Introduction

[Danoby]

Hello everyone. I have been doing extensive research on swapping vortec heads onto the TBI 350 in my Caddy (in signature). While doing research, I was led to this site. My biggest hesitations with doing this swap are: not making the car run worse, not dealing with a check engine light, and not getting buried and overwhelmed with details like making a custom EGR setup or eliminating it altogether and tuning becoming a nightmare, not hurting gas mileage at all or too much. Anyway, I am a mechanic by trade, and thus very capable. I have a few other toys too including a '69 GTO project car, an '86 F150 Flareside 4x4, an '02 Harley Low Rider, a '71 M35A2 deuce and a half, and an '88 Baja Sunsport. My Caddy is my daily driver and my baby. It's a great cruiser that's just a little short on power. I get about 12 MPG city and 18-20 highway. I'd love to get some help getting the Caddy some more power. I want to retain the TBI EFI and swap on a good set of vortec heads I have. I don't know if I should make a separate thread for that in the GM EFI section or delve right into it here.

[dave w]

I had excellent results using TBI heads on a roller camshaft Vortec 5.7 liter short block assembly. Using TBI heads saved money, time, and several headaches. Admittedly, the Vortec heads would yield slightly better performance. The Vortec roller camshaft required some timing and fuel table adjustments to the PROM chip programming to get things dialed in.

dave w

[Danoby]

I have read that I can expect a minimum of a 30 HP gain switching to vortecs. My current heads need valve seals pretty bad. It smokes on start up. And when it's fully warmed up - and I mean after driving for at least 15 minutes - I start getting a knock signal under load to the point where the ECM pulls out timing causing a significant power loss. I suspect the oil is getting past the seals enough to contaminate combustion. I am pretty sure being a car engine that it's equipped with flat tops, putting SCR at about 9.8:1 which is pretty high with pump gas. The vortecs would increase SCR further to about 10:1, but that should be okay with it's superior chamber design. You see, the vortecs would solve a few different problems I am having plus I would see a nice power increase.

I am now realizing all the headaches I will endure, like tuning and EGR. I am fine with the mechanical aspect or doing the work, but I am not familiar with tuning an engine electronically, and I am not sure what I would do about the EGR. I guess I would either find a way to make it work, which is a headache, or forget about it, eliminate the system, and deactivate that part of the programming.

I am not sure what to do here. There are lots of things to consider. I guess what I need to know is approximately how many hours would it take for me to learn how to program? How many hours would it take to learn how to program and burn a chip and then execute the process? How much would it cost to have someone else do it for me? In fact, I probably need a new tune already, so regardless of if I do the head swap or not, I need some programming done, just perhaps not as extensive. I guess I would need to log some data somehow and then send it to someone so they could burn me a chip? I had talked to Brian Harris at TBI Chips, but I am a bit wary of using a chip from him based on things I have read. He was very informative about how to upgrade TBI engines though.

[Fast355]

I have read that I can expect a minimum of a 30 HP gain switching to vortecs. My current heads need valve seals pretty bad. It smokes on start up. And when it's fully warmed up - and I mean after driving for at least 15 minutes - I start getting a knock signal under load to the point where the ECM pulls out timing causing a significant power loss. I suspect the oil is getting past the seals enough to contaminate combustion. I am pretty sure being a car engine that it's equipped with flat tops, putting SCR at about 9.8:1 which is pretty high with pump gas. The vortecs would increase SCR further to about 10:1, but that should be okay with it's superior chamber design. You see, the vortecs would solve a few different problems I am having plus I would see a nice power increase.

I am now realizing all the headaches I will endure, like tuning and EGR. I am fine with the mechanical aspect or doing the work, but I am not familiar with tuning an engine electronically, and I am not sure what I would do about the EGR. I guess I would either find a way to make it work, which is a headache, or forget about it, eliminate the system, and deactivate that part of the programming.

