Estimated 1/4 mile - 71 Roadrunner 340 4 speed

[Phantomx]

4.10s are a miserable street gear if you have to travel any distance unless you have overdrive or live where you won’t be traveling over about 55 mph sustained. 4.10s without overdrive are not modern traffic friendly.

Any Dana 60 from a truck is going to require narrowing and car style bearing ends to be installed to run car axles and brakes.

Travis..

 

[Curiousyellow71]

Ok, is there any way really to figure out what your final compression ratio is without peeling off the heads? I know about the compression testers that screw into the spark plug hole, but am unsure how the psi would convert into a compression ratio

As for boost, a stroked out 426 small block with a roots blower sounds nice, the fiberglass hood ill get so I don't chop up my original would also save a bit of weight..

Now wondering, why do you say don't go deeper than 4.10s, specifically on an NA build though? Would you say the same if I went with a 28 inch tall tire

The dana 60 was always a thought in the back of my head, also easier to since I can decently easy find limited slip 4.10 versions of the axle from trucks, and I believe I can use my brakes I already have if I'm not wrong

At the point of split monoleafs and caltracs with adjustable shocks, I'm gonna probably be in around 2 to 2 and a quarter grand. Is it really worth it to keep leafs instead of going to 4 link?

You don't need cubic inches with boost. Bigger dispacement engines that are boosted just become harder to hook up out of the hole. Roots blower build heat and are usually not a pump gas thing. Turbos and belt driven centrifugal superchargers can fit under the hood and are usuall pretty efficient. They din't have the wow factor and roots has.
When you do a compression check, you have your cam information. It will tell you the health of your engine and you can use online calculators to estimate your static compression. It won't be exact..but good info.
The last Split mono's with caltracs I bought were around 800 bucks and is just a bolt in. Shocks you need no matter what. Not sure which 4 link your referring to. Some bolt in the stock location while the other require heavy body modifications.
We have narrowed Pickup dana 60s with a 3inch tube. We are running split mono's and caltracs. There is no pinion snubber mount, so you have to go with some kind of traction control. Or just buy a s60 new and drop it in.
We run 4.10s with 30.2 tall tires. 28's would still work. Any deeper gears then that we swap pigs for a race. Quiet exhaust helps tolerated 4.10s. 3.90s would be similiar to our gearing w 28s.

 

[Phantomx]

There will always be people that doubt your times, but they can find out easy enough if they line up.
Travis..

 

[340runner]

4.10s are a miserable street gear if you have to travel any distance unless you have overdrive or live where you won’t be traveling over about 55 mph sustained. 4.20s without overdrive are not modern traffic friendly.

Any Dana 60 from a truck is going to require narrowing and car style bearing ends to be installed to run car axles and brakes.

Travis..

I dailied 4.10s for a while in the roadrunner, it was surely a pain in the *** on the interstate but I personally think that tradeoff is worth it

Well, I knew that about the dana 60, the plan was to take it to a weld shop or drivetrain shop that did axle narrowing to have it to OEM spec mounts and length, then install my brakes and slap it in after having the driveshaft shortened, it really doesn't sound that difficult since I'm not going with custom length but that might just be my overconfidence talking

 

[Phantomx]

Ok, it sounded like you were talking swapping your brakes onto a truck axle without needing the narrow job. You got it.
Travis..

 

[Phantomx]

Hey, if you liked the 4.10s then go ahead and run them.
Travis..

 

[340runner]

You don't need cubic inches with boost. Bigger dispacement engines that are boosted just become harder to hook up out of the hole. Roots blower build heat and are usually not a pump gas thing. Turbos and belt driven centrifugal superchargers can fit under the hood and are usuall pretty efficient. They din't have the wow factor and roots has.
When you do a compression check, you have your cam information. It will tell you the health of your engine and you can use online calculators to estimate your static compression. It won't be exact..but good info.
The last Split mono's with caltracs I bought were around 800 bucks and is just a bolt in. Shocks you need no matter what. Not sure which 4 link your referring to. Some bolt in the stock location while the other require heavy body modifications.
We have narrowed Pickup dana 60s with a 3inch tube. We are running split mono's and caltracs. There is no pinion snubber mount, so you have to go with some kind of traction control. Or just buy a s60 new and drop it in.
We run 4.10s with 30.2 tall tires. 28's would still work. Any deeper gears then that we swap pigs for a race. Quiet exhaust helps tolerated 4.10s.

