I searched and didn't find the direct answers I need/wanted.

I decided I would keep the slant six in my 1973 Duster 340.
With this decision also comes with the quest for more power. I am NOT building a racing slant, or even 'building' a slant for that matter. I just want to get the most power I can with simple bolt ons. I want the engine to perform while I drive it spiritedly and still be a true daily driver with super high reliability and pretty good economy. I realize this is a tough mission on my budget. I also do not want it to cost me anywhere near what I have into one of my small blocks or big blocks which is why I chose to leave the slant in for now in the first place.

As it sits the car is pretty much bone stock with some lightweight components to help it handle more like a modern vehicle. It has the 340 torsion bars and a set of super stock leafs out back. A little overkill but my dad bought them back in the 80's and they are still new so I decided to put them to use. The car has factory power steering and factory power disk brakes which I upgraded with the Mopar Performance aluminum master cylinder and a set of stainless steel braided brakes hoses. The car also has an 8-1/4 rear filled with 3.55:1 gears and I ditched the small rear drum brakes in favor of 1995 Jeep Grand Cherokee rear disk units for a little something different. They were pretty much a bolt on deal and I got everything needed in like new condition for $175.00 shipped to my door. The wheels are aluminum slots and wrapped in new tires (215/60R-14 front & 255/60R-15 rear). The car does have the factory electronic ignition which I plan on adding the HEI mod everyone around here likes. I run an electric fan and am picking up an aluminum radiator soon as well. The exhaust manifold collector has been hogged out and the exhaust is 2.25" and uses a 2.25" Dynoflow 'UltraFlo' muffler and exists our the back of the car. I also want to get this car as light as possible so I lightend up a lot of stuff, swapped some parts out for lightweight replacements, and removed anything not being used so long as it didn't need it to be a daily driver (brackets, small metal chunks, clips, clamps...). Just trying to help out the power to weight ratio a bit and hopefully it'll be a little easier on fuel in town and slightly more gentle on the brakes and tires and front end parts. The power brakes, power steering, A/C and windshield washer system are all weight penalty items that so far are worth having. The only other thing on the engine that is performance orientated is a lightweight high torque mini starter.

The engine is a bone stock /6 1-bbl. running an automatic transmission. I have the following components ready for the casr but are not yet installed: a complete aluminum Super Six set-up with correct kickdown linkage, an aluminum O/D manual 4-speed transmission with /6 belhousing and Hurst competition shifter & A-body bucket seat chrome shifter handle. Obviously I will be swapping to a stick shortly after I dig through my parts bin and find some of the small components and buy a clutch.
I am not sure if I'll get the 2-bbl. set-up or the 4-speed installed first.

I realize oversize valves are a little bit more then a simple bolt on, however they seem like a great mod that will only pay off the more changes the engine goes through.

I went on eBay and bought the S.S. oversized valve kit from Engnbldr.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0298880604

I got it for $103.00 shipped to my door and the 'kit' comes with (6) S.S. 1.70" intake valves, (6) 1.44" exhaust valves, full set of H.D. locks, and (12) maganese bronze valve guides.

That is the background and here is my question(s).
I know quite a few of you are running these same valves. The selller claims there are fully CNC machined with a full undercut.

Are they really that nice?

Is an undercut valve the same as the backcut valve?

I read in the Mopar Performance 6 cyl. engine book that they gained 23% on the intake side and 34% on the exhaust side with the same size valves a backcut and simply blending the sharp edge left at the bottom cut from the new larger valve seat.
I want to at duplicate these results if I can.

Is this bottom cut blending something that can be done by me, or is it better to just have the machine shop do it?

While I am having the O/S valves and new guides installed I'd like to shave the head as far as I can go without having to change the pushrods and such. I will also be running a standard Felpro style head gasket. I do not remember if the /6s have the thin steel shim factory head gasket or not.

What is the most I can shave off the head while running my combo?

I will be using the factory camshaft for now and will upgrade the camshaft somewhat soon, but will keep it semi-mild when I do.

What is a good streetable power cam or cam specs?

My machine shop seems to be very reasonable as far as pricing goes and really give me deals on my oddball/custom projects. This is the only reason why I decided to get involved with the cylinder head on this engine. They are looking forward to doing this head as they never 'built' a 'performance' slant head before and the guy is partial to Mopars so it works out well.


Other than making sure everything is tuned right (degree the camshaft, and get the distributor & advance dialed in) is there any other simple relatively cheap mods I am missing?

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1969-1/2 Dodge Super Bee A12 (440 Six Pack, 4-spd, Dana 60)
1974 Plymouth Duster 360 (4-spd, 8.75")
1973 Plymouth Duster (225, auto, 8.25")
2001 Dodge Ram 1500 QC 2wd (5.9L, auto, Dana 60)

Dan,

The head will easily take .100 being milled off. All mine are and I may go back and take some more off. Or try the angle mill. Have the manifold side lightly cleaned too. Mine cc'd with .100 off at 9.3 CR. Able to just bolt back on the rocker arm set...I am solid lifters though. Be sure to CC it while you are in there.

My belief is the valves are every bit as good as claimed. I am using 2 sets and my shop couldn't believe they were as cheap as they are. Be sure to have your shop unshroud your big valves. A little porting helps a lot too.

If you already have the 2bbl set, it will do just fine. I run 4bbls but I don't know that they breathe any better than 2bbls. Depends on what kind of driving you do...I built mine to jump from a stop and jump when stomped at 65. My personal opinion is the head is critical. If you can't breathe you can't move, whether you are lance armstrong or mr. slant six.

rock
'64d100

I had originally planned on shaving the talked about .100" off the head, but I read a few posts where people recommended not doing that without having some other changes to correct the valvetrain angle I think...

