Is it worth it?

[BLG355]

Nice cam, I would have gone with the RR257/265 grind, but then I am a torque junky.

I wanted to go a little bigger, but at the time I was dealing with TBI Chips.com and I was told I can't go over 210@ .050, that it can't be tuned. I picked a smaller one that was within is tuning capabilities, which I later learned didn't exist. But overall I'm happy with it, good torque, good idle, pulls strong.

[Roadknee]

I wanted to go a little bigger, but at the time I was dealing with TBI Chips.com and I was told I can't go over 210@ .050, that it can't be tuned. I picked a smaller one that was within is tuning capabilities, which I later learned didn't exist. But overall I'm happy with it, good torque, good idle, pulls strong.

I think the cam you have is a very good choice in a 355 in a heavy truck. The larger one mentioned would pull stronger, although not by much, above 4,000 rpm at WOT. However, it would give up some low speed torque and part throttle response. If you increase the airflow into the engine as already discussed and install the headers your engine should pull strong through 5,200 rpm with proper tuning.

[jim_in_dorris]

sorry Roadknee, I have to disagree on the low speed torque and part throttle response. That slightly bigger cam actually has a lot more torque down low. I was not a big fan of Isky cams, ( I like lunati cam profiles) but the grind I mentioned actually has more area under the curve than the lunati cam I like. I model my builds in DD2003, and while I understand that actual numbers may not be exact, when you create a model and only change one part, it will give you a good indication of how that part affects the build. Of course, like always, I have been known to be wrong. I do however think that the cam he chose isn't a bad cam for his truck, just that I like gobs of torque.

[BLG355]

I think the cam you have is a very good choice in a 355 in a heavy truck. The larger one mentioned would pull stronger, although not by much, above 4,000 rpm at WOT. However, it would give up some low speed torque and part throttle response. If you increase the airflow into the engine as already discussed and install the headers your engine should pull strong through 5,200 rpm with proper tuning.

I was scared when I ditched the TBI heads that I would loose that idle-3000rpm grunt that it had, but I was very impressed with the ease this thing roasts the tires. It doesn't seem to have the throttle response I had from stock, but I am only running on a starter chip and will try to get some of that back. It's almost no fun to drive in the rain, a little burp on the throttle and the tires spin. I've been trying to get decent 1/8 and 0-60 times with the GTECH, but no luck, every time I get wheel spin, sometimes all the way through to second gear. I managed a 9.89 1/8 mile time one time, but I still left 25ft of black marks on the road... I'm not intending it to be build for speed, but it is always fun just to see what it can do. I'm excited to see what I can get out of it with some more upgrades this summer, it will be fun for sure.

[steveo]

I wanted to go a little bigger, but at the time I was dealing with TBI Chips.com and I was told I can't go over 210@ .050, that it can't be tuned.

"it cant be tuned.."

my junker is a 9x8 VE table.

i can imagine that would just SUCK if your cam didnt even operate in half of it, suddenly you'd have a 4x6 VE table, the rest would just be decel.

but it could be tuned, just not well, it'd probably be one of those 'as good as a highschool tuned carb' things.

ecm upgrade to something with higher resolution VE - problem solved?

[Fast355]

"it cant be tuned.."

my junker is a 9x8 VE table.

i can imagine that would just SUCK if your cam didnt even operate in half of it, suddenly you'd have a 4x6 VE table, the rest would just be decel.

but it could be tuned, just not well, it'd probably be one of those 'as good as a highschool tuned carb' things.

ecm upgrade to something with higher resolution VE - problem solved?

I have tuned a 230/230 @ .050 cam in a 305 with that same little VE table you are talking about. Works just fine!

[steveo]

no shit?

good to know!

[BLG355]

Well, I decided to bore the 3704 intake, even after reading about people having issues about going through to the water jacket. I figured f I go through I will just ditch it and get a decent dual plane anyways. I did the deep side tonight since it would take a lot longer. It is now 2.008". I am doing the short side tomorrow. And of course this post would be useless without pictures, so I attached some.


BLG

[Six_Shooter]

I have tuned a 230/230 @ .050 cam in a 305 with that same little VE table you are talking about. Works just fine!

IIRC my buddy's Olds BB, has something like 240* duration, and while it only uses the upper half of the VE table for idle (Idle KPA is around 55 KPA after a lot of playing and fudging to force it that low), it starts like a stock vehicle, and idles mean. During cruise MAP readings will actually go into the 40's.

It's not that it can't be tuned it's that it is more difficult to do.

[billygraves]

...........

[Fast355]

I gotta had it to you Mister!! YOU ARE RIGHT ON with the transmission pressures. At GM I learned why TBI used small throttle bodies and small runners. First was Emissions BUT with this is to keep the velocity in Motion inside the intake runners. If it slowed down, it would "Rain" and the fuel droplets would fall out of suspension, then run a liquid to the combustion chambers.
Second, the TBI engines usually run rich to keep the lean cylinders satisfied with fuel.
Port Fuel is the way to go if you select a intake that matches your requirements of your powertrain and the camshaft is selected.
Actually the TV trans should have parts to increase it's pressure overall. If it's a L60/65/70-E I still would add pressures. For the most part the L80 has enough pressure cushion to be pretty safe. (Unless it's a very hi torque engine or S/C or turbo)

Or a Duramax! I had to put extra pressure in that tune by eliminating what the tune was pulling during shifts.