Performer RPM Cylinder Heads For S/B Chrysler

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Would these cylinder heads work on a 1965 Mopar 273?
Aluminum Cylinder Heads - Chrysler - Small-Block - Performer RPM - Edelbrock, LLC.
Is the 63 cc chamber too large, hence, compression ratio would be too low? Could I "shave the head" to raise the compression, or, would it be better to swap the pistons?

No, they will not. Please be aware that the 273 bore is too small for the 2.02/1.60 valves to clear.
In order to use 2.02/1.60 valved heads you will need to have the blocked notched for valve clearance. You will also have to determine the piston height with relationship to the deck. The HP 273 Commando/Charger engine has a positive piston to deck height. If that's the
case you will have to use the Edelbrock 60179 heads. Regardless of this you must notch the block! 65'
 
Never buy the open chamber heads is my suggestion. Adjust the piston to head clearance using a gasket, not a chamber.

Valve clearance to bore can be an issue on a 273
 
Hello from a fellow Canuck

273s are a tuff performance build. Are you married to it?

If I was, I think I'd stuff a 3.58 stroke in her to make a 300cuber. That crank will raise your pistons .1325, so you might need custom pistons. In this way, you can make almost any compression ratio you want with any head you choose, just by dictating the design of the piston crown. No decking, no shaving, no intake machining. and everything fits like stock.
To run a 268* cam with this combo, it will like 10/1 compression, and that will mean a total chamber volume of 68.3cc. This should be fairly easy to achieve. 6.4 in an .028 gasket, 5cc in the eyebrows and so 57 in the heads, all with a zero-deck.
But you may not have any eyebrows left, so then the head can be 62cc.
With an .028 gasket , you're gonna have to lower the piston a bit, say to a deck of -.011, and that would add 1.87cc, and so the head could now be 63.9. You see how easy this is?
I would use magnum heads with 1.92 valves, and notch the bores, no big deal.
So to recap, the 360 small-main crank, and custom pistons and you can generate quite a bit more torque and power, yet get better fuel mileage than a hot teener.
It may be possible to use 2 bbl pistons, but I think they'll be a bit far down,still. I heard they're often down .157, so after the crank boots them up .133, the pistons are still .024 down and that won't work with a .028 gasket; not enough Squish. This combo will like squish of .035 to .045, so the max down would be .017.
But if your decks need cleaning up, well then you're back in the game.
Keep in mind that this is just a hypothetical build. If you were to go this way, you'll probably have to balance the crank, and check the piston to valve clearance etc.
In the end...........you're gonna spend more money than necessary, in terms of performance.
Just throwing out ideas
 
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Thanks for the great information. I was thinking of the heads as a way of getting around the issue of the limited selection of intake manifolds, but, Exeter Auto Supply have the Offenhauser 5489, so, it might be best for me to go that route. The Offenhauser was a common upgrade for such cars and it would likely match well with either a Holley 390 or Edelbrock 500 carburetor. For the most part, I want to keep the vehicle "stockish", it's just things like brakes, ignition and induction that I want to be 21st century (I suffered enough fear from crappy brakes). Do any of you have any experience with roller camshafts and rockers in the 273? I think that Lunati and Comp Cams have such hardware, don't they? For ignition, I was thinking of getting an MSD set up. Also, I was thinking about the retro looking Holley Terminator Stealth TBI. The ads say "easy to install" but, I have heard that too many times. Have any of you done an install with this hardware? Thanks again for all the great suggestions!
 
Just put 66 up heads on it, problem solved. These have the bolt angles standarized, so anything that fits on a SBM will fit and bolt on.If you swap to the later heads, you have to choose the closed chamber type to preserve as much compression as possible.
But I gotta warn you; if you don't do something about the dynamic compression ratio, bolting a 4bbl onto a 2bbl 273, is IMO almost a waste of time.

The low cylinder pressure can be partially offset by a bigger TC and performance gears.
But this will end up costing you almost as much as proper hi-compression pistons, and will cost you more money per mile driven in terms of fuel-mileage, and without the cylinder pressure. the engine will be a bit of a dissappointment.

In all honesty, the cheapest way to power is a bigger engine.

