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225 slant 6 build
https://slantsix.org/forum/viewtopic.php?t=58763		 Page 1 of 2
Author:  bigcasey123 [ Tue Dec 01, 2015 7:52 am ]
Post subject:  225 slant 6 build
I am new to slant sixes but have read a lot of info on this website. i just bought myself a 1969 dodge dart with a 225 slant 6. i would like to rebuild the engine and give it a little get up and go. i dont have any specific horsepower goals but i would like a very strong and fun engine. i have helped put chevy motors together but never a mopar so i was just wondering if the set up i would like to run would be a decent one.
i was considering running:

a 450 quickfuel carb
an aussie speed long runner intake manifold
a howard cam with .473/.473 lift with 220/220 duration
ford 170 144 oversized valves and ported heads with maybe .80 taken off for compression
headers and exhaust

Like i said i dont know for sure how good of a setup that is but if anything would be an issue or if i left anything out please let me know. i would just like some feedback about the potential build.

Thanks- casey
Author:  bigcasey123 [ Tue Dec 01, 2015 8:06 am ]
Post subject: 
oh and i forgot that the duration on the cam was @0.050
Author:  Joshie225 [ Tue Dec 01, 2015 8:37 am ]
Post subject: 
I don't know that anyone here has experience with that carburetor. What does Quickfuel give for intended applications? The 500 CFM Edelbrock Performer AFB is probably easier to get running well.

From what I've seen here results with the AussieSpeed manifold have been mixed. For a street oriented build with an exhaust heated intake the Offenhauser manifold is hard to beat and the Clifford manifold is proven for higher output engines. Both cost less than any AussieSpeed manifold. Hopefully we can get some feedback here.

I like the lift on the Howard cam, but the duration is short and that's fine for a mild build.

Who's doing the head work and who is calculating the compression ratio?

Are you sure you want headers? Have you lived with headers long term? What's the climate? Is the car driven in the Winter?

Is the car an automatic? If so what's the budget for the torque converter and gears? Still have the 7 1/4 rear end and 9" drum brakes? What's the budget for brake and handling upgrades?
Author:  bigcasey123 [ Tue Dec 01, 2015 12:35 pm ]
Post subject: 
the cams duration is 220 @0.050. it is advertised at 256.
and you think that the clifford intake will be a better bang for my buck?
And i wasnt sure if 500cfm was too big of a carb. my rule of thumb for a street/mild strip car is to double the ci and thats what cfm to run.

yes the car is an auto. it does have a 7 1/4 rear. i was planning on getting a bigger maybe 8 3/4 rear with about 3.23 gears after the motor, along with front disc breaks down the road. i figured i was gonna need a torque converter because of the cam. i was thinking 1800 or 2000 stall.
it will be driven in the winter in pennsylvainia but i assumed the headers would be fine.
thanks for your input
Author:  bigcasey123 [ Tue Dec 01, 2015 12:41 pm ]
Post subject: 
oh and there is a small machine shop down the road from me a friend recommended. i have not talked to them yet because i wasnt 100% sure what i wanted. and there is another one about 40 min away if the close shop cant port, mill, or install the oversized valves
Author:  wjajr [ Wed Dec 02, 2015 6:29 am ]
Post subject: 
Selecting a hodge-podge of parts based on criteria other than actual pre rebuild measurements of your engine will cause much disappointment, and be a waste of money.

Once one designs their engine build based on actual measurements of various pertinent parts, distances, & volumes of engine to be rebuilt, and intended use of car (DD to full race) determined, only then can various parts and parameters such as compression, cam size, power and rpm band engine will operated at, rear gear & tire size, and converter stall can be selected to achieve a combination that fits one's needs.

Too much cam, not enough stall and or rear gear = dog and poor drivability in traffic.

not enough compression for cam = dog

Power band too high for DD= dog or speeding tickets

Carb too big = poor drivability and fuel economy

Wrong advance curve = dog


An unheated intake manifold (headers in use) and a North East winter DD= gas guzzling (single digit mpg), carburetor icing stumbling pig below 40 degrees until it warms up, if ever. Colder it gets the worse drivability becomes.

The whole build has to be looked as if it were a band, where each chair has to be on the same page, playing to same beat, and in tune; anything less would be dreadful.

You can figure all this out on paper before dropping in at the machine shop.
Also a good engine rebuilder should be able to figure all this out as well. Select a shop open to do what you want done, and not what they think you need.

So measure twice, and calculate & recalculate until a combination that fills your needs, and pocket book is arrived at.

That said, there are several varieties of builds various members are running to be found in the site's archives that may be of help to your project.
Author:  Joshie225 [ Wed Dec 02, 2015 7:50 am ]
Post subject: 
For your situation I would use the Offy manifold with exhaust heat or the factory Super Six manifold, carb and linkage to make life easy. I've run unheated manifolds in cold, damp weather and it's no fun at all. With a mild build up like this I'd either keep the stock exhaust manifold in stock condition or modify the stock manifold and get a Dutra front exhaust manifold.

A torque converter rated for 2400 stall behind a 318 will get you close to what you need with that cam. Target a true (measured and built) 9:1 compression ratio or it won't run well. I would advance the cam a total of 6° (2° more than spec).

