Intake Fitment

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carfreak6970

carfreak6970

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Hello,

So I inherited a 70 charger that I have been having some issues with and have posted about this car a couple times here on the forum. It is a 440 HP out of a 68 New yorker, with the 727 auto and an 8 ¾ rear end. I know the engine was bored, block decked, heads shaved, running XE274H-10 cam with the cast iron heads, cast iron four barrel intake, stock exhaust manifolds and a holley 750 cfm vacuum secondaries carb I got 3 years ago new.

While running the initial at 12 btdc I am only pulling 11-10 inHg at idle in gear. When I started down the path of trying to dial in the carb in This Thread I started to think something else may be causing some of my issues. It is even stated in that thread that the vacuum I am experiencing seems kind of low. I wouldnt know but I dont have much experience with non-stock engines. My issue is that cold start is beyond miserable. I set the choke (automatic) and start it and initially it starts right up fine, goes to about 1400-1600 rpms but then the engine rpms drop and it starts to smoke out the tail pipes. It will continue to stumble before it eventually dies. In order to get it past this issue you have to hold the throttle open more than the fast idle allows it to get it through this stumbling issue before the engine starts to smooth out and fast idle fine.

Now I attached a vacuum gauge to manifold vacuum during these episodes and during initial start up vacuum is as high as 15 inHg then drops to 8-5 inHg while stumbling and smoking. Once it gets past the stumbling vacuum goes back up to where it was and a little higher. Another test I ran is I increased how long the choke stays closed and stays on the fast idle cam. Once it gets past the stumbling the rpms increase to well over 2000 rpms. I verified that the fast idle cam did not move between the initial start and once it got past the stumbling.

My question is why is it doing this? I have a theory and would like your opinion on whether I am on the right path and how to check this out:

When installing the intake it was always a ***** to get all the bolt holes to line up. To the point that you can see where the bolts deformed the valley pan at the intake ports due to the bolts contacting where I believe they shouldnt be. I am only running the valley pan as a gasket because putting that other gasket material below and on the top of the valley pan just added more frustration. My theory is that when the block was decked and the heads shaved it moved that head/block mating surface lower and close together which almost moved the head to intake mating surface lower and closer together to the point that the intake isnt sitting where it should causing a vacuum leak there. I am guessing this vacuum leak is present when the engine is closed and mostly sealed up once the engine gets some heat to it. I do not know how much was shaved or decked, but I did need to get shorter pushrods. Now I tried to do the propane test (spraying propane around there to see if the rpms increased), but I did not get any increase in rpms. The plugs always looked very white and dont have a hint of tan or black on them which makes me think it is running a little lean, which would make sense if there is a vacuum leak.

Does any of this make sense? Is this something that could happen? there has to be some information out there that mentions the dimensions that the intake needs to be to fit on the engine, which would mean there would have to be something out there that says where the intake ports should be positioned on the engine in order to properly mate up with the intake. Is there a way to check that out? I guess I should mention that the engine the car was initially in was in a fire. Hot enough to melt the carb, but according the machine shop not enough to distort the engine. The machine shop did have the heads and block, but I can not say for certain if they had the intake.

Thank you for the help
 
Most machine shops have a tool to check what the angle of the intake should be cut at. You will need to get the intake fitted before you go any farther. This probably was not done before installing the intake.

Take starting fluid and give small squirts around the parting line at the intake and head. also around the base of the carb. If the engine raises in RPM's this will locate a vacuum leak if any. The better way is a smoke machine tester . If you cannot drive the car to a shop with one use the starting fluid. Be careful not to spray to much at once if there is any spark you will start a fire.
 
Your main problem is not enough timing at idle.......because of the cam. That cam will need 25-35* at idle. Easily achieved by using an adj vac unit connected to manifold vacuum. You start with this........

img287.jpg
 
^^Or even just a spray bottle and water mist will upset the idle if leaking

There are so many other things. Cam timing, distributor curve and initial timing, as well as several things to do with carb calibration.
 
Bobzilla said:
Sounds like the choke is staying closed too much once started.
Click to expand...

So the choke doesnt stay on that long. I have it sent towards the middle on the lean side of the pull off setting. I can try to see if loosening it up more would help.

wawarnick said:
Did you get the intake machined to match your decked block and shaved heads?
Click to expand...

To my knowledge, no. I dont believe the intake went to the machine shop.

Oldmanmopar said:
Most machine shops have a tool to check what the angle of the intake should be cut at. You will need to get the intake fitted before you go any farther. This probably was not done before installing the intake.

Take starting fluid and give small squirts around the parting line at the intake and head. also around the base of the carb. If the engine raises in RPM's this will locate a vacuum leak if any. The better way is a smoke machine tester . If you cannot drive the car to a shop with one use the starting fluid. Be careful not to spray to much at once if there is any spark you will start a fire.
Click to expand...

I tried something similar with MAP gas. But I guess starting fluid would probably be best. I will also give this a try.

67Dart273 said:
^^Or even just a spray bottle and water mist will upset the idle if leaking

There are so many other things. Cam timing, distributor curve and initial timing, as well as several things to do
Click to expand...
I can try with water as well.

