intake ?

[dalefan88]

does anyone know if edelbrock ever made a intake for a AMC 258 i6 / 4.2l . i have a guy saying he has one from a add i put on craigslist. i never seen a edelbrock one.

 

[fzsk4p]

does anyone know if edelbrock ever made a intake for a AMC 258 i6 / 4.2l . i have a guy saying he has one from a add i put on craigslist. i never seen a edelbrock one.

According to sir Google while using the following search terms.

edelbrock jeep AMC 258 i6 / 4.2l intake manifold

I do not see one either.

 

[dalefan88]

According to sir Google while using the following search terms.

edelbrock jeep AMC 258 i6 / 4.2l intake manifold

I do not see one either.

i did the same thing and couldnt find one. he said he will send me a pic today. when he does ill post it. i think its a v8 one and he dont know what he is talking about or its a different one and hes calling it a edelbrock.

 

[dalefan88]

i was right its a offenhauser. is this a good intake? i can get a adaptor at work to put my motorcraft carb on it. he wants $AMC 150 for it. this and the header i got should reelly wake my engine up.

 

[fzsk4p]

A buddy of mine uses that same manifold. We set it up with an Edlebrock 2 BL 470 IIRC on the CFM. On a CJ7 .

Installed an external fuel pressure regulator so it would se around 4/lbs of FP.

Leaned out the primary jetting and played with the accel. pump shot. Turned out to be a great combination. Runs great and a definite performance increase.

Offer him a 100 bucks and go from there.

If you decide to go this route I can get you the jetting specs etc. that we used.

 

[dalefan88]

A buddy of mine uses that same manifold. We set it up with an Edlebrock 2 BL 470 IIRC on the CFM. On a CJ7 .

Installed an external fuel pressure regulator so it would se around 4/lbs of FP.

Leaned out the primary jetting and played with the accel. pump shot. Turned out to be a great combination. Runs great and a definite performance increase.

Offer him a 100 bucks and go from there.

If you decide to go this route I can get you the jetting specs etc. that we used.

i was thinking of offering $100. i was looking for a clifford intake and this guy text me about this one.

 

[73jeep]

i was right its a offenhauser. is this a good intake? i can get a adaptor at work to put my motorcraft carb on it. he wants $AMC 150 for it. this and the header i got should reelly wake my engine up.

Thats a dual port or dual plane manifold. Its best to use a 4bbl carb on these manifolds.
With a 4bbl Carb, during Part throttle you are only using the primaries which is only allowing fuel and air into half of the manifold (see pic). This allows it act like a small runner manifold, allowing higher velocity air flow in the manifold which keep the fuel particles in better suspension leading to better performance. Under full throttle the secondaries open allowing fuel and air in the other half of the manifold at high velocity.
Running a 2 bbl carb on that will feed both sides the same effectively making the manifold similar the stock single plane. With the low velocity at part throttle and it being unheated manifold you run the risk of fuel falling out of suspension, puddling or condensing in the manifold.

 

[dalefan88]

so i might be better off getting a clifford or get this and find a 4bl. if i get a 4bl in need like what around a 390cfm?

 

[Rescue Diver]

$AMC 150 is pretty cheap for that manifold since they run about $300 new, but I can't justify installing one on a AMC 258 i6 / 4.2l unless it's got a serious cam and port work to run much higher RPMs and needs more carb than a stock AMC 258 i6 / 4.2l would use. With as little flow as a stock AMC 258 i6 / 4.2l needs, I doubt anyone can show dyno numbers that prove changing intakes really added any hp at all. A 300 CFM 2 barrel carb and intake will always produce better results than a 4 barrel on a AMC 258 i6 / 4.2l in the RPM range they're built to run. A bigger carb and intake will only rob you of your low RPM torque.

 

[dalefan88]

$AMC 150 is pretty cheap for that manifold since they run about $300 new, but I can't justify installing one on a AMC 258 i6 / 4.2l unless it's got a serious cam and port work to run much higher RPMs and needs more carb than a stock AMC 258 i6 / 4.2l would use. With as little flow as a stock AMC 258 i6 / 4.2l needs, I doubt anyone can show dyno numbers that prove changing intakes really added any hp at all. A 300 CFM 2 barrel carb and intake will always produce better results than a 4 barrel on a AMC 258 i6 / 4.2l in the RPM range they're built to run. A bigger carb and intake will only rob you of your low RPM torque.

so since my engine is stock it wont help me much? i dont want to hurt my low end since what i do with it needs it all down low. i was looking to keep my mc2100 and just put a adaptor on it. would a clifford intake be a better choice or stick with my stock intake and header.

