Beginner's Bucks-Down /6 Build...Suggestions Welcome

[Bill Dedman]

Holy slant six treasure trove! So much info in one thread! I love it!

Thanks for the kind words! There's a lot to know, and this is a really good place to find answers! I know I have learned a lot from this site!

:happy1:

 

[mopar68a]

I'll tell you what I know (or, think I know.)

TUNING is more important than most folks realize... getting a fuel delivery system that can give your engine exactly what it needs in terms of mixture, both under boost and at cruise, is not the easiest thing in the world to do. For starters, carburetors were never designed to function under boost. Particularly, under 20+ pounds of boost. But, that's where the power is. And, that's where the fun is! But the negative aspects of this tuning business is, if you make a mistake and happen to get it lean under boost (a disturbingly easy thing to do,) detonation can (and will) destroy your engine in the twinkling of an eye. That is particularly true if you have built the engine on a budget and have used stock, cast pistons with stock-type rings. That is why it is just about impossible to build one of these things without the aid of a wideband oxygen sensor,

That piece of equipment is the first thing I'd recommend a clant six turbo builder buy... for sure!

More later... morphrus calls...:glasses7:

Ah. OK. Noted. Thanks. But maybe I should stick with NA for now. I don't have the budget to replace the engine should I get it wrong.

 

[mopar68a]

I understand the best band for the buck, but lets face something here, what is the OP's history of automotive experience? does he have the ability to put a turbo system together, tune it properly, and maintenance it properly? OP if you can do this in your sleep i apologize as your first posts made it seem you were new.

IMO if this is your first build you need to do the basic NA build we laid out for you. It will be easy and cheap to build, it will be a big return for your work, and most importantly you will cut your teeth and learn from mistakes. IMO most people go to boost for return without spending the time to LEARN what makes an engine work (build matrix, tune, etc). Boost is not just blow and go, its something that you learn to control and use to your advantage. That said if you cant do a prep and clearance a head for a goal, install and tune an NA induction, and build off of it to make it more efficient, you have no place running boost.

These boost guys are always in favor of blow because they can get their quick hp boost, but if you want to LEARN dont do exactly what someone else did because all the mistakes are fixed, i.e. you wont learn that way, it was given. Every motor i build and help build i learn a ton, you'll do good to do the same.

A reality check. Thanks. I needed that. I got ahead of myself. Appreciated. No apology necessary. I should note that I'm not inexperienced. I have helped to tune, build, and rebuild engines and transmissions, and helped to redo interiors. I have not yet built my own. And I have no experience hands-on with forced induction. There is much I have yet to learn. That's why I came here, and I'm glad I did. So for now, I will put the turbo idea on hold and stick with NA.

 

[/6 Matt]

A wise choice^^^

I'm in the same boat as you, so I don't have plans for a turbo build... yet...

Whenever you find a car and start your build you should start a thread to document your build in the member restorations section here. I'd love to watch another slant build.

 

[nm9stheham]

And you can tune a car to run aggressive turbo boost in certain conditions and have it survive fine, and then it'll blow when conditions change if you run it too close to the edge. I tend to keep my turbo rally engines on the conservative side, use known tuning, and keep some adjustability in the field 'just-in-case'. Going from humid warm air to dry, cool fall air requires an equivalent of 3-4 points of octane change or the equivalent change in boost and fuel control. Yes, sticking with NA is a good idea!

 

[mopar68a]

A wise choice^^^

I'm in the same boat as you, so I don't have plans for a turbo build... yet...

Whenever you find a car and start your build you should start a thread to document your build in the member restorations section here. I'd love to watch another slant build.

Thanks. I plan to. I'm still looking hard for a car atm. Me, also. I always learn something, even if it doesn't directly apply to what I plan to do.

 

[805moparkid]

Here is the great thing 68. you can build a 9.2:1 motor, do all the head work, intake/4 barrel/headers, build the rest of the car and bolt a turbo on and go! your not cutting the turbo out by any means, you just need to have a solid footing before you jump in IMO.

 

[mopar68a]

Here is the great thing 68. you can build a 9.2:1 motor, do all the head work, intake/4 barrel/headers, build the rest of the car and bolt a turbo on and go! your not cutting the turbo out by any means, you just need to have a solid footing before you jump in IMO.

That's true. The turbo is still an option, for later. After I become more familiar with how to tune and maintain one and after I have maybe 2 /6 engines in the garage as spares just in case...

It's the same with what I do for a living. Electronics recycling, computer repair/refurb/resell. In order to do that well, I had to become thoroughly familiar with their parts, how they worked together, and how to do moderately advanced troubleshooting. I still can't do board-level repairs...yet.