Bewy said:
Your main problem is not enough timing at idle.......because of the cam. That cam will need 25-35* at idle. Easily achieved by using an adj vac unit connected to manifold vacuum. You start with this........

View attachment 1716321964
Click to expand...

I tried increasing the timing and the car did not like it. I would get pinging at part throttle. Anything more than 14 degrees at idle and I have to close the throttle blades so much so the screw does not touch its stop in order to keep the rpms between 500-700.



67Dart273 said:
with carb calibrat
Click to expand...
 
Pinging at part throttle means the engine needs tuning. Not a reason not to give the engine more idle timing. With more idle timing, it will run cooler, which in turn helps with pinging.
Expecting a 500 rpm idle with a 727 & XE 274 cam in a 440 is unrealistically too low. If the pri blades cannot be closed enough, I would be checking for:
- air leaks
- sec blades not fully closing
- PCV not closing off at idle due to low vac [ very likely ]

img333.jpg
 
Find an assistant to help you. On the next cold start when the engine starts acting up try moving the choke blade opening more or less to see if the pull off setting is what the engine wants. Also check the pull off to make sure it’s not leaking. And or if the choke is opening too fast or slow.
All your factory settings may need to be changed due to the non factory cam. Such as idle speed, choke and timing.
Even if the manifold doesn't line up perfectly it could still be sealed up but you should verify to make sure it isn't leaking.
Chokes can be a real pain to get perfect. Especially all electric chokes. Sometimes you have to compromise. Good luck.
 
You are all over the map, and I’m not even sure what you want to fix.

That cam, in gear, will probably idle at 11 - 12 in.hg.

If you have cold start running issues, it’s in the choke system and adjustments.

If it does not come off the fast idle setting, the rpm’s will continue to go up as it warms up

Spraying stuff around the intake is not a great way to determine if you have a vacuum leak.

Vacuum readings during cold start up will not provide any meaningful info.

Maybe share what color the smoke is. November in Pittsburgh, all cars smoke when they start.

If your plugs are reasonably clean, your problem is likely not that bad.

After it’s all warmed up, is the 10-11”hg your only issue? Add initial timing.
 
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BSB67 said:
You are all over the map, and I’m not even sure what you want to fix.

That cam, in gear, will probably idle at 11 - 12 in.hg.

If you have cold start running issues, it’s in the choke system and adjustments.

If it does not come off the fast idle setting, the rpm’s will continue to go up as it warms up

Spraying stuff around the intake is not a great way to determine if you have a vacuum leak.

Vacuum readings during cold start up will not provide any meaningful info.

Maybe share what color the smoke is. November in Pittsburgh, all cars smoke when they start.

If your plugs are reasonably clean, your problem is likely not that bad.

After it’s all warmed up, is the 10-11”hg your only issue? Add initial timing.
Click to expand...

So.. this car always smoked on cold start, doesn't matter on the time of year. If you back this car into the garage and cold start it the next day it will smoke out the garage and your eyes will water. Once it runs for a bit and the fast idle stabilizes it is fine.

adding any more additional timing at idle requires me to close the throttle blades to the point the idle stop screw is backed off of its stop in order to keep the rpms in the 600-700 rpm range.



But to prove it to myself, I got a smoke machine. I am in talks with a machine shop out here and he said to plug the smoke machine into the valve covers and see if I can get smoke out of the carb. Well I was able to get smoke out of the vacuum port at the back of the block and the port where the PCV is plugged into the carb.

IMG_3031.jpg


IMG_3029.jpg


According to some other people I was talking too, there should be some oil residue in the intake ports if there is a leak at the intake once the intake is removed, and there is.

IMG_3033.jpg


IMG_3034.jpg


IMG_3035.jpg


IMG_3036.jpg


Hopefully you can see it in this picture but you can see how the ports on the intake and the mounting holes in the head don't quite line up with their respective ports on the valley pan:

IMG_3037.jpg


The machine shopped mentioned the easiest way would probably be machining the intake, but I am not sure if that would be the best course of action. I am not to sure if this misalignment of the ports in the valley pan to the heads would require a thicker head gasket/spacers to raise the heads up to the proper position. This is the first time I am experiencing stuff like this, so I guess I will see what options I have.
 
carfreak6970 said:
So.. this car always smoked on cold start, doesn't matter on the time of year. If you back this car into the garage and cold start it the next day it will smoke out the garage and your eyes will water. Once it runs for a bit and the fast idle stabilizes it is fine.

adding any more additional timing at idle requires me to close the throttle blades to the point the idle stop screw is backed off of its stop in order to keep the rpms in the 600-700 rpm range.



But to prove it to myself, I got a smoke machine. I am in talks with a machine shop out here and he said to plug the smoke machine into the valve covers and see if I can get smoke out of the carb. Well I was able to get smoke out of the vacuum port at the back of the block and the port where the PCV is plugged into the carb.

View attachment 1716334124

View attachment 1716334125

According to some other people I was talking too, there should be some oil residue in the intake ports if there is a leak at the intake once the intake is removed, and there is.