 

[Rescue Diver]

so since my engine is stock it wont help me much? i dont want to hurt my low end since what i do with it needs it all down low. i was looking to keep my mc2100 and just put a adaptor on it. would a clifford intake be a better choice or stick with my stock intake and header.

You might look at the clifford web site and see if they have flow numbers compared to stock. I'm using a stock intake and Mr. Gasket #1937 adapter with my 4.0 head upgrade and my only real complaint is that it has a lot of extra on it. I'd be inclined to think a clifford 2 barrel would be better just because it will match the size of your venturis without an adapter. Instead of spending the money on a clifford, I will be radiusing the sharp edges of the intake that will be under the carb with the adapter plate. A little blending can do wonders. I'm sure it'll flow good enough for my motor with the stock cam at the low RPMs I want to operate in. If I ever decide I want to put a bigger cam in for more HP with the peak torque being at higher RPMs, I'll probably spend the money on a clifford, but I doubt that day will ever come.

 

[fzsk4p]

$AMC 150 is pretty cheap for that manifold since they run about $300 new, but I can't justify installing one on a AMC 258 i6 / 4.2l unless it's got a serious cam and port work to run much higher RPMs and needs more carb than a stock AMC 258 i6 / 4.2l would use. With as little flow as a stock AMC 258 i6 / 4.2l needs, I doubt anyone can show dyno numbers that prove changing intakes really added any hp at all. A 300 CFM 2 barrel carb and intake will always produce better results than a 4 barrel on a AMC 258 i6 / 4.2l in the RPM range they're built to run. A bigger carb and intake will only rob you of your low RPM torque.

Respectfully disagree based on personal experience.

Used the Edlebrock 1403. Which is a 4 barrel, square flange. Mistakenly said it was a 2 BL in an earlier reply.
Edelbrock.com - Carburetors & Accessories - Performer Series Carburetors

We saw a definite performance increase on an otherwise stock engine.

 

[Rescue Diver]

I've built a lot of small block Chevys for performance over the years and I have yet to see any noticable gain in power by changing to any intake. Where you gain horse power in a naturally aspirated engine is through higher compression, better flowing heads, and a bigger cam with more duration. The down side of all of this is every time you improve the flow through head porting, more lift and duration on your cam, and an intake with bigger runners, you give up low end torque. You might gain torque with these mods, but it won't kick in untill you're reved a lot higher. I personally like my AMC 258 i6 / 4.2l making good torque below 2000 rpms. Not to mention that raising the redline from 4000 RPMs or whatever it is stock to something higher will shorten the life of your motor.

 

[Rescue Diver]

Respectfully disagree based on personal experience.

Used the Edlebrock 1403. Which is a 4 barrel, square flange. Mistakenly said it was a 2 BL in an earlier reply.
Edelbrock.com - Carburetors & Accessories - Performer Series Carburetors

We saw a definite performance increase on an otherwise stock engine.

What carb did you replace with the 1403? Do you know if it was in perfect operating condition? If you saw better performance running a 500 CFM 4 barrel on a AMC 258 i6 / 4.2l , there must have been something seriously wrong with the old carb. I'm not doubting that it ran better, but a lot of things could have explained it running better. If you're running a AMC 258 i6 / 4.2l , you might see even more improvement by running a good 2 barrel that flows 300 CFM or slightly less. 500 CFM is too big for a stock AMC 258 i6 / 4.2l .

 

[dalefan88]

im might stick stock for now cause i want to keep my mc2100. i thought if i bought the adaptor with a better intake i would get alittle more out of my engine. dont have the money to go out and buy a 4bl.

 

[Rescue Diver]

im might stick stock for now cause i want to keep my mc2100. i thought if i bought the adaptor with a better intake i would get alittle more out of my engine. dont have the money to go out and buy a 4bl.

You wouldn't need an adapter with a new aftermarket intake, but the adapter costs $13 and a new aftermarket intake would run you around $300. If you have a dremel tool or a die grinder, you might think about blending the old intake to take the sharp edge away that will be left where the adapter meets the intake. When you look down in it with the adapter bolted to the intake, you'll see what I'm talking about. But keep in mind that the old intake would be useless if you ever wanted to go back to a stock carb, or sell it to someone who wants to run stock.

 

[dalefan88]

You wouldn't need an adapter with a new aftermarket intake, but the adapter costs $13 and a new aftermarket intake would run you around $300. If you have a dremel tool or a die grinder, you might think about blending the old intake to take the sharp edge away that will be left where the adapter meets the intake. When you look down in it with the adapter bolted to the intake, you'll see what I'm talking about. But keep in mind that the old intake would be useless if you ever wanted to go back to a stock carb, or sell it to someone who wants to run stock.

all the aftermarket intakes ive seen are 4bl and i have a 2bl so i would need to put a adaptor on the aftermarket intake.

