I assume this question has been asked several times, but my Google search skills aren't up to the task. I have an 87 LA block. Premag headers (like the Edelbrock 68512/68513) are more or less non-existent. However, 92+ headers are rather available from many sources. The question is....will they fit? Are there any additional concerns?

This is a kind of a hobby truck to me. I don't really have the need or interest in a V8 swap, even if it's more cost effective. I tend to get too wrapped around the axle with such things and never actually do anything. Buying bolt on parts, even if they are $500, is more doable for me.

 

Quote:

Originally Posted by 87longbed

I assume this question has been asked several times, but my Google search skills aren't up to the task. I have an 87 LA block. Premag headers (like the Edelbrock 68512/68513) are more or less non-existent. However, 92+ headers are rather available from many sources. The question is....will they fit? Are there any additional concerns?

This is a kind of a hobby truck to me. I don't really have the need or interest in a V8 swap, even if it's more cost effective. I tend to get too wrapped around the axle with such things and never actually do anything. Buying bolt on parts, even if they are $500, is more doable for me.

I "think" they will bolt to the engine. Hopefully someone will chime in who knows more. Also, you may want to consider the walker headpipe for the newer truck. That would eliminate that small converter in the factory headpipe, and I believe they are only about $50.00

Like to see pictures of your truck and hear more details. ie 4wd? manual or automatic?

And btw Welcome to the forum!!
I thought about trying something like that on mine, but here is the problems I found. 1. The distributor is a odd fire. I am pulling from memory, but I think the reluctor ring is set at 116 degrees and 124 degrees, rather then 120 each like a slant 6. Years ago, mopar made a high performance dist. for the 3.9 but its long gone. 2. carb is a o2 feedback carb "6280" I have heard of using a older 2280...... and agin, no aftermarket intake available anymore.
At the end of the day, I have come to the conclusion that it would be easier just to find a 5.2 (they are cheap) go with a carb intake (edelbrock 7577) a small 4bbl carb, and a aftermarket dist. You will need to sandwich 2 electric fans between the radiator and condenser. But I believe the exhaust off of the 92-96 will bolt up.

 

Thank you for the kind welcome. I had a suspicion the conclusion you reached may be the case and if so, I'll probably just keep the 3.9L. It's not the best, but I'm not certain I really want to take on an engine swap.

The truck is the most basic I've ever seen, honestly.

What I'm going through is something I've seen here on many of my searches. Prior owners just remove failing parts instead of replacing them. It seems the trucks are good, but the owners aren't. In my case, the prior owners just chose to straight pipe a failed cat, and randomly removed emissions parts. I'm not trying to rebuild all that but instead just remove the parts properly, plug the leaks, etc.

 

If you work it out before I do, let me know how you handle the EGR ...

Especially on a Magnum motor using the LA intake.

RwP

 

Well in this case, it would have been magnum headers on a LA block.

 

Yep, would still be the same problem; the LA uses the exhaust gas passages in the LA heads to do the EGR on the intake, but the Magnum used a pipe from the passenger side exhaust manifold.

Which was piped into the kegger intake.

That was what I was talking about.

RwP

 

Interesting. Since the truck has experienced many "methods" of repair (that is removing the failing part or just emissions parts), I wasn't sure how the EGR was involved. My truck (currently) does not have any tubing that connects the EGR to the exhaust manifold. There is a pipe that connects the left and right manifold that has been capped. None of the other emissions components exist (AIR pump, check valves, etc). When I replaced the cat, I opted for a version that did not require AIR injection tube. We have emissions testing here and it passes. They only do a sniff test.

What I may try to do is see if 92-93 Magnum manifolds will fit. There's some available at a pick-and-pull that I can get fairly cheaply. The way I understand, these manifolds flowed well and since much of the emissions / EGR equipment is missing anyway, it wouldn't hurt to see what happens. As I understand, I would need to acquire a 92-93 Y pipe as well but everything after would mate up, correct?

EDIT: From looking at a parts diagram, it appears the 92-93 manifolds do not have a bung for the O2 sensor. Given the existing conditions, should I tap into the manifold to create one or ?

 

Probably easier to weld an O2 bung to the pipe just after the manifold. Drilling/tapping cast iron really isn't much fun.

 

Yah, the 1987 put the O2 bung on the driver's manifold (where my truck has a dead O2 sensor since its driver side manifold came from an 1987).

The EGR on our trucks is on the intake manifold; the exhaust gases are piped across via passages in the heads to do a manifold warm up for carburation or TBI, to keep the fuel from puddling out of the stream.

There is no tubing on the LA blocks for the EGR.

You can put the bung on the exhaust pipe right below the manifold if you want to; the later trucks put it on the passenger side right in front of the "Y" join.

As to that pipe in the back ... that's for the AIR pump; it injects air high (before the cat) when the motor's cold (switched via the diverter valve off the AIR pump). The diverter drives it down into the cat proper after the truck warms up enough to start getting into closed loop (since the air in will screw up the O2 sensor).

If you don't have the AIR pump, then don't sweat that any.

RwP

 

Thanks so much for the details / clarifications.

So if I got this right, the exhaust manifolds on the LA blocks are designed to move air into the intake for the EGR system. And that magnum style manifolds / headers may physically bolt up, but do not have the passages.

If that's the case, I could go EGR delete and remove the EGR entirely. However, as I understand EGR isn't simply some emissions hocus-pocus, it actually helps improve performance as it puts more air into the combustion chamber. If that's the case, then it appears I either need to source those edelbrock ones in my original post or just keep the ones I have.