Here's a mental test, for your 273 2bbl factory stock engine
Draw a flat line 5 inches long. Mark the left end 0, and measure off every inch.On the right end of the line make a mark 1/4 inch above the line. Connect that dot to the 2 inch mark.Next make a mark on the flat line at 4.5 inches, and draw a vertical line up and across both lines. Erase everything to the right of that vertical.
Now imagine that the flat line is the WOT power of your 273 2bbl........and the sloped line is the power that the 4bbl will add, and every inch is 1000 rpm.

Ok now, under the 3rd mark from the left,write 33mph, and at the 4inch mark, write 44, and at the 4.5inch mark,write 50mph . These are the mphs your car will be doing with 2.76 gears. Notice that at 33mph/3000rpm there is only a tiny horsepower gain. And the most gain will be at the right end of the line, which is now 50 mph.
See what I mean about a 4bbl being almost a waste.
I can't tell you what the power difference in that sloped line is, but at the right end, at 4500rpm,at 50mph; I doubt it would be 10hp.
This is just an exercise.

Here is another exercise
Draw a parallel line 1/2 inch above your 273 flat line,and 5 inches long, to represent a stock 318.
Next go up another 1/2 inch and draw another flat line, but 6.5 inches long, to represent a 360.
Next , draw a diagonal line to connect the zero mark on the 318 line to the 6.5 inch end of the 360 line, to represent a 340.
The 360, represented here is not stock, but has all the 340 goodies on/in it
These are just representations, and imply no accuracy, and only hint at power increases;just exercises.
Consider about 20 cubic inches as one step up in engine size. So from 318 to 340 is 22. and from 340 to 360 is 20 and so on. But from 318 to 273 is 45 cubic inches,over 2 sizes smaller. Just an observation. They work very well in the lightweight-As they came in, having the same or similar cubic inche to weight ratios, as the regular-As with 318s.

I see you're getting ready to spend some hard-earned money on your combo, and I'm just afraid that the end result might be disappointing.
To put a cam in her, to be effective,will require the cylinder pressure to be brought up as well, else the bottom end will be very disappointing. The roller conversion thus will quickly exceed $3000, and you stil don't have heads to go with that cam So now its gonna be $4500. And since you went this far, you're gonna need that 2800TC and 3.55s or better. Now you're up to $6000ish,before bolt-ons, which can easily add up to another $1200
And the saddest part is what did you get for your $7200? I'll guess 40 to 50 hp, or about what a stock Magnum has......which you might find a low mileage unit of, for a fraction of that.
Now it might sound like I'm dissing your 273, but this has nothing to do with her. It's all about how much power per dollar do you have to spend.
When it comes to labor, it costs the same to build a 360 as it does a 273, and you are instantly 87 cubes bigger,instantly. Even if the 360 is a 2bbl, this is likely to be over 60 horsepower more.
When it comes to parts, it will be cheaper to build the 360, on account of the pistons, and ballancing. And the 360 won't need the 2800 nor the 3.55s, nor headers nor even a 4bbl in an early-A.
And if you can find a Magnum, you already have an excellent platform to work with. Sock for stock, it's hard to fault a Magnum.
So let's say you do find a low-mileage 5.2 with log-manifolds, for $600 delivered to your door. She's gonna need in induction system and an ignition system, and that's the expensive things taken care of for about $1000 with all new parts. Total say $2000. And that 5.2 is gonna put out maybe 240 just like that,with a 4bbl,compared to your 273 which was rated at 180 IIRC. so that would be 60 hp for $2000, compared to 50hp for $7200. Which will you choose?
And as if that's not enough; a stock 360 2bbl engine will put out about the same 240hp, with a 4bbl and headers. But if you spend the 7Gs on it, you will be looking at 400 plus hp, maybe as much as 430, or 450 with a mega roller cam. So now its 250 hp for 7200. Oh hey, lessee 40/50 for 7200, vs 250/280 for 7200.
Just FWI, the 400hp 360 only needs a 230*@.050 cam with hi-flo heads, and is a very driveable combo. The next smaller cam will be dynomite.
So there are some things to think about. A 273 build can be a run-away train on a short track. The builds just seem to escalate and end in many dollars spent for, in a lot of cases, a disappointing ending; in terms of dollars spent to hp increase, or even to dollars spent to performance increase.
And just to drive the point home; once you get down to 10pounds per hp, first-gear traction becomes non-existant, and you will spend another couple of grand trying to solve that. So you might as well budget for that now,lol.
 
