Intake Manifold EFI 350

[Dbelk33]

Hey guys this may have been covered in another thread. I am new to the forum and am looking for some information/guidance on my intake manifold set-up. I have an '87 GMC with the Fuel Injected crate 350 290hp motor. I bought the truck after the engine was put in (has less than 5000 miles on motor). It looks like they used all original injectors and intake manifold, throttle body, etc. What I want to know is if I can put an OEM Vortec 350 manifold on so I can have more options for throttle bodies / air intakes / etc.

Any advice or suggestions are greatly appreciated. Will add pics as the project comes along

Thanks guys!

 

[ali_c20]

Welcome from Austria.

Vortec manifolds bolt holes would need to be modified to fit gen 1 heads. you will also have issues with port matching etc.
If you go that route get a vortec manifold and vortec heads.

https://www.chevyhardcore.com/tech-...m-1st-gen-heads-vs-vortec-heads-reader-guide/

 

[Dbelk33]

Thank you! Looks like several options available for kits including manifolds and heads. Trying not to get too deep into the motor because it runs great. I will be adding some long tube headers and exhaust and just want it to breathe a little easier on the front end.

 

[Bextreme04]

Hey guys this may have been covered in another thread. I am new to the forum and am looking for some information/guidance on my intake manifold set-up. I have an '87 GMC with the Fuel Injected crate 350 290hp motor. I bought the truck after the engine was put in (has less than 5000 miles on motor). It looks like they used all original injectors and intake manifold, throttle body, etc. What I want to know is if I can put an OEM Vortec 350 manifold on so I can have more options for throttle bodies / air intakes / etc.

Any advice or suggestions are greatly appreciated. Will add pics as the project comes along

Thanks guys!

I'm confused by a few things on this. What crate motor is in it now? What fuel injection system? Is it a RamJet 350? If its a stock replacement crate motor and they reused the TBI stuff, you can't do a Vortec Anything without major mods. The Vortec intake bolt pattern is different than Gen I SBC and TBI patterns. I would never suggest you put an OEM Vortec manifold on anything... they suck and have a central injection system that is a pain to work with.

Pics always help!

 

[Dbelk33]

It has 2 injectors above throttle body inside air filter box. (Sorry for the ignorance) I just don’t know where to even begin to find new components.

 

[GTP51]

Sounds like you possibly have the stock TBI
Changed mine to Edelbrock heads, Holley Sniper and a Comp Cams set up, it gets up and boogies now. If you would like part numbers let me know but as Bextreme04 says you really need to know exactly what you have, before you start playing, there are a lot of differences in Early 350 to Vortec engines, perhaps post some photos to show the guys here, there are a lot of very knowledgeable people on the site that can help you.
BTW sorry to be the bearer of bad news, if you have the Stock TBI set up on that motor it isn’t anywhere near 290 HP unfortunately
good luck with you build enjoy the ride

 

[Dbelk33]

I will get some better pics today. Would the dealer who installed it he motor still have any paperwork? It should still be under warranty through this year? I agree that I will not be doing anything until I know what I have. I am just going off what the guy told me (290hp). He wouldn’t lie to me intentionally, said he had 3 power options when he got the motor (maybe 220ish, 265, and 290). Maybe he is mistaken.

 

[Dbelk33]

Looks like I have a direct factory replacement 350 crate motor. Part number is 12568758. Specs I see so far online is that this thing is about 2/3 the horsepower I was told it had lol.

That being said:

What are some good options for intake manifolds/ heads / throttle body, etc to get the most out of this thing without digging into drivetrain?

Other modifications to this truck will be long tube headers with 2.5" or 3" duel thrush rattlers with no cats and 35 or 37" tires. Everything else will be cosmetic (paint / badges / seals)

Any suggestions or feedback is greatly appreciated. This truck is 2 months older than me and I have had it 2 weeks. I am completely green other than the reading I have done on this forum the past few weeks.

Thanks again everyone

 

[Bextreme04]

Looks like I have a direct factory replacement 350 crate motor. Part number is 12568758. Specs I see so far online is that this thing is about 2/3 the horsepower I was told it had lol.