If I remember correctly, in the older Clifford catalogs, the Old Man used to include a basic upgrade list with estimated results for the slants and other inline 6's. Stage I was basic, and est. 25% more rwhp. Stage II included headwork, cam, and headers, etc. and est. 40% more rwhp. I forget what Stage III included and what it's est. results were.

 

[2 Darts]

Sounds like a good starter project. There isn't so much stuff out there to tempt massive overkill, but there is enough to tweak better performance out of the old /6 A-body.

I am working on getting the car now. I hope for a 68 Dart 270 more door, but I will be OK with a 70-74 Dart Custom more door. Running or not, as long as it's a solid foundation for a good build and is not wrecked. Running preferred, though. I'd like to drive it during the week and wrench on it on the weekends.

As I said in the title, it's a bucks-down build. I'm planning to do this over a 3-5 year timeframe and I want to use as many used / junkyard / rebuilt parts as I can. There is much I can do myself, and much I'm willing to learn from others concerning this build.

I'd like the car to be street-only, run a bit faster, handle, and stop a bit better than it did when new. With that in mind, based on what I have learned, I have come up with the following tentative build...

It's an ambitious set of goals. Wrenching regularly on a DD has its pitfalls, such as when the car is needed for service but not available due to parts/tools/labor. Recommend keeping a dependable beater around until all reliability issues are resolved and upgrades that are going to have the car non-op are installed and working properly.

Engine= '72-'74 head if '68-'71, '73+ electronic ignition with orange box and Pertronix coil if '68-'72, NGK ZFR5N-3459 plugs, '71+ stock cam if '68-'70, Offy intake with 2v adapter plate, Holley 2300 350cfm 2bbl., stock manifold > 2.25 headpipe and Y-pipe > 2.25in / 2.5out muffler > 2.5 tailpipe.

• There's no magic needed for a good machine shop to put in hardened valve seats. No need to limit head selection.
• Before I'd go to the Offy w/2v plate, I prefer the factory Super 6 or the M1 (pn /P4529115). I'm not showing current production on either but there are several on eBag at any given time. AussieSpeed makes a beautiful 2v and 4v manifold. They are a bit pricey, sadly.
• Your exhaust pipe plan looks good on paper, not so well in real life. As exhaust gas cools it contracts. If exhaust gas velocity is enhanced, as in scavenging headers, it allows the engine to breathe better. The best way to maintain or improve exhaust gas velocity would be to have the tube constrict rather than expand (expecially for 4-stroke engines. Suggest you run the exhaust 2.25 all the way.

Transmission= B&M Shift Improver kit

- Good move. Recommend the R/V kit. IMO the next level up is harsher than it needs to be for mainly street use.

Rearend= '73-'76 8.25 if '68-'72, SureGrip and 3.23:1.

- The 7.25 is adequate for a street /6. Beware all 7.25s are not equal. The LBP 7¼ has longer axle tubes and different off set to the backing plates. The LBP 7¼ is found on disk brake 73 - 76 A-bodies. That said, I have not seen a SBP 8¼. If you go that route, remember to get the saddles and clips, too. The 8¼ has a 3" diameter tube, where the 7¼ has a 2.75" tube.

Suspension= OEM HD / Rallye with front sway bar.

Good handling improvements with this. Recommend you get the LCA along with all the hardware. Major change in bar (and K-member) beginning with MY73. It is a largely futile exercise to try to put the later bar in the earlier K-frame or vice versa. Note: If you have (for example) a 72 body, A 73 k-frame bolts right in. While your car is being aligned, you can get aggressive with + caster. Do a search for SKOSH chart on FABO.

Brakes= '73-'76 LBP front disc / rear drum if '68-'72.

??? Disk/Drum is possible with SBP or LBP. Besides the brakes, recommend the proportioning valve and a dual well master cylinder. Only the 65 & 66 A-bodies with disk brakes had single well master cylinders.

Steering= '87-'94? Dodge Dakota 2WD manual or power rack and pinion.

With the 73 or later K-frame, the M/J body cop car boxes can be used.

Wheels and Tires= 14x6 steelies with dog-dish caps, Goodyear 205/70R14 or 215/70R14.

The widest 14" Mopar-made SBP wheels were 5½ wide. Anything wider has to come from the aftermarket. Which leads to the attraction of converting to LBP axles. I had 15X7 Magnum 500s (4¼ backspacing) on a 73 Custom mounted with 205/60-15 tires. No hiccups or bumps with install or operation. My 72 Demon has 15X7 cop car wheels (same bs). Fit is tight, ft fenders installed "wide". At full jounce/compression, the tires bounce off the rear inner fender and the front fender lip when being turned. No problems under normal situations. Note: Conversion from drum brakes to LBP single piston (factory) widens the front track by a little over an inch.

