Life after Holley Sniper - back to Carb

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jakuzzie

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After a couple of years with the Holley Sniper EFI and it’s problems I now decided to go back to carb.
I need some suggestions, so I buy one I can work with.
I tried Edelbrock 1405 and 1406 before the Sniper, was never happy with.

318 with 904.
Edelbrock RPM Airgap intake
Edelbrock RPM Aluminium heads
Zero deck (10.5:1)
I beam rods + KB Pistons
Lunati Cam 10200702

Thanks!
 
Welcome back.
Carburetors have worked for over 120 years but some people think the wheel needed to be reinvented.
It didn't.
Carburetors can be tuned to run great and make plenty of power.
OEM fuel injection is great but they had millions of dollars to work out the problems.
Small companies didn't have that much money so you're going to be the one that deals with the problems. Many times, they have helpful people you can call but you're still more likely to be towed back home from a problem with aftermarket EFI than you are from a car with a carburetor.
I've spoken with numerous guys that had electronic control unit failures, fuel pumps conking out, other things too.
I don't recall the last time I had a problem with my carburetors that I couldn't fix with a basic rebuild.
 
Totally. Fell for their lies. Nothing on this thing is self adjusting. If you want to do it right you need a dyno and an online course.

The in-tank fuel pump (walbro) was louder than the exhaust.
Pressure regulator failed after a week.
IAC Valve turned it self out a couple of times and left me with idle at 1500.

What a waste of time and money..
 
The Edelbrock AVS2 1906 (650 CFM) would do well for you. With its annular boosters you'll get superior throttle response. I too, like you, tried the earlier model without success. If you go with a 1906 I encourage you to also get the tuning kit so you can zero in on just what the engine wants.
 
The Edelbrock AVS2 1906 (650 CFM) would do well for you. With its annular boosters you'll get superior throttle response. I too, like you, tried the earlier model without success. If you go with a 1906 I encourage you to also get the tuning kit so you can zero in on just what the engine wants.
The AVS2 is my favorite so far.
There is no other carb which gets more recommended for Mopar SB with atm.
 
Send that information to AED carbs they will get you setup just need to remember they are little slow on response but they will get back with you and you will be happy with there carbs.
Tom
 
I too converted back after 2 years of FI Tech. Always running rich and always lots of noise but not power to back it up like what you get with. 4 bbl secondary opening. I loved the concept but the factory spends millions of dollars to developing a system to fit their engine or design an engine to fit their fuel injection. It’s not the “bolt on” that they sell. But it is a great idea for issues with this new fuel. Sealed systems eliminates the vapor lock, ethanol evaporation and water by products. I bought a street avenger carb for my small block and with some tuning am very happy with the results. I may try the new AVS with annular boosters, as many seem to love these carbs. Still getting over the cost of the swap back first. lol.
 
I’m sure an Ede avs650 is a suitable choice, but I prefer Holley style carbs myself.

I’d probably lean towards something like a QFT Slayer 600vs.

When the retrofit EFI systems work as advertised they’re great.
When they don’t………it’s not fun.

A local shop does a fair number of installs, and has had several that have been problematic.
One of the more recent problem child’s had an issue where it would randomly just lose its tune.
Poof! Gone.

That’s fun.
 
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IMO, one of the best for out of the box performance is the Holley Street Demon. The 625 would be right on the money.
 
I went with a street demon and i am very happy so far... best deal was from speedway motors was like 500 with a air cleaner..
 
Great carb idea, unfortunately they are a pia to disassemble.
I've never noticed that and I've had multiple ones apart many times. My first one was one I got CHEAP off ebay, because it needed repair. That's when I found out the Thermoquad air door spring works perfect on them. It was a 625. I just put a 750 on my Ford truck and I think all the tuning it's gonna need is adjusting the accelerator pump and air screws. I don't see how they're a pain to disassemble at all. Just like a Thermoquad. You sure we're talkin about the same carburetor?
 