Ok, i was mistaken, as i thought the leafs were sold individually and not as a pair. I was referring to the qa1 4 link by the way, but now that I see the new price it doesn't seem too terrible.
Yeah I ran around with my 4.10s, I didn't mind as much but I always ran around on big trips with a earbud in for music/Waze. One ear bud was left out so I could have some situational awareness, mostly the radar detector I run

 

[340runner]

You don't need cubic inches with boost. Bigger dispacement engines that are boosted just become harder to hook up out of the hole. Roots blower build heat and are usually not a pump gas thing. Turbos and belt driven centrifugal superchargers can fit under the hood and are usuall pretty efficient. They din't have the wow factor and roots has.
When you do a compression check, you have your cam information. It will tell you the health of your engine and you can use online calculators to estimate your static compression. It won't be exact..but good info.
The last Split mono's with caltracs I bought were around 800 bucks and is just a bolt in. Shocks you need no matter what. Not sure which 4 link your referring to. Some bolt in the stock location while the other require heavy body modifications.
We have narrowed Pickup dana 60s with a 3inch tube. We are running split mono's and caltracs. There is no pinion snubber mount, so you have to go with some kind of traction control. Or just buy a s60 new and drop it in.
We run 4.10s with 30.2 tall tires. 28's would still work. Any deeper gears then that we swap pigs for a race. Quiet exhaust helps tolerated 4.10s. 3.90s would be similiar to our gearing w 28s.

Eh, honestly turbos just ain't my thing, I'd honestly rather have nitrous and more cubes over turbos or a centrifugal. The big reason is I don't wanna swap over to a blow through or EFI now that I've heard everyone's opinion about it, but also it just clutters the engine bay.

Secondary note, now these days I'd say turbos have more of a wow factor instead of a roots, not my personal opinion but based off of every person who just thinks twin turbos are Gods greatest inventions and nothing else makes any power at all at car meets. God i can't stand those people along with the LS swap the world people and the "why don't you swap a modern drivetrain" people. Sorry for the tangent

 

[340runner]

You don't need cubic inches with boost. Bigger dispacement engines that are boosted just become harder to hook up out of the hole. Roots blower build heat and are usually not a pump gas thing. Turbos and belt driven centrifugal superchargers can fit under the hood and are usuall pretty efficient. They din't have the wow factor and roots has.
When you do a compression check, you have your cam information. It will tell you the health of your engine and you can use online calculators to estimate your static compression. It won't be exact..but good info.
The last Split mono's with caltracs I bought were around 800 bucks and is just a bolt in. Shocks you need no matter what. Not sure which 4 link your referring to. Some bolt in the stock location while the other require heavy body modifications.
We have narrowed Pickup dana 60s with a 3inch tube. We are running split mono's and caltracs. There is no pinion snubber mount, so you have to go with some kind of traction control. Or just buy a s60 new and drop it in.
We run 4.10s with 30.2 tall tires. 28's would still work. Any deeper gears then that we swap pigs for a race. Quiet exhaust helps tolerated 4.10s. 3.90s would be similiar to our gearing w 28s.

I also guess a compression tester is in order, so I can finally figure out at least my rough compression ratio

 

[Curiousyellow71]

Eh, honestly turbos just ain't my thing, I'd honestly rather have nitrous and more cubes over turbos or a centrifugal. The big reason is I don't wanna swap over to a blow through or EFI now that I've heard everyone's opinion about it, but also it just clutters the engine bay.

Secondary note, now these days I'd say turbos have more of a wow factor instead of a roots, not my personal opinion but based off of every person who just thinks twin turbos are Gods greatest inventions and nothing else makes any power at all at car meets. God i can't stand those people along with the LS swap the world people and the "why don't you swap a modern drivetrain" people. Sorry for the tangent

I hate LS swaps.

