Another cam question
Thread Starter
Burning Brakes
Joined: Jul 2004
Posts: 1,133
Likes: 2
From: GEAUX TIGERS PSL FL.
Another cam question
Does a carburated engine use a different type cam than one that would be used in an EFI engine? Given otherwise the same engine components.
Last edited by RushThruLife; Nov 5, 2009 at 08:26 AM.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Yes and no. Hows that for an answer. Most FI engines will run a wider LSA than a carbed engine. Not to say it won't run OK but a lot depends on duration and overlap. I am running a big solid flat tappet 252/260 @ .050 and it ran great with a carb. Changed over to FI and it runs good but the cruise and idle are tough. The O2 sensors did not like the big duration and long overlap, so I bought a new cam more suited to FI. Wider LSA and shorter duration but a higher lift, also solid roller from a solid flat tappet. Hoping to not give up and high end HP but make it more driveable.
Race Director
Joined: Oct 2000
Posts: 15,036
Likes: 79
From: central FL, near the beach.
Gordon
Does your EFI use IR, a dual plane, or a single plane?
I can't imagine IR not liking a bigger cam.
OTOH a single plane
Does your EFI use IR, a dual plane, or a single plane?
I can't imagine IR not liking a bigger cam.
OTOH a single plane
Last edited by Matt Gruber; Nov 5, 2009 at 02:43 PM.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
The big cam at WOT is not a problem. It is cruising down the road with an OD transmission. There is so much overlap at 2000 or so rpm that the exhaust gets some raw fuel in it. This tells the O2 sensor hey we are running rich lean tha tsucker out. So I get a lean misfire at cruise rpm. WOT it just screams and has a ton of power. I'm hoping for a little more midrange torque also. To fool the system I have unplugged the O2 sensor and upped the fuel pressure. The lean misfire stopped but it is running somewhat rich at lower rpms. It is a port fuel system with a single plane intake. The cam I got is a 242/248 @ .050 so it is no slouch in the duration either.
Race Director
Joined: Oct 2000
Posts: 15,036
Likes: 79
From: central FL, near the beach.
Gordon
if it was my car, i'd make it into a dual plane EFI, fully separated. (if i couldn't afford 8 runners).
TRUE Dual plane makes a world of difference. My powerband went from 2400 and up, down all the way to 1000
when i fully separated my dual plane. EFI should have a similar improvement.(i'm no expert on EFI, but i can't imagine why u'd want a single plane)
if it was my car, i'd make it into a dual plane EFI, fully separated. (if i couldn't afford 8 runners).
TRUE Dual plane makes a world of difference. My powerband went from 2400 and up, down all the way to 1000
when i fully separated my dual plane. EFI should have a similar improvement.(i'm no expert on EFI, but i can't imagine why u'd want a single plane)
Thread Starter
Burning Brakes
Joined: Jul 2004
Posts: 1,133
Likes: 2
From: GEAUX TIGERS PSL FL.
So if I understand this... a cam made for a EFI system will probably work fine in a carbed engine but a cam made for a carbed engine may not run well in a EFI engine. This could also account for my engine running really lean.
Last edited by RushThruLife; Nov 5, 2009 at 04:01 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Burning Brakes
Joined: Jul 2004
Posts: 1,133
Likes: 2
From: GEAUX TIGERS PSL FL.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
That is a very mild cam and should work pretty well in a carb or EFI situation. There is going to be very little overlap with that cam.
If you are running a carb with that cam it should provide good low end to mid range torque.
If you are running a carb with that cam it should provide good low end to mid range torque.
Race Director
Joined: Oct 2000
Posts: 15,036
Likes: 79
From: central FL, near the beach.
Gordon
u need a Hillborn EFI. Have u researched individual runner EFI? They cost a lot.
Me,being cheap, I would buy the very best dual plane, and get most of the benefits of the Hillborn at a fraction of the $$$$, by converting it to EFI.
Single plane sucks on the street w/big cams and OD, 9 times out of 10. EFI or carb is going to suck at low revs. Overlap is to blame w/big cams. Hillborne or a dual plane can cure that. Dual plane is the best value. I don't even know if they sell it, so if they don't i'd make it.
u need a Hillborn EFI. Have u researched individual runner EFI? They cost a lot.
Me,being cheap, I would buy the very best dual plane, and get most of the benefits of the Hillborn at a fraction of the $$$$, by converting it to EFI.
Single plane sucks on the street w/big cams and OD, 9 times out of 10. EFI or carb is going to suck at low revs. Overlap is to blame w/big cams. Hillborne or a dual plane can cure that. Dual plane is the best value. I don't even know if they sell it, so if they don't i'd make it.
Thread Starter
Burning Brakes
Joined: Jul 2004
Posts: 1,133
Likes: 2
From: GEAUX TIGERS PSL FL.
Thanks Gordonm. Before I removed the EFI, it provided a nice little lobe at idle. Now to put the right carb back on it.
Melting Slicks
Joined: Mar 2004
Posts: 2,141
Likes: 2
From: Pittsburgh Pa
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Not saying anything defines a carb cam. Just saying most fuel injection runs better with a wider LSA than a tight one. There are way to many variables in any engine to say which cam is best for any given application.
Thread Starter
Burning Brakes
Joined: Jul 2004
Posts: 1,133
Likes: 2
From: GEAUX TIGERS PSL FL.
The reason I asked the question was because I called Comp cams for some specs on my cam. I need to order my dist (Davis Unified) and they require that info to provide me with the best one suited to my engine needs. Comp Cams has 2 xe 262cams. one for a carb and one for EFI.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
The reason I asked the question was because I called Comp cams for some specs on my cam. I need to order my dist (Davis Unified) and they require that info to provide me with the best one suited to my engine needs. Comp Cams has 2 xe 262cams. one for a carb and one for EFI.
Once again I will bring up LSA on the cam. The standard one is ground on a 110 LSA the computer controlled or the one for fuel injection is ground on a 114 LSA. The duration and lift are almost identical. The wider LSA is more computer and fuel injection friendly. Most of the mild FI cams you are talking about can be used with a stock computer system.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
You should be able to use the cams interchangeably, GM has been doing it for years....its that FI`s distribute the fuel better...and actually more economical until you start building a more radical all out racing engine....
