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And, as promised, the video. I ran it from idle (around 750-800 RPM) to about 3200 RPM. You can hear where it gets rougher around 1500-1800, and then starts to smooth out a little bit. I didn't want to take it past 3200 RPM because that didn't seem like a good idea while parked.
Looking forward to your insights!
Also, I'm in the southeast Nashville area, so if anyone is around here and wants to come help me with my car, beers are on me...
Just had yet another person look at the car, whose brother apparently owns a 1984. He said he's almost certain it's the injectors that are the issue (an opinion shared by many people in this forum).
I've been super impressed by how many cool people I've met in the week I've owned this car. Already worth it
Took the car to good mechanic I know-he drove it for about 2 minutes and came back and told me he thinks the problem is an aftermarket cam that's wrong for the car. He says it's running on all 8 cylinders but that cam is throwing the timing way off, especially in lower RPM range. from 1500-2000 is really rough, but by 3000 RPM the engine runs near perfectly.
This goes well beyond my current skill level. I'm willing to do the repair, but...
1-What is the difficulty of swapping the cam out? Anyone aware of a good writeup for this job?
2-How accurate do you think this diagnosis is? I highly trust this mechanic and he's very good, but I still am looking for opinions.
3-While I'm taking all of this apart, any other suggestions for things to take care of?
Thanks guys!
Since we don't know, is there any chance of asking the PO what exactly he did? Are the rockers stock? If I were going to change the cam, I'd go back to stock, change the lifters and make sure the rockers are stock. That said, I can't be sure he is right. Was the cam degreed right?
I'm betting you can turn around and resell it when you are done with it for about the same amount.
Sure he can but why? It would be kinda silly to buy it, fix your issue and resell it only to find that you need it a couple months down the road, IMO. Then what? Buy and sell again? If he is keeping an EFI car, I'd suggest buying and keeping it. Just my $0.02.
I had eventually planned on taking the engine apart and replacing gaskets, cleaning things out, etc, anyway-sounds like this might be the opportunity to do that. I've never done deep engine work before, but I'm confident if I take my time and do the research beforehand, I can do pretty much anything on this car.
I also happen to be a professional wedding videographer, so...recording audio/video isn't an issue! Small victory there, at least.
Or you can yank the engine and go through it once and for all. At the end of the day, you will have a fresh engine. Obviously, I'd pull the cam bearings, change lifters, check pushrod for length and straightness and the rockers. Also, what the PO may have done to the heads is another story. You might also be in for a spring check and if you are going there, might as well replace the springs. See where this is going?
Since we don't know, is there any chance of asking the PO what exactly he did? Are the rockers stock? If I were going to change the cam, I'd go back to stock, change the lifters and make sure the rockers are stock. That said, I can't be sure he is right. Was the cam degreed right?
The car went through a few owners very quickly it seems. I'm not entirely sure the history but all I know is that a PO replaced several ignition pieces (distributor, cap, rotor, plugs, and wires), then let it sit for a few years, then the guy I bought it from bought it, messed around for a month, couldn't fix it, and sold it to me.
If the cam was swapped there's no record of it available to me. Only the ignition parts mentioned above.
Or you can yank the engine and go through it once and for all. At the end of the day, you will have a fresh engine. Obviously, I'd pull the cam bearings, change lifters, check pushrod for length and straightness and the rockers. Also, what the PO may have done to the heads is another story. You might also be in for a spring check and if you are going there, might as well replace the springs. See where this is going?
I do. I had originally thought I was going to be rebuilding the engine eventually, so that's not a huge surprise. I just wasn't going to do it this soon...but hey, it's a fun project, right?
Just had yet another person look at the car, whose brother apparently owns a 1984. He said he's almost certain it's the injectors that are the issue (an opinion shared by many people in this forum).
I've been super impressed by how many cool people I've met in the week I've owned this car. Already worth it
84 is a totally different car.
I'm certain your injectors have an issue. They are either partially clogged or the Multecs are on the way out. It might not be THE issue but they will be AN issue if they are Multecs. Multecs are fuel cooled and they do NOT play nice with Ethanol in the fuel. It eats the insulation in the windings and well........ See which you have. If you have Multecs, I'd definitely toss them. If you don't, get the Bosch 3 rebuilt and be done with that end.
Have you done a fuel pressure check at KOEO? Does it leak down quickly? Also, can you do a WOT run and see what it does for fuel pressure? Just to rule out the fuel supply
I do. I had originally thought I was going to be rebuilding the engine eventually, so that's not a huge surprise. I just wasn't going to do it this soon...but hey, it's a fun project, right?
Wouldn't you like to know...
If you are yanking the motor, might as well build it to a 383. Not much more money.
Actually, I'd like to see. Knowing doesn't do much.
Yeah injectors are high on the list of todos. At WOT the car performs its best, I'm thinking the fuel supply isn't really the issue. I need to get the pressure test setup and test the cylinders, that's high on the list as well.
First thing, I'm going to try to pull the injectors one by one and test for the misfiring cylinder this afternoon. That ought to narrow it down at least.
Thing is, the car ALMOST runs great. It starts right up, and when you put your foot down it really takes off. I just need to solve this misfire and it's going to be a great car.
Yeah injectors are high on the list of todos. At WOT the car performs its best, I'm thinking the fuel supply isn't really the issue. I need to get the pressure test setup and test the cylinders, that's high on the list as well.
First thing, I'm going to try to pull the injectors one by one and test for the misfiring cylinder this afternoon. That ought to narrow it down at least.
Thing is, the car ALMOST runs great. It starts right up, and when you put your foot down it really takes off. I just need to solve this misfire and it's going to be a great car.
Usually it is hard to tell with the SOTP dyno unless something is far out which is why I usually don't use it. When I serviced the injectors on my diesel car, nothing changed. It ran great. Picked up 1.5 mpg but otherwise no difference. IIRC, they changed the nozzles because they were out of spec and worn out.
Sure he can but why? It would be kinda silly to buy it, fix your issue and resell it only to find that you need it a couple months down the road, IMO. Then what? Buy and sell again? If he is keeping an EFI car, I'd suggest buying and keeping it. Just my $0.02.
I agree, I would too. I just wanted to point out that he could recoup his investment if he wanted to.
I'm certain your injectors have an issue. They are either partially clogged or the Multecs are on the way out. It might not be THE issue but they will be AN issue if they are Multecs. Multecs are fuel cooled and they do NOT play nice with Ethanol in the fuel. It eats the insulation in the windings and well........ See which you have. If you have Multecs, I'd definitely toss them. If you don't, get the Bosch 3 rebuilt and be done with that end.
Have you done a fuel pressure check at KOEO? Does it leak down quickly? Also, can you do a WOT run and see what it does for fuel pressure? Just to rule out the fuel supply
85 did not come with multecs. they come with bosch.
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