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327 SBC Dirt Track Motor

  
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327 SBC Dirt Track Motor

 
tuffnuff tuffnuff
Moderator | Posts: 7827 | Joined: 12/09
Posted: 10/21/11
11:10 PM

Icon Quotetuffnuff:
The build is back on the forum from PM's.,. in case others are interested and want to duplicate it.

copy/paste

rdm48 (96.35.254.13)
New User | Posts: 9 | Joined: 10/11 Posted: Today 10:05 AM

ok, so my parts list is as follows

sbc 400 block, go 60 over, does it need to be decked, does it need to be 2 or 4 bolt

sbc 327 3.250 crank

do I need 5.7 or 6.0 rods

400 sbc pistons 60 over that will match rods above, does it matter if its 2 or 4 valve relief

vortec heads with stock valves or do I need to go with 2.08 and 1.65

Air gap intake dual plane

I can only run a 500 cfm 2 berrell

Am I missing anything does it matter what ring or lifters I run.  And of course my racing cam.  All this will equal out to be a sbc 358?  IF I have the parts list then I can build it.  LOL  Again thanks for everything.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

you're welcome

Smile


Yes,

1) Get a 2 bolt 400 block and have splayed 4 bolt main caps installed with ARP bolts., Eagle and Coleman makes them, among others. The Eagle main caps are a good plan too, for only $70 and they come with a drill pilot.

Eagle4boltmaincaps356 C4103S

2) No, there is no decking required.,. perhaps a clean-up cut of .005" to true the deck surface.

3) A large journal 327 or 307 crank, with a 3.25" stroke will work.,. King Bearing spacers will be needed.

4) Use the 6" rods.,. and have ARP rod bolts installed, then get them resized and fitted for full floating wrist pins, or if the aftermarket rods have cap screws, then all of this is not required.,.
Using the 6" rods, you may need a small base circle cam, depending on the style of fasteners on the rods, there is possible cam lobe/rod bolt interference.,. with cap screws there is usually no issue.

5) KB 400 flat top claimer pistons or Speed Pro with 4 valve reliefs will work, but you have to remove about .040" from the piston crown, by machining (turning) on a lathe. These pistons are for the 5.7" rod (the ones you want) and come in +.030, +.040 and +.060 oversize.,. Speed Pro 844-H616CP30, 844-H616CP40, 844-H616CP60 and for compression issues, the dished ZH601P30 will work, since .040" gets removed from the crown.,. leaving a slight dish.
This is simple enough of a job, for a "good" machine shop.

Speedpro844 H616CP40

Here is the math.,. to arrive at .013" compression height with this combo.
The 400 KB pistons are for a 5.7" rod and a 3.75" stroke.,. this build uses 6" rods that are .300" longer.
Now our shorter 3.25" stroke is .500" (1/2") shy of the 400 stroke 3.75".,. but we need to divide this in half, because .250" is at TDC and .250" is at BDC, for a total of .500"
So if we take the .300" of the longer rod and deduct .250" or half the stroke difference.,. there is .050" to deal with.
But, there is a .023" OEM compression height (piston crown sits below deck surface) and we are going to reduce that to .013".,. by only removing .040" from the piston crown.
Now if we take the .013" compression height, and add .040" for the gasket, the squish band becomes a nice .053" +/- a few thou.

Squishband

The rotating assembly will need to be balanced after all the surgery.
Oh, almost forgot to mention, swing the pistons around 180 degrees on the rod and take advantage of the .060" offset of the wrist pin.,. it's NOT centered on the piston, by the way.
This enhances rod angle a bit more.
Hope I didn't lose anyone yet.

6) Use a set of Vortec heads and go with 2.02"/1.5" valves because 2.06"/1.60" will not fit in a stock 64cc chamber head and for class rules there is no porting permitted.

Vortecchamber

All done, 2.02" Intake and 1.5" exhaust in the 906 heads

Vortec906with202s

7) The air gap is a great manifold, use it.

8) I thought the rules only mandated 500 CFM and Edelbrock makes a 500 4bbl.
Your earlier post makes reference to 2 or 4 bbl carb.,. what gives?

This build is not a walk in the park, but it can easily be done by those not faint of heart.

