Aluminum intake problems

[josehf34]

My '74 Fury came with a factory 2 BBL 360 V8, a long time ago I decided to change the intake for an aluminum dual plane raised deck 4 BBL, I don't remember which brand but isn't an edelbrock for sure. Since then my car has a very serious erratic idle and erratic vacuum signal and I can really notice that sometimes the engine is misfiring (all symptoms are only while idling) but after 15 or 20 minutes of driving just when the engine is really hot the erratic idle and vacuum goes away and the light throttle response improves a lot!. I'm sure isn't a carb problem because right now I'm running a brand new street demon and before it I was using a carter AFB but the problem was the same , timing and advance are ok and ignition system is working well

I read somewhere that some intakes has fuel distribution problems and is something that you only can fix it replacing the intake with another one. Does somebody has previous experience with that kind of problem?

 

[traintech55]

Cars with carburetors need the heat riser passage open if you are going to use it on the street. Did you block off your heat riser passage when you replaced the intake? This was a common problem on high mileage small block Chrysler engines, (I repaired many of them by cleaning out the intake and heads). You need to heat the intake to help atomize the fuel.

 

[josehf34]

Cars with carburetors need the heat riser passage open if you are going to use it on the street. Did you block off your heat riser passage when you replaced the intake? This was a common problem on high mileage small block Chrysler engines, (I repaired many of them by cleaning out the intake and heads). You need to heat the intake to help atomize the fuel.

When my car had the stock exhaust system never noticed the heat riser block and my new dual muffler setup doesn't have them. Does chrysler cars have the heat riser on the exhaust or is located in other part?

I still have the stock iron intake sitting in the garage

 

[saylor]

not to argue with traintech - he is waaay more mechanic than me - but to throw out something to think about:
if it gets better when the engine warms up, I say its a leak. my example is I had a header exhaust leak - that would go away once the car was up to temp.

im thinking of stuff like block the air cleaner intake, and see if you can hear it sucking in air from elsewhere, or the spray chemtool test see if your motor revs change, etc.

I have no comment on the whole heat crossover/riser thing. I have mine blocked off with the felpro valley pan that has no cutouts for heat xover. I changed pans from one that WAS open xovers, but I was fighting a heat boiling gas issue...

try not to die -

- saylor

 

[josehf34]

not to argue with traintech - he is waaay more mechanic than me - but to throw out something to think about:
if it gets better when the engine warms up, I say its a leak. my example is I had a header exhaust leak - that would go away once the car was up to temp.

im thinking of stuff like block the air cleaner intake, and see if you can hear it sucking in air from elsewhere, or the spray chemtool test see if your motor revs change, etc.

I have no comment on the whole heat crossover/riser thing. I have mine blocked off with the felpro valley pan that has no cutouts for heat xover. I changed pans from one that WAS open xovers, but I was fighting a heat boiling gas issue...

try not to die -

- saylor

A leak like a vacuum leak? Because I've tested with carb cleaner and with cigarrette smoke but didn't found any leak, maybe is time to test again. If could be other kind of leak I'm sure I've a leak in the exhaust somewhere but I haven't paid attention to it, I don't know how can a exhaust leak can affect my idle quality

I was a bit lost with the heat rise passage, I though traintech was talking about the heat block in the exhaust that some cars specially GM cars have, my new intake doesn't have the rise passage but I'm using gaskets that doesn't block the passage in the heads

How much time this engine can take to get into operative temp? I'm running a 180 º thermostat and I thought one of these engines can get into operative temp in 5 to 10 minutes but I feel like my car is taking too long to get to that point

 

[max1196]

Did you use the cork front and rear intake end gaskets? With some aluminum intakes, these cork gaskets can be too thick and make it difficult to get a good seal on the cylinder head to manifold surface, use a thick bead of silicone instead. Also the dowels some times has to be removed from the "china wall" because the aluminum intake may not have a provision for them.

 

[traintech55]

not to argue with traintech - he is waaay more mechanic than me - but to throw out something to think about:
if it gets better when the engine warms up, I say its a leak. my example is I had a header exhaust leak - that would go away once the car was up to temp.

im thinking of stuff like block the air cleaner intake, and see if you can hear it sucking in air from elsewhere, or the spray chemtool test see if your motor revs change, etc.

I have no comment on the whole heat crossover/riser thing. I have mine blocked off with the felpro valley pan that has no cutouts for heat xover. I changed pans from one that WAS open xovers, but I was fighting a heat boiling gas issue...

try not to die -

- saylor

Saylor, thank you for the compliment. This problem seems to only happen to the small block series of engines. I have never seen it on a big block Chrysler, or any engine from G.M. or Ford.