After a couple of years with the Holley Sniper EFI and it’s problems I now decided to go back to carb.
I need some suggestions, so I buy one I can work with.
I tried Edelbrock 1405 and 1406 before the Sniper, was never happy with.

318 with 904.
Edelbrock RPM Airgap intake
Edelbrock RPM Aluminium heads
Zero deck (10.5:1)
I beam rods + KB Pistons
Lunati Cam 10200702

Thanks!
PM me for my buddy's contact info. He will build you a custom carb that will change your entire view of how to fuel an engine. J.Rob
 
suggestions
Bosch K-Jetronic mechanical fuel injection just to be different, lol. (It's also my favorite fuel injection system.)

I hear many good things about the Edelbrock AVS2 carbs, plus they are in stock at many autoparts stores so you could be up and running in a day.
 
Edelbrock and Holley make solid products. I tend to lean more on Edelbrock for street, and Holley for performance builds. It might be old school thinking? But also go with what you know.

The old saying about FI. "Had fuel injection been invented first. And someone introduced the carburetor? They would have been hailed as a genius!"
 
Lunati Cam 10200702
262/268/114 cam, 220/226@050
That looks like a sweet combo, I bet it could make some really great mpgs. I think a spreadbore around 650 would be real snappy, or a Thermoquad.
But
I have a 750 DP that I install on everything, lol
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But I'll tell ya, I'd throw that cam away simply for it's 114 Lsa..
Same cam on a 108 Lsa would get you an extra 12* of overlap and an extra 12 * of Compression plus power, which you can split to say 127* compression, leaving 112* for power. And that 127* could bump your Dcr up to 9.0 where it needs to be with alloy heads.
And the 112*power would have the potential to better your mpgs

I know; it's in there now;
just know that it's costing you
up to ~16psi and
up to ~16% low-rpm torque, compared to same cam on a 108Lsa in at 102.
and 12* of overlap is nearly two cam sizes worth, so power over the nose is down as well. unless you have log manifolds.........
I just hate to see your 10.5Scr to not live up to it's potential.
Jus saying.
 
650 AVS 2 would probably be damn near PNP out of the box, that and the ease of tuning would get my vote.

going the other direction, the tried and true 1850/3310 wonder twins would be a solid choice as well. or you could keep it in the holly family with one of their new lines like the brawler, demon, donnybrook or fracas-- all of which have endless tuning capabilities.

you don't need anything more than a 750 to make that thing sing.
 
What?
Pretty simple if you know how to use a Phillips screwdriver.
From what I understand, screws from the bottom up as in you have to drain and remove the carb to take it apart unlike a TQ which unscrews from the top, easy to adjust or unstick the floats.
 
What was the problem with the Edel 1405/6 carbs?
Got them tuned right, but in winter when I put it in drive both died immediately. I guess it was my fault.
Then I made the decision to sniper swap.. Also my fault I guess…
 
262/268/114 cam, 220/226@050
That looks like a sweet combo, I bet it could make some really great mpgs. I think a spreadbore around 650 would be real snappy, or a Thermoquad.
But
I have a 750 DP that I install on everything, lol
--------------------------------------

But I'll tell ya, I'd throw that cam away simply for it's 114 Lsa..
Same cam on a 108 Lsa would get you an extra 12* of overlap and an extra 12 * of Compression plus power, which you can split to say 127* compression, leaving 112* for power. And that 127* could bump your Dcr up to 9.0 where it needs to be with alloy heads.
And the 112*power would have the potential to better your mpgs

I know; it's in there now;
just know that it's costing you
up to ~16psi and
up to ~16% low-rpm torque, compared to same cam on a 108Lsa in at 102.
and 12* of overlap is nearly two cam sizes worth, so power over the nose is down as well. unless you have log manifolds.........
I just hate to see your 10.5Scr to not live up to it's potential.
Jus saying.
I know. Wanted to be sure to have a smooth idle back then before tuning. Didn’t change the cam since.

