Tuning options

[crimespree]

i need some suggestions as to what i should do to get the most power out of my motor. this is the set up...


-350 bored to 355
-Crower Cam with around .502 lift (dont know the duration)
-Roller Rockers
-Edelbrock Performer RPM, Dual Plane Intake Manifold
-2" spacer w Holley 650cfm carb on top
-GM HEI ignition with Accel parts(coil, cap, etc.). It had an MSD ignition module, but was dead, and ended up going back to a stock GM ignition module to get it running.
-Headers are 1 5/8" primaries, 3" collector
-Exhaust is full 3" with "H" pipe into Flowmaster 1 chambers


let me know what you think,

[ll____b0t____ll]

You forgot the most important part for making H/P the heads .
what ya got?
Also you need to know what RPM the cam pulls in to match that with the intake .
And headers with 1 5/8 off into full 3" exhaust may net you a couple of H/P at top end but youll lose more torque on the bottom end.
Be carefull also of starving the moter for air and fuel by not using a stock fuel pump and not using a small air cleaner element.
Remember when dealing with heavy trucks torque woops horse powers butt all day .

[nitrojunkie383]

Originally Posted by ll____b0t____ll

You forgot the most important part for making H/P the heads .
what ya got?
Also you need to know what RPM the cam pulls in to match that with the intake .
And headers with 1 5/8 off into full 3" exhaust may net you a couple of H/P at top end but youll lose more torque on the bottom end.
Be carefull also of starving the moter for air and fuel by not using a stock fuel pump and not using a small air cleaner element.
Remember when dealing with heavy trucks torque woops horse powers butt all day .

I have been helping crimespree with his truck and in a previous conversation; I think that the cam's rpm range is between 3500 - 6500.

The PO set the motor up for drag racing, but also wanted it as a daily driver. So the PO installed that Edelbrock Performer RPM, Dual Plane Intake Manifold along with the Holley 650. His thoughts were that this would give him better mpg.

The motor, IMO, needs to have an Edelbrock Victor Jr. Single Plane Airgap manifold with a mild Holley 750. With what little we know about the motor, I believe that combination would help wake that motor up.

[C20-67_N_MO]

Originally Posted by nitrojunkie383

I have been helping crimespree with his truck and in a previous conversation; I think that the cam's rpm range is between 3500 - 6500.
The motor, IMO, needs to have an Edelbrock Victor Jr. Single Plane Airgap manifold with a mild Holley 750. With what little we know about the motor, I believe that combination would help wake that motor up.

Well if you go with a single plane intake it will literally kill your low end torque. But if thats what the RPM range of the came is then it may help just will loose a lot of low end power.

Just IMO.

[PanelDeland]

I agree with bot.You need to include which heads you're running and is you can find out cam duration.I'm thinking with that much lift your duration would have to be long.This would knock off the low end and torque.

[crimespree]

i wish i knew... thats the beauty of my project. i have no idea. the mods on this motor have been told to me by a friend of the previous owner. so i dont know where to start identifying what has been done. im trying to get a list from the guy but he has his own projects and whatnot that he is working on. so, im not sure what to do.


is there any way to identify what heads have been used?

[crimespree]

ok, found out that the heads are stock / ported and polished. i picked up a holley 850 today for a steal and thought about tuning it way down so not to flood the motor. my plans involve building up the motor without getting into the internals. any suggestions?

[Jacfourteen]

Originally Posted by crimespree

ok, found out that the heads are stock / ported and polished. i picked up a holley 850 today for a steal and thought about tuning it way down so not to flood the motor. my plans involve building up the motor without getting into the internals. any suggestions?

As you already know the 850 is too much carb for the engine and I think it will cause more problems. I would stick with the 650, if you don't like the edelbrock you have why not sell the two carbs and buy what you want? Also if you get some pics of the heads and the casting numbers off of them I'm sure someone will help you identify them.

[mclairmo]

I would not change anything unless you want to start spending some serious money on better flowing heads, better carb, RPM intake, etc. However, you have a great torque motor now and that is best for a heavy truck. I say leave it be and enjoy it.

[PanelDeland]

I would swap the cam if I wanted street manners.If I was racing I would go with bigger heads and some more carb though not an 850.

['72customdeluxe]

Why bother with a new carb, manifold etc. when even well ported stock heads suck? Slap some Patriot Vortecs on that mug for 650$ a pair and along with your dual plane manifold you'll have 420+ horsepower and matching or greater torque at a reasonable rpm. Slap a Lunati Voodoo 268 or 274 in there as well. Your cam might be an old outdated grind. That 850 is way to big even for 7000 rpm, and will take a ton of tuning just to make it acceptable. You'll lose torque and won't gain any power. That 650 Holley is perfect. Though I don't understand the 2" carb spacer. That might be hurting you aswell. i would get a 2.5" dual exhaust setup with an x-pipe. And ignition companies claim with aftermarket coils you should be running an upgraded module. It can do some weird things w/o one.