View attachment 1716334123

View attachment 1716334122

View attachment 1716334121

View attachment 1716334120

Hopefully you can see it in this picture but you can see how the ports on the intake and the mounting holes in the head don't quite line up with their respective ports on the valley pan:

View attachment 1716334119

The machine shopped mentioned the easiest way would probably be machining the intake, but I am not sure if that would be the best course of action. I am not to sure if this misalignment of the ports in the valley pan to the heads would require a thicker head gasket/spacers to raise the heads up to the proper position. This is the first time I am experiencing stuff like this, so I guess I will see what options I have.
Click to expand...

If I’m following what you are saying…then you need to machine the intake.
 
That looks like silicon around the intake ports; sil should not be used in the presence of gasoline, it turns to jelly.
 
Once you get all the angle of the dangle sorted out, the only type thing you should use to seal the bathtub gasket is something like High Tack, Copper Coat or Gaskacinch. I use Copper Coat spray. A good thick coat on either side. Never had an issue.
 
what is this hooked up to on the other end?

Messages Image(2236134408).png


depending on what's going on, it may be one of your sources of trouble.
 
RustyRatRod said:
Once you get all the angle of the dangle sorted out, the only type thing you should use to seal the bathtub gasket is something like High Tack, Copper Coat or Gaskacinch. I use Copper Coat spray. A good thick coat on either side. Never had an issue.
Click to expand...
I like Hylomar blue on the tub gasket. The stuff you listed works too. I used the high tack years ago and I use the Gaskacinch when using paper gaskets. never tried the copper coat.
I think it comes with the Felpro tub now.
 
Newbomb Turk said:
If I’m following what you are saying…then you need to machine the intake.
Click to expand...

Thats where the machine shop is at as well. I just sent them additional pictures and I am seeing what they can do and how we do it.

RustyRatRod said:
Once you get all the angle of the dangle sorted out, the only type thing you should use to seal the bathtub gasket is something like High Tack, Copper Coat or Gaskacinch. I use Copper Coat spray. A good thick coat on either side. Never had an issue.
Click to expand...

thanks for the heads up. Ill keep that in mind once I get that that point!

junkyardhero said:
what is this hooked up to on the other end?

View attachment 1716334635

depending on what's going on, it may be one of your sources of trouble.
Click to expand...

That is connected to the brake booster. According to the manual for the carb I got, that is where I plug the brake booster too. I tried just plugging that port before in my earlier diagnostics with no change to my situation.
 
From this point, my next step would be to thoroughly clean the mounting surfaces of the heads and manifold, then dry fit the intake on the heads with no pan or gaskets, to see how it sits against the heads(angle wise) and to get a look at the bolt alignment situation.
 
PRH said:
From this point, my next step would be to thoroughly clean the mounting surfaces of the heads and manifold, then dry fit the intake on the heads with no pan or gaskets, to see how it sits against the heads(angle wise) and to get a look at the bolt alignment situation.
Click to expand...

The machine shop mentioned something along those lines early on in our discussions. He currently wants pictures to see if the intake mounting bolts were contacting the mounting holes in the intake and they were. I just sent those pictures off last night.

However, the engine is currently in the car and an hour away from the machine shop. I hope the machine shop has a better way to measure the angle difference than just an "eye balling" because currently I dont have a way to get the engine out and too him.
 
carfreak6970 said:
The machine shop mentioned something along those lines early on in our discussions. He currently wants pictures to see if the intake mounting bolts were contacting the mounting holes in the intake and they were. I just sent those pictures off last night.

However, the engine is currently in the car and an hour away from the machine shop. I hope the machine shop has a better way to measure the angle difference than just an "eye balling" because currently I dont have a way to get the engine out and too him.
Click to expand...

They cannot tell with pictures, You need to do it with feeler gauges. Incorrect angles between the intake and head are not uncommon. You also need to make sure the intake is not getting hung-up on the China-wall and its hold down hardware.

If it was mine, I’d skip worrying about the possible angle issue. I’d have the intake milled a minimum of 0.060”, maybe 0.80”. Purchase four 0.015” and four 0.030” thick paper intake gaskets. Make a gasket/pan/gasket sandwich for the reinstall. Between the the two gasket sizes you’ll be able to get good alignment. Use the same combination on the drive side as passenger side. This will seal any angularity issues. The other beauty is you won’t need magic sealants to seal it up.
 

BSB67 said:
They cannot tell with pictures, You need to do it with feeler gauges. Incorrect angles between the intake and head are not uncommon. You also need to make sure the intake is not getting hung-up on the China-wall and its hold down hardware.

If it was mine, I’d skip worrying about the possible angle issue. I’d have the intake milled a minimum of 0.060”, maybe 0.80”. Purchase four 0.015” and four 0.030” thick paper intake gaskets. Make a gasket/pan/gasket sandwich for the reinstall. Between the the two gasket sizes you’ll be able to get good alignment. Use the same combination on the drive side as passenger side. This will seal any angularity issues. The other beauty is you won’t need magic sealants to seal it up.
Click to expand...

huh... when you put it like that it doesnt sound as complicated as my brain was making it. Thanks for that!
 
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