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Username Post: EFI require specific cams?        (Topic#374591)
Posts: 182
Loc: Middlesex, CT
Reg: 01-02-09
02-28-24 07:26 PM - Post#2867365    

Brought my block to a machine shop for some prep work.
Went over my overall build plan:
348=> BWR Aluminum heads => Edlebrock 7159 Intake => EFI Setup. (Most likely Terminator Stealth)

Shop says EFI's require special cam grinds in order to make them run right.
Really? Never heard of this before.
Any experience with truth to the claim?



Posts: 223
Age: 76
Loc: Southern California
Reg: 07-18-03
02-29-24 02:26 PM - Post#2867396    
    In response to 3483x2

EFI Needs vacuum to run properly therefore you need a lobe separation of at least 112 degrees.
Comp Cams has a series of XFI Cams that are designed for most EFI Systems %20...

"7th Year" Platinum Supporting Member
Posts: 519
Age: 77
Loc: Neosho, MO.
Reg: 04-01-18
03-03-24 09:11 AM - Post#2867490    
    In response to asbicca

Put a roller cam in my first gen 350, manufacturer requires firing order be changed to LS, why?

1952 Styleline Sedan-
Blue 1967 C-20, Survivor.
The only running vehicles I own.

Posts: 182
Loc: Middlesex, CT
Reg: 01-02-09
03-03-24 05:45 PM - Post#2867522    
    In response to asbicca

Asbicca - Thanks for the reply. Now, the claim make more sense. Since the cam I have has only 110 lobe separation, looks like I'll be in the market for a replacement.
Grind Intake Exhaust Dur Intake Exhaust .050 Intake Exhaust Lobe Separation
Camcraft Cam 3830690 0.504 0.515 HYD 0.274 0.271 0.237 0.241 113.5


"6th Year" Silver Supporting Member
Posts: 2751
Loc: Belchertown, MA
Reg: 04-06-03
04-14-24 11:37 AM - Post#2868844    
    In response to asbicca

Duration also plays some role in a cams vac quality.
The RamJet 350/HT383/Marine 395 cam runs a LSA of 109*......05 dur is 196/206 if I recall at the moment and it pulls enough vac for EFI

Very Senior Member
Posts: 5007

Reg: 12-29-02
04-18-24 10:11 AM - Post#2868951    
    In response to 3483x2

It's easier to tune EFI with a milder EFI type cam, but every cam made can be tuned to run with EFI.

Swapping cams into factory EFI systems and not wanting to tune it requires cams that doesn't deviate too far from the stock one.

Super Senior Member
Posts: 6646

Loc: paradise
Reg: 09-05-03
04-21-24 10:31 AM - Post#2869041    
    In response to 3483x2

i would ask the efi manufacturer

70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails.

"8th Year" Silver Supporting Member
Posts: 1244
Loc: Western NY
Reg: 06-15-02
04-25-24 07:41 PM - Post#2869183    
    In response to 3483x2

A large overlap cam has times, especially at low RPM, where the Lambda/O2 sensor is fooled and thinks that the mixture needs to be enriched. I've read some information where some have had luck turning the learning off below 1500 RPM and creating a manual tune.

As well if you are running a cam with a large overlap, and making very little vacuum, a vacuum advance distributor get difficult.

How much vacuum and at what RPM does your car idle in gear?


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