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Vortec 350

de3en16

de3en16

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The engine and intake will fit. Headers can be iffy, so verify before you buy. Make sure they are not for the trucks (which changed platforms in 88). You will need some variety of adaptor to bolt the TBI unit onto a spread/square bore manifold. They are pretty common:

http://www.summitracing.com/search?SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=tbi%20adapter

I think there might be an actual manifold that will bolt up to Vortec heads that has a TBI-compatible mounting base, but IIRC it's a GM part that's very pricey.

I can't recall how the throttle/TV cables are mounted on a TBI truck, but on my carbed 350 the bracket bolts to the intake bolts. If that's the case for you, since the Vortec heads and manifold have different mounting bolt locations and orientations, you will have to either modify your existing throttle/TV bracket, or buy one compatible with the Vortec manifold. I want to say Jegs or Holley make one that bolts onto the Vortec manifold, and has provisions for the throttle cable, TV, and cruise control. Check your setup, I'm pretty sure the centerbolt valve covers are the only thing in common with a Vortec head, but I could be mistaken.

The TBI computer may need an EPROM chip to run properly with the Vortec. The cam in those is pretty mild and computer friendly, but Vortec heads flow a lot more air and the engine has higher compression. Some of the TBI experts (check the injection section) will be able to tell you how extensive the work on the TBI system will be. At the least you'll probably have to bump up the pressure some, which may mean a new fuel pump, since the stock unit struggles to provide factory pressure.

Best of luck on your build!
 
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Thanks I kind of forgot about the bolts being different, tried looking at a few different intakes but its hard to say. It looks like my TV bracket is on the second from the last intake bolt. But Bowtie overdrives has 2 kits that should work if the intake bolts don't work.

The headers say there for a blazer 87-91 But I'm still checking to make sure.

The computer part of this is going to be the hardest part off this swap I think.

Thanks for the help.
 
You'll want 13PSI minimum, really will depend on what the engine needs. If the stock injectors are enough for your motor, may need to bump up the pressure a PSI or two (If the pump can do so) to get enough fuel, but that's relatively simple/minor.

The PROM tuning will be the tricky part, but it's been done enough that getting it working properly shouldn't be too tough.

IMO the Hedman headers listed in the giant header thread here are the "go-to" ones, but if you find others that have experience on these trucks, with the headers you are considering, I wouldn't be opposed to using them. Realistically fitment and thickness are the two problems people run into with headers, and on the trucks, fitment SHOUDLN'T be an issue, it's not like there isn't enough space. Just not enough effort by the manufacturer if they don't fit.

IMO, which is based on what I've seen of others dyno tests, long tubes should be run when possible. The motor you are looking at isn't going to be a high revver, and in that case, between short and long tubes, long tubes are the way to go. The longer tubes should go a long way to keeping good velocity, which is where the Vortec's shine.
 
Thanks for the info, my current setup is at 12 psi but if I remember right stock can go to 13 psi. I don't see any harm in going up 1 psi to see if my system can handle it but I did find a replacement pump too.

I think I might have to hold off on headers till after I get the new engine broke in. From the warning labels and others in the header thread braking in an engine on headers is a bad idea.

Thanks for the help its much appreciated!
 
I can verify that breaking an engine in on headers is a very bad idea. Mine discolored even after "break-in", I just didn't wait long enough.

You are going to need to datalog after it's running to determine if fuel correction is necessary, and how it will need correcting. Highest I could get my Dad's stock fuel pump was 14PSI, but it was enough.
 
He might be alright. On flat tappet engines you have to run the engine between 2-3k rpm for 20-30 minutes. That's why headers with certain coatings advise using old manifolds for the break-in period to prevent discoloration or damage to the coating.

That Vortec is a roller cam motor, so that intense type of break-in procedure isn't required. I can't imagine that a more modern break-in procedure (varying RPMs, no full throttle sprints, no redlining, etc) would put too much stress on the headers. Nonetheless, they're easy enough to change out, so you don't lose anything by playing it safe.
 
Mine was with a mild roller cam, so I dunno. Ran it for ~20 minutes on manifolds, swapped over to headers, burned them.

I know the motor was running lean in the first place, but they all obviously get hot on initial break in, perhaps some more than others.
 
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