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engine getting FI... cam ideas?

jekbrown

jekbrown

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ok gang. I've got a newish crate 350 in my truggy that currently has an edelbrock intake, rebuilt Q-jet and Edelbrock headers, but is otherwise stock. Here is the plan:

1. Install TBI (have the parts already)

2. Get a custom harness/chip from Affordable FI (no emissions, egr, etc... keep it simple!)

3. remove all the extra BS I don't need, mainly emissions stuff.

This crate 350 is pretty much your standard 350... no real bling to it. IIRC, its this one:

Engine Name: 350 LM1
Horsepower: 249 HP @ 5,000 RPM
Torque: 304 Ft/Lbs @ 3,500 RPM
Compression Ratio: 8.50 to 1
Block: 4 – Bolt, 2 Piece Rear Seal, 4.000” Bore
Crankshaft: Cast Nodular 3.480” Stroke
Heads: Cast Iron, 76cc
Valves: 1.940” / 1.500”
Camshaft lift: 0.390” / 0.410” Hydraulic
Duration @ 0.050”: 195° / 202°
Intake: Edelbrock (forget the part number, 2101?)

Right now, my rig is completely stripped down for the truggy conversion so accessing the engine to work on it is no problem. Would this be a good time to recam for better low end torque? I am getting a custom chip anyway. If so, which one should I go with? I don't want to get to extreme with it... gotta be reliable... just want a little more low end grunt if I can get it. Alternatively, should I just leave it as-is? What say you, ck5 lounge? :grin:

j
 
oh yeah, where on the engine do I find the numbers that would identify exactly which engine it is? I seem to have lost my receipts...
 
rgr, thanks!

any ideas on what cam to use? I don't really know jack about them.. what kinda lift/duration is a good thing in a cam for a 4x4?

truck use: trails and rocks... never really do mud or hammer down a lot. Low RPMs is the norm.

j
 
A mild choice would be somewhere around 206/218 .450/.450 112; A little more power could be had with something like 218/226 .500+/.500+ 114. The more duration the more LSA you're going to want. In any instance, I'd try to keep it above 112, 114 is better. In addition to the PROM tuning, you may have to bump the fuel pressure and/or add an aftermarket regulator if you're going with a cam that is the size of the second or larger. The factory LT1/4 cam(s) are good choices and are available used on ebay, the LT1 HOT cam can also be used. I would consider doing valve springs and 1.6 rockers for more power, too.

Check Comp's Extreme FI grinds, and Crane's Z-car grinds- Summit sells some similar ones under their brand name for quite a bit less.

The less cam, the less tuning you'll have to do. If you don't mind tuning and getting a WB 02 I'd get something bigger. Seeing as how you're getting a chip made, you may be able to eliminate most of the tuning right off the bat, and only have to dial things in with the fuel pressure. I just haven't read a single post in any BBS of anyone being able to do that yet. It usually takes several different PROMs and several hours of tuning to dial in a larger cam correctly.
 
As stated LSA is a big deal. I was e-mailing with the guy at tbichips.com about this same question.

My current cam with carb has 218* at .050" and LSA only 110. He told me the LSA is no good for TBI.

His recommendation was a cam designed for computer controlled engines and an LSA of 114* He also recommended 1.6 ratio rocker arms for better mileage and power. The only thing is this setup may put the low end RPM higher than you'd like.
 
for a second lets all just operate under the premise that I know nothing about engines or FI systems.... LSA? WB 02? :crazy:

j
 
thanks much for the links/tips, it is appreciated! Anyone else care to chime in?

j
 
LSA= lobe seperation angle The seperation between intake and exhaust lobes on each cylinder.

It helps keep the vacuum up which for MAP setups is very important. For TBI I have always read that 112 is minimum for sufficient vacuum.

Another thing if you go with 1.6 rockers make sure you have sufficient head valve to piston clearance at TDC. It would suck to knock a hole in a piston:o

Ira
 
The Edelbrock Performer is a good mild cam. They will send you a chip for free too! I had a different one put in my 383. I will have the specs later.
 
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