Chevy & GMC Vans

i know there have been numerous topics about headers for the stock 4.3l, but while on minitruckinweb.com i came across an article about putting JBA headers on an S-10, and they show a side by side pic which makes them look relatively compact and comparable in mass the the stock manifolds. So i guess my question is has anyone ever made a pair fit their stro before? If yes was it worth the hassle? I have a custom cat and flowmasters and would love to put some headers on as well.

I know when I put a 350 in my S-10 years ago,,there was an issue with manifolds and wound up using Monte Carlo. Think the headers for an S-10 are made differently or at least they were in the early years of the S-10 Blazers. The difference is the steering shaft actually runs through the header tubes but not sure this is true for later models or pick ups. Guess this doesn't help at all,,not unusual.

You have the same exhaust set up I have, the Magnaflow Cat and 40 series flowmaster muffler. I was also looking for some headers for the stock 4.3 and came across this http://www.autopartswarehouse.com/searc ... 5599&Nty=1 So I went ahead and ordered them. IF (and that's a big IF) they actually fit I'm wondering how I should run my existing exhaust with the new headers so that I'll get some more power. Any input would be great, Im kinda new to the whole exhaust thing.

The real trick is if they are going to mate up to your stock Y pipe.
sounds like you've already done the exhaust down stream with the cat and muffler.
Whether you feel a difference in the low or high rpm range is dependent on the primary tube size at the flanges.
Here's some basic reading on exhaust theory if you like: http://www.nsxprime.com/FAQ/Miscellaneo ... theory.htm
Let us know how it comes out.

Thanks! I really hope this will work.

Got em in yesterday and guess what?! Theyre for a V8, and even if they were for a V6 you were right saying there would be problems lining them up with the Y-pipe because the headers wouldnt go anywhere near it.

yep, I did some searching on other manufacturers as well, some of them say " some fabrication required", which I assume means a connector pipe from the header to the Y.
I've even mused about getting V8 headers for a 350, cutting off the front primary and welding it shut. Dorky I know, but I have these .....thoughts...

i'm goig to open this back i will be ordering these from summit here in the next week i will let you know if they fit. they should b/c the stock manifolds are the same part # for the blazer and the astro so we will see

Let us know, I'll be watching.

as will i!

As the link I am about to post says,headers all onto it's self is just a part of the combo of compressions,heads,cams,type of intake system and normal rpm ranges the engine runs in.This is a long read,but well worth the time.The summary I have in my head is headers are more likely to be effect in the mid to high rpm ranges.When I speak of mid ranges I am talking about it starting at 3,000 rpm and up.

Take a peek:

http://www.chevyhiperformance.com/techa ... index.html

good article Gary. I didn't see the dyno chart they mentioned. I'm curious about the torque curve between idle rpm and 3000. They mentioned a gain of 26 ft/lbs. at 3000 rpm or so on the daily driver -wonder what it was below 3000.
If I could press the gas peddle the way I normally do, and feel the difference starting off from a traffic light, I think I'd be satisfied with the effort and cost. Personally, headers are at the low end of my priority list at the moment, but I am interested in the outcome of this thread.

the jba ones i'm getting are for the 96 blazer and c1500, the older vans 85-91 can use the dynomax headers that were made for astros i think even edelbrock made some back in the day

kings-x59 wrote:good article Gary. I didn't see the dyno chart they mentioned. I'm curious about the torque curve between idle rpm and 3000. They mentioned a gain of 26 ft/lbs. at 3000 rpm or so on the daily driver -wonder what it was below 3000.
If I could press the gas peddle the way I normally do, and feel the difference starting off from a traffic light, I think I'd be satisfied with the effort and cost. Personally, headers are at the low end of my priority list at the moment, but I am interested in the outcome of this thread.

Sanderson headers has a interesting fact in this link where smaller primary tubes are actually better for street driven vans.Now I didn't send a email to them to see if they would build a set for a 4.3 Astro,but they do say they build custom sets for one off's.I would suggest you contact them if your interested.It's the concept that I am trying to show to you folks.There is the link:

http://www.sandersonheaders.com/tech_get_technical.php

yep, understand the concept. bigger is not always better. the smaller primaries scavenge the exhaust from the cylinders better. I suspect the longer the primaries the better as well.