Hitting 400rwhp in an LT1
I hear ya. There was myself and another guy who both had very similar setups done at about the same time, and both of us had complications. His is more electrical based we thing whereas mine was mechanical. Don't get me wrong. I loved the cam. Even with two cylinders way down on compression my car pulled 365/355 on the dyno when we didn't know what was wrong. It's a great mid sized off the shelf cam for a street machine.
Elysian your running the LT4 heads and it has more material then the LT1 so it can be ground out further usually in most parts of it in contrast to the LT1 heads. But matching it to LS1 type heads may be a little more difficult.
If your just trying to match it to a fel pro exhuast gaskets???.......and if your mainly talking about lowering the floor meaning the bottom of the exhuast port when looked at exactly as it would be on the engine......then ppl have tried this on LT1 heads and hit the water jacket specifically when trying to match to the gasket. I don't think you face a problem on the walls as much as you do in lowering the floor.
Here's a link it has side by side comparisons of LT1 heads vs. Lt4 heads the comparisons are cutaways right down the intake and exhuast ports.
From there you can see just how much material you have between yourself and the water jackets.
http://renko.org/autos/1996_corvette...T1-and-LT4.htm
There isn't much more metal on the floor of the LT4's than the LT1's so it would be just as easy too hit the water jackets when lowering the floor on LT4's. But look at the LT4's huge advantage right in the valve guide area, it almost begs to get hogged out.
In my opinion work the bowls and narrow, deepen, widen, narrow, the valve guide areas.
If your just trying to match it to a fel pro exhuast gaskets???.......and if your mainly talking about lowering the floor meaning the bottom of the exhuast port when looked at exactly as it would be on the engine......then ppl have tried this on LT1 heads and hit the water jacket specifically when trying to match to the gasket. I don't think you face a problem on the walls as much as you do in lowering the floor.
Here's a link it has side by side comparisons of LT1 heads vs. Lt4 heads the comparisons are cutaways right down the intake and exhuast ports.
From there you can see just how much material you have between yourself and the water jackets.
http://renko.org/autos/1996_corvette...T1-and-LT4.htm
There isn't much more metal on the floor of the LT4's than the LT1's so it would be just as easy too hit the water jackets when lowering the floor on LT4's. But look at the LT4's huge advantage right in the valve guide area, it almost begs to get hogged out.
In my opinion work the bowls and narrow, deepen, widen, narrow, the valve guide areas.
Thread Starter
Launching!
Joined: Jul 2003
Posts: 204
Likes: 0
From: MI
Heads / Cam are installed and the motor RUNS!!! Idles like crap & wants to stall on the stock tune, but that should be fixed with some PCM tuning. Hopefully in the next couple of weeks here, I will have some dyno graphs to post.
TECH Apprentice
Joined: Jan 2004
Posts: 315
Likes: 2
You could hit 400rwhp with a cam as little as the LT4 Hotcam. I put out 375rwhp, 363rwtq with this cam and heads. This is with an auto and not all the bolt-ons most guys have. With your 6-speed car, a good set of heads
with a good balanced block from the factory, you could hit 400rwhp with
this cam. Although it would be easier with something bigger, this cam is very streetable.
with a good balanced block from the factory, you could hit 400rwhp with
this cam. Although it would be easier with something bigger, this cam is very streetable.
Thread Starter
Launching!
Joined: Jul 2003
Posts: 204
Likes: 0
From: MI
A friend of mine who is very knowledgable about LS1's seems to think I won't have much trouble breaking the 400rwhp mark. I'll believe it when I get a dyno-graph, not until then. Tell you this, after having driven the car around for a few days, I'm glad I didn't go any SMALLER with my cam selection. It cruises just fine at 1500rpm on a stock tune. If I had the bottom end and computer to rev higher, I would go with a cam bigger than the one I have. But then, I don't do much city driving . . .
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Originally Posted by OneMeanZ
Question......Where can I get this GM 847 cam?
CRANE CAM: GM847 - PN#12370847 - 234/242 @ 0.050, 112 LSA
Jason Cromer: 877-726-8295 or 850-243-8826 (direct parts dept ph #)
email: gmparts@samtaylor.com
Sam Taylor Buick/Cadillac Ft. Walton Beach, FL
* Crane Cam 109841 grind # HR-296-2S-12 IG (CAM) $209.00 from Jason
* KM# 16214681 $29.95 from Jason - 96 Corvette 5.7 L w/55 LT4 Knock Sensor
* Crane Kit #10308-1 (SPRING KIT) Crane Spring 99893-16 . Use this kit if you plan on running 1.6 or higher RRs.
* I'd recommend Comp-R's while your in there & tuning.
Thread Starter
Launching!
