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**xxrollin** · 04-05-2004, 05:22 AM

Shawn, the 95 topend is a big improvement over the stock 3.1, however, if you can, you should look into the newer, say 2000 and up 3100. I was told and I've measured the valves myself, have the 1.76 intake valves and a better designed intake manifold. Basically larger runners which increases flow. If you already have the 95 gear, go for it.
The rocker arms will work with some clearance issues that need to be cleared out with the intake manifold. You'll have to install them and scribe some lines out on the manifold to grind off some material, no big deal. But other than that, I dont see any problem in your ideas. I hope you've got some good valve jobs done..

**dbtk2** · 04-05-2004, 11:11 AM

I already have '95 heads. I am currently trying to pick up a '95 3100 from a junkyard or ebay or something for the other parts above that. I know the '00 and newer 3100 heads & intake and all 3400 heads & intake flow better, but the '95 is easier to install because there isn't as much stuff to change, and it flows plenty for what i am looking for.

What all exactly has to be done to the intake manifold to make the rockers fit? Is it just grinding down a few spots?

Thanks,

Shawn

**geoffinbc** · 04-05-2004, 12:13 PM

You will only have to do grinding for clearance on the intake if you are using big machined rockers like Crane Cams gold race roller rockers. For a turbo vehicle you may want to take another look at cams. There are better choices out there.

**dbtk2** · 04-05-2004, 10:31 PM

Originally posted by betterthanyou

You will only have to do grinding for clearance on the intake if you are using big machined rockers like Crane Cams gold race roller rockers. For a turbo vehicle you may want to take another look at cams. There are better choices out there.

So with the rockers I am looking at I won't need to do any grinding???

I know there are better choices out there for cams, but will they work without needing computer work? I have heard that it is very difficult to tune the computer for even the powermax 260. I like the 260 because it is a decent turbo cam and doesn't have huge amounts of lift (like I said, I'm not looking for a car that idles rough and sounds like it has a big cam, just a little more power), but like I said, it needs computer work, and a lot of it from what i have heard. I know this cam will work with the stock computer, and it is bigger than the stock cam. I was thinking of just replacing the stock cam with a stock cam because I have heard that the lobes wear off due to not getting enough oil, and I'm sure this is the case with mine, but I figured I might as well go a little bigger. Not only that but that cam and 1.6 rockers equates to .451 valve lift, which that alone should give a significant boost over the stock .394/.410, even if the rest of the cam (lobe seperation and duration) was exactly the same as the stock cam.

The main reason I am tearing the engine down is because I am pretty sure I have a slightly blown headgasket. I haven't lost any noticable power (hell, I dynoed 182 hp to the wheels (~227 crank hp) with basically no mods, it obviously is still making power), but it smokes pretty bad at low rpms and uses a lot of coolant and some oil, and it used NO oil before. I just figured while I was in there I may as well do a few power adding mods like a topend swap and a little cam.

If you have a suggestion for a good turbo cam that will work without any computer work, or a better cam that will work with no computer work, I am up for suggestions. I would like to go bigger, but I don't want to have to get a custom chip made or anything like that.

I don't want to sound like I am set on what I am doing to the car, because I'm not, I'm open for suggestions, I just really don't want to have to mess with any computer work right now.

Shawn

**xxrollin** · 04-06-2004, 05:15 AM

Cam wise, I'd say higher lifts, (.450-.500) and near factory duration numbers, (on the plus side), and about 114 lobe sep should work. A regrind isnt that bad. Get ahold of someone and explain that you want this to work with the factory comp and they should be able to tailor the cam for a big difference in power. All engines will go from Vacuum in the manifold to zero in as little as 2000rpm's. Your goal isto keep vacuum at idle and the low end to keep the comp happy, everything else is based off rpm's and tps. But if you got a turbo GP, the comp should be ok even if the vacuum changes to boost alittle sooner, which is gonna happen with a bigger cam.

**xxrollin** · 04-06-2004, 05:26 AM

Oh, bad rings will send your vacuum on the low side also. We were able to get a real good idea of what the cam does by using a vacuum gauge and measuring the vacuum in the engine of an N/A 3100, then we took the cam out and sent it off to crane for this one and they called us in 2 days and gave us a damn near idea of where and when this engine was making its peak power. They gave us a more radical intake profile and a better exhaust profile with a little more duration and keep the overlap about the same. The engine gained 3points on vacuum at idle but dropped sooner as measured and didnt cause any problems. Lifts were just under .500 and it pulled hard to the 6500rpm's. I'll try to find the cam card for that one. Mine now is 220/215 duration at .05
.310/.303 lift at the lobe X1.6= .496/.4848
114 lobe sep
idles good, alittle noticable

**dbtk2** · 04-06-2004, 11:00 AM

Well the lift with this cam is .451 with the 1.6 rockers and the duration is just a little bigger than stock. The problem is the lobe seperation is only 109. A cam just like this one only with more lift so I don't need the rockers, and more lobe seperation (like 112-114 like you said) and I think it would be about perfect.

My boost gauge usually reads 18-22 InHg at idle.

Is .500 safe lift with the 3.1? The valves won't hit the pistons and the heads can handle it and flow decent with that kind of lift? I know with L67's the heads start flowing worse at about .500 lift, I would think that the 3100 heads would do the same thing, only probably at lower lifts. I haven't had any valve work or anything done to the heads I am putting on, they are basically stock heads. I was told by the person that I bought them from that he had a valve job done on the heads, but I am guessing that was just to clean up the valves.