What's wrong with the engine that it needs to be rebuilt? If the engine is sound I would concentrate first on brakes, suspension, wheels/tires long before trying to go faster.
Author:  bigcasey123 [ Wed Dec 02, 2015 8:13 am ]
Post subject: 
well the engine seems to run pretty well. but it was sitting for 3 years before now so anything could pop up.it has never been rebuilt in the 46 years it was in the car so who knows what its like on the inside. I want to rebuild it to gain performance. As much performance as possible being a DD.

Now by a heated manifold you mean an intake? i am not familiar with what you mean.
Author:  Joshie225 [ Wed Dec 02, 2015 10:54 am ]
Post subject: 
Intake manifolds that are meant to have fuel flowing through them are heated to vaporize the fuel. V engines have an exhaust crossover passage between cylinder banks. The slant six has an exhaust manifold open on the top to heat the bottom of the intake manifold. Take away the heat without improving fuel vaporization at the carburetor and the engine runs poorly gobbling gas and washing the oil off the bores wearing out the engine.

At this point I am going to encourage you to take a big step back in order to evaluate what you're doing and why. See if you can find a copy of David Vizard's book Performance With Economy. I hope you understand that you are beginning with an economy car and that it will need upgrades in many areas to be a performance car.
Author:  bigcasey123 [ Wed Dec 02, 2015 2:21 pm ]
Post subject: 
Yeah I realize that i have very little experience with slant sixes. I have been looking into this for a while but you don't really get much experience sitting behind a computer screen. I love the idea of making good power with a commonly overlooked engine but I think I might try to get a pretty mild 318 to put in my Dart for now. I think I'll keep the 6 cylinder and when I know exactly what I want to do with it then I will do it the right way with no short cuts and put it back in. Plus that will give me time to build up a budget so I can put together a really nice motor.

Thanks for your feedback
Author:  Reed [ Wed Dec 02, 2015 2:26 pm ]
Post subject: 
It really doesn't take much money to build a decent slant six, just time, patience, and a little homework. Pick your cam based on your estimated RPM range of operation. Pick the amount of material you mill off the head and/or block based on your target DYNAMIC compression ratio and the measurements of the engine and the cam you want. Pick your engine components for a rebuild based on your budget and intended use for the engine (i.e. do you REALLY need nitrided connecting rods?). Then you tailor your timing advance curve based on the engine and vehicle the engine is installed in.

Mostly you can use stock or near stock components for everything, unless you are going racing.
Author:  bigcasey123 [ Wed Dec 02, 2015 3:26 pm ]
Post subject: 
money is not too big of an issue. sure id like to spend as little as possible. but in my eyes if i dont have the money right away i can save a few months until i have a bigger budget.

what do you think the highest rpm that should be run is for the street. i read stock the 225s peak at 4000. and what compression do you think is reasonable for the streets.
Author:  SlantSixDan [ Wed Dec 02, 2015 4:07 pm ]
Post subject:  Re: 225 slant 6 build
Quote:
i was considering running:

a 450 quickfuel carb
an aussie speed long runner intake manifold
a howard cam with .473/.473 lift with 220/220 duration
ford 170 144 oversized valves and ported heads with maybe .80 taken off for compression
headers and exhaust
This collection of parts probably will not get you a good result. Don't just pick out a stack of mods and parts that you think are cool. That's a good way to waste money, time, effort, and energy and wind up very disappointed. Start from the very start: Exactly what do you want the car to do differently than it does now—with actual, realistic specificity—and how much money and time and effort can you actually, really afford to put into it?

Buying parts is easy. Buying the right parts is hard. Once you've figured out exactly(!) what you want and exactly(!) how much money and effort you can put into it, then your options are wide open. You'll hear the name "Clifford" come up, but be very careful before you decide to spend any money with Clifford. They have a long and ugly reputation for being a bunch of clowns and screwing their customers; see for example here, here, here, here, and here. Much of what they sell is inaccurately described, and a lot of it is not even slightly cost-effective. The good news is that you don't need to go to Clifford to get hot rod parts for slant-6s; there are lots of other, better options. See for example Dutra Duals and header options discussed in this thread and this one, Erson custom cams, HEI ignition upgrade, Mike Jeffreys windage trays, Hurricane intakes, other exotic intakes. Hi-perf engine buildup here, high-perf parts and build info here.
Author:  bigcasey123 [ Thu Dec 03, 2015 10:14 am ]
Post subject: 
Thanks for the input.

I think what you said is exactly right. i should just wait untill i know how much money/time i have and what exactly i want to get out of it.

Im fine with waiting and then building it the right way.

And im positive that there are many other things i can upgrade in the car until then.


I do have one more question
Does anyone know where to find a decent deal on a solid A body 8 3/4 rear end that is ready to drop in
Author:  SlantSixDan [ Thu Dec 03, 2015 12:03 pm ]
Post subject: 
Quote:
Thanks for the input.
Y'welcome.
Quote:
Im fine with waiting and then building it the right way.
Much happier result that way.
Quote:
And im positive that there are many other things i can upgrade in the car until then.
YEP! See here.
Quote:
Does anyone know where to find a decent deal on a solid A body 8 3/4 rear end that is ready to drop in
Get in your time machine and set it for 1981. I wish I were joking.
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