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327 SBC Dirt Track Motor

  
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327 SBC Dirt Track Motor

 
rdm48 rdm48
New User | Posts: 12 | Joined: 10/11
Posted: 10/15/11
10:12 AM

OK, I need your help.  I was challanged to build a 327 3/8 dirt track motor with mdium banking out of a 1967 impala 327.  Listed below are the rules.

1. 362 cubic inch MAXIMUM.

2. Stock production cast iron heads only. No porting or polishing.

3. Stock rocker arms only. No roller tip or roller rocker arms.

4. Screw-in studs and guide plates allowed.

5. After market camshafts are allowed. No rollers.

6. Must pull 15 inches of vacuum at 1000 RPM’s. Vacuum to be pulled from base of carburetor or intake. Top three (3) cars will be checked after Feature Race. 12 Volt hookup for track tack required. All engines must be turned off after vacuum test.

7. Flat top or dished pistons only. Two valve relief piston allowed.

8. Stock rods. (Example: Chevy 350 5.7 only. After market rod bolts okay).

9. Stock aftermarket crank OK (No cutting).

10. Stock HEI or point distributor. No supercoils or magnetos or MSD.

11. Cast iron intake only. 2 or 4 barrel okay. No polishing!

12. Carburetor’s spacer NOT EXCEDDING 2 inch IN HEIGHT.

13. Mechanical fuel pump in stock location. Stock manual fuel pump. No electric or belt driven pumps.

14. Headers or exhaust manifolds allowed. No 180 degree headers.

15. Carburetor can be NO larger than Holley 500 CFM 2 barrel and must pass inspection from top side with gauge. (Must be stock venture 1 3/8 inch). Choke horn may be removed.

I really need your help with this project from carb to oil pan.

Thanks to all and everyone.  

waynep7122 waynep7122
Guru | Posts: 1130 | Joined: 08/09
Posted: 10/15/11
01:03 PM

first.. this is probably going to be a great forum to help you build a motor..

can you identify what parts you have to work with???? casting numbers...

there is also 2 circle track magazines..

http://www.circletrack.com/index.html

http://www.stockcarracing.com/index.html  

rdm48 rdm48
New User | Posts: 12 | Joined: 10/11
Posted: 10/15/11
01:45 PM

Dont know the casting number yet, I still have to go pick it up.  All I know that its been sitting in the car will all original parts since the car was built.  He said that its all original.  As far as the parts goes, I will probably end up buy new pistons crank and ect.  Thanks for you input so far.  

Darklark Darklark
User | Posts: 127 | Joined: 10/11
Posted: 10/15/11
04:19 PM

rdm,this engine combo is a popular build for stock class type racing,right now I am heading out for the evening but will post some combo's tommorow (sunday) your block and crank will work fine so no need to replace that but we gonna change most of the rest.you will see about 360 -370 horse power and a good 350 ft.lbs. torque.  

rdm48 rdm48
New User | Posts: 12 | Joined: 10/11
Posted: 10/15/11
05:01 PM

OK, Thanks.  Will this set up out perform the 350s.  

tuffnuff tuffnuff
Moderator | Posts: 7828 | Joined: 12/09
Posted: 10/15/11
11:54 PM

It's possible, IF you can pull enuff RPM's out of the 327. But the chances are slim that it will outmuscle a 350, coming out of the corners.
There is no replacement for displacement, sorry.
However, the short stroke 327 lends itself to higher RPM's, which means taller gearing and that relates to better engine braking on deceleration.
Let's see what Lark comes up with.,. I'll have a few ideas to fuse in.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

Darklark Darklark
User | Posts: 127 | Joined: 10/11
Posted: 10/16/11
07:41 AM

Like tuff said,torque is your friend and the longer stroke of the 350 crank provides this.now on an asphalt track that would be the only way to go and in a heavy car over 3,250lbs.really the only way to go.dirt cars are typically allowed to be lighter so the advantage can be to a higher revving and more Geared car,but not so much with 'stock parts cause you can rev a 350 about as high as a 327 without failure.All these parts can be used in either size engine.First a two bolt block is fine at these power levels what you want to look for is Core shift, look straight at the cam opening Is the hole Centered"material is same width around the opining"If you see it isn't get another block.have it decked to 9.0". Cast crank of your choice 3.25/3.48 they are not going to check the rod length so use an aftermarket 6.0" rod,do not tell your friends as you have NONE at the race track!this can also help with Vacuum. there are a plethora of heads to use,but 64cc heads are a must for comp.and usually a 58cc head is not an advantage cause putting in 2.02 Intake valve becomes Shrouded most double hump heads will work and one with an X after the number means the intake ports are Larger.If you start with a head that used 2.02 valve you save a few bucks on shop work,but 461/462 040/041 Please Study the numbers on Chevymania.com and save a BUNCH of typing then ask more. between decking block and some on the heads(very little) you can get over 11to1 with a flat top piston and there are some tricks in here too!I say very little because you may need to have the intake milled to line up the new heights. a marine Intake is usually a good one as it was designed to make torque and is a High rise but most are for quadrajet carbs(not a problem) but a3872-783/788 is for a Holley square bore but I like the Boat Intake.For the Carb get the Center carb from a tri power big block and look at Holley's site in the RE-conditioned carb list this is by far the best way to go with stock type carb for price unless you know of one laying around.If you choose to use a Vortec head 906/062 also use intake 12366573 for torque or the 12496822 for RPM.that should get you started. I like the Steel head gasket at .025 thick and lots of copper coat sealer.  

