Cam Selection for 94 LT1 Project
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Joined: Apr 2003
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From: Jacksonville Florida
Cam Selection for 94 LT1 Project
I plan on doing a Head and Cam package this summer on my 94 LT1 Auto, which I drive daily. I have been doing a ton of reading and reviewing, trying to decide on the exact cam to use, so I can get the heads set up right. I have decided to use the Competition Cams 276HR14 Grind, with with 220 / 230 Intake and Exhaust numbers at .050.
Have any of you guys used this cam? Have you had any problems with vacuum at idle, like problems with the brake booster?
Any insight you can provide is much appreciated. BTW, my heads are being ported and polished, and I will be installing 2.00 / 1.56 Manley Race Flo swirl polished valves with LS1 Beehive springs. The intake will be gasket matched, and the throttle body has been ported to 52mm. On the exhaust side, I have Jet hot coated shorties, almost new stock cats, and Corsa exhaust.
I expect to have to reprogram the computer to accomodate the cam, I just dont know exactly what needs to be changed. Maybe you could enlighten me on that as well.
Thanks for your time.
:cheers:
Have any of you guys used this cam? Have you had any problems with vacuum at idle, like problems with the brake booster?
Any insight you can provide is much appreciated. BTW, my heads are being ported and polished, and I will be installing 2.00 / 1.56 Manley Race Flo swirl polished valves with LS1 Beehive springs. The intake will be gasket matched, and the throttle body has been ported to 52mm. On the exhaust side, I have Jet hot coated shorties, almost new stock cats, and Corsa exhaust.
I expect to have to reprogram the computer to accomodate the cam, I just dont know exactly what needs to be changed. Maybe you could enlighten me on that as well.
Thanks for your time.
:cheers:
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Cam Selection for 94 LT1 Project (Da Wiz)
I'm running a CompCams which is close to what you're considering - 224/230 @ .050 HR on 114s I chose the lobes from the rear section of the CompCams catalog where many of their lobes are listed.
My lobe #s are 3315/3192.
It pulls 14" of vacuum, at idle in gear (auto trans) which increases to 15" at engine speeds 1000 rpms and higher. No power brake problems.
Whoever re-burns your PROM should know what changes are called for. I suspect the commanded idle speed will need to be raised. Mine was set to 800 RPM in gear idle.
Hope this helps.
Jake
My lobe #s are 3315/3192.
It pulls 14" of vacuum, at idle in gear (auto trans) which increases to 15" at engine speeds 1000 rpms and higher. No power brake problems.
Whoever re-burns your PROM should know what changes are called for. I suspect the commanded idle speed will need to be raised. Mine was set to 800 RPM in gear idle.
Hope this helps.
Jake
Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
Re: Cam Selection for 94 LT1 Project (Da Wiz)
The Comp cam you are talking about is a pretty good all around cam to use. Tuning for it will be pretty easy. I have done several PCMs for 94 and 95 Y and F bodies using that cam. Its not too big or too small I think for what you are doing it will be just right. You need not worry about vacuum with this cam. With its modest duration and wide LSA it will work fine as a daily driver. I have a Comp custom grind with 224/236 on a 112 in my car with big block lift numbers and I don't have a problem with vacuum.
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From: Jacksonville Florida
Re: Cam Selection for 94 LT1 Project (tjwong)
Thanks for the replies. TJ, do you have your Dyno yet?
BTW, do you need me to send you my PCM, or do you have a rotatable pool of them yet?
Thanks for the input, and keep it coming....
:cheers:
BTW, do you need me to send you my PCM, or do you have a rotatable pool of them yet?
Thanks for the input, and keep it coming....
:cheers:
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Re: Cam Selection for 94 LT1 Project (Da Wiz)
Well the dyno people have my money but I don't have the dyno yet :( It is on its way as it shipped last Friday sometime. I am currently out of the 16181333 PCMs, I have some coming. They are getting harder and harder to get these days. It is best that you send me your PCM, that way I can have the latest GM flash file to use as a base file for your calibration. When you get ready let me know. I can usually turn them around in one day.