What can I expect, over stock, with this build? Suggestions for changes welcome. I know there are things I have overlooked or not considered. Thanks for your time and consideration.

 

[mopar68a]

Sounds like a good starter project. There isn't so much stuff out there to tempt massive overkill, but there is enough to tweak better performance out of the old /6 A-body.

I am working on getting the car now. I hope for a 68 Dart 270 more door, but I will be OK with a 70-74 Dart Custom more door. Running or not, as long as it's a solid foundation for a good build and is not wrecked. Running preferred, though. I'd like to drive it during the week and wrench on it on the weekends.


It's an ambitious set of goals. Wrenching regularly on a DD has its pitfalls, such as when the car is needed for service but not available due to parts/tools/labor. Recommend keeping a dependable beater around until all reliability issues are resolved and upgrades that are going to have the car non-op are installed and working properly.

• There's no magic needed for a good machine shop to put in hardened valve seats. No need to limit head selection.
• Before I'd go to the Offy w/2v plate, I prefer the factory Super 6 or the M1 (pn /P4529115). I'm not showing current production on either but there are several on eBag at any given time. AussieSpeed makes a beautiful 2v and 4v manifold. They are a bit pricey, sadly.
• Your exhaust pipe plan looks good on paper, not so well in real life. As exhaust gas cools it contracts. If exhaust gas velocity is enhanced, as in scavenging headers, it allows the engine to breathe better. The best way to maintain or improve exhaust gas velocity would be to have the tube constrict rather than expand (expecially for 4-stroke engines. Suggest you run the exhaust 2.25 all the way.

- Good move. Recommend the R/V kit. IMO the next level up is harsher than it needs to be for mainly street use.

- The 7.25 is adequate for a street /6. Beware all 7.25s are not equal. The LBP 7¼ has longer axle tubes and different off set to the backing plates. The LBP 7¼ is found on disk brake 73 - 76 A-bodies. That said, I have not seen a SBP 8¼. If you go that route, remember to get the saddles and clips, too. The 8¼ has a 3" diameter tube, where the 7¼ has a 2.75" tube.


Good handling improvements with this. Recommend you get the LCA along with all the hardware. Major change in bar (and K-member) beginning with MY73. It is a largely futile exercise to try to put the later bar in the earlier K-frame or vice versa. Note: If you have (for example) a 72 body, A 73 k-frame bolts right in. While your car is being aligned, you can get aggressive with + caster. Do a search for SKOSH chart on FABO.


??? Disk/Drum is possible with SBP or LBP. Besides the brakes, recommend the proportioning valve and a dual well master cylinder. Only the 65 & 66 A-bodies with disk brakes had single well master cylinders.


With the 73 or later K-frame, the M/J body cop car boxes can be used.



The widest 14" Mopar-made SBP wheels were 5½ wide. Anything wider has to come from the aftermarket. Which leads to the attraction of converting to LBP axles. I had 15X7 Magnum 500s (4¼ backspacing) on a 73 Custom mounted with 205/60-15 tires. No hiccups or bumps with install or operation. My 72 Demon has 15X7 cop car wheels (same bs). Fit is tight, ft fenders installed "wide". At full jounce/compression, the tires bounce off the rear inner fender and the front fender lip when being turned. No problems under normal situations. Note: Conversion from drum brakes to LBP single piston (factory) widens the front track by a little over an inch.

Thanks much. Noted. I will revise my build plan to include a few changes.

 

[ntsqd]

I'm a little late to this party, but:

I have Fred Puhn's book. I'd recommend Herb Adams' book over it. Easier to read and understand, and his tuning approach is better suited to street cars rather than race cars. My first pass through it I wasn't impressed, the second time that I read it I liked it a whole lot better and it is now the book that I reach for when I need a reference.

If you want to dive deeper then Paul van Valkenburg's "Race Car Engineering & Mechanics" followed by Allan Staniforth's "Competition Car Suspension." If still deeper yet then it's time to bring out THE source, Miliken & Miliken's "Race Car Vehicle Dynamics", but if you do this be prepared for multi-variable calculus.
Somewhere between van Valkenburg and Miliken/Miliken fits Olley's "Chassis Design: Principles and Analysis." It's a tough read and I haven't finished it, yet.

I searched and got this, for a start...

http://auto.howstuffworks.com/question432.htm

There is a Fred Puhm book from 20+ years ago called "How to Make Your Car Handle". ....

snipped in the interest of brevity.

