Slant 6 Turbo 68Dart Project
- Thread starter Serj22
- Start date
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Serj22
Well-Known Member
I just got back inside from starting the car for the first time in about a week. I popped a new freeze plug back in, and naturally it started right up. I filled it with coolant/water and let it get up to temp and run for a bit. I inspected around the carb and it had cold liquid around the carb hat which means fuel is getting up there for some reason and dribbling. That also means a boost leak. So tomorrow the carb is coming back off the car to be inspected and see what I can do about the tube routing that may be leaking. Something's wrong. I'll take some more pics of the carb I built as well when it's off.
I keep making the slant just run when I should rebuild it... oh well. It's so hard to take this car off the road for any amount of time.
I keep making the slant just run when I should rebuild it... oh well. It's so hard to take this car off the road for any amount of time.
I don't know the answer to that question, but, I am sure the door is longer on a 2-door than a 4-door. The front cap is likely the same, but the trunk lid may be longer, front-to-rear, on a 2-door.
Serj22
Well-Known Member
No. Those didn't happen till 1979 I believe on Volares and ASpens. Mine came with a Holley 1920.
Then I bought a 2bbl manifold and put a Weber 38/38 on it, and it was great, but I didn't want to cut that beautiful carb up for boost, so I went to a Holley 350 since the information for modifying them was readily available.
The fenders do. The hood does. The doors do not. 4 doors have shorter doors. The two door has longer doors. The windshields do not interchange either. 4 door windows sit up higher, so basically nothing interchanges besides the mechanical stuff, and the front fenders, bumpers, hood, etc.
I found an offy for 200 I'm gonna get and might run that mighty demon just jet it down and put the dial a jet in and I will have alot of room to grow into the carb with cam and pistons and stuff later I've ported alot of cummins heads so the slant shouldn't be too hard. Do you think it's something that will work or is it just too much carb?
RustyPlymouth
Well-Known Member
i ran a 650 holley dp in my setup for a year. it works but not that great. has a nice dead spot off idle cruise. just not enough vacuum signal to get the boosters dumping quickly. it will work though.
I don't know how much you know about turbochargers and how they affect slant sixes, but the standard thinking of: "more cam is better" just doesn't apply to these boosted motors.
My engine is a virtual clone of two highly-successful boosted slants that each make a little over 500 horsepower, and they do it with camshafts that idle just like a stock cam. That means they have very little overlap, which is "the plan." The fact is, it doesn't do much good to run 25 pounds of boost if you're just going to blow it all out the exhaust valve on overlap.
That means, the cams that seem to work best in these boosted engines, have very conservative specs as regards duration. My cam is pretty much a copy of those 500-horsepower engines' cams. It has 210-degrees duration (both intake and exhaust,) at .050"-lift and is ground with 115-degrees of lobe separation. Bigger numbers in lobe separation help ensure less overlap. Lift is a problem with short-duration cams, and about .484" is the most you can get with a cam like this one. So, some 1.6:1 rockers are a big help, here, pushing max-lift to over.500". They are expensive to buy, but you can make your own by slicing about .100" out of the stock 1.5 arm and welding it back together. See pics...
One big help in the camshaft department is the fact that these motors never are asked to turn over 5,500 rpm. They just won't perform well beyond that. That means that not much valve spring is needed to control the valve-event, so a flat-tappet cam can last a long time. Also, since there is not a lot of rpm necessary to make maximum power, the requirements on the ignition-system are not too demanding. I use a stock Mopar electronic distributor and an MSD 6-AL and have, to my knowledge, never experienced a misfire or any kind of ignition failure.
I think both of those 500 horsepower engines I make reference to, use Holley 650 4bbl. DP's.
That's not to say their road manners or mileage are good, but, they sure are F-A-S-T!!!! :cheers:
That's what I was figuring cam wise something with little overlap and decent lift and duration I was just wondering if it would be to much carb right now I could always run a 4-2 barrel adapter till I can go more fuel?
Serj sorry about the hijack so how's the car coming u gonna pull the motor or find another to rebuild and just put a bandaid on that one to get you by till the other motor is done?
Serj sorry about the hijack so how's the car coming u gonna pull the motor or find another to rebuild and just put a bandaid on that one to get you by till the other motor is done?
My experience with turbos is alot in diesel applications but not so much in gas and none in slant 6 I was just figuring if u have a valve that opens farther and stays open longer will help with the lack of flow from the head design I understand that lobe separation needs to be alot due to the air wanting to take the path of least resistance which would be out of the partially open exhaust valve. What I was wondering is if I can get a cam ground that will open the valves a little farther and longer I could squeeze more air into the hole and along with air comes the fuel and a bigger bang. But mostly am I just shooting myself in the food going to a 4 barrel intake to have a boosted slant with good road manners and reliability?
Also serj are you making the racks for trunks kinda like the challengers use to have for luggage racks?
Also serj are you making the racks for trunks kinda like the challengers use to have for luggage racks?
Brandon Weaver
Well-Known Member
Poor road manners would come from no choke, unheated intake, and very large carb on a engine that (naturally aspirated) could use half of the carb most likely. Also, poor fuel distribution may have a part in it as well. Possibly doggy off boost by means of low compression, very high geared? Bill and serj might be able to tell you more on driveability issues, I'm just spitballing with educated guesses.
RustyPlymouth
Well-Known Member
if you keep your foot out of it and tune it properly (conservative jets for cruising and making up the difference with the power valve) it does ok, not great but ok. if you give into the boost and floor it everywhere like i enjoy doing mileage goes out the window and down to single digits. driveability is decent. cruising and putting around are decent. the only problem that i had was punching it from a cruise. would take a second for the boosters to kick in but all was good after that.
side note. the first carb i tuned for boost i disconnected the secondaries and wired them shut. basically working on the cruising circuit and dialing in the power valve as a 2bbl. just a thought.
i ultimately wound up going down to a 600cfm. pretty happy with it.
CichliDart
Well, where is it now?
RustyPlymouth
Well-Known Member
there are header flanges on ebay
I didn't build that header; my partner did, but, I THINK I got the flanges off ebay. They are 3/8" and work fine. The pipe is 1-5/8" diameter, and seems large enough for this turbo application. I don't think that the diameter on the primary pipes is critical, from the head to the turbo. Just my (ignorant) opinion...
Good luck!
RustyPlymouth
Well-Known Member
that diamiter should work fine. go to big and it will be slow to spool to small and it will restrict. that should be good though.
given the way the manifolds are held to the block you wanna measure the intake to see what that is and get a header flange to match. ive ran different size intake and header flanges and had to put a spacer in there because the triangle wouldnt hold both, just not enough room for it to sit on that much of an angle.
Serj22
Well-Known Member
Having no choke is a big one. It causes you to have to mash the gas in the morning a lot till it comes up to a higher temp. You can't let it warm up in the driveway, you have to babysit the gas pedal so it doesn't die till it gets warm.
My carb is not large enough that it makes an effect on drivability when off boost. If anything the car drives pretty normal while under vacuum, and I am personally running a much lower boost rating, at only 8-10lbs. I still maintain close to 15-16mpg out of it if I just drive around normal.
The other thing with road manners and driveability is the constant monitoring. You can go drive your NA slant around and just do whatever, but with a turbo, you're constantly checking AFR, RPM when boost is on, etc... so there's no relax and drive, and if you say you can just drive it - I am calling your bluff. Take all the monitoring gauges out and drive it. You can't.
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