Computer controlled cam

[REM777]

Not trying to nit pick, but your stock cam simulation is a bit off as far as cam timing goes. Stock cam is 191/194 @ 0.050, .414/.428 lift, 111 LSA and 106 ICL.

The 196/206, .431/.451 marine cam on a 109 LsA and 106 ICL makes over 300 hp and nearly 400 tq and makes 390 ft/lbs as low as 2,500 rpm.

109 LSA is a recipe for tuning hell with the MPFI - but some people have to experience the pain .. the 203 203 is the biggest drop in cam for GMT400 that wont give you computer grief period - that is the only point I am trying to make - PROFLO or Carb - have at it - by the way, the VORTEC heads hit the wall above .500 lift unless ported ..I like the marine cam with 1.6 rockers and a spring kit - but 109 is going to kill your vacuum signal and then the fun begins with these old computers - 1998 and the later LS computers - different story - but you are talking another $1K for either a computer swap ad tune . TO me I wanted all I could get out of the stock setup but wanted a daily driver I could depend on .

 

[sync]

The 196/206, .431/.451 marine cam on a 109 LsA and 106 ICL makes over 300 hp and nearly 400 tq and makes 390 ft/lbs as low as 2,500 rpm.

On a 350 or a 383?

 

[Supercharged111]

That might work on a stock tune, but in all reality there is more power to be had with tuning and the stock cam than there is from a cam swap and no tuning. L31 starts out pig rich in power enrichment, when it ever gets into it and the timing curve and total advance is limp wristed.

This is 1000% true. I wish more people would get it through their heads that tuning is NOT something that should be avoided. Aside from the blower, the biggest gain I've seen from a single (I'm using this term loosely) component has been the tune. Bigger than the headers and exhaust, bigger than the marine cam/rockers, way bigger than the (now non-existent) underdrive pulley. . . you get the idea. And yes, I retuned after the cam.

 

[Supercharged111]

109 LSA is a recipe for tuning hell with the MPFI - but some people have to experience the pain .. the 203 203 is the biggest drop in cam for GMT400 that wont give you comouter grief period - that is the only point I am trying to make - PROFLO or Carb - have at it - by the way, the VORTEC heads dont do Sheeeeeeeeeeeeet about 500 lift unless ported ..

You've obviously never owned one of these trucks with a 109 LSA. Maybe a donkey dick cam would be difficult, but not the wee little cams we're talking about.

 

[L31MaxExpress]

On a 350 or a 383?

350, I put down 310 rwtq through a 4L85E and 9.5" 14-bolt on 91 octane with that cam at 9.6:1 static.

 

[L31MaxExpress]

109 LSA is a recipe for tuning hell with the MPFI - but some people have to experience the pain .. the 203 203 is the biggest drop in cam for GMT400 that wont give you comouter grief period - that is the only point I am trying to make - PROFLO or Carb - have at it - by the way, the VORTEC heads dont do Sheeeeeeeeeeeeet about 500 lift unless ported ..

Wrong, mine was perfectly driveable on the stock tune. Went back to the stock fuel and timing settings and tweaked from there.

Initial fireup after installing the 395' and 1.7 rockers.

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[REM777]

Not trying to nit pick, but your stock cam simulation is a bit off as far as cam timing goes. Stock cam is 191/194 @ 0.050, .414/.428 lift, 111 LSA and 106 ICL.

The 196/206, .431/.451 marine cam on a 109 LsA and 106 ICL makes over 300 hp and nearly 400 tq and makes 390 ft/lbs as low as 2,500 rpm.

Agreed on the "bit off" - this is because this was on a digital cam checker - the differences are meaning less because they are small - BUT- this is the actual measurements from a stock cam - VS specs - what is the tolerance on a factory cam ?

 

[L31MaxExpress]

Agreed on the "bit off" - this is because this was on a digital cam checker - the differences are meaning less because they are small - BUT- this is the actual measurements from a stock cam - VS specs - what is the tolerance on a factory cam ?

IMO tolerances on these later 350s were better than any of the small blocks before. They had to be because of the random nature of the emissions certification process and the tighter restrictions in place. I have degreed several of them though and found they fairly closely match the specs in the engine. I found the factory cam does degree in advanced in the two I have bothered to check. The factory LT4 cam was a screamer in the L31 I installed it into. 203/210 @ 0.050 on a 115 LSA and it degreed in on a 116 ICL using a cloyes single roller chain set.

 

[REM777]

IMO tolerances on these later 350s were better than any of the small blocks before. They had to be because of the random nature of the emissions certification process and the tighter restrictions in place. I have degreed several of them though and found they fairly closely match the specs in the engine. I found the factory cam does degree in advanced in the two I have bothered to check. The factory LT4 cam was a screamer in the L31 I installed it into. 203/210 @ 0.050 on a 115 LSA and it degreed in on a 116 ICL using a cloyes single roller chain set.

Actually the machine work in Mexico was freekin horrible - not 6 sigma - look at the deck RA value on the VORTEC blocks - lousey .. BTW - this 203 203 uses the lobe off the 203/210 factory cam .

 

[REM777]

You've obviously never owned one of these trucks with a 109 LSA. Maybe a donkey dick cam would be difficult, but not the wee little cams we're talking about.

Wrong, mine was perfectly driveable on the stock tune. Went back to the stock fuel and timing settings and tweaked from there.

Initial fireup after installing the 395' and 1.7 rockers.

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Well, you said " . . Rhoads V-Max lifters tame the thing around idle to the point it pulls 18 in/hg @ 650 rpm. The rhoads lifters make the cam smaller on the low-end but the full duration and lift extend the powerband above 4,000 rpm. With them I was able to bump the cam size for more power but still have the manners and off-idle torque of a smaller cam. . . " So you have a little more going on here than JUST the 109LSA Marine cam - you "got your vacuum signal back" with the RHODES lifters - which are NOT recommended with computer controlled engines - why ? they trigger the knock sensors which results in timing pull back. AND, like the louder roller tip magnum rocker these RHODES are even louder. So you have a van with a whole lot of machine noise under the cowl I bet. So we are not taking just an 109 LSA in the VORTEC, you have a 109 LSA crutched to work with the computer using the rhodes lifters. And no doubt the tune is was to make it work without codes - my point, the 203 203 is a drop in, makes more power and torque, longer torque with no codes nor tuning.