 

[saylor]

I was only using the exhaust leak I had as an example to illustrate that metals heat up and seal up , , not meaning an exhaust leak is what is causing your issue. sorry for the confusion.

metals can grow and warp (warp is a strong word here) but change shape a thousandth or two when heated. or shrink when frozen. etc.

when I had the leak issue, my exhaust leak would be noticeable at cold start but would go away once the pipes were hot.

to what max is saying - the alum intake weighs a lot less than the iron stock piece. and you cant tighten down on alum very much - IIRC 25ft.lb. or so.. so the theory is you need gaskets to help. or the gasket can be like .010+ too thick and your intake is sort of sitting 'on top' and not 'in' so it never sat down and sealed up well. so he says use sillycone. I believe I used both pooky + gaskets.

to further that thought, you could find that simply removing the intake, cleaning the surfaces, good gaskets and silicone, putting it all back on nice and clean, and you will be in business.

but its hard to say that based off what we know right now. if all the other stuff can be eliminated as you suggest - carb good, timing good, spark good, etc, etc, - its almost got to be an air leak.

try not to die -

- saylor

 

[traintech55]

A leak like a vacuum leak? Because I've tested with carb cleaner and with cigarrette smoke but didn't found any leak, maybe is time to test again. If could be other kind of leak I'm sure I've a leak in the exhaust somewhere but I haven't paid attention to it, I don't know how can a exhaust leak can affect my idle quality

I was a bit lost with the heat rise passage, I though traintech was talking about the heat block in the exhaust that some cars specially GM cars have, my new intake doesn't have the rise passage but I'm using gaskets that doesn't block the passage in the heads

How much time this engine can take to get into operative temp? I'm running a 180 º thermostat and I thought one of these engines can get into operative temp in 5 to 10 minutes but I feel like my car is taking too long to get to that point

Joseph, Again this problem only seems to happen to small block Chrysler engines. The heat riser passage in the intake manifold helps atomize the fuel mixture into the cylinders. It does not matter about headers but the intake should be hot. The fact that your car takes so long to come up to operating temp is another sign. I would change to the Edelbrock performer manifold with the heat riser passage. I hope this explains the problem, if not send me a PM and I will give you my phone number.

 

[josehf34]

Did you use the cork front and rear intake end gaskets? With some aluminum intakes, these cork gaskets can be too thick and make it difficult to get a good seal on the cylinder head to manifold surface, use a thick bead of silicone instead. Also the dowels some times has to be removed from the "china wall" because the aluminum intake may not have a provision for them.

No, I'm not using them because is a really nightmare have the intake installed with those gaskets in place so I'm using RTV

I was only using the exhaust leak I had as an example to illustrate that metals heat up and seal up , , not meaning an exhaust leak is what is causing your issue. sorry for the confusion.

metals can grow and warp (warp is a strong word here) but change shape a thousandth or two when heated. or shrink when frozen. etc.

when I had the leak issue, my exhaust leak would be noticeable at cold start but would go away once the pipes were hot.

to what max is saying - the alum intake weighs a lot less than the iron stock piece. and you cant tighten down on alum very much - IIRC 25ft.lb. or so.. so the theory is you need gaskets to help. or the gasket can be like .010+ too thick and your intake is sort of sitting 'on top' and not 'in' so it never sat down and sealed up well. so he says use sillycone. I believe I used both pooky + gaskets.

to further that thought, you could find that simply removing the intake, cleaning the surfaces, good gaskets and silicone, putting it all back on nice and clean, and you will be in business.

but its hard to say that based off what we know right now. if all the other stuff can be eliminated as you suggest - carb good, timing good, spark good, etc, etc, - its almost got to be an air leak.

try not to die -

- saylor

I think would be better to check for leaks tomorrow and torque again the intake, when Installed the intake used 40 ft.lb but maybe is time to check again

Joseph, Again this problem only seems to happen to small block Chrysler engines. The heat riser passage in the intake manifold helps atomize the fuel mixture into the cylinders. It does not matter about headers but the intake should be hot. The fact that your car takes so long to come up to operating temp is another sign. I would change to the Edelbrock performer manifold with the heat riser passage. I hope this explains the problem, if not send me a PM and I will give you my phone number.

I'm considering too the option of changing the intake again, does all edelbrock performer intakes has the heat riser passage or just some of them ?

 

[traintech55]

No, I'm not using them because is a really nightmare have the intake installed with those gaskets in place so I'm using RTV



I think would be better to check for leaks tomorrow and torque again the intake, when Installed the intake used 40 ft.lb but maybe is time to check again



I'm considering too the option of changing the intake again, does all edelbrock performer intakes has the heat riser passage or just some of them ?

Every Performer manifold I have seen has one. The Torkers do not. Look for a smaller rectangular passage in the middle of the manifold on each side. If it is there it has it.

 

[CanCritter]

lve been finding alum casting stuff can leak/weep...had issues with a alum tranny cover and another alum mech piece...wouldn't surprise me in the least if you had some sorta vacuum leak through intake,casting issue..weeping ect
anyway l avoid alum stuff now