I didn't really want to mess with getting a custom cam made just because I didn't want to go through the hassle. About how much more do you think it would cost to get a custom regrind than just buying an already made cam like I was going to do?

Also, that cam you were talking about for the 3100. Do you think that cam profile would work well for me? Or the cam that you have? If they would work well, could you get me the card for them so I can get one made?

I appreciate all your help so far.

Thanks,

Shawn

**xxrollin** · 04-07-2004, 05:24 AM

I havent seen much on flow numbers for the 3100 heads so I cant answer that question. The 109 lobe sep wont work on your turbo motor. That cam will have way to much overlap and wont be consistant with your computer. The bigger the number, the better. If your were able to get that cam with a 114 lobe sep, you'd be set, but theres more to a cam than lift/duration #'s. Lobe design can play a huge role also. A faster ramp speed might affect idle and/or vacuum. I'm not sure as to what type of lobe profiles my cam has. But at 800rpm's you can almost tell theres a slight lumb.

A regrind will run from 100 to 200 with a set of lifters, maybe up to 300 with the proper springs. I'm almost sure your running a flat tappet cam, and if you are I'd try a cam with maybe another .040 more lift to .490 and slightly more duration and go for a set of those Rhoads Lifters with there variable duration lifters. I got these in my 385's Mercs in my boat. I cant tell much but they do idle real smooth with a cam spec of .450/.460 and 228* at .050 with a 112 lobe sep. When I gun it, a wave comes out and we are haulin. Just an idea. But comp cams or crane can probably help you out more. I'd talk to them and see what they say and ask about the variable duration lifters, you might be able to run a bit more duration with those to get a good idle and maintaine the computer. I'll call my friend later and see if he's around to get his cam card...

**skalor** · 04-07-2004, 07:31 AM

Doesn't the stock cam have 109* lobe seperation?? I agree that more lobe seperation is definitely needed, especially in the case of a TGP. With such a small turbo a lot of lobe seperation will help reduce exhaust gas reversion.

While on the subject of reversion, I'm in the process of testing exhaust backpressure before the turbo with an 02 plug adapted to a boost gauge. I plan on testing it with the stock exhaust, and with no exhaust(downpipe back). Now, If I see a significant difference in backpressure readings between the two then comes in the 3" exhaust.

**dbtk2** · 04-07-2004, 10:25 AM

I havent seen much on flow numbers for the 3100 heads so I cant answer that question. The 109 lobe sep wont work on your turbo motor. That cam will have way to much overlap and wont be consistant with your computer. The bigger the number, the better. If your were able to get that cam with a 114 lobe sep, you'd be set, but theres more to a cam than lift/duration #'s. Lobe design can play a huge role also. A faster ramp speed might affect idle and/or vacuum. I'm not sure as to what type of lobe profiles my cam has. But at 800rpm's you can almost tell theres a slight lumb.

I know that the 109 lobe seperation isn't good for a turbo motor, but like skalor said, that is the lobe sep on the stock cam.

I have never heard of these lifters that you are talking about. What exactly do they do???

I like the Powermax 260 & 272. Those seem like very good cam profiles, I just wish there wasn't computer problems with them.

Shawn

**xxrollin** · 04-08-2004, 04:56 AM

Those lifters are supose to reduce lift by .025 and duration by a few degrees causing a big cam to run like a smaller cam till like 3000rpm's and then restore full lift and duration for the top end. BAM marine over in sarasota got me on these cause I wanted some topend but wanted to have the bottom end to troll.... I like them, but I cant compare these with any standard lifters cause the factory motors were 350's with like .420/.440 and 204/210 with a 112. So I stroked em and bored em to gain power and these guys got me a cam thats workin real good. I'm still burning nearly the same fuel but picked up speed, so I'm happy.. (25 GPH, any improvement is a big improvement)..

I'll try to talk to a guy hear in town who's worked on a GTP a few times. He might have some ideas. But those lifters are standard SBC size, .842 dia, these are the same on our motors so you wont have a problem with them fitting...

**geoffinbc** · 04-08-2004, 03:18 PM

What kind of roller rockers are you going to use? Show me a picture it will help alot.

**dbtk2** · 04-08-2004, 10:29 PM

Originally posted by betterthanyou

What kind of roller rockers are you going to use? Show me a picture it will help alot.

http://store.summitracing.com/partdetail.asp?part=CCA%2D1414%2D12

**xxrollin** · 04-09-2004, 04:39 AM

I got a set of harland sharpe 1.6 roller tip roller rocker arms with some ARP studs for these and some guide plates. I'm lookin for 100, but I paid total like almost 200 complete, I never used them, so if your interested, let me know.

I did call this guy I was talkin about and he said something like GM has a cam in there catalog like the one your looking at. He tried some cam with a 110 lobe sep and he claimed it work out ok but he said it idled alittle rougher but didnt pull as hard above 4500rpm's. He says "a small lobe sep will give an engine peaky power, like climb fast and drop faster, a wider lobe sep will give a broader power range across the whole rpm range". So thats all I got from him...

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Cam Swap, 3100 Topend Swap, etc... Sugestions or opinions??

Cam Swap, 3100 Topend Swap, etc... Sugestions or opinions??

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