What specific cam would you recommend?
I guess I have to take a closer look to the engine anyway, because I still have some bad vibrations going faster then 60.
 
I know. Wanted to be sure to have a smooth idle back then before tuning. Didn’t change the cam since.

What specific cam would you recommend?
I guess I have to take a closer look to the engine anyway, because I still have some bad vibrations going faster then 60.
when I put it in drive both died immediately
As to the carb(s)
I can almost guarantee you that your throttles were too far closed, and the transfer-slots had gone to sleep. This almost always happens when guys try to run too much Idle-Timing.
The cure is embarrassingly simple; just increase the curb idle screw adjustment to open the transfers, set the idle-speed with less timing, then reset the mixture-screws as may be required..
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As to what cam to choose,
well they tell me I'm lousy at that game, so, keep this in mind while I rant.
Here are some things that will help you get started down this road.

1) Budget

2) Application; what do you expect out of this combo?
a) low-speed torque
b) hi-speed Power
c) midrange pull
d) fuel economy
e) long cam-life

3) the Chassis
a) the transmission
b) the stall
c) the rear gear ratio
d) overdrive
e) power to weight ratio

Because you already have a generous compression ratio, alloy heads, and an AG intake, you are way ahead of the game, and cam selection will make or break the smile factor.
Your cam selection will depend on how you answer the big three questions above.

If yur anything at all like me, you want everything! and that's gonna require;
1) a generous budget
2) an overdrive;
3) a race-type rear gear, cuz that will keep your small engine on the pipe
4) a modest but generous stall, to get you launched
5)
as for #1;
cuz there's no sense dreaming if yur broke; save up
As for #2,3,and 4;
the OD is not just for hiway economy, but more; so that you can run appropriate street gears for the modest sized engine.
For a small-engine-streeter, having the right gear at the right time is probably more important than anything. This allows you to choose alternates among the other parameters. For instance; if you can use 4-series gears, you won't need a big stall.
But this goes back to budget. If you need or want to hit the hiway for lotsa miles, but you cannot afford an overdrive, then you have to sacrifice something else, be it gears or stall or both.
I'll tell ya, installing an overdrive is the best move I ever made on my combo. I saved up 4 years to get it, and during that time, there was a lot of stinking parts swapping going on.

So then, say you have no budget for an overdrive, nor for a higher than current factory stall, and are stuck with say 3.23 gears. This is gonna require a hi-torque cam to get off the line, and when she gets into Second, she'll be done early.
But if you can at least afford a higher stall convertor, say going from 2000 to 2400, now you can up-cam maybe two sizes. This will push your powerpeak up a similar 400rpm, which causes a power increase at the top.
But, with 3.23s, now you find out the the powerpeak is at 75 mph, where you almost never drive or don't want to drive. So now you need say at least 3.91s, to bring the powerpeak into a more useable mph range. And thus your long-distance hiway cruising rpm becomes, lets say, "harsh".

So, as you can see, cam selection, with existing chassis limitations, becomes very important.
Now
lets talk about your already existing engine;
With a tight quench design this alloy-headed dream-318 can run 190 psi still on 87E10. As compared to 155psi with iron open chamber heads, the entire low-rpm torque is increased, which is like bolting on a turbo; and this amount of pressure makes a stunning streeter. And it doesn't stop there, that increased torque translates directly to top end power. If you keep the pressure up in that 190 plus range, you can run nearly any modest rear gears, and your engine will feel much bigger than it actually is.

