What's a 4 bolt main, and a 2 bolt main? Which is better and why?

------------------
2.8 Liter V6
No Current Mods

 

It refers to the number of bolts in the main bearing caps holding the crank in. 4 bolt mains are stronger, but are really only necessary if you're making a lot of power. 2 bolt main blocks can be drilled and tapped for the extra holes to turn them into 4 bolt mains.

 

it;s the nuber of bolts on each main cap on the engine block. the main caps hold your crankshaft in place.

------------------
'86 IROC 5-speed
305 LG4
edelbrock performer rpm intake
edelbrock 600 cfm carb
msd pro billet hei distributer
'95 3.23 rearend
hotchkis rear suspension
PST front polygraphite suspension
"speed kills. buy a f@&d, live forever."

 

for street driven car a four bolt main is overkill but if it a stripe car that's going to produce a good amount of HP it's a idea to have a four bolt main.

------------------
1991 banditt2 #130 of 600
Project 350 TPI Banditt II
http://www.street-dawg-racing.cityslide.com
www.gcfba.com (Greater Cincinnati F-Body Association)
http://www.cincyspeed.com/

 

I've heard that LS1's have 6 bolt mains. How does that work? Where do the extra 2 bolts per main go?

------------------
No guts, no glory.

 

Does anyone have a pic that i can refer to about these 4 bolt mains?

------------------
2.8 Liter V6
No Current Mods

 

Here ya go.



-edit Ok I think It works now (hopefully)

[This message has been edited by Black 91 Z28 (edited November 19, 2001).]

 

geaocities does not support this feature, try uploading your pics to www.webshots.com . then you can use the image feature.

 

Aw, sure it does.

Right-Click on the "broken" pic; choose "View Image" from the menu; when you get the new page saying "Geocities doesn't do this", click on your "Location" line (with the www link), and press Enter. Voila! Picture.

------------------
-Tom P (Hot rodded 1986 Firebird 2.8l)

[This message has been edited by TomP (edited November 19, 2001).]

 

Are the pictures above, a 4 bolt main?

------------------
2.8 Liter V6
No Current Mods

Third Generation Camaro Site

 

Yes.

Look at the main caps, which are sort of brown in that motor, where the crank and rods are more gray colored. Note that each has 4 bolts. A 2-bolt block only has the 2 center bolts in each cap.

That motor also has the studs for attaching a factory-style windage tray. All of the inner ones in the pic except the one at the top right are that kind of stud.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited November 22, 2001).]

 

The LS1s do indeed have six bolt mains. They have four bolts holding in the caps from the bottom (just like a four bolt main SB chev) and also have one bolt on either side of the block (2 per cap) that go through the sides of the oil pan rail area (kinda hard to explain since they don't resemble a regular SB chev at all..) and thread into the main caps themselves. This is a VERY rigid design and basically strengthens the webbing of the block where the crankshaft lives. If I can find a pic of one I will post it.

------------------
1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

and the reason why there all aluminum

 

here is an alright pic of an LS1 lower end:



The caps have bolts that pass through the sides of the block and thread into those main caps. All of the caps have six bolts as well.

And, as you can see, they aren't all aluminum... This one is iron. The trucks have cast iron blocks.....

[This message has been edited by Matt87GTA (edited November 22, 2001).]