Thanks for your post.

Anyone else?

_________________
1969-1/2 Dodge Super Bee A12 (440 Six Pack, 4-spd, Dana 60)
1974 Plymouth Duster 360 (4-spd, 8.75")
1973 Plymouth Duster (225, auto, 8.25")
2001 Dodge Ram 1500 QC 2wd (5.9L, auto, Dana 60)

Will any of the other gurus chime in here?

_________________
1969-1/2 Dodge Super Bee A12 (440 Six Pack, 4-spd, Dana 60)
1974 Plymouth Duster 360 (4-spd, 8.75")
1973 Plymouth Duster (225, auto, 8.25")
2001 Dodge Ram 1500 QC 2wd (5.9L, auto, Dana 60)

Angle milling?

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'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

I have never heard of angle milling at least I do not remember it.
Do you mean milling one side of the head more then the other?

Can I get away with milling my head .100" with the stock cam, valve train, and running the HEI mod?? or will it ping and be seriously down on power?

_________________
1969-1/2 Dodge Super Bee A12 (440 Six Pack, 4-spd, Dana 60)
1974 Plymouth Duster 360 (4-spd, 8.75")
1973 Plymouth Duster (225, auto, 8.25")
2001 Dodge Ram 1500 QC 2wd (5.9L, auto, Dana 60)

Daniel
.100 off the head will work fine with the stock componants. I have seen NO draw backs on my 2 engines that are running this way.
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Not having done a leak down test on my .090 head I wonder if my guides are badly worn. Or did the machinest do a crappy job?

Next time it comes off I think I will take more off it. Everything is 10% ethanol here. Might as well take advantage of the alky, and help the loss in VE.

_________________
'72 Duster 198 stock cam, 3:23's Hookers on jack stands for 8 years in the driveway
'79 Maxivan 360 Offy Qjet Comp RV cam/rusting in the driveway.
93 D350 160HP Cummins Auto Dually Clubcab needs a injector pump
2005 Golden Couch Buick

Hello Daniel and Rug,

Yep, angle milling is cutting a head more on one side than the other. For a real good explanation see a post from Jan 17 re head milling. Dart270 explaiins it neatly.

rock
'64d100

I recently had a head done with the Engnbldr valves and the power increase along with the installation of a Holley 390, an Offy intake and 2 1/4" exhaust was very welcome. Over 2 seconds off the 1/4 mile ET. My head was milled .080" and the steel shim head gasket was replaced with Fel Pro. Compression ratio is now 8.5:1. The stock pushrods are working OK, but the rocker adjusting screws are backed out pretty far. Some .040" shorter pushrods would be great. In the grand scheme custom pushrods from Smith Brothers are not expensive.

Undercut valves have reduced diameter stems under the head of the valve. Back cut valves have the back side of the valve machined for better flow. If you look at your new valves and compare to stock valves you'll see there is no back cutting to be done.

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Joshua

Compression, air flow (head work) and spark timing are all important to a great running SL6.

As others have already pointed-out, building a performance head will be the "most bang for the buck" as long as the bottom-end of the engine is in good condition.

Once the head is in place, you can recurve the distributor to take full advantage of the compression / fuel / driving combination you have.

If you do not have the $$ to do a performance head now, you can still find some extra "pep" from distributor recurving and free flowing exhaust but you will have to re-do the distributor curve if you increase compression and air-flow later.
DD

I am about to bring a head in to have done so I just wanted to be sure.

It looks like I'll remove .100" and run the flepro gasket...



Thanks guys!

_________________
1969-1/2 Dodge Super Bee A12 (440 Six Pack, 4-spd, Dana 60)
1974 Plymouth Duster 360 (4-spd, 8.75")
1973 Plymouth Duster (225, auto, 8.25")
2001 Dodge Ram 1500 QC 2wd (5.9L, auto, Dana 60)

Do some reading on "pocket porting".
Have the machine shop dis-assemble the head and check it for cracks and damage Get a written estimate on the cost to rework the head.

If you want them to do the work, ask them if you can take the head for a few days so you can do a little port grinding ("port and polishing") work to it, before they do the final milling, valve grinding and assembly.
A few hours of porting work is well worth the extra effort and can be done yourself.
DD

I have been wanting to try porting my own heads, but do not know the first thing about it.
It has alway been something I wanted to try, but I cant afford to mess up a good set of my big block 915 heads, small block X heads, or the MP R/Ts such.
On the other hand I hate to start with a plain old 318 2-bbl. head and sink all that time in it just to end up with something that still isn't as good as the R/T's. I guess thats why cylinder head guys get paid the big bucks.

I have quite a large selection of quality tools I have purchased the past few yearsand I guess the only way to learn is to do it.

If only I had 100's of hours of spare time and a flowbench...

_________________
1969-1/2 Dodge Super Bee A12 (440 Six Pack, 4-spd, Dana 60)
1974 Plymouth Duster 360 (4-spd, 8.75")
1973 Plymouth Duster (225, auto, 8.25")
2001 Dodge Ram 1500 QC 2wd (5.9L, auto, Dana 60)

How much does the finish matter when you get a head planed? The local machinist doesnt do engines but he does everything else. I know he could plane some off but can it be too smooth? And to clarify, .100 off is safe for a stock motor?

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68 Valiant Signet, 225, auto.