Almost forgot to mention.,. it;s still a 327, but with a huge bore and even the neutral balance damper makes this combo the ultimate sleeper.
Also the static compression with 64cc Vortecs is well over 10 to 1

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

rdm48 rdm48
New User | Posts: 12 | Joined: 10/11
Posted: 10/22/11
07:56 AM

500 cfm 2 bbl.  We can use a 2 or 4 bbl intake.  

rdm48 rdm48
New User | Posts: 12 | Joined: 10/11
Posted: 10/22/11
07:58 AM

This is some really good stuff.  Thank you for all of you time on this so far.  Yep, I said so far cause I am sure I will have more qeustion when the build starts.  LOL  

tuffnuff tuffnuff
Moderator | Posts: 7827 | Joined: 12/09
Posted: 10/22/11
10:28 AM

No problem, ask away cuz we're here to help.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 10/22/11
09:38 PM

G'Day POP Shocked  Grin  
skyeking

rdm48 rdm48
New User | Posts: 12 | Joined: 10/11
Posted: 10/29/11
09:01 AM

Hey Tuffnuff......We are going to build this motor and run it as a super street/hobby stock instead of tunning it in the pure street class.  What heads did you use?  That way we can use the 2.08 and 1.65 valves.  Here are the hobby stock class rules.
1. All cars must use 2 barrel stock carburetors no more than 500 CFM max 1 11/16 throttle bore maximum. Holly OK.

2. No aluminum heads.

3. Any intake iron or aluminum.

4. Engine set back. Front spark plug hole can be no farther back than center of upper ball joint.
Big diffrence from my other rules.  LOL  Thanks  

tuffnuff tuffnuff
Moderator | Posts: 7827 | Joined: 12/09
Posted: 10/29/11
10:29 PM

Ok, so roller rockers are allowed???
To run those large valves, offset rockers are needed.,. 4 left and 4 right.
Available from Jegs #555-20111 price for 8 is $119.99
Aluminum Roller Rocker Arms
1.5 Ratio
7/16" Stud
8/Pkg.
The intake guide bosses will need to be offset bored, to move the 2 big valves apart in the chamber, then bronze guides installed, by a good machine shop.
Are roller rockers allowed in this class Confused

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

tuffnuff tuffnuff
Moderator | Posts: 7827 | Joined: 12/09
Posted: 10/30/11
10:03 AM

Icon Quoteskyeking:
G'Day POP Shocked  Grin

Howdy Skye down under.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

Pontiacman2 Pontiacman2
Moderator | Posts: 8956 | Joined: 09/08
Posted: 10/30/11
12:06 PM

Hi skyeking.  
Pontiacman2
Pontiacman2

Professional Hi-performance engine builder

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 10/30/11
03:59 PM

Smile   Hi People,
  R U Busy Confused
 All the best Cool  
skyeking

tuffnuff tuffnuff
Moderator | Posts: 7827 | Joined: 12/09
Posted: 10/31/11
05:37 AM

Awwwman

Nicethread

Thread Direction Forum

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

tuffnuff tuffnuff
Moderator | Posts: 7827 | Joined: 12/09
Posted: 10/31/11
05:56 AM

Almost forgot to mention.,. the block needs to "scalloped" to clear/unshroud the big 2.08" intakes!

Bbcylinderscallops

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

Pontiacman2 Pontiacman2
Moderator | Posts: 8956 | Joined: 09/08
Posted: 10/31/11
06:07 AM

+1 that big of valves aren't really a benefit to the 327-350 engine I would only use 2.08 valves on 383's and 400's or bigger sbc's.  
Pontiacman2
Pontiacman2

Professional Hi-performance engine builder

tuffnuff tuffnuff
Moderator | Posts: 7827 | Joined: 12/09
Posted: 10/31/11
06:22 AM

Agreed, those 2.08's were on (maximum) Mighty Mouse and at 7500 R's they are a benefit with AFR 195 ported heads.
For this build, the revs will be much lower and smaller valves would work OK.
The limiting factor will be the ports, since there is no porting allowed.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

zman123 zman123
Enthusiast | Posts: 531 | Joined: 06/08
Posted: 10/31/11
07:25 AM

Tuff, How would this motor work in a street car? With Aluminum heads (64cc or larger) and a different cam, performance intake, headers etc? Interesting build, but practical?  

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