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Wow, thanks for all the great information!!
I was thinking it might be better to get a 360 crate engine so as to get more modern heads and valve train, but, I will have to put some more thought into this.
As for Abbotsford and Saskatchewan. I was working in Saskatchewan until 2012, but, was transferred to BC in 2012.

Thanks again!
 
Wow, thanks for all the great information!!
I was thinking it might be better to get a 360 crate engine so as to get more modern heads and valve train, but, I will have to put some more thought into this.
As for Abbotsford and Saskatchewan. I was working in Saskatchewan until 2012, but, was transferred to BC in 2012.

Thanks again!
What's the rest of your combo look like?
If it's performance you're after, you can't go wrong with a crate Magnum.And they come in several flavors. And even the smallest one will more than double your current power with a 273 2bbl. And probably triple your torque.
But if you just want a lil more pep for your early-A, a 380 crate is waaay more than you need. Remember that SBM horsepower always goes hand in hand with increased rpm, and rpm is always accompanied by increased mph. So to effectively use that horsepower, you rapidly run out of legal mph.
Take my combo for instance. It makes peak power at about 5400rpm. The top of the curve is broad and flat and it likes to be shifted at maybe 6200. Well with typical street gears, which can barely be satisfactorily driven on the hiway, being 3.55s ; 6200 would be 55mph with an auto and 5% TC slip. I have a stick, and a very low first gear, so for me,6200 is 45mph. Having a stick also means I can slip the clutch out to where peak torque is and instantly fry the tires. With an auto, you would not be able to do that, the TC may hold your launch rpm to something like 2250 to say as high as 2800, and your starter gear is only 3.55 x 2.45 =8.70, compared to my 10.97.
The point I'm getting to is that even tho the crate engine might have 380 hp, you may not be able to access all of it on the start line.Maybe not even half of it.I'm guessing only 100 to 120 ftlbs at say 2800 rpm. Well your average stock318LA can make that too! A Magnum can do a little better.
So you have to be careful when going after power. Many times you will get way more power than you need at 50 mph, and not enough at 2800rpm on the start line,lol.
When that happens as it so often does, then you look to TM(TorqueMultiplication), to make up the difference from what you got to what you need/want. And pretty soon you are running 3.91s, and the car can no longer cruise comfortably on the hiway. And so that leads to an overdrive transmission, or a deep low gear, or both!.. Lotsa more money,in any case.So if you are currently running a 2.76 rear gear, you might as well figure on ditching that right away, for 3.23s minimum with an automatic, and at least 3.55s with a stick.
But if you're just looking for more torque, to buzz around town with, there's a much cheaper way to achieve that.And it may not even involve a crate engine.
 
I hear you about the gears.
Many years ago, one of my friends was running a 427 in a 1966 chevelle and he had a wild camshaft + Victor intake + tricked out heads, so, he ended up running 456 gears..... The car was a total 1/4 mile machine, but, it was unbearable to drive more than about 50 km.
I'm not looking to race, rather, I am looking for minimal grief. Something that I can drive to California without constantly monitoring gauges + driving under 90 kmh or needing a jug of octane boost in the trunk for fear I may get a bad tank of fuel.
Hence, total daily driver type machine. That is what has me interested in some of the newer TBI systems. The ones from the 1990s were not great, but, in recent years, quality has improved and price has decreased.
As for the 273 block, I do like to keep things as "stock" as possible, but, it is not as though anyone can tell from a glance that it is really a 360.
 
