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Engine Foxbody idle/throttle issues

  • Thread starter Thread starter red5.0fox
  • Start date Start date Mar 8, 2023
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AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
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Jan 29, 2024
#101
  • Jan 29, 2024
  • #101
Without you taking a set of calipers and measuring the height and width of each runner opening it’s hard to say.
 

red5.0fox

Active Member
Dec 1, 2019
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Hope Mills, North Carolina
Jan 30, 2024
#102
  • Jan 30, 2024
  • #102
AeroCoupe said:
Without you taking a set of calipers and measuring the height and width of each runner opening it’s hard to say.
Click to expand...
Gotcha. I just read jhricker’s post about lower intake gaskets and I’m beginning to wonder if I just keep putting them in wrong. I’ve changed them twice, but never used any sort of adhesive. I just lay them in there and hope for the best. At this rate, I’m going to continue with the head gaskets, and this time, use the weatherstrip adhesive he was referring to so that I can be sure the gaskets don’t move. And I’ll use the RTV to “bondo” the gasket surface on the intake to make sure everything is smooth.
 

red5.0fox

Active Member
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Hope Mills, North Carolina
Jan 30, 2024
#103
  • Jan 30, 2024
  • #103
I’m also looking at rebuilding my injectors (they’ve already been cleaned). While looking at this kit, I’m wondering, what are the things highlighted in white? Not sure where they’ll go.
Also appreciate all the help.
 

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AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,832
3,964
183
Claremore, OK
Jan 30, 2024
#104
  • Jan 30, 2024
  • #104
Strainer or filter. Go here and the replacement of the strainer/filter is at about 7:15

 
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AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,832
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183
Claremore, OK
Jan 30, 2024
#105
  • Jan 30, 2024
  • #105
Installation of cylinder heads and valve train:


Installation of lower intake:

 
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TwoRockTwo

Member
Mar 28, 2021
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Rustburg, Virginia
Jan 31, 2024
#106
  • Jan 31, 2024
  • #106
I mean, it’s never going to run correctly if you don’t get the base timing correct.

You said it wouldn’t run at 8°-12° BTDC, so where did you end up with for the base timing?

- engine at operating temperature?
- spout removed?
- properly using a timing light on #1 wire?
- verified TDC on cylinder 1 reads 0° on the balancer?

There are things that will cause a stall at idle, and make it hard to set the base timing, things like a vacuum leak, messing with the throttle stop, aftermarket cams, but you have to overcome those.
If it will run with a little bit more throttle, I stick a penny or nickel in between the throttle stop screw and the block just to give it enough rpm so I can finish what I’m doing. It’s just like holding the gas pedal down a little bit.

The only 100% way to find a vacuum leak is with a smoke test, and you can build one for about $10 if you don’t have access.

You have to ensure TDC = 0° and you don’t have any vacuum leaks before you can go any further
 
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red5.0fox

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Dec 1, 2019
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#107
  • Jan 31, 2024
  • #107
TwoRockTwo said:
I mean, it’s never going to run correctly if you don’t get the base timing correct.

You said it wouldn’t run at 8°-12° BTDC, so where did you end up with for the base timing?

- engine at operating temperature?
- spout removed?
- properly using a timing light on #1 wire?
- verified TDC on cylinder 1 reads 0° on the balancer?

There are things that will cause a stall at idle, and make it hard to set the base timing, things like a vacuum leak, messing with the throttle stop, aftermarket cams, but you have to overcome those.
If it will run with a little bit more throttle, I stick a penny or nickel in between the throttle stop screw and the block just to give it enough rpm so I can finish what I’m doing. It’s just like holding the gas pedal down a little bit.

The only 100% way to find a vacuum leak is with a smoke test, and you can build one for about $10 if you don’t have access.

You have to ensure TDC = 0° and you don’t have any vacuum leaks before you can go any further
Click to expand...
I set the timing the way as last described, so I’m sure it was done properly. Used a timing light aswell, it just wouldn’t run. The main issue is it does not run properly with the MAF plugged in, it has no throttle, misfires, etc. when the maf is unplugged, it runs smooth, but won’t idle. I did the timing with maf plugged in. There was a vacuum leak sounding like the lower intake, I have a smoke machine and it wasn’t leaking anywhere, no vacuum leaks visible. So currently I’m just replacing head gaskets and everything while I’m here, and I’m going to use jhricker’s way of ensuring the gaskets don’t move so I have a good seal.
 
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red5.0fox

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#108
  • Jan 31, 2024
  • #108
red5.0fox said:
I set the timing the way as last described, so I’m sure it was done properly. Used a timing light aswell, it just wouldn’t run. The main issue is it does not run properly with the MAF plugged in, it has no throttle, misfires, etc. when the maf is unplugged, it runs smooth, but won’t idle. I did the timing with maf plugged in. There was a vacuum leak sounding like the lower intake, I have a smoke machine and it wasn’t leaking anywhere, no vacuum leaks visible. So currently I’m just replacing head gaskets and everything while I’m here, and I’m going to use jhricker’s way of ensuring the gaskets don’t move so I have a good seal.
Click to expand...
I’m also going to set engine timing with everything taken apart since apparently that’s the true correct way to do it.
 