 

[340runner]

I hate LS swaps.

They have a place, but that place sure as **** ain't in a classic American car. I wouldn't think twice though if it was some Japanese car that originally had a 4 banger or a rotary. I think a cammed stroked NA ls swap miata would be a riot to whip around before died wrapping it around a tree cause I accidentally tickled foot on the gas during a corner

 

[polyjohn]

My favourite Mopar a 71 Runner!
A fellow UK Moparmate had a 72 340 4-speed too.

He ran that down the track on may occasions at around 14.00.
Its now an auto with a 408, so that's where you end up I guess?

I have a 71 GTX that I hope to run in Superstock UK this year.
What do I expect?

Same as my 70 GTX mate from the 90's, Mid elevens or he will rib me bad!

 

[dvw]

It takes experience , knowledge, and cash to do work properly. Read everything you can about how everything works. Engines, trans, axles, carbs, injection, turbos, electrical, suspension, etc. There is a ton to learn. Fortunately it's easy to learn when you are young. Pack that brain with knowledge. Start making changes as you learn. Enjoy the hobby. Then when you really want go fast on the street, do this. Then you can run mid 9's in street trim.
Doug

 

[340runner]

It takes experience , knowledge, and cash to do work properly. Read everything you can about how everything works. Engines, trans, axles, carbs, injection, turbos, electrical, suspension, etc. There is a ton to learn. Fortunately it's easy to learn when you are young. Pack that brain with knowledge. Start making changes as you learn. Enjoy the hobby. Then when you really want go fast on the street, do this. Then you can run mid 9's in street trim.
Doug




View attachment 1791819

Oh yeah, that's a big *** turbo.
Honestly I interpreted a lot of the previous posts as people saying if your going to make a car fast, forget about having it streetable and that'd it'd be race-only. This makes a lot more sense on how a fast street car is almost easier to make as fast as it doesn't have to follow class rules, almost like its jailbroke

 

[padam]

To be fair, dvw is master level at this stuff. Not everyone can do what he does no matter how hard they try.

 

[67 WS23]

I had a 70 Duster 340 with the new process 4 speed and factory Hurst shifter, and the 8 3/4 rear with 390 gears. All stock I believe the comp ratio of the 1970 340 is 10.5 to 1. Back in the early 80s the gas was degrading so I installed an Edelbrock water injection kit in which I ran drug store alcohol. Worked really well to kill knocking and didn't freeze in the winter. One water tank full every 2 fill ups of gas. I drove the car for about 3 years, about 65k miles commuting to work and school. On the open highway it got about 10 mpg as I recall, where many trips from Long Island to Carlisle PA, about 240 mi, took 2 fill ups each way. It was a fun car for a guy in college at the time.

 

[1967coronet]

Yeah I don't get why 7k is that hard of a push for redline as it's a fully forged 71 340 with upgraded roller valvetrain and better flowing heads, exhaust, intake and better fueling system so it doesn't go lean. It also has a 8 qt oil pan so lack of oil isn't an issue

I would book some time on a drive on dyno. Find out what RPM that 340 starts to fall off. It may turn more RPMs but after the nose over your just making noise.
Also use that time to play with timing and carb getting.
Getting it all balanced so to speak will drop your times. Cam , ignition , carb all need to be matched to their respective power band,
There is a lot of power to be had in a good tune.

