.

On a different note I pulled the trigger and bought the car today. I also just realized that it's the first car I've ever bought, lol. It was actually just posted for sale here in the cars for sale forum not too long ago, but I'll try to get some pics up for the fun of it so you all can get a chuckle at the struggles I'll face, lol.
 
TxSwimDad said:
As for 1/4 ET's....try using one of the online ET calculators http://robrobinette.com/et.htm . Using 380 wheel horsepower and ~3300 lbs for the loaded car. ~380 hp is achievable w/ strictly a cam swap on the block and heads stock 5.7 . That shows a 12.19, ( in a perfect world) Either way that is solidly into the 12's. All you did was put a cam in, so you have barely scratched the surface as far as making some hp.
Click to expand...

The more I look at it the more I may be leaning toward a 5.7 build up. I would love to go 6.1 with the SRT Max cam and pump out 450 rwhp, but when I look at the numbers I think I could do the same with a 5.7 cheaper. I like the idea of the 6.1 having a more robust block for extra power down the road, but I'm not sure what my pocketbook would allow. What kind of hp can you get out of a 5.7 with stock 6.1 heads on it? On that note how much do stock 6.1 heads tend to cost? I love the sound of the SRT Max Rumbler cam as well and would love to put one in (another reason to go 5.7), but can I put one in a 5.7 with 6.1 heads with no issues?
 
TxSwimDad said:
Unless you get a smoking deal on the 6.1, you can get stock 6.1 power out of a 5.7 for considerably less money though trading the cam & heads which are both easily handled as bolt-ons. The later a-body v8 k-member is preferable by many especially if you are planning on using the TTI motor mounts. In fact, I think it is required for TTI mounts




.
Click to expand...

the 6.1 heads have bigger chambers doesnt that lower the cr on the 5.7 ?
has anyone tried a megasquirt setup on a 3g hemi yet ?

a lot of questions as usual :toothy10:
 
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