FWIW No professional auto trans rebuilder that I know (& would take my stuff to) uses B&M internal trans products. To a person they use TransGo products. So I've used TransGo products and never been unhappy with performance or trans life-span. If there is a correct way and an inexpensive way to do something in an auto trans you can count on B&M not doing it the correct way. That usually is to the long term detriment of the trans.

 

[Johnny Dart]

Suggestions ?
Buy a 318 small block car. Add a 4bbl with headers and dust that sixxer.
You will be miles ahead $ wise as well.

 

[Bill Dedman]

here is the great thing 68. You can build a 9.2:1 motor, do all the head work, intake/4 barrel/headers, build the rest of the car and bolt a turbo on and go! Your not cutting the turbo out by any means, you just need to have a solid footing before you jump in imo.

x-2!!!

 

[/6 Matt]

Suggestions ?
Buy a 318 small block car. Add a 4bbl with headers and dust that sixxer.
You will be miles ahead $ wise as well.

Boring!

**GASP!!!**

Thats right! I said it.:-D Lol!

 

[Bill Dedman]

Here is the great thing 68. you can build a 9.2:1 motor, do all the head work, intake/4 barrel/headers, build the rest of the car and bolt a turbo on and go! your not cutting the turbo out by any means, you just need to have a solid footing before you jump in IMO.

Do you have any kind of a time frame for getting a PISHTA turbo-mount exhaust pipe modified/built and ready for sale?

Have you considered a price for the finished product?

You whetted my appetite... and I don't even have a car to put it on.... yet.:blob:

?????????????????????????????????????????????????????????????????????????

 

[805moparkid]

Do you have any kind of a time frame for getting a PISHTA turbo-mount exhaust pipe modified/built and ready for sale?

Have you considered a price for the finished product?

You whetted my appetite... and I don't even have a car to put it on.... yet.:blob:

?????????????????????????????????????????????????????????????????????????

I have all the parts and the turbo, just getting married next month and I have been swamped.. I have it and 3 sets of headers I need to have coated and will be going for sale to.

 

[Bill Dedman]

I have all the parts and the turbo, just getting married next month and I have been swamped.. I have it and 3 sets of headers I need to have coated and will be going for sale to.

WOW!!! Getting MARRIED? Congratulations!!!

That's GREAT!!!

Kudos to you! :cheers:

 

[Bill Dedman]

I have all the parts and the turbo, just getting married next month and I have been swamped.. I have it and 3 sets of headers I need to have coated and will be going for sale to.

Put it on your '68... two head gaskets and ten pounds of boost... instant 12's... :violent1:

 

[805moparkid]

WOW!!! Getting MARRIED? Congratulations!!!

That's GREAT!!!

Kudos to you! :cheers:

yea it is, were both excited after almost 6 years together. Im just been so swamped with work and wedding junk i dont even have time for oil changes!

Put it on your '68... two head gaskets and ten pounds of boost... instant 12's... :violent1:

i would rather do it NA and streetable. Maybe 9's and boosted on the street would get me curious though.

 

[Bill Dedman]

I would rather do it NA and streetable. Maybe 9's and boosted on the street would get me curious though.

Thing is, what's the one item that destroys the street-ability of a high performance engine? A long-duration cam.... and they are a necessary evil on a N-A engine for decent performance; ESPECIALLY so in a slant six because the head is so crappy.

A turbo engine has no use for a long duration cam, nor high revs... they have a personality like a stock motor until they get into boost... a perfect setup, if you limit your boost to 10 pounds or under, and keep the spark advance under 18 degrees. It's a pump gas motor.... and is still pretty quick.

Think about it...:coffee2:

 

[805moparkid]

Thing is, what's the one item that destroys the street-ability of a high performance engine? A long-duration cam.... and they are a necessary evil on a N-A engine for decent performance; ESPECIALLY so in a slant six because the head is so crappy.

A turbo engine has no use for a long duration cam, nor high revs... they have a personality like a stock motor until they get into boost... a perfect setup, if you limit your boost to 10 pounds or under, and keep the spark advance under 18 degrees. It's a pump gas motor.... and is still pretty quick.

Think about it...:coffee2:

actually my next cam will be about 241* @ .050 5* smaller

 

[sireland67]

I have all the parts and the turbo, just getting married next month and I have been swamped.. I have it and 3 sets of headers I need to have coated and will be going for sale to.

Best wishes on getting married.

 

[1930]

Rest in Peace

 

[805moparkid]

Best wishes on getting married.

thanks!

Rest in Peace

haha

 

[mopar68a]

I'm still around. Sorry I haven't been on lately. Life got in the way for a bit. Still is, so my search is on hold atm. I haven't forgotten, and I plan to continue this project as soon as I can. Thanks again for all the good helps.