SBC LT4 Hot Cam Question
12-04-2011 | 01:20 PM
#11
Thread Starter
Registered
Joined: Sep 2011
Posts: 39
Likes: 0
From: 1000 Islands
...One other thing, the lt4 cam has to much lift for a stock set of springs and you have machine the spring seats on the vortec heads to get the lt4 springs to work. You will see what I mean once you get it torn down, but it's a must to run that cam with vortec heads. And use the truck valve covers, the 1.6 roller rockers do clear them inside with no issue
Trying hitting up mr fixall, haxbyspeed, or tomz. These guys can help you with the fine tuning details.
Trying hitting up mr fixall, haxbyspeed, or tomz. These guys can help you with the fine tuning details.
12-04-2011 | 06:22 PM
#12
Registered
Joined: Apr 2010
Posts: 897
Likes: 10
From: Daniels, WV
I switched from the center bolt style coupler to the triangular coupler and when we tries to start it it wouldn't turn over. Upon inspection we found the coupler busted the bell housing, so you will need one that is from a boat with a triangular coupler in it for clearance. Also on the vortec engine you will need a new style circulating pump to clear the timing cover. The new style has a slightly longer neck on it I believe.
12-04-2011 | 10:11 PM
#14
Registered
Joined: Jun 2011
Posts: 1,211
Likes: 145
I offer this only for reference as I didn't use the Hot Cam but used a Crower 00483LM EFI roller cam and it has worked well. Specs are a little higher than the LT4.
221/230 @ .050" and .525/.545" on a 1.5 rocker. 114 LSA. No reversion noticed. The Vortec heads would need some work with this kind of lift. I used Dart heads instead. This is all in a standard bore 377 EFI stroker motor. Bone stock Merc 350 Mag EFI tune would hold 650 rpm idle with this cam.
221/230 @ .050" and .525/.545" on a 1.5 rocker. 114 LSA. No reversion noticed. The Vortec heads would need some work with this kind of lift. I used Dart heads instead. This is all in a standard bore 377 EFI stroker motor. Bone stock Merc 350 Mag EFI tune would hold 650 rpm idle with this cam.
12-08-2011 | 03:06 PM
#15
Thread Starter
Registered
Joined: Sep 2011
Posts: 39
Likes: 0
From: 1000 Islands
I have the lt4 hot cam, ran it all last year with no issues. My setup isn't quite where I want it but I believe the carb needs some adjusting to get all the power out of it. I can tell you this, it's a hard and fast revving SOB.
Also showing no signs of reversion with stock exhaust.
The lt4 also will allow you to run a mechanical fuel pump but the block you have won't. I used the block from a 1997 Chevrolet truck and they did away with place to mount the mechanical pump in the later years. I'm running a Mallory marine electric pump and have had no trouble.
Here Is a link to my build:
http://www.offshoreonly.com/forums/d...under-way.html
Also showing no signs of reversion with stock exhaust.
The lt4 also will allow you to run a mechanical fuel pump but the block you have won't. I used the block from a 1997 Chevrolet truck and they did away with place to mount the mechanical pump in the later years. I'm running a Mallory marine electric pump and have had no trouble.
Here Is a link to my build:
http://www.offshoreonly.com/forums/d...under-way.html
12-08-2011 | 05:55 PM
#16
Registered
Joined: Apr 2010
Posts: 897
Likes: 10
From: Daniels, WV
The way it's setup now I'm getting 5000-5100 in the dead of summer, on a cool day it will spin to 5400 no problem. I'm gonna tune on it this spring. Don't use my numbers as a goal but more of a baseline.
12-09-2011 | 08:37 AM
#17
Thread Starter
Registered
Joined: Sep 2011
Posts: 39
Likes: 0
From: 1000 Islands
Another question; what are you running for fuel (octane)?
12-09-2011 | 11:42 AM
#19
Thread Starter
Registered
Joined: Sep 2011
Posts: 39
Likes: 0
From: 1000 Islands
12-12-2011 | 07:57 PM
#20
Registered
Joined: Mar 2010
Posts: 62
Likes: 0
From: Salisbury, NC
I offer this only for reference as I didn't use the Hot Cam but used a Crower 00483LM EFI roller cam and it has worked well. Specs are a little higher than the LT4.
221/230 @ .050" and .525/.545" on a 1.5 rocker. 114 LSA. No reversion noticed. The Vortec heads would need some work with this kind of lift. I used Dart heads instead. This is all in a standard bore 377 EFI stroker motor. Bone stock Merc 350 Mag EFI tune would hold 650 rpm idle with this cam.
221/230 @ .050" and .525/.545" on a 1.5 rocker. 114 LSA. No reversion noticed. The Vortec heads would need some work with this kind of lift. I used Dart heads instead. This is all in a standard bore 377 EFI stroker motor. Bone stock Merc 350 Mag EFI tune would hold 650 rpm idle with this cam.
