Down to my last marble
02-21-2009, 08:38 PM
#1
2nd Gear Member
Thread Starter
Join Date: May 2005
Location: Oregon
Posts: 206
Down to my last marble
Okay, let us review the chronology of my despair and allow it to serve as a technical challenge to the most knowledgable of you.
I started out, 18000 miles ago, with a new 5.0 shortblock from FRPP. To that I added E303 cam, 1.7 rockers, AFR 165 heads and the stock intake and injectors from the '89 Mustang motor I previously had in my '74 Bronco.
So far, so good. I have been very pleased with the performance of this setup for the last two years, and then, about two months ago, I developed a head gasket leak. I pulled the heads and took them to a very reputable shop that I've used before. They did a routine surfacing on them, disassembled, thoroughly cleaned them and put them back together. In the process of removing the intake to get to the heads, I noticed that my stock '89 GT upper intake was cracked, so I decided that this would be a good time to upgrade to the Explorer intake. I purchased a used but very nice upper and lower intake and installed them along with my cleaned-up AFR heads.
Upon completion of this project, I found that my old truck felt about 50 hp down from prior to the head gasket job! I located and fixed a couple of vacuum leaks, but that made no noticable differance. So I thought that since my Bosch fuel pump was about ten years old, I'd replace it with a new, higher flow unit. This also made no difference. I then figured that maybe my 20 year old, 19 lb/hr injectors were probably old, dirty and tired and needing replacement. So, I bought brand new FRPP 24 lb/hr injectors, a brand new 70 mm, 24 lb/hr calibrated mass air meter and a brand new 70 mm BBK throttle body. I installed all of those components today and went for a test drive - no difference!
When I'm running at a constant speed, all is well, but when I go to accelerate in what used to be my power band (2800 to 4000 rpm), the truck just feels like it's bogging. It doesn't miss or stumble, it just doesn't have anywhere near the umph that it did before.
So, another idea hit me. Maybe my 20 year old distributor isn't advancing properly. I went and bought a brand new distributor and installed that. Now it feels like I have about half the missing power back! When I installed the distributor, I set the timing to about 12° (where it's always been).
The only items left to replace are the plug wires (they're about 6 years old), the coil (about 20 years old) and the computer (twenty years old). I didn't have any problems with any of these before the head gasket change, but I'm willing to try replacing them. I thought about replacing the oxygen sensors, but I recall that before I installed them, I used to run without oxygen sensors and actually got slightly better power.
I've done a compression check and I've got one cylinder that's about 20 psi lower than the rest (all at 175 psi). I don't know why this would be after only 18000 miles and never having taken the engine over 4200 rpm. I did a bleed-down test, and it appears to be rings in this one cylinder. However, I read an article in Carcraft where they were saying that they did a re-ring and hone on an engine where all the cylinders were way low, and it made virtually no difference in power.
What's going on guys? Where did my power go? I would have thought that adding the 70mm throttle body, 70 mm mass air meter and 24 lb/hr injectors would have given me quite a boost over the old, stock '89 GT parts, especially in combination with my AFR heads, but nothin!
I started out, 18000 miles ago, with a new 5.0 shortblock from FRPP. To that I added E303 cam, 1.7 rockers, AFR 165 heads and the stock intake and injectors from the '89 Mustang motor I previously had in my '74 Bronco.
So far, so good. I have been very pleased with the performance of this setup for the last two years, and then, about two months ago, I developed a head gasket leak. I pulled the heads and took them to a very reputable shop that I've used before. They did a routine surfacing on them, disassembled, thoroughly cleaned them and put them back together. In the process of removing the intake to get to the heads, I noticed that my stock '89 GT upper intake was cracked, so I decided that this would be a good time to upgrade to the Explorer intake. I purchased a used but very nice upper and lower intake and installed them along with my cleaned-up AFR heads.
Upon completion of this project, I found that my old truck felt about 50 hp down from prior to the head gasket job! I located and fixed a couple of vacuum leaks, but that made no noticable differance. So I thought that since my Bosch fuel pump was about ten years old, I'd replace it with a new, higher flow unit. This also made no difference. I then figured that maybe my 20 year old, 19 lb/hr injectors were probably old, dirty and tired and needing replacement. So, I bought brand new FRPP 24 lb/hr injectors, a brand new 70 mm, 24 lb/hr calibrated mass air meter and a brand new 70 mm BBK throttle body. I installed all of those components today and went for a test drive - no difference!
When I'm running at a constant speed, all is well, but when I go to accelerate in what used to be my power band (2800 to 4000 rpm), the truck just feels like it's bogging. It doesn't miss or stumble, it just doesn't have anywhere near the umph that it did before.
So, another idea hit me. Maybe my 20 year old distributor isn't advancing properly. I went and bought a brand new distributor and installed that. Now it feels like I have about half the missing power back! When I installed the distributor, I set the timing to about 12° (where it's always been).
The only items left to replace are the plug wires (they're about 6 years old), the coil (about 20 years old) and the computer (twenty years old). I didn't have any problems with any of these before the head gasket change, but I'm willing to try replacing them. I thought about replacing the oxygen sensors, but I recall that before I installed them, I used to run without oxygen sensors and actually got slightly better power.
I've done a compression check and I've got one cylinder that's about 20 psi lower than the rest (all at 175 psi). I don't know why this would be after only 18000 miles and never having taken the engine over 4200 rpm. I did a bleed-down test, and it appears to be rings in this one cylinder. However, I read an article in Carcraft where they were saying that they did a re-ring and hone on an engine where all the cylinders were way low, and it made virtually no difference in power.
What's going on guys? Where did my power go? I would have thought that adding the 70mm throttle body, 70 mm mass air meter and 24 lb/hr injectors would have given me quite a boost over the old, stock '89 GT parts, especially in combination with my AFR heads, but nothin!
03-03-2009, 10:25 AM
#5
Join Date: Feb 2009
Location: Arizona
Posts: 48
The spout connector completes the circuit so that the computer can alter the timing based on rpm and load, etc. When you pull the connector, the timing will never advance, no matter how high you rev the engine (or try to - it won't rev very high without the advance feature). Once you plug it in, the timing will be controlled by the computer and it WON'T be where you set it at! Take the spout connector off, set the timing to 10 or 12 degrees, then reconnect it and you're done!
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