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Joined: Apr 2003
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From: Jacksonville Florida
Re: Cam Selection for 94 LT1 Project (tjwong)
Thanks TJ. What all information do you need from me? I won't know what my compression will be until I get the deck height measured, and get the info on the heads from Gary Johns here in Jacksonville. My plan is to use the Impala SS head gaskets to make up for increasing the combustion chamber when I unshroud the valves. Is there a CR number I should shoot for?
My target date for starting this job is August 1. Gary will turn the heads and intake around in a week, which is plenty of time for me to get the bump stick done. The Opti is new, (Dynaspark), the waterpump is new, timing chain and gears, rear differential (3.45 Dana 44), Corsa, OEM cats, all new.
I can't see any reason to change out the lifters or pushrods. Will be using Pro magnum roller rockers. Self aligning or guideplates?
Keep the info coming. It makes for a better thought out process.
:cheers: :flag :cheers:
My target date for starting this job is August 1. Gary will turn the heads and intake around in a week, which is plenty of time for me to get the bump stick done. The Opti is new, (Dynaspark), the waterpump is new, timing chain and gears, rear differential (3.45 Dana 44), Corsa, OEM cats, all new.
I can't see any reason to change out the lifters or pushrods. Will be using Pro magnum roller rockers. Self aligning or guideplates?
Keep the info coming. It makes for a better thought out process.
:cheers: :flag :cheers:
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Re: Cam Selection for 94 LT1 Project (Da Wiz)
If you are using the stock heads, you may as well use the self aligning rockers. No sense modifying the heads for the others. I suggest getting some better rocker studs as well. Get a set of ARP studs. Depending on your choice of springs you can either stay with 3/8 studs or go to the HD 7/16 for a bit more rigidity. The 3/8 studs will handle up to 130# of seat pressure with no problem. If you go any higher than that I suggest the HD studs, then you need to get the 7/16 rockers to match.
I would shoot for the highest compression you can. As you know your machinist can always angle mill the heads to get the chambers back to where they were. Even with the unshrouding it would take a minimal amount of milling to bring them back to 54cc. You will probably find that your uncut block is going to be around 9.032" and blueprint spec is 9.025". That is what I have been seeing. So that means that the pistons are in the hole around .030 or more. Which isn't real good for making good CR numbers :( Are you planning on decking the block?
I would shoot for the highest compression you can. As you know your machinist can always angle mill the heads to get the chambers back to where they were. Even with the unshrouding it would take a minimal amount of milling to bring them back to 54cc. You will probably find that your uncut block is going to be around 9.032" and blueprint spec is 9.025". That is what I have been seeing. So that means that the pistons are in the hole around .030 or more. Which isn't real good for making good CR numbers :( Are you planning on decking the block?
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Joined: Apr 2003
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From: Jacksonville Florida
Re: Cam Selection for 94 LT1 Project (tjwong)
You really think the pistons are going to be that far down the bore?
I do not plan on decking the block, since I am going to do the work with the engine still in the car.
I think I will be able to at least maintain stock compression, but I won't know for sure until I get the deck height measured. It would be nice to get it up in the 10.8 range, but i don't know if there is enough material on the heads to get there, particularly if the piston is that far down. The eternal quest for squish continues....
:cheers:
I do not plan on decking the block, since I am going to do the work with the engine still in the car.
I think I will be able to at least maintain stock compression, but I won't know for sure until I get the deck height measured. It would be nice to get it up in the 10.8 range, but i don't know if there is enough material on the heads to get there, particularly if the piston is that far down. The eternal quest for squish continues....
:cheers:
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Melting Slicks
Joined: Apr 2000
Posts: 3,490
Likes: 2
From: Oviedo FL
Re: Cam Selection for 94 LT1 Project (tjwong)
I'm having a 383 built as we speak. I believe my deck height is now 9.005" and my pistons only sit .005 in the cylinder. I think John said our CR will be 10.8 using the Felpro head gaskets (.039").
I went with a cam similar to Jake's 224/230 w/113 LSA using 3192/3194 lobes... I think the lift numbers are .605/.622 with 1.6 RR's. I had to switch to the 977-16 springs with this cam. I'll be very curious to see what kind of numbers John can squeeze out of this thing.
Keep us posted with your results.