I am not sure what to do here. There are lots of things to consider. I guess what I need to know is approximately how many hours would it take for me to learn how to program? How many hours would it take to learn how to program and burn a chip and then execute the process? How much would it cost to have someone else do it for me? In fact, I probably need a new tune already, so regardless of if I do the head swap or not, I need some programming done, just perhaps not as extensive. I guess I would need to log some data somehow and then send it to someone so they could burn me a chip? I had talked to Brian Harris at TBI Chips, but I am a bit wary of using a chip from him based on things I have read. He was very informative about how to upgrade TBI engines though.

I wouldn't follow any of his TBI build-up advice to be honest. As for the heads you won't gain 10-15 HP with Vortecs over the TBI heads running your stock cam. The cam in that Cadillac is the same weakling that came in the LG4 and L03 305 engines. You are a full 30 HP down on a TBI truck with the same engine and a non roller hydraulic flat tappet cam. Best thing you could do is get your current heads cleaned up, new guides or more likely new valve stem seals and put a '395 marine cam in it. That being said your current engine is being held back more by the stock exhaust manifolds than anything else. If you switch to vortecs the compression ratio will be unaffected and stay right at 9.6:1.

[Danoby]

I really appreciate your input. I don't want to be rude, but how do you know what cam came in my engine? I have searched endlessly and cannot find any information to verify what cam came in my engine. It would seem really stupid of GM to put the same cam from lower compression and smaller cubic inch engines in a flat top 350 with 9.8 CR.

I bought 906 L31 vortec heads for either my Caddy or my SBC powered boat. I was going to put them on the Caddy but now I am rethinking that. If you really think the cam is tiny and holding it back, maybe I'll go back to my original plan of retaining the swirl heads and doing the valve seals and changing the cam. The 906 heads I bought came with a stock L31 roller cam in good shape. I measured the lobes and got .411/.426. Based on the lift I believe it is the same cam that comes in a brand new L31, like off of Jegs where I got these specs: 191/196 .414/.428 111 lobe centerline. It's really not that much smaller than the 395 cam that comes in the Ram Jet 350 and HT383 with 196/206 .431/.451 with a 109 LSA. Correct me if I'm wrong, but that L31 cam might be a good upgrade, plus it was free and in good shape. And if I use 1.6 rockers I'll get .442/..457.

I still don't know what all will be involved in tuning this thing with all of these changes...

[Fast355]

I really appreciate your input. I don't want to be rude, but how do you know what cam came in my engine? I have searched endlessly and cannot find any information to verify what cam came in my engine. It would seem really stupid of GM to put the same cam from lower compression and smaller cubic inch engines in a flat top 350 with 9.8 CR.

I bought 906 L31 vortec heads for either my Caddy or my SBC powered boat. I was going to put them on the Caddy but now I am rethinking that. If you really think the cam is tiny and holding it back, maybe I'll go back to my original plan of retaining the swirl heads and doing the valve seals and changing the cam. The 906 heads I bought came with a stock L31 roller cam in good shape. I measured the lobes and got .411/.426. Based on the lift I believe it is the same cam that comes in a brand new L31, like off of Jegs where I got these specs: 191/196 .414/.428 111 lobe centerline. It's really not that much smaller than the 395 cam that comes in the Ram Jet 350 and HT383 with 196/206 .431/.451 with a 109 LSA. Correct me if I'm wrong, but that L31 cam might be a good upgrade, plus it was free and in good shape. And if I use 1.6 rockers I'll get .442/..457.

I still don't know what all will be involved in tuning this thing with all of these changes...

I know the cam well. Its the same one that came in the civilian L05 Caprice, as well as Olds and Buicks variants of the B/D-car. 179/194 @ .050, .350/.385 lift, 109 LSA, 106 ICL.

Your engine is ~9.6:1 with the stock 6cc valve relief flat top pistons, stock deck height, and the stock headgaskets.

I am not a big fan of the factory Vortec cams. I have had them piled up like cordwood in the shop and started tossing them recently.

[Fast355]

Lookup Melling CCS-39. It is your factory cam. The 9C1 cop cars had the L98 TPI cam in them and had 25 HP more than you with the same longblock, manifolds and TBI (bigger injectors only).