So let's talk about TM
Say your 273 makes 100 ftlbs at 1750 stall speed, and you have a 904, and you have 2.76 rear gears.So on the start line you will have 100x2.45(low-gear)x2.76( in the back)=676ftlbs to launch with. Well that's pretty sorryazz. To really get moving you need over 1000 with a 3400 pound pkg. To fry the tires you will need maybe 1400 with skinny tires.
So you can get there in several ways
1) a bigger engine, or
1B) an engine that thinks it's bigger
2) a higher stall rpm
3) more TM
4) less weight
5) supercharging the one you got
So let's say you make no other changes except installing a 318 which makes 120 ftlbs at the same 1750rpm. this maths out to 811ftlbs, which is plus 20%.
But let's say instead that with same 273engine, you increased the stall rpm to achieve the same 120ftlbs, Now you're blasting off like a 318 with plus 20% Torque at the start line. However, don't get too excited, cuz the 45 cube difference will quickly become apparent with rising speed and rpm.
But let's say you put 3.55s in the back and go back to a 1750 TC. This maths out to 870ftlbs. But hang on, this 28% TM advantage is carried all the way thru the gear and every gear. That's a good thing right? Well yes it is if you don't mind the plus 28% cruising rpm.
But we're still not kissing the magic 1000 ftlbs. So what if we add the TC back in? Well that maths out to 120 x 2.45 x 3.55=1044! badaboom! You can now show taillights to any stock 318 running 2.76s in a similar weight chassis.
But we're not finished yet. There is a deep-low trans you can score in the junkyard called the A999, which externally is identical to your 904, but it has a 2.74 low first gear. What can we do with that? Well let's keep the 3.55s and the higher stall TC as in the previous combo and sub in the 2.74 lowgear. This maths out to 1167 ftlbs.
And we haven't touched the engine yet.
But let's say 1167 is more than you need. Lets take a bit of rear gear out, say going to 3.23s to get the hi-way buzzzzzz down. This maths out to 1062ftlbs.
Or say the hi-stall was not to your liking and you went back to the stocker. This maths to 885ftlbs.Well you might want the 3.55s back to get 973,pretty close.
But lets back up;
Lets put a 4bbl on there. and pick up 10 ftlbs at 1750 rpm, and put the 3.23s back in, to get 974ftlbs. Ok, how about headers, or in your case just hi-po logs and dual exhaust, add another 10 at 1750, now we're back up to 1167, so the 3.23s can return, for 1071ftlbs.
But suppose you don't like the 1-2 split of that A998, cuz admittedly it's pretty wide for a 273. Ok so lets work it with the 4bbl273 with hi-po logs, that 2.45 low of the A904, plus the higher stall, cuz they're just so much fun,and 3.23s the max that you have decided to run. Ok then;140 x 2.45 x 3.23=1108; and you're spinning tires.
The sweet part of this combo, is the TC and 4bbl will cover the hole from stall to peak torque, and the gears will make a difference of plus 17% in every gear.
So to recap, this combo is not for racing,period ; as soon as you get into third gear you'll know why. The engine is just too small. No, this is a first gear runner, to about 40 mph.
And when you pull out to pass at 60, when she downshifts to second and the secondaries open, something is finally going to happen!
So what's all this gonna cost. Well a 4bbl and intake plus hi-po logs and a 3.23 gearset installed, plus the fun TC, Ima guessing , change back from $2Gs. But here's the kicker, you only need to install as much as you need until the performance gets to the level you want.
I would install them in this order; gears first, then the TC, then free-flowing exhaust and the 4bbl dead last. You could swap the exhaust and 4bbl, but I don't think you'll see much of an improvement with a 4bbl into a single exhaust; they have kindof a symbiotic relationship with better results when the exhaust is opened up first.
Altho on you combo, I'm not so sure.
I tell you what, do the 4bbl first and then measure the back pressure in the pipe before it gets to the muffler. If it's over 4psi, make some duals, and retest.. If it's under 2psi at full-load WOT, leave it alone, you won't gain much for the money spent. Between 2 and 4 is a judgement call.Drive it for a week with the pressure gauge mounted somewhere you can see it . Then just keep an eye on it whenever you get to pressing the go-pedal. If it generally stays below 3 psi, I'd pass on the hi-flo exhaust, and save a buncha money. Now you're into it for maybe $1200

I did all this a couple of times allbeit with a teener, and it turned out great! I used 3.55s, a 2800 and the A998 with a factory TQ. One had headers and 3"full length duals which sounded awesome. The teener handled the wide-splits of the A998 OK.The teener was otherwise stock and was maybe a little tired. This in a 3650 car.
 