Joined: Jul 2003
Posts: 204
Likes: 0
From: MI
Finally got my new PCM in. Cam/heads combo pull strong all the way to about 6700rpm. It pulls noticably better above 4500rpm than it ever did before. The car doesn't so much "feel" faster than it did before, but when I look down at the speedo, my first reaction is "oh, I'm going that fast already?" This thing hits 90 in the time it used to take it to hit 60 or 70. Strange as it may sound, response across the rpm band is actually more linear than it used to be. On stock cam/heads, torque used to be really high on the low end. Now it seems pretty much flat from about 2500rpm on up. Another thing, the only reason I would be inclined to call the 233/239 cam "big" is because the computer would have trouble running a cam that wanted to rev above 7000rpm. If I had a stronger bottom and and a FAST efi setup, I wouldn't hesitate to throw in a cam 10 degrees bigger. Granted I don't do much city driving, but my car cruises no problem above 1500rpm. None of that kicking, bucking or jerking I was forewarned of.
Originally Posted by Elysian
but my car cruises no problem above 1500rpm. None of that kicking, bucking or jerking I was forewarned of.
Thread Starter
Launching!
Joined: Jul 2003
Posts: 204
Likes: 0
From: MI
I installed the new PCM and everything was working great for about a day. My friend chino_man279 drove it - it drove wonderfully. Tires went up in smoke through 1st gear and the tail started coming around through second. Chirps the tires into third. Then I drove the car into town, did a few full throttle accelerations . . . Now, my car runs like A$$. It was running really smooth and now it is "chugging" along pretty hard. Only thing is, there doesn't seem to be much power loss. We're pretty sure it is misfiring - I have a blinking SES light - BUT - when I plug my code scanner it, it reads "PASS, no codes returned." Go figure. I figure the guys from PCMforless deleted some codes because of the size of my cam. Not really sure, though. When we finally did get a code, it was a bad O2 sensor on bank two. We replaced the sensor and it still runs bad. My new theory is that the valves might need to be adjusted. Has anyone else had trouble with COMP-R lifters, adjusting non-self aligning rockers and misfiring? We pulled the valve covers b/c you could hear some faint ticking and some of the rockers were loose (should I be using lock-tite on the rocker studs?). We re-adjusted them, but it still runs like crap. HELP!!!
Originally Posted by Elysian
I installed the new PCM and everything was working great for about a day. My friend chino_man279 drove it - it drove wonderfully. Tires went up in smoke through 1st gear and the tail started coming around through second. Chirps the tires into third. Then I drove the car into town, did a few full throttle accelerations . . . Now, my car runs like A$$. It was running really smooth and now it is "chugging" along pretty hard. Only thing is, there doesn't seem to be much power loss. We're pretty sure it is misfiring - I have a blinking SES light - BUT - when I plug my code scanner it, it reads "PASS, no codes returned." Go figure. I figure the guys from PCMforless deleted some codes because of the size of my cam. Not really sure, though. When we finally did get a code, it was a bad O2 sensor on bank two. We replaced the sensor and it still runs bad. My new theory is that the valves might need to be adjusted. Has anyone else had trouble with COMP-R lifters, adjusting non-self aligning rockers and misfiring? We pulled the valve covers b/c you could hear some faint ticking and some of the rockers were loose (should I be using lock-tite on the rocker studs?). We re-adjusted them, but it still runs like crap. HELP!!!
And your right, loose valves or not set right will cause a multitude of problems, backfiring, rough-idle, performance yada yada yada.
Good luck!
TECH Regular
Joined: Sep 2003
Posts: 442
Likes: 3
From: Raleigh, NC
Originally Posted by HellTeeOne
Has anyone ever heard of www.advancedinduction.com ?
But again, just because you toss a cam in doesn't mean anything if the supporting mods aren't there. Don't forget injectors either. My stock ones are pretty much maxed out on my 224/230 (thus my peak rwhp of 366). Once I bump up to 30 pounders I should be at fastbird93's power levels 
Unfortunately, I'm not near 400 RWHP even factoring in that we dynoed the car when the motor had about 500 miles and was tight as hell.
Honestly, with the 224/230 on a 112* LSA, a GOOD set of stock ported heads, and a set of 1.7 rockers, you may make it to 400 with everything right. That's what I was shooting for before I found my bottom end took a crap.
Thread Starter
Launching!
Joined: Jul 2003
Posts: 204
Likes: 0
From: MI
Originally Posted by BRETTINATOR
There is a special thread compound for the rocker studs, highly recommend using it. Comp-Rs are not that big a deal really, just set your zero lash by finger tightning the roller rocker nut (make sure your set screw is about a 1/16" showing) until you have no up&down play with your pushrod (thats zero lash). You should still be able to twist the pushrod which is ok. Next set your pre-load by doing a 1/4 to 1/2 turn on the RR nut (a lot of folks like the 1/4 turn with these lifters, your choice just don't make it too tight). Now set your lock and you should be ok. I also recommend a $10.00 hand bump start to set them, makes it quick, easy and precise. Just hooks to the ignition relay wire top of starter solenoid and the + batter side. If you need the sequence to setting them using this method let me know?
And your right, loose valves or not set right will cause a multitude of problems, backfiring, rough-idle, performance yada yada yada.
Good luck!
And your right, loose valves or not set right will cause a multitude of problems, backfiring, rough-idle, performance yada yada yada.
Good luck!