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 Post subject: Oodles of questions.
PostPosted: Thu Jun 24, 2010 10:10 pm 
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1 BBL (New)

Joined: Sun Sep 09, 2007 8:54 pm
Posts: 7
Location: Burlington NC
Car Model:
Alright, I've been driving a '72 dodge dart with a really (really really) tired 225 slant six for four years now. Ever since the day I bought it I've been meaning to, and planning to, and going to build it up. Well, now I've got a little bit of financial wiggle room, and I figure I'm going to start wrenching. I've read most all the articles here and at allpar and valiant, and I lurk here frequently, but I could use some guidance on a number of things.

First question:

I'm looking at buying a re-ring & gasket kit off e-bay: Link
The seller emphasizes this is a TRUCK six rebuild kit. Everything I've read about the slant six says there's no difference between the truck and car sixes that would affect my choice of rebuild kits. Is there any reason this wouldn't work?

I'm also designing a dual 2-barrel/1-barrel intake with two sets of bosses in the intake runners which I'll be casting in aluminum. (essentially I'm making a bolt-on-whatever-the-heck-you-think-will-work-and-try-it manifold.)

second question:

What are the dimensions of the intake ports on the slant six head? (rectangularly approximated) I had a gasket to compare, but It got tossed accidentally, and I don't want to re-buy one until I'm putting the motor together. I wanna say 1 1/8" x 1 3/8" but maybe it was more like 1.25" x 1.5"

I'm also, of course, camming the motor. later on I'll deck the block and shave the head and all those goodies, but for now I'm keeping the stock compression. So I'll be looking for a cam that runs well from 8.2-1 through 9.5-1 compression, 1500-4000 rpm.

Third question:

What is the highest valve lift the stock springs can work with given a 4500rpm redline?

Fourth Question:

I've seen the comp cams 264S cam, and it seems to be what I want, has anyone run it? Is it worth the price? Should I go with a custom cam instead? Does anyone have a cam they'd recommend?

Fifth Question:

If I purchase a camshaft by itself, is it a really bad idea to use oem replacement lifters instead of the cam manufacture's lifters?

The Next stage of the build after getting the motor freshened up and perkier would be to add some forced induction. I hear about plenty of people running as high as 22psi of boost and getting awesome 1/4mile times.

Sixth Question:

Properly tuned (I know this makes a huge difference) given stock compression, what is the most boost (Intercooled or not) anyone has run on 93 octane?

Seventh question:

I know the stock pistons are tough and enormous, but how much boost can they take compared to say 2.2 swap pistons or forged slugs? (I'm talking being VERY careful here with engine tuning, by the way.) Or does the common wisdom hold up that you shouldn't run cast anything in a boosted motor?

Eighth question:

Wet nitrous on top of boost? or is even the mighty slant six not tough enough for that kind of overkill?

Thanks everyone!


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 Post subject:
PostPosted: Thu Jun 24, 2010 10:16 pm 
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EFI Slant 6
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Joined: Thu Jul 19, 2007 10:18 pm
Posts: 317
Location: Phoenix, AZ
Car Model:
1st Q answer: Just make sure you buy a rebuild for the crank that you have i.e. cast or forged. Pull the numbers off the motor.

,Cliff

_________________
'72 4 dr Dart
'63 4 dr Dart
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 Post subject: Re: Oodles of questions.
PostPosted: Fri Jun 25, 2010 2:57 pm 
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Guru
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Joined: Mon Oct 14, 2002 4:32 pm
Posts: 4880
Location: Working in Silicon Valley, USA
Car Model:
derranged-gadgeteer wrote:
... I lurk here frequently, but I could use some guidance on a number of things.

First question:

I'm looking at buying a re-ring & gasket kit off e-bay: Link
The seller emphasizes this is a TRUCK six rebuild kit. Everything I've read about the slant six says there's no difference between the truck and car sixes that would affect my choice of rebuild kits. Is there any reason this wouldn't work?