tuffnuff tuffnuff
Moderator | Posts: 7828 | Joined: 12/09
Posted: 10/16/11
09:45 AM

1

All good tips Lark.
Here is a pic of a 400 block's cam bore with NO core shift.,. this is what you're looking for.

Missingfrontmountholes

Modify the oil channel in the rear main, for more oil delivery.

Rearmaincapmods

Don't run a HV oil pump, it takes power to turn the bigger pump.,. instead beef up the pressure relief valve on a stock pump and do the mods in the pic.

Modifiedchevypump

Do this to the pick-up to discourage cavitation

Moddedoilpickup1

You can experiment with 1.6 rockers from a Pontiac, visually, they look the same as the Chevy 1.5's.,. try them on the exhaust first. The ex needs help on old heads.

Rockergeometry

The .025" steel gasket that Lark is talking about, gives you a tighter squish band for increased velocity of the displaced air/fuel, at or near TDC.
Instead of Copper-Coat, I use several coats of rattle can silver paint.

Squishband

Get the 4 valve relief pistons.,. the wrist pin is NOT centered.,. there is a .060" offset.
Turn the pistons 180 degrees, for less drag and friction.,. the extra piston noise is negligible.

Trwpiston

Good luck

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

Pontiacman2 Pontiacman2
Moderator | Posts: 8956 | Joined: 09/08
Posted: 10/16/11
09:53 AM

+1 all good info.

Here's another pic of a sbc cam tunnel (bore).

Dsc03589res20  
Pontiacman2
Pontiacman2

Professional Hi-performance engine builder

Darklark Darklark
User | Posts: 127 | Joined: 10/11
Posted: 10/16/11
12:50 PM

Old School ROCKS !!!!!!!!!!!! This is a thousand dollar engine, that will turn 7200 rpm ALL Day Long.  

tuffnuff tuffnuff
Moderator | Posts: 7828 | Joined: 12/09
Posted: 10/16/11
01:07 PM

Can't see why it won't go 7200 Lark.,. with a solid cam.
A hydraulic cam will go 7000, at zero lash.

Olddog

Old school is far from dead in the water.,. anyone who entertains that notion, has much to learn.
Here we are again,,,, helping a guy do a budget build.,. that he can afford and have fun with.
Let's dig deep in our bag of "tricks".,. for him.
Sooo, where are all these racers?

Anyone


Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

tuffnuff tuffnuff
Moderator | Posts: 7828 | Joined: 12/09
Posted: 10/16/11
01:11 PM

Almost forgot.,. at those RPM's, the cam priority system on the SB is going to flood the top end with oil.,. this needs to be managed.
Use pipe cleaners, the bristly ones with wire on them, in the pushrods.,. this trick works wonders.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

skyeking skyeking
Addict | Posts: 2738 | Joined: 08/09
Posted: 10/16/11
04:34 PM

Hi People,
A 3.625" crank will just get under 362 Cu/ins with a tight bore.
The 222/222 cam 447/447 would pull good mid range torque with a
650 carby. Good luck...Skyeking Cool  
skyeking

tuffnuff tuffnuff
Moderator | Posts: 7828 | Joined: 12/09
Posted: 10/16/11
06:13 PM

Nope, a 4" bore with clearance and a 3.625 crank ends up at 365 cubes.,. now where is he going to get that crank from.
It's not 350 @ 3.48" stroke and not 400 which is 3.75" stroke.
This is a budget build 327, if I recall.
Off the wall cranks are forged and costly, sorry.

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: 10/16/11
07:47 PM

Guys, this is getting good,  I want this old school 327 to blow there minds after the race wanting and begging to know what I got.  LOL  Once I get the build going, I will be posting some pictures on here and of course I know that I can count on you all for the step by step info when its time.  Time to bring some of this NC racing to Missouri.  Again, thank you all.  

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