Mike
I went with a cam similar to Jake's 224/230 w/113 LSA using 3192/3194 lobes... I think the lift numbers are .605/.622 with 1.6 RR's. I had to switch to the 977-16 springs with this cam. I'll be very curious to see what kind of numbers John can squeeze out of this thing.
Keep us posted with your results.
Mike
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From: Jacksonville Florida
Re: Cam Selection for 94 LT1 Project (JAKE)
Hi Jake. I called Comp Cams last night, and they steered me to a cam similar to one with your numbers, 224/230 on 114LSA. How did you settle on your cam, and are you running a stock block? I would enjoy talking to you about it, so if you've got the time, send me a number and I will give you a buzz.
:cheers: :flag :cheers:
:cheers: :flag :cheers:
Thread Starter
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Joined: Apr 2003
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From: Jacksonville Florida
Re: Cam Selection for 94 LT1 Project (Da Wiz)
Jake,
I just took a look at your mods, and I am nowhere near where you are regarding displacement or engine mods. Not sure we can compare how these beasts will react with that cam grind.... :eek:
Sure would like to feel that sucker launch though.... :D
I just took a look at your mods, and I am nowhere near where you are regarding displacement or engine mods. Not sure we can compare how these beasts will react with that cam grind.... :eek:
Sure would like to feel that sucker launch though.... :D
Melting Slicks
Joined: Sep 2000
Posts: 2,710
Likes: 1
From: Green Bay WI
Re: Cam Selection for 94 LT1 Project (Da Wiz)
I just got done doing a heads/cam package and I went with a custom CC grind (224/230 112LSA). All I have to say is that this cam sure does lope quite a bit. :D
It sounds mean and pulls very hard!
As Jake mentioned, I have to get my in gear idle adjusted upwards as it has a helluva time idling in anything but park or neutral...
It sounds mean and pulls very hard!
As Jake mentioned, I have to get my in gear idle adjusted upwards as it has a helluva time idling in anything but park or neutral...
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Joined: Apr 2003
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From: Jacksonville Florida
Re: Cam Selection for 94 LT1 Project (cprgmr)
Hey CPRGMR,
That is the grind they recommend for nitrous aps, right? I called Comp Cams, and they recommended 224/230, but with 114 LSA. Any thoughts?
Tell me what you did to your heads. Any flow numbers? What did you do to your intake? Finally, did you deck your block?
:cheers:
That is the grind they recommend for nitrous aps, right? I called Comp Cams, and they recommended 224/230, but with 114 LSA. Any thoughts?
Tell me what you did to your heads. Any flow numbers? What did you do to your intake? Finally, did you deck your block?
:cheers:
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Re: Cam Selection for 94 LT1 Project (Da Wiz)
I am not positive about the piston deck height in relation to the block deck. But the nominal decks I have seen in several LT1 blocks did measure out to between 9.030 and 9.032. I did measure piston to deck in a couple of them that I worked on and what I found was that they were .020 to .025 in the hole. But like you said its best to measure it first and see what it really is. There is so much differences in manufacturing tolerances between engine runs at the factory so in reality no two blocks are the same.
I know this may not be what you want to hear, but seeing how you have an A4 car, with the heads off the engine it would take another hour and the block would be out of the car and on the floor. Stripping it down to the bare block is another hour then you can easily machine the block, and freshen the engine up as well with new bearings and rings :)
[Modified by tjwong, 9:31 AM 5/7/2004]
I know this may not be what you want to hear, but seeing how you have an A4 car, with the heads off the engine it would take another hour and the block would be out of the car and on the floor. Stripping it down to the bare block is another hour then you can easily machine the block, and freshen the engine up as well with new bearings and rings :)
[Modified by tjwong, 9:31 AM 5/7/2004]
Thread Starter
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Joined: Apr 2003
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From: Jacksonville Florida
Re: Cam Selection for 94 LT1 Project (tjwong)
You're slaying me, TJ.
Actually, when I pull the pan, i am going to check some of the bearings and see what I have. If they are marginal, I will do just that.
:cheers:
Actually, when I pull the pan, i am going to check some of the bearings and see what I have. If they are marginal, I will do just that.