[Danoby]

Well, okay you have me convinced I have the infamous "peanut" cam. And since that appears to be the case, my prior idea of installing 1.6 rockers to make the cam act a little bigger is completely inadequate. That cam has to go! I found an LT1 on ebay, but it's the smaller one. This one: 1994-1996 B-bodies (including L99 4.3L): 191/196 0.418/0.430 lift 111 LSA. It has specs very similar to the 264 cam I have. I am really thinking the 264 might be a good one to use, especially with 1.6 rockers. Fast355, why do you dislike the 264 vortec cam? It's more or less only slightly smaller than all the LTX cams, and only a 1/2 step down from the renowned 395 cam. With 1.6 rockers it should be more like 194/199 .442/.457... That's not that much smaller than these other ones, plus it's free, probably a little easier to tune, and a vast improvement over the garbage that's in there now. If you really think the 264 is a waste of time I'll wait for a better LT1 cam to come on to ebay, but I don't really understand why you have this animosity towards it.

[Fast355]

Well, okay you have me convinced I have the infamous "peanut" cam. And since that appears to be the case, my prior idea of installing 1.6 rockers to make the cam act a little bigger is completely inadequate. That cam has to go! I found an LT1 on ebay, but it's the smaller one. This one: 1994-1996 B-bodies (including L99 4.3L): 191/196 0.418/0.430 lift 111 LSA. It has specs very similar to the 264 cam I have. I am really thinking the 264 might be a good one to use, especially with 1.6 rockers. Fast355, why do you dislike the 264 vortec cam? It's more or less only slightly smaller than all the LTX cams, and only a 1/2 step down from the renowned 395 cam. With 1.6 rockers it should be more like 194/199 .442/.457... That's not that much smaller than these other ones, plus it's free, probably a little easier to tune, and a vast improvement over the garbage that's in there now. If you really think the 264 is a waste of time I'll wait for a better LT1 cam to come on to ebay, but I don't really understand why you have this animosity towards it.

Not a fan of the Vortec cam because the torque curve drops from 2,600 rpm. With the L31 in my Express you could roll on the throttle at 80-85 MPH, catch a downshift to 3rd, engine would rev up to about 4,000rpm and the acceleration would drop off. I put a LT4 cam and 1.6s in it. Lost NOTHING down low and saw gains of close to 40 HP up top near the 5,200 rpm shifts. Same thing with the F-car LT1 cams I put in the L05 in my 83 G20 and the L31 that went into my brothers 99 Suburban with a F-car LT1 cam.

Here is the nail in the B-car LT1/Vortec cams coffin for me. It idled rougher and got poorer fuel economy than the F/Y car cams.

Stock Cam/Tuned
http://www.youtube.com/watch?v=vc1lHlBLdkw

LT4 Cam/1.6s/Same Tune/Shorties
http://www.youtube.com/watch?v=7SgptElOCpY

[Danoby]

Hmm. Do you think some of the added power came from the shorties and 1.6 rockers? I mean you went from 191/196 .418/.430 111 LSA to 196/206 .431/.451 109 LSA which is not that big of a difference, but also added 1.6 rockers for .460/.481 plus the headers. The biggest difference it looks like to me is the added lift, most of which is attributed to the 1.6 rockers, plus the shorty headers. I am not saying the 395 isn't a better performer than the 264 as it certainly is, but I think the difference is marginal compared to the difference the 1.6's and headers provide. You actually have vortec heads on that van, too. I am still working with the swirl ports...

In any case, I think I need to learn to tune this thing. It would probably benefit dramatically from a tune right now with the air cleaner, TBI mods, high flow y pipe and cat delete, etc... Maybe I should get acquainted with the process now before I swap in the cam and have more severe changes to deal with? I would hate to swap in a better cam - almost any cam is better than the one I have - and have performance and idle quality problems. That would suck.