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I hear you about the gears.
Many years ago, one of my friends was running a 427 in a 1966 chevelle and he had a wild camshaft + Victor intake + tricked out heads, so, he ended up running 456 gears..... The car was a total 1/4 mile machine, but, it was unbearable to drive more than about 50 km.
I'm not looking to race, rather, I am looking for minimal grief. Something that I can drive to California without constantly monitoring gauges + driving under 90 kmh or needing a jug of octane boost in the trunk for fear I may get a bad tank of fuel.
Hence, total daily driver type machine. That is what has me interested in some of the newer TBI systems. The ones from the 1990s were not great, but, in recent years, quality has improved and price has decreased.
As for the 273 block, I do like to keep things as "stock" as possible, but, it is not as though anyone can tell from a glance that it is really a 360.
Well in this case pick the biggest engine the lowest gears and as stock as possible for the long block. To cruise 85 will take 2.45s; so get those from a Fifth Ave. Run the tallest tires you can fit and the A998, also from the 5th will get you off the line reasonably well. I'd run a 360 or a 5.9 Magnum preferred cuz it will have the torque to pull this off.
Say the 360 makes 140ftlbs at 2800; 140 x 2.74 x 2.45=940 which is pretty close to the magic 1000. So now you have take-off, and can cruise 85=2600 with 27s. The 360 needs duals and a 4bbl but not much else. And a bonus is the 8/1 compression LA will burn anything. While the Magnum will make a bit more power to pass, hitting about 3200 at 65 in second gear. Horray for TM.
If you've never cruised your car at 65=2000, well you're in for a treat. Well except for the windnoise lol.
If fuel mileage is important to you, then run the 273 with an A500 and 3.55s. This will get you the same final drive of 2.45, yet the 3.55 x 2.74 x 120of the hi-stalled 273 will catapult you into next Tuesday with a starter of 1167 ftlbs. This will also cruise at 85 = 2600 with 27s. I have tuned stock 2bbl 273s to get very high 20s IMP, so say 24mpgUS, and it wasn't hard.That will get you close to 300miles per tank,give or take. Add a 4bbl and free-flow exhaust and you could be looking at 1362 ftlbs Which is well able to spin 245s. Maybe even 275s,lol.
The vehicle that provides the A500 could be an early Dakota 2wd, and might have a 3.91rear gear. That rear can be made to fit your car A-body relatively easily. This will up the cruise rpm to 85=2850, but those gears will allow you to run the273 as a 2bbl single exhaust and the stock A-500TC. I'll guess this comb could make 110 x 3.91 x 2.74=1178ftlbs on the start-line. So now you're down to finding a suitable donor vehicle. The A-500 will not drop into an early-A, and a later-A needs a bit of tunnel/cross-member work. But Let me tell you; those 3.91s will really wake your 273 up. She'll have a whole new personality.
I think I actually would like this combo for myself. Well, I know I would, cuz I ran my 318 with a 10.96 starter gear a time or two, and a final drive of 1.97,lol, with a stick, and it was awesome. The 273 would have been icing-on-the-cake, in the drive-past-the-pump department.
Oh wait we were talking automatics.Ok I ran my 318 with a 9.73 starter and a 2800TC with direct Drive, and it was awesome. I also ran it with a final drive of 2.73, which was sluggish out of the gate all right,(starter of just 7.48), but was fairly frugal in the fuel-consumption department.
 
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Hey there Saskatchewan, I'm in Langley so just up the road from you!

If you're looking for some upgrades, or decide on a 318 / 360, I have a bunch of parts that are coming off my demon.
Have a set of 2.02 valve J-heads, comp 275DEH cam & lifters, 360 exhuast manifolds, etc ready to go.

PM if you're interested, I have some of the parts posted on craigslist.
My 360 block cracked, so am doing a much bigger buildup now:
360 Advice Needed - Autocross / Street Engine Build


Ryan
 
I had not thought about swapping transmissions, but, that could be an option. I checked out the Hot Rod blog and there is a description of what is involved in taking one of the Dakota trans and putting them in a earlier model Mopar.
Mopar Overdrive Transmission Swap - How To - Hot Rod Magazine

Since the car had optional manual transmission, would there be any 5 speeds that would fit?

As for dual exhaust and 4bbl, I would always do the two simultaneously. How much you can "flow in" depends on how much can "flow out". Once I put a 4bbl on a /6 and there was an ENORMOUS improvement in power and drive ability, however, I later installed dual exhaust and there was another noticeable improvement in power.
 
Hey there Saskatchewan, I'm in Langley so just up the road from you!