:cheers:
Melting Slicks
Joined: Sep 2000
Posts: 2,710
Likes: 1
From: Green Bay WI
Re: Cam Selection for 94 LT1 Project (Da Wiz)
That is the grind they recommend for nitrous aps, right? I called Comp Cams, and they recommended 224/230, but with 114 LSA. Any thoughts?
Tell me what you did to your heads. Any flow numbers? What did you do to your intake? Finally, did you deck your block?
:cheers:
Tell me what you did to your heads. Any flow numbers? What did you do to your intake? Finally, did you deck your block?
:cheers:
The verdict is still out on the 112 vs 114 LSA. It's pretty darn lopey at idle right now and I'm hoping with some fine tuning it'll still sound mean but be a little more manageable. :)
The heads themselves are CNC Stage III heads. I don't have flow numbers for them but I'm thinking about getting them flowed next winter.
I did absolutely nothing to the LT-1 intake. I wanted to gasket match it, but Pete told me that the LT-1 intake flows remarkably well in stock form and that they've actually seen power loss on the dyno by porting it.
As for the block, no work there.
One thing is for sure... You'll be pleased with the new found power after the top end is done! :)
Melting Slicks
Joined: Apr 2000
Posts: 3,490
Likes: 2
From: Oviedo FL
Re: Cam Selection for 94 LT1 Project (cprgmr)
I just had comp cams grind a cam for me and it has the same duration (224/230) but on a 113 LSA. The lift numbers are .605/.622 with 1.6's. I also have the Stage III CNC heads.
I'll let you know the results when we have them.
Mike
I'll let you know the results when we have them.
Mike
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Joined: Apr 2003
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From: Jacksonville Florida
Re: Cam Selection for 94 LT1 Project (luvmy92)
That is a great cam! I have been trying to decide whether I wanted to go with a solid roller or not. One of the things I admired about the roller was all the area it had under the curve. Based on the valves I am using (2.00), most of my flow is going to occur in the .500 area. I will still pick some up after that, but proportionately it will be small. The time the valve is off the seat on the solid roller really appeared to be far superior to what was offered in the Hydraulic section.....
And then you posted the 3192/3194 grind numbers. That combination has the same benefits without the maintenance issues associated with Solid roller cams. I really appreciate the precision of your post.
Now the questions: Did you run this in the stock 350 or the 383? Any ideas on advantages / disadvantages of 110 to 114 LSA's ? I am going to be using this car daily, in traffic, playing on the weekends. Autocross and short sprints mostly.
This has turned into a fascinating project.
Thanks a ton to all. I remain in a constant state of amazement and awe at these spectacular machines and the people that try to find the limits of what they can do.
:cheers: :flag
And then you posted the 3192/3194 grind numbers. That combination has the same benefits without the maintenance issues associated with Solid roller cams. I really appreciate the precision of your post.
Now the questions: Did you run this in the stock 350 or the 383? Any ideas on advantages / disadvantages of 110 to 114 LSA's ? I am going to be using this car daily, in traffic, playing on the weekends. Autocross and short sprints mostly.
This has turned into a fascinating project.
Thanks a ton to all. I remain in a constant state of amazement and awe at these spectacular machines and the people that try to find the limits of what they can do.
:cheers: :flag
Melting Slicks
Joined: Apr 2000
Posts: 3,490
Likes: 2
From: Oviedo FL
Re: Cam Selection for 94 LT1 Project (Da Wiz)
This is going to be for the 383... I am using a 210/224 in the 350.
My engine builder selected this cam. Like you, I too have the 2.00"/1.56" valves, and am using the R series lifters (875-16). The springs are the 977-16's (the 210-/224 used the 986-16's). I really don't know what to expect with this cam but John said it performed very well on his dyno analyzer software.
My car will be mostly a road racer with some occasional street use.
Mike
My engine builder selected this cam. Like you, I too have the 2.00"/1.56" valves, and am using the R series lifters (875-16). The springs are the 977-16's (the 210-/224 used the 986-16's). I really don't know what to expect with this cam but John said it performed very well on his dyno analyzer software.
My car will be mostly a road racer with some occasional street use.
Mike