The sad news is that in a given engine, cam selection, pressure, and operating elevation, go hand-in-hand; the later the Intake valve closes, the lower the pressure will be. and the same at higher elevation. So then, to keep the pressure up, with each bigger cam, the Static compression Ratio has to keep up.
Now, in post #1, you say the Scr is 10.5. to be sure, this is a very good number. To achieve that in a 3.94 bore, requires a TOTAL combustion chamber size of 69.6cc. That's pretty small. and that's gonna be hard to get down to with 63cc heads. So I'm assuming your builder actually knew what he was doing, and that 10.5 is real and True. If it is, then any cam with an Ica of 54* is gonna hit the 190 psi mark....... at sealevel.
In Austria, at 3000 ft, the pressure is predicted to drop to 173psi........ So you see where I am going right?
Now, a cam with an Ica of 54* is generally considered a pretty small street cam, like about a stock 360 2bbl cam. Your Lunati at 262/268/114 cam, 220/226@050, in at 110 has an Ica of 61*, which, at 3000 ft is predicted to make just 163 psi. The Scr would have to be pumped up to 11.8, to get to 190 psi.
Here's the part where I tell you to go do a compression test, to see where you currently stand; as others have already suggested. Here's the deal, at 163 psi you could have just run iron heads at 10.5Scr and made more power on them with the same cam. How is that possible? Because the alloy heads suck so much heat out of the chambers that at your power level, you need about an extra point of compression, just to break even.
So, Like I think I said in a previous post, I would throw that heat-sucking, pressure bleeding, power not making 114LSA cam away........ lol.
Of course you see what I did there right?
I assumed that you have a true 10.5 engine and
I assumed the cam was in at 4* advanced, and
I assumed that Jakuzzie lives in Austria, and
that Wiki is correct when it says the average elevation in Austria is about 3000 ft.
if you're at Neusieidler Lake, elevation 377ft, that's gonna be a different calculation.

Ok now lets talk a lil bit about cams. I have a rudimentary understanding of cams, and experience with only a few of them , so here's what I have found;
1) for gas mileage
you need about 108 or more degrees of Power Extraction, the more the better. Going down to 100 degrees the cam will suck dry every gas pump in your neighborhood. By 112*, it is steeling degrees from somewhere else. Is that bad? Not every time.
2) as for compression, you need about 120*s. This will vary with the desired cylinder pressure
3) as for over the nose power, you need a bunch of overlap, 60* is good, 66 is better 72 or more is getting to the limit of streetability. A reasonable compromise would be 62*.
4) ok lets add up what we got so far. This is an exercise.
120+108+say 62=290. We only have two full revolutions plus the overlap in the which we can make this work, so, in this case; 720+62=782 degrees. Subtracting the 290 leaves 492 for intake plus exhaust. Now adding back the overlap of 62= 554 total, and dividing by 2=277 degrees to be allocated to each of intake and exhaust durations.
However, for flexibility in setting the installed center line, and maintaining a decent overlap, I'm gonna give 4* from the intake, to the exhaust, making it 273 intake/281 to the exhaust. Next I'm gonna take these numbers and calculate the Lsa, like this
(intake plus exhaust) less overlap, divided by two, and I get 107.5.
Next, I'm gonna gather up all those numbers and get;
273 intake/120 comp/108 Power/281 exhaust/on a 107.5/ in at 103.5
Next I'm gonna see what might be commonly available. And I see;
272/280/108 which, installed at 104, at 3000 ft is predicted to make just 163 psi
272 intake/120 comp/108 Power/280 exhaust/on a 108/ installed at 104.
Compare that to your Lunati cam
262 intake/119 comp/108 power/268 exhaust/on a 114/installed at 110
Easy peasy. Is this (the one in Blue) the cam you should get?
Answer ; NO!,
the Ica is too late! with only 120 degrees of compression, the cylinder pressure is predicted to be just 164@[email protected] Scr. This would be fine for an iron-headed 318, great actually, but with alloy heads, it will be down on power/torque, as compared to what it could be, cuz the alloys with a tight Q can easily support 190 psi, which I previously mentioned, would take an Ica of 54 degrees@3000ft.
So I gotta stop talking here, cuz all this talk is based on assumptions of elevation and true Scrs, and the total lack of hard data, lol. At this point, it is all just parlor talk, designed to get you thinking.
Happy HotRodding
 
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