red5.0fox

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#109
  • Jan 31, 2024
  • #109
Update: heads are off the engine. I’m going to hot tank them, and powdercoat. Just clean everything up and do it right. However, whoever installed the roller rockers before I got the engine must’ve put a rocker bolt in wrong. It came out tight, and snapped a very small bit off the end in the head. Probably going to have to drill that out. While inspecting the block, I noticed cylinder 3 has some thick clean spots on it, while all the other pistons have a thin coating of grime on them, no clean spots. Unsure what’s going on there..
 

red5.0fox

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Dec 1, 2019
190
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#110
  • Jan 31, 2024
  • #110
red5.0fox said:
Update: heads are off the engine. I’m going to hot tank them, and powdercoat. Just clean everything up and do it right. However, whoever installed the roller rockers before I got the engine must’ve put a rocker bolt in wrong. It came out tight, and snapped a very small bit off the end in the head. Probably going to have to drill that out. While inspecting the block, I noticed cylinder 3 has some thick clean spots on it, while all the other pistons have a thin coating of grime on them, no clean spots. Unsure what’s going on there..
Click to expand...
Also, how do I find out what bolt I need to replace it? Not sure what length and everything it is.
 

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,832
3,964
183
Claremore, OK
Jan 31, 2024
#111
  • Jan 31, 2024
  • #111
You probably know this but GT40 heads are pedestal style rocker heads stock so they have press in studs. Yours have been converted to bolt in studs which you inherited from the previous owner. With all that said they are most likely 3/8” diameter. I would say that if you have the following dimensions a replacement can be found.



From there call ARP and see if they have one that matches that.
 
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TwoRockTwo

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Mar 28, 2021
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Rustburg, Virginia
Feb 1, 2024
#112
  • Feb 1, 2024
  • #112
The only proper way to set base timing is with a timing light, while the engine is running.
If you don’t use the timing light, it’s just a guess.

Now, since you used one, where did you end up with the base timing? It’s important to know exactly because it will help diagnose your problem.

You have yet to determine the actual issue, only taken more things apart.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
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Feb 1, 2024
#113
  • Feb 1, 2024
  • #113
I skimmed through the thread so don't shoot me if this has been mentioned...

Are you sure your harmonic balancer isn't shot/garbage? This, aside from what I believe is a bad MAF or MAF wiring that you're working through.
 
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red5.0fox

Active Member
Dec 1, 2019
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Hope Mills, North Carolina
Feb 22, 2024
#114
  • Feb 22, 2024
  • #114
TwoRockTwo said:
The only proper way to set base timing is with a timing light, while the engine is running.
If you don’t use the timing light, it’s just a guess.

Now, since you used one, where did you end up with the base timing? It’s important to know exactly because it will help diagnose your problem.

You have yet to determine the actual issue, only taken more things apart.
Click to expand...
Honestly the only reason I went down to the lower intake was because of a vacuum leak. Once I got to that point, I just had the time, and the money so I just wanted to do head gaskets. I’m happy I have, as there were some issues found.
 

red5.0fox

Active Member
Dec 1, 2019
190
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Hope Mills, North Carolina
Feb 22, 2024
#115
  • Feb 22, 2024
  • #115
Noobz347 said:
I skimmed through the thread so don't shoot me if this has been mentioned...

Are you sure your harmonic balancer isn't shot/garbage? This, aside from what I believe is a bad MAF or MAF wiring that you're working through.
Click to expand...
If it is, I have a new one! I didn’t feel like restoring the old one and got sick of not being able to see the timing marks, so I scooped up a new one to put on since I get good discounts at my auto stores local to me.
 

red5.0fox

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Feb 22, 2024
#116
  • Feb 22, 2024
  • #116
Thanks everyone for the added posts. The new bolt has been secured, and it is thankfully the right one lol. I have gotten almost everything I can powdercoated, and even if the engine doesn’t run right, well, it’ll be super pretty. Before I go further, the only issue I have right now is that my valve stem seals were toast. Now, I have dual valve springs, so the oem style seals don’t work.. however, I’m not sure how to find the correct valve stem seals for my application. Any tips?

As for everything else, here is what I ordered and will be replacing.
- Full Gasket Kit (Doing everything except oil pan and rear main seal)
- Fel-Pro Headbolts
- Harmonic Balancer
-Water pump
- PCV Valve
- Steering shaft rag joint (super easy to reach with everything out)

I’ll take some photos of everything that has been powdercoated aswell because I believe it’s gonna look really good.
 
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red5.0fox

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Feb 22, 2024
#117
  • Feb 22, 2024
  • #117
(ignore this message)
 
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TwoRockTwo

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Feb 23, 2024
#118
  • Feb 23, 2024
  • #118
You never did answer the very simple question of where exactly you set the base timing using your timing light……
 

red5.0fox

Active Member
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Hope Mills, North Carolina
Feb 24, 2024
#119
  • Feb 24, 2024
  • #119
TwoRockTwo said:
You never did answer the very simple question of where exactly you set the base timing using your timing light……
Click to expand...
I mentioned in my previous post on the last page that timing was set to 12ish° BTDC and as it would not idle, I simply turned it until it would (I needed the car to move).

I’m setting the engine to TDC on compression stroke while I have the valve covers off.
 

TwoRockTwo

Member
Mar 28, 2021
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18
Rustburg, Virginia
Feb 25, 2024
#120
  • Feb 25, 2024
  • #120
Yeah but how much did you turn it? Which direction did you turn it?
Advance or retard?
Where did it end up?

Where you started is not as important as where it actually ended up.
 
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