 

[dvw]

When I started out as a young guy I new nothing. Never had much money either. I laugh at the dumb stuff I did in early years. Didn't really start to get a handle on it until I was nearly 30. Being a car mechanic as a living helped for sure. I read evrything I could find. Remeber no internet then. It helped to find smart people and learn from them. Dave Koffel and Lou Mancini had a big influence on me. I can tell you that in my years in the repair business ther were a lot of guys who never rebuilt an engine, transmission , or rear end. Most couldn't fabricate either. They just all weren't real car guys. For then it was a job. My son and his buddies had it easy. They lived it growing up around our household. I have two boys. One has very little interest in cars. The other? We drove to a race in Cordova from Detroit. I had a 63 Dodge N/SS car. My son had a 73 Duster 340. He showed up with his buddy Friday at about 6:30. They promty started pulling the trans. "What are you doing"? The response was it lost 3rd gear last night on the street. They pulled the trans apart, fixed it themselves. He ended up winning the NMC class that weekend. Him and his buddy were 19. In th eprevious post that's his 62 Plymouth when it had the turbo small block. Built it himself. It now has a low deck and has turned into a dedicated racecar. I built a Duster for a friend last winter. The turbo motor is in it now.
Doug

 

[340runner]

When I started out as a young guy I new nothing. Never had much money either. I laugh at the dumb stuff I did in early years. Didn't really start to get a handle on it until I was nearly 30. Being a car mechanic as a living helped for sure. I read evrything I could find. Remeber no internet then. It helped to find smart people and learn from them. Dave Koffel and Lou Mancini had a big influence on me. I can tell you that in my years in the repair business ther were a lot of guys who never rebuilt an engine, transmission , or rear end. Most couldn't fabricate either. They just all weren't real car guys. For then it was a job. My son and his buddies had it easy. They lived it growing up around our household. I have two boys. One has very little interest in cars. The other? We drove to a race in Cordova from Detroit. I had a 63 Dodge N/SS car. My son had a 73 Duster 340. He showed up with his buddy Friday at about 6:30. They promty started pulling the trans. "What are you doing"? The response was it lost 3rd gear last night on the street. They pulled the trans apart, fixed it themselves. He ended up winning the NMC class that weekend. Him and his buddy were 19. In th eprevious post that's his 62 Plymouth when it had the turbo small block. Built it himself. It now has a low deck and has turned into a dedicated racecar. I built a Duster for a friend last winter. The turbo motor is in it now.
Doug

Yeah, I have a lot to learn, I mean if I was a mechanic I'm not sure it'd even help that much, everything now is diag then replace and then you're not getting much experience actually experiencing the racing and performance side aside from I guess working with turbos and boosted cars now, but that's also not fabrication, just swapping out parts and diagnosing. My auto teacher outside of schooling hasn't ever rebuilt a trans or rear end, doesn't even know how to weld. People aren't getting to the fabrication. I'm just right now trying to gather how to I guess do all of that "real car guys" type of thing. I've rebuilt my fair share of small engines, just need the funds to start on a car engine but I feel quite comfortable on the topic and have researched extensively. Not to mention I have here to look for help. Rear ends are going to be a challenge. Actually went to the pick and pull today and stopped by, there is a dana 60 on a chevy express van, the guy wants 250$ for the whole thing and 120$ for the housing. I don't want anything really but the housing, would 120$ be worth for a housing, main caps and cover? My big stop with fabrication is I don't know how to weld. I also don't really know where to learn, my school doesn't even offer it. My dad knows how to run stick and wire welders, he's helped me weld exhaust before with a borrowed machine and I know a little bit of flux core and mig, but I don't have big experience on it and don't know really what looks good and will hold and what doesn't.

Side note, if you dont mind divulging on that small block, whats the specs on that thing? more and more I think about it, I'm leaning towards turbo as a method for boost but at the same time I've never worked on anything boosted and am scared of fabricating the piping is what it really comes down to

first comes tires and then reconvening though

 

[Curiousyellow71]

Is your RR a original 340 car? Engine have matching numbers? Just thought I'd ask because for what your wanting to do you may want to enjoy your 340 as is and build your first engine on the side...and do a stroked big block. It would be a easy swap. They make a 4 speed bellhousing that has both SB and BB patterns.
What year is the van? 8 luggage wheels or 6? Modern Dana's can have really thick axles and instead of a 3" they can be larger. You will also find S60's and dana 70's. They all can be cut down but its extra work and not the same as a older Dana 60 rearend say out of the 1960s. Anyway, I don't know what your looking at..do research on it. The internet is your friend.