If you're looking for some upgrades, or decide on a 318 / 360, I have a bunch of parts that are coming off my demon.
Have a set of 2.02 valve J-heads, comp 275DEH cam & lifters, 360 exhuast manifolds, etc ready to go.

PM if you're interested, I have some of the parts posted on craigslist.
My 360 block cracked, so am doing a much bigger buildup now:
360 Advice Needed - Autocross / Street Engine Build


Ryan
Hey Kicker92, I am still very much in the preliminary stages, so, not ready to be making any hardware purchases.
 
Well in this case pick the biggest engine the lowest gears and as stock as possible for the long block. To cruise 85 will take 2.45s; so get those from a Fifth Ave. Run the tallest tires you can fit and the A998, also from the 5th will get you off the line reasonably well. I'd run a 360 or a 5.9 Magnum preferred cuz it will have the torque to pull this off.
Say the 360 makes 140ftlbs at 2800; 140 x 2.74 x 2.45=940 which is pretty close to the magic 1000. So now you have take-off, and can cruise 85=2600 with 27s. The 360 needs duals and a 4bbl but not much else. And a bonus is the 8/1 compression LA will burn anything. While the Magnum will make a bit more power to pass, hitting about 3200 at 65 in second gear. Horray for TM.
If you've never cruised your car at 65=2000, well you're in for a treat. Well except for the windnoise lol.
If fuel mileage is important to you, then run the 273 with an A500 and 3.55s. This will get you the same final drive of 2.45, yet the 3.55 x 2.74 x 120of the hi-stalled 273 will catapult you into next Tuesday with a starter of 1167 ftlbs. This will also cruise at 85 = 2600 with 27s. I have tuned stock 2bbl 273s to get very high 20s IMP, so say 24mpgUS, and it wasn't hard.That will get you close to 300miles per tank,give or take. Add a 4bbl and free-flow exhaust and you could be looking at 1362 ftlbs Which is well able to spin 245s. Maybe even 275s,lol.
The vehicle that provides the A500 could be an early Dakota 2wd, and might have a 3.91rear gear. That rear can be made to fit your car A-body relatively easily. This will up the cruise rpm to 85=2850, but those gears will allow you to run the273 as a 2bbl single exhaust and the stock A-500TC. I'll guess this comb could make 110 x 3.91 x 2.74=1178ftlbs on the start-line. So now you're down to finding a suitable donor vehicle. The A-500 will not drop into an early-A, and a later-A needs a bit of tunnel/cross-member work. But Let me tell you; those 3.91s will really wake your 273 up. She'll have a whole new personality.
I think I actually would like this combo for myself. Well, I know I would, cuz I ran my 318 with a 10.96 starter gear a time or two, and a final drive of 1.97,lol, with a stick, and it was awesome. The 273 would have been icing-on-the-cake, in the drive-past-the-pump department.
 
I had not thought about swapping transmissions, but, that could be an option. I checked out the Hot Rod blog and there is a description of what is involved in taking one of the Dakota trans and putting them in a earlier model Mopar.
Mopar Overdrive Transmission Swap - How To - Hot Rod Magazine

Since the car had optional manual transmission, would there be any 5 speeds that would fit?

As for dual exhaust and 4bbl, I would always do the two simultaneously. How much you can "flow in" depends on how much can "flow out". Once I put a 4bbl on a /6 and there was an ENORMOUS improvement in power and drive ability, however, I later installed dual exhaust and there was another noticeable improvement in power.
Five-speed manuals are big money. BIG BIG money.
There is a guy here on FABO who is experimenting with fabbing up a kit to install an AISEN in a SBM, which would easily handle your 273, or even a 318.....but I forget his name and the title of his thread.There were 2 ratio sets available in the Aisen, and you would need the closer ratio set. You'll have to do a search.

I found it!
6 Speed Slant Six
Scroll down to the final post.
He built this for a slanty, but I seem to recall him saying something about fabbing up an adapter for the SBM, send him a PM if interested.
 
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Thanks for the link, but, it is for taking a six speed manual from a Nissan and that sounds kind of complicated for my purposes. I was thinking of a 1990s era five speed manual from a Mopar. Would it be that much of a challenge? I would have thought that the flexplate from the original drivetrain could be machined to work with a manual trans?
 
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