454 efi

[brooks7810]

I have a 75 454 that I am looking to upgrade, planning on doing a Holley sniper efi, but would like to upgrade the intake and cam, I want a cam that has a real rough idle, I was looking at the comp cams big mutha thumpr, but don’t know how good that would be on a stock 454, any recommendations on a nice cam and intake to go with basically stock 454 with efi?

 

[Doppleganger]

After reading the reviews on the Holly EFI, I passed and bought the Edelbrock ProFlo4 instead. I called Edelbrock and they gave me a shopping list of everything that would match up. I chose the whole route....EFI, heads and cam. The one tech there has a speed shop in Cali - said he's built so many motors he can almost tell you the HP numbers you'll run depending on the combo of parts.

 

[QBuff02]

asking that question will get you a mixed bag of results. half will say Sniper EFI is the cats ass and half will say it's absolute garbage. I'm still researching what EFI route I want to go for mine, but depending on your needs/wants you still can't beat a big block sucking cool night air through a big cfm 4 barrel. Lol Any good dual plane intake would work, I have a Performer RPM on mine with good results. As far as the cam goes. I would absolutely steer you away from the "big mutha thumpa" because they are literally all smoke and no show. You'd be better suited to something along the lines of a comp cams XE series cam. Or a Lunati voodoo series cam. The problem with the big mutha is it's basically a cam designed to make noise, so short of it is they have lots of overlap built in to give it the sound everyone wants at idle without much regard to actual performance. I've seen two guys with edelbrock carbs and those cams literally have them be almost untunable because the intake signal is so wild. So that should play into your choice regarding your fuel delivery avenue. There's way better cams on the market. As far as selection, a couple of things to think about. You've got a 3/4 ton with a low compression-ish 454 so you don't want to get too wild on cams because although a big cam sounds cool the engine will be a turd. Look for ones that don't call out for grossly higher compression and big stall converters. You can get on the edgy side of things, have a decent lope, rumpety rump, and useable power if you keep your duration on the cam somewhere in the neighborhood of .220-.230 lift @ .050. Might have to bump your torque converter up to around 2,000ish+ once you start nearing that .225-.230 @.050 mark though. But there are a lot of cams in that range that will give you the sound you want and have a good useable power band and not feel like a slug.

 

[Dooley]

Things have changed sooo much from my younger days.
Back in the days a quick short answer for a BB cam warmup would just install the cam for a 390 hp 427.
Used to keep them in stock at local Chevy dealerships.
Especially worked wonders for the milder 396's and later 454's.

 

[Rick Dobbins]

On my 454 I stuck with the Q-Jet. I was going to go Sniper, but I've got dual tanks, so the fuel return/hi pressure fuel pump etc. was just too much work and cost. The stock Q-Jet is 700CFM yet those small primaries will give you great fuel mileage. Dyno tests on race engines (all WOT stuff) have shown a big carb will make MORE HP than FI. Now, you and I aren't driving a race car, but you get the idea. There are a ton of carb shops and online sources (plus new ones) to buy so you'll get a great carb.

Linkage is different too. So is the vacuum booster fitting. But to me, Sniper/Hi-Pressure Fuel Pump is one more electronic thing that can fail. I've never had (in 50 years of driving) a carb put me on the side of the road.

 

[Frankenchevy]

Cams with lots of overlap are harder for self learning efi systems to build a base fuel table. So if you want that lumpy cam, heads up you’ll have to learn a bit more about the tuning process.

I’m happy with my sniper/ecu controlled timing. If you follow the Holley forums, almost every problem with their efi systems is installation and or tuning error. Wiring has to be on point and it’s not as simple as slapping it on there, even if they try to make it seem that way. You need to learn the software to fine tune the system.

Plan on spending a couple grand. You’ll want to do the full ignition control, 8.5mm super conductor wires, new plugs, etc.

With the amount of time I spend above 10,000’, sea level and everything in between; EFI was a no brainer.

If maintaining that gen 1 carbureted look isn’t important to you, a good mpfi system is probably better in a lot of aspects. Whether it be aftermarket or going LS...

 

[omillan99]

If I'm not mistaken when you go EFI, the self learning acts to reduce the lope of the cam and reduces the noise? I remember reading it in a magazine but can't recall which. I may be wrong however.

 

[Frankenchevy]

Not that I’m aware of. Fuel down the intake is fuel down the intake. Different 4150 based EFIs introduce fuel in various ways which may change the intake sound. Some have injector pods hanging out into the bores. The sniper has nothing hanging out there.

 

[Matt69olds]

On my 454 I stuck with the Q-Jet. I was going to go Sniper, but I've got dual tanks, so the fuel return/hi pressure fuel pump etc. was just too much work and cost. The stock Q-Jet is 700CFM yet those small primaries will give you great fuel mileage. Dyno tests on race engines (all WOT stuff) have shown a big carb will make MORE HP than FI. Now, you and I aren't driving a race car, but you get the idea. There are a ton of carb shops and online sources (plus new ones) to buy so you'll get a great carb.

Linkage is different too. So is the vacuum booster fitting. But to me, Sniper/Hi-Pressure Fuel Pump is one more electronic thing that can fail. I've never had (in 50 years of driving) a carb put me on the side of the road.

All Q-Jets are capable of 800plus cfm, the factory would restrict the airflow for the smaller engines by using a small limiting tab on the secondary air door. Not that this has anything to do with your question, just sharing useless info!

 

[Rusty Nail]

Y u no consider a TBI swap and use only GM off the shelf parts?
That's the smart route, at least to get it goin.

In addition a hella lumpy camshaft will screw up a great many variables which all cost money to fix. Coupled with aftermarket EFI?
Hope this ain't your daily LOL. What could possibly go wrong?

You have another ride, right? Haha

TBI conversion WOULD be a fantastic upgrade and could be done for SUPER CHEAP, just sayin.

 

[omillan99]

Not that I’m aware of. Fuel down the intake is fuel down the intake. Different 4150 based EFIs introduce fuel in various ways which may change the intake sound. Some have injector pods hanging out into the bores. The sniper has nothing hanging out there.

https://www.onallcylinders.com/2015...fi-affects-cam-idle-hint-you-may-not-like-it/

This was what I was talking about it has to do more with the sensors.

TL;DR The vacuum signal gets dampened to look like a smooth line than a jagged one, carbs "see" jagged thus idle is instable, computer sees smooth and keeps idle stable. Lots more in play but this is a very very simplistic overview. Its a good read.

 

[4WDKC]

You want a single plane for efi. A dual plane will play hell with the fuel distribution and tuning. Call a cam manufacturer and get a recommended cam.

 

[Frankenchevy]

Tons of guys running dual planes with Sniper efi, myself included. I did think about single plane, but Holley suggested dual plane for lower range power.

https://forums.holley.com/showthread.php?21250-Single-plane-or-dual-plane-intake