[Fast355]

Hmm. Do you think some of the added power came from the shorties and 1.6 rockers? I mean you went from 191/196 .418/.430 111 LSA to 196/206 .431/.451 109 LSA which is not that big of a difference, but also added 1.6 rockers for .460/.481 plus the headers. The biggest difference it looks like to me is the added lift, most of which is attributed to the 1.6 rockers, plus the shorty headers. I am not saying the 395 isn't a better performer than the 264 as it certainly is, but I think the difference is marginal compared to the difference the 1.6's and headers provide. You actually have vortec heads on that van, too. I am still working with the swirl ports...

In any case, I think I need to learn to tune this thing. It would probably benefit dramatically from a tune right now with the air cleaner, TBI mods, high flow y pipe and cat delete, etc... Maybe I should get acquainted with the process now before I swap in the cam and have more severe changes to deal with? I would hate to swap in a better cam - almost any cam is better than the one I have - and have performance and idle quality problems. That would suck.

I have played musical cams with the Express.

1.) 264 was the stock cam
2.) 142 LT4 cam w/1.6s 203/210 @ .050 on a 115
3.) Comp 4x4 206/210 @ .050 on a 110
4.) Comp Custom 215/220 @ .050 on a 114 (On Etec170s)
5.) 395 Marine cam w 1.6s (May go with 1.7s soon)

The Marine cam has more aggressive lobes, 5° more intake duration, 10° more exhaust with less .06" duration, 2° tighter LSA which makes it noticeably more powerful. It also has .017" more intake lift and .023" more exhaust lift. When you put 1.6s as opposed to the stock 1.42s on the Marine cam it is really close to a LT1 cam with 1.42 rockers except its cut on a tighter LSA. It specs about 200/210 @ .050, .451/.481" lift, 109 LSA. It has a slightly noticeable idle but it pulls hard from off-idle through 5,000 rpm.

My old G20 van had an 8.75:1 TBI 350 with 350 heads in it. Used the 142' LT4 cam in it back in the day. Very nice running and driving setup even with the stock 1,600 rpm converter in the 700r4 and 3.08 gears.

There is another guy that tested a Vortec cam vs 1995 F-car LT1 cam in his 1996 K1500. Back to Back testing even untuned showed a gain starting at 4,000 rpm and a peak gain of 13.5 HP at the tires at 5,100 rpm. Lost NOTHING from the start of the test to redline.

[Fast355]

You are correct though. You do need to learn how to tune as well as check your engine over carefully and get it ready for more mods. Adjustable fuel pressure regulator, Stronger fuel pump, tuneup stuff good, compression checked, etc. I would also recomeend that you check to make sure you don't have the 048 ignition control module and have either a 369 or a DUI Dynafire module. The 048 module retards the timing over 3,500 and makes the engine gutless above that.

[dave w]

For a modest low cost, for modest performance gains, for ultra easy tuning, and for next to nothing headaches using TBI heads on a stock L31 roller camshaft short block assembly is an option worth considering. Other options available will: add cost, add headaches, increase performance, and add time for tuning.

dave w

[Danoby]

Okay, you have me convinced I need at least an LT1 cam or better yet the 395 cam. But, maybe I need to look into the tuning stuff first. I already have an adjustable regulator set to about 12 psi and a TPI fuel pump. Does the ignition module retard spark advance based on feedback from the knock sensor?? The tune up stuff is all done as well - new plugs, wires, cap rotor, distributor. It has a new knock sensor, new EGR valve. Basically, this thing is ready to go except for the valve stem seals, which will get replaced with the cam and 1.6 rockers install, and perhaps the ignition module you mentioned. How can I identify the module that I have? How do I get started with tuning?

[Fast355]

This was a stock vortec with only a cam change and a slight bit of exhaust rework prior to the dynos.



I played with a TBIs years ago.



This engine was rated at 190 HP/300TQ at the flywheel and only had headers, exhaust, edelbrock 3704, TBI mods, and Tuning.




Open center TBI spacer, open element, hypertech powerbowl, and 1.6 rockers.


Then I dropped a 454 TB on it with high pressure injectors, LT4 cam, left the 1.6s, and ran it.