This kit will work fine for any 1960 - 75 (forged crank) SL6

Quote:
I'm also designing a dual 2-barrel/1-barrel intake with two sets of bosses in the intake runners which I'll be casting in aluminum. (essentially I'm making a bolt-on-whatever-the-heck-you-think-will-work-and-try-it manifold.)

Why....??? :?

Quote:
Second question:

What are the dimensions of the intake ports on the slant six head? (rectangularly approximated) I had a gasket to compare, but It got tossed accidentally, and I don't want to re-buy one until I'm putting the motor together. I wanna say 1 1/8" x 1 3/8" but maybe it was more like 1.25" x 1.5"


Factory ports are 1.1" wide x 1.4" tall or use 1 1/8 x 1 7/16 for the nearest fractional size

Quote:
I'm also, of course, camming the motor. later on I'll deck the block and shave the head and all those goodies, but for now I'm keeping the stock compression. So I'll be looking for a cam that runs well from 8.2-1 through 9.5-1 compression, 1500-4000 rpm.


If you are not increasing compression, just re-use the factory cam.
Change the cam when you increase compression.

Quote:
Third question:
What is the highest valve lift the stock springs can work with given a 4500rpm redline?


When increasing lift on a SL6 past the .460 raange you must machine-off the tops of the valve guides or the spring retainer will hit the top of the guide and crush / split the valve stem seals.
In general, the factory SL6 valve springs are good to 5000 RPM if you shim them .060

Quote:
Fourth Question:

I've seen the comp cams 264S cam, and it seems to be what I want, has anyone run it? Is it worth the price? Should I go with a custom cam instead? Does anyone have a cam they'd recommend?


Do not use a bigger cam unless you match it with the correct compression ratio. The Comp 264S in a 8 to 1 CR SL6 would make the engine a "pig".

Quote:
Fifth Question:

If I purchase a camshaft by itself, is it a really bad idea to use oem replacement lifters instead of the cam manufacture's lifters?


Todays aftermarket solid lifters are a total "crap-shoot", many are made in China by many different (lowest bid) manufacturers.
I would trust "older stock" over any newer batch of aftermarket lifter.
The good news, a SL6 with light valve springs and a mild cam is pretty easy on the lifters / cam lobes.

Quote:
The Next stage of the build after getting the motor freshened up and perkier would be to add some forced induction. I hear about plenty of people running as high as 22psi of boost and getting awesome 1/4mile times...


Take things one step at a time...
BTW... do a boosted engine and the factory 8 to 1 compression ratio is where you want to be.

Quote:
Sixth Question:

Properly tuned (I know this makes a huge difference) given stock compression, what is the most boost (Intercooled or not) anyone has run on 93 octane?


I will pass on this question...

Quote:
Seventh question:

I know the stock pistons are tough and enormous, but how much boost can they take compared to say 2.2 swap pistons or forged slugs? (I'm talking being VERY careful here with engine tuning, by the way.) Or does the common wisdom hold up that you shouldn't run cast anything in a boosted motor?


Common wisdom... run forged pistions in a boosted engine.

Quote:
Eighth question:

Wet nitrous on top of boost? or is even the mighty slant six not tough enough for that kind of overkill?


It would be all about the set-up but in the real world, you would distroy an engine or two... before getting it right.
DD


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 Post subject:
PostPosted: Sat Jun 26, 2010 8:12 pm 
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1 BBL (New)

Joined: Sun Sep 09, 2007 8:54 pm
Posts: 7
Location: Burlington NC
Car Model:
I can't thank you enough! That's exactly what I need to know.

As for the manifold, just because I can. I feel the need to justify building a waste oil foundry in the back yard, and so I figured I'd see if I can make something more than little trinkets and sculptures. If it doesn't work, I'll just go looking for a super six manifold and be done with it. It's my idea of fun.


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