 

[fzsk4p]

I've built a lot of small block Chevys for performance over the years and I have yet to see any noticable gain in power by changing to any intake. Where you gain horse power in a naturally aspirated engine is through higher compression, better flowing heads, and a bigger cam with more duration. The down side of all of this is every time you improve the flow through head porting, more lift and duration on your cam, and an intake with bigger runners, you give up low end torque. You might gain torque with these mods, but it won't kick in untill you're reved a lot higher. I personally like my AMC 258 i6 / 4.2l making good torque below 2000 rpms. Not to mention that raising the redline from 4000 RPMs or whatever it is stock to something higher will shorten the life of your motor.

Then an entire industry must be wrong. Including the OEM manufactures.

It is not the quantity of the intake charge, it is the quality. Sometimes increasing intake area improves the quality. A good example would be the pre 2000 4.0 intake compared to the newer design.

The 4.0 engines has a rev limit set at 5200 RPM. There are plenty of stroker engines running AMC 258 i6 / 4.2l cranks. Including ones sold by MOPAR that will validate that AMC 258 i6 / 4.2l `s will run safely to 5200. Much above 5200 then you get into harmonic vibration issues within the camshaft.

The AMC 258 i6 / 4.2l engines came in various flavors. The HP ratings ranged from 3200 to 3800 RPM. Torque ratings were in between 1800-2200 RPM. I`d find it hard to believe that you quantify a measurable difference between an engine that never ran above 4,000 to one that was revved to a higher amount.

Cams are a science of their own. You can change how an engine runs with many factors. Not just lift and duration.

Lobe center-line, cam timing events, ramp angle, pattern just to name a few of many factors. All affect how an engine will respond.

Even compression will affect how a cam responds. A cam that is designed to run in a 13:1 engine will run poorly in the same engine that has 8:1 compression.

Hanging you hat on lift and duration is short-sighting yourself. Same goes for intakes, exhausts and any other part of how an engine will breathe.

 

[Rescue Diver]

Then an entire industry must be wrong. Including the OEM manufactures.

It is not the quantity of the intake charge, it is the quality. Sometimes increasing intake area improves the quality. A good example would be the pre 2000 4.0 intake compared to the newer design.

You could use this example to compare the OEM AMC 258 i6 / 4.2l intake to the aftermarket offerings.

The 4.0 engines has a rev limit set at 5200 RPM. The AMC 258 i6 / 4.2l will safely run 5200. There are plenty of stroker engines. Including ones sold by MOPAR that will validate that fact.

The AMC 258 i6 / 4.2l engines came in various flavors. The HP ratings ranged from 3200 to 3800 RPM. Torque ratings were in between 1800-2200 RPM.

Cams are a science of their own. You can change how an engine runs with many factors. Not just lift and duratioin.

Lobe centerline, cam timing events, ramp angle, pattern just to name a few of many factors. All affect how an engine will respond.

Even compression will affect how a cam responds. A cam that is designed to run in a 13:1 engine will run poorly in the same engine that has 8:1 compression.

Hanging you hat on lift and duration is short-sighting yourself. Same goes for intakes, exhausts and any other part of how an engine will breathe.

I wasn't planning to go into all the other aspects of a cam, and for this thread, the topic is about a stock AMC 258 i6 / 4.2l with a stock cam that's not made for higher RPMs. Throwing a 500 CFM carb on a stock AMC 258 i6 / 4.2l is over kill. Sure it'll run fine on the carb's primaries, but when you put your foot on the floor, you're throwing money down the drain on gas, and bogging your engine down. That deep throaty sound coming from under the hood while acceleration stays flat is a good indicator of this. Please show me ANY industry doccuments that say to put a 500 CFM carb on a stock AMC 258 i6 / 4.2l ? I'd love to see that!

This is why the most common carb swap on stock or near stock AMC 258 i6 / 4.2l engines it the 287 CFM 1.08 venturi Motorcraft 2100, and not the 351 CFM 1.21" venturi model.

 

[Rescue Diver]

all the aftermarket intakes ive seen are 4bl and i have a 2bl so i would need to put a adaptor on the aftermarket intake.

You're right. I was picturing the Clifford intake for 1991 and newer 4.0 with FI. It looks like a 2 barrel carb intake but it isn't. So you were definitely correct when you said you would need an adapter. Clifford just sells it with their 4 barrel intake. My bad....