GM L31HD and cam choice

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rangrayy

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Yes it is another which cam thread and I have scoured the inter webs for information on what others have done. Not many people in the truck world have shared their stories, shocking I know. The tool box sticky I read a few times and it has suggested a few and another thread had different heads with their cam selection. I want to know what others, if they’ve even done so, have put in their stock L31 crate motors.

I have 256k miles, to my knowledge, on my truck currently and I can feel a rebuild coming on. General consensus is it is cheaper to buy a crate engine over rebuild. I am purchasing this :http://www.jegs.com/i/Chevrolet-Performance/809/12530283/10002/-1, and both jegs and summit have good reviews. There are 2 from summit that had issues as soon as they first fired but I’m not as concerned about that as I am on changing the cam to void the warranty. I figure there’s a lot of red tape to deal with if a warranty issue should arise that it goes out the window.

Now while the crate waits to go in why not install a better cam.(springs too, if the need should arise) The only helpful information I could find were in the tool box sticky and there is only 1 cam for stock springs and 2 for I am assuming the beehive springs. Also from what I have read a minimum of 112° LSA is required to keep the computer from having a fit. Can anyone shed some light on this?

Along with the crate engine there will be other upgrades as well. Such as a set of long tube headers(unsure of deleting EGR or not) 2.5 dual pipes with Magnaflows, transmission overhaul and a Black Bear Tune. I am not building a drag, race or mud truck. I just want to drive it and do some towing on the farm. Figured while I am going through the effort to install a new engine why not do some minor enhancements while I am there. The truck is still stock with tires, gears(3:73) and transmission(4l60e).

I am wide open to options and suggestions. I greatly appreciate any and all input.
 

Stokes1114

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Since your getting a tune, you can look at cams with less than 112 lsa. The 112 and up will usually work better on stock tune. I would look at the gm hot cam. I have used it before and it pulls very nice. Definitely want to upgrade springs to take advantage of the better cam. I would go with beehives or look at Alex's spring kit for the vortecs. He's a big help if you have questions.
 

Supercharged111

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Marine cam all the way. You DO NOT need a 112+ LSA for a stock tune, stock cam LSA is ****** 111. Hot cam will give up low end to stock or marine. Marine isn't the only option, bit it is a cheap, proven, reliable one. I run mine with 1.6s and stock springs. When I got to looking turns out the ramjet engine uses the same spring part number as stock L31. Problem with LS beehives is they're to be installed at 1.800" and the Vortecs are 1.700" or 1.720". You can offset them by 50 thou, but not enough.
 

rangrayy

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Since your getting a tune, you can look at cams with less than 112 lsa. The 112 and up will usually work better on stock tune. I would look at the gm hot cam. I have used it before and it pulls very nice. Definitely want to upgrade springs to take advantage of the better cam. I would go with beehives or look at Alex's spring kit for the vortecs. He's a big help if you have questions.

I kinda figured that a tune would open up more options. Isn’t the gm hot cam the same as the lt4 cam I’ve been seeing on google and what HoneyBadger did on YouTube?

Just to be clear also this is the site for the spring kit? https://www.alexsparts.com/valve-spring-kit-sb-chevy-vortec-hi-perf-hyd-roller/
 

Stokes1114

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No the hot cam is the same as the ram jet. The lt1 and lt4 cams are in there own. They are descent cams that pull very good as well. Most of these cams will run off the stock tune, just not good. To get the full benefits of a cam you NEED a tune. And yes that's the guy to talk to on springs. You NEED new springs to be able to control the cam. If you run your stock springs then not too smart.

Also... The lt1 and lt4 cams you see online are not the real original ones bc they are not made anymore. Most likely regrinds, which are fine to run. You can always buy a used roller cam and will be just good as long as the journals are not messed up. You want them smooth. I have a 97 lt1 cam that I ran for years and loved it. I tuned it myself which woke it up big time. That was my first cam swap.
 
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rangrayy

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Do you have a p/n for the ramjet cam? Or is it the same cam that is in the HT383?

I knew I needed springs and from what I have gathered also is to use the comp cams retainers and locks to achieve max lift of .550”
 

Stokes1114

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Do you have a p/n for the ramjet cam? Or is it the same cam that is in the HT383?

I knew I needed springs and from what I have gathered also is to use the comp cams retainers and locks to achieve max lift of .550”
Yes it's the same cam as the ht383. I personally would use the spring kit that Alex puts together over beehives. He knows his stuff and It's a lot cheaper as well.
 

rangrayy

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Also... The lt1 and lt4 cams you see online are not the real original ones bc they are not made anymore. Most likely regrinds, which are fine to run. You can always buy a used roller cam and will be just good as long as the journals are not messed up. You want them smooth. I have a 97 lt1 cam that I ran for years and loved it. I tuned it myself which woke it up big time. That was my first cam swap.

I did not see this edit till now. People are saying that the ramjet/ht383 is a mild cam but certainly an improvement over stock. Now when you ran the lt1 and tuned your computer, did you do the 411 swap or stick with the black box?
 

Supercharged111

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Stock LT1 or LT4 cam will also give up a considerable amount of torque over stock or ramjet. Whatever you choose you want a narrow LSA to build torque. We see it in our racing class when an engine builder orders the wrong LT1 cam. The difference is in the 20-30 ft/lb range.
 

Stokes1114

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I did not see this edit till now. People are saying that the ramjet/ht383 is a mild cam but certainly an improvement over stock. Now when you ran the lt1 and tuned your computer, did you do the 411 swap or stick with the black box?
The lt1 cam was in my 93 so it was a different PCM obd1. The pcm was older than the black box but much better tuning wise. Any truck with a black box for tuning purposes should be swapped to 411. And there will soon be a alternative to all the high dollar tuning software. It is coming out open source, and could be ready anytime now. There are a group of guys that have been working on it for a year plus and I hear it's VERY close.
 
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