std 4-bolt vs splayed caps
Thread Starter
Melting Slicks
Joined: Dec 1999
Posts: 2,816
Likes: 2
From: Austin, TX
std 4-bolt vs splayed caps
Hi all.
I'm pulling together parts for a new engine (LTX). Haven't landed the details yet, but looking for around 500 crank HP with the ability to do 7K-ish RPM. Mostly roadrace and street (endurance and sustained high RPM, not drag-race).
I already have a spare 4-bolt block I was planning on using. Assuming the rotating assembly is appropriate, for this type of motor is a standard 4-bolt OK or should I pick up a 2-bolt block and splay it? I thought about just getting billit caps for the standard 4-bolt, but haven't seen them available anywhere. Not overly concerned about the cost since machining and caps are cheap compared to a new bottom-end.
Thanks!
I'm pulling together parts for a new engine (LTX). Haven't landed the details yet, but looking for around 500 crank HP with the ability to do 7K-ish RPM. Mostly roadrace and street (endurance and sustained high RPM, not drag-race).
I already have a spare 4-bolt block I was planning on using. Assuming the rotating assembly is appropriate, for this type of motor is a standard 4-bolt OK or should I pick up a 2-bolt block and splay it? I thought about just getting billit caps for the standard 4-bolt, but haven't seen them available anywhere. Not overly concerned about the cost since machining and caps are cheap compared to a new bottom-end.
Thanks!
Last edited by MarkBychowski; Nov 20, 2006 at 04:55 PM.
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
Originally Posted by MarkBychowski
Hi all.
I'm pulling together parts for a new engine (LTX). Haven't landed the details yet, but looking for around 500 crank HP with the ability to do 7K-ish RPM. Mostly roadrace and street (endurance and sustained high RPM, not drag-race).
I already have a spare 4-bolt block I was planning on using. Assuming the rotating assembly is appropriate, for this type of motor is a standard 4-bolt OK or should I pick up a 2-bolt block and splay it? I thought about just getting billit caps for the standard 4-bolt, but haven't seen them available anywhere. Not overly concerned about the cost since machining and caps are cheap compared to a new bottom-end.
Thanks!
I'm pulling together parts for a new engine (LTX). Haven't landed the details yet, but looking for around 500 crank HP with the ability to do 7K-ish RPM. Mostly roadrace and street (endurance and sustained high RPM, not drag-race).
I already have a spare 4-bolt block I was planning on using. Assuming the rotating assembly is appropriate, for this type of motor is a standard 4-bolt OK or should I pick up a 2-bolt block and splay it? I thought about just getting billit caps for the standard 4-bolt, but haven't seen them available anywhere. Not overly concerned about the cost since machining and caps are cheap compared to a new bottom-end.
Thanks!
We machine alot of 4 bolt blocks for splayed caps and your LTX block must an 94 as I believe that was the only year they used a 4 bolt block.
Just going wiith a standard 4 bolt billet caps still put all the stress on just the main webbing of the block as a splayed cap pulss on the pan rail and ties the pan rail and the webbing together.
We use caps from Kenny at Program=Engineering and we use the flat bottom ones with the outter bolts at a 10 degree angle as some caps are at 15 to 22 degree angle and when drilling and tapping there is a good chance of gettin into the water jackets.
Using flat bottom caps you get a much better fit the using a stepped cap which in most cases fit to tight in the registers.
Here is a pick of a block we put caps on for another shop.
Team Owner
Joined: Nov 2005
Posts: 28,154
Likes: 2,872
From: Beach & High Desert Southern California
This thread raises a question about a similar thread in the C1/C2 section regarding line boring an '870 327 block to 2.45" (350) main journals. Is it worth the trouble to fit 4-bolt splayed caps to an '870 block, and is there enough web strength to line bore the result and maintain the block integrity?
The goal is a period correct C1/C2 look and crankcase vent system with a longer stroke crank in an '870 block (3.48, 3.5, 3.5625, or 3.75), and gain the benefit of the mid-size main journal for overlap and crank stiffness. The 350/400 based crank also allows the builder to exploit the ample supply of rod lengths and inexpensive alternatives to stock rods (as opposed to the weak stock & custom world of small journal rods).
Will splayed caps and line boring an '870 block to the 2.45" main journal diameter weaken or strengthen the final assembly?
The goal is a period correct C1/C2 look and crankcase vent system with a longer stroke crank in an '870 block (3.48, 3.5, 3.5625, or 3.75), and gain the benefit of the mid-size main journal for overlap and crank stiffness. The 350/400 based crank also allows the builder to exploit the ample supply of rod lengths and inexpensive alternatives to stock rods (as opposed to the weak stock & custom world of small journal rods).
Will splayed caps and line boring an '870 block to the 2.45" main journal diameter weaken or strengthen the final assembly?
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
Originally Posted by BlackIce86
Good info Blockman. What are your thoughts on overboring the mains on a 350 block to the 2.65" on the 400? Is it worth the extra overlap between the crank main journal & rod journal?
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
Originally Posted by 63 340HP
This thread raises a question about a similar thread in the C1/C2 section regarding line boring an '870 327 block to 2.45" (350) main journals. Is it worth the trouble to fit 4-bolt splayed caps to an '870 block, and is there enough web strength to line bore the result and maintain the block integrity?
The goal is a period correct C1/C2 look and crankcase vent system with a longer stroke crank in an '870 block (3.48, 3.5, 3.5625, or 3.75), and gain the benefit of the mid-size main journal for overlap and crank stiffness. The 350/400 based crank also allows the builder to exploit the ample supply of rod lengths and inexpensive alternatives to stock rods (as opposed to the weak stock & custom world of small journal rods).
Will splayed caps and line boring an '870 block to the 2.45" main journal diameter weaken or strengthen the final assembly?
The goal is a period correct C1/C2 look and crankcase vent system with a longer stroke crank in an '870 block (3.48, 3.5, 3.5625, or 3.75), and gain the benefit of the mid-size main journal for overlap and crank stiffness. The 350/400 based crank also allows the builder to exploit the ample supply of rod lengths and inexpensive alternatives to stock rods (as opposed to the weak stock & custom world of small journal rods).
Will splayed caps and line boring an '870 block to the 2.45" main journal diameter weaken or strengthen the final assembly?
Over the years we have installed many set of splayed caps on the old 327 blocks for our engine shop and other shops as well as alot engines builders use this block for there circle track engines and use a Honda rod 283 mains as this frees up some bearing friction and the cranks we have used weigh around 31 pounds when balanced.
Now I do have a 327 block that is double tanged and right now its a 327 main line and is also tanged for a 350 main and it has the good 350 webbing and takes the 1 quart spin on filter.
I can up load a pic if some one wants to see it.
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Team Owner
Joined: Nov 2005
Posts: 28,154
Likes: 2,872
From: Beach & High Desert Southern California
Originally Posted by BLOCKMAN
Now I do have a 327 block that is double tanged and right now its a 327 main line and is also tanged for a 350 main and it has the good 350 webbing and takes the 1 quart spin on filter.
I can up load a pic if some one wants to see it.
I can up load a pic if some one wants to see it.
Great first-hand info
I would like to see the 327 if you have a chance to post the photo.
Is this one of the '67 transition era blocks with the 350 main webs and the small journal bore?
Thanks.