That being said:

What are some good options for intake manifolds/ heads / throttle body, etc to get the most out of this thing without digging into drivetrain?

Other modifications to this truck will be long tube headers with 2.5" or 3" duel thrush rattlers with no cats and 35 or 37" tires. Everything else will be cosmetic (paint / badges / seals)

Any suggestions or feedback is greatly appreciated. This truck is 2 months older than me and I have had it 2 weeks. I am completely green other than the reading I have done on this forum the past few weeks.

Thanks again everyone

TBI is great for drivability and mileage. Tunability is not a strong point of the system though. You need to do some research and decide what your use case is going to be, and then make sure you select components that will match what you want. The stock TBI can be made to work up to about 400hp without too terribly much modification, but you would need to select a bunch of parts that work well together and then specific modifications to the TBI system followed by a good tuned PROM chip. The easiest solution(but definitely not cheapest) would probably be to get a good towing/RV cam, new summit vortec heads(they will match the stock swirl port chamber volume but greatly improve combustion efficiency and flow), and an edelbrock Pro-flow 4 EFI system. You'll need to replace your TBI in-tank fuel pump with an EP-381 to support the higher fuel pressure needed by the MPFI system.

Looking at the specs on that crate motor... it is a california smog legal engine and is absolutely hog tied by the cam. Going to a decent cam will make a huge difference on that motor. I would bet you pick up a bunch of power just from a good cam choice, some long tube headers, and a PROM flash

 

[Dbelk33]

TBI is great for drivability and mileage. Tunability is not a strong point of the system though. You need to do some research and decide what your use case is going to be, and then make sure you select components that will match what you want. The stock TBI can be made to work up to about 400hp without too terribly much modification, but you would need to select a bunch of parts that work well together and then specific modifications to the TBI system followed by a good tuned PROM chip. The easiest solution(but definitely not cheapest) would probably be to get a good towing/RV cam, new summit vortec heads(they will match the stock swirl port chamber volume but greatly improve combustion efficiency and flow), and an edelbrock Pro-flow 4 EFI system. You'll need to replace your TBI in-tank fuel pump with an EP-381 to support the higher fuel pressure needed by the MPFI system.

Looking at the specs on that crate motor... it is a california smog legal engine and is absolutely hog tied by the cam. Going to a decent cam will make a huge difference on that motor. I would bet you pick up a bunch of power just from a good cam choice, some long tube headers, and a PROM flash

Thank you so much for the suggestions. This truck will roll out of the garage on nice weekends throughout the year once I am done with it. Not building a race truck, and it will be a pavement princess. I have a few other trucks I beat up and work with (they aren’t making any more of these).

I just want it to look good / sound good / run good, and not struggle pulling bigger tires. 400hp would likely be absolute max for my application unless I am rich and bored one day (highly unlikely )

I am going to do a little more digging, I will post progress pics as I go. Here she is at beginning phase (at least from me)

 

[GTP51]

Bextreme04 is on the money a cam will make a big difference straight up.

 

[Dbelk33]

Bextreme04 is on the money a cam will make a big difference straight up.

Thanks guys!

Filled a cart on summit racing with some fun items. Looks like for less than a few thousand this thing could really be a strong motor. I will likely start with the camshaft and exhaust and go from there.

Camshaft I am considering is the Summit SUM-1102.

Do you guys know if it is "drop in" or do I need anything else with it (lifters or anything?)

 

[Bextreme04]

Thanks guys!

Filled a cart on summit racing with some fun items. Looks like for less than a few thousand this thing could really be a strong motor. I will likely start with the camshaft and exhaust and go from there.

Camshaft I am considering is the Summit SUM-1102.

Do you guys know if it is "drop in" or do I need anything else with it (lifters or anything?)

I have the 1102 in my truck right now. You will NEED new lifters, just get the K1102(its the 1102 cam with the lifters included as a kit). I am still running some massaged stock heads and flat top pistons with .020 taken off the deck to get me to a 9:1 compression ratio. If you are planning on doing street only driving or want something lumpy or a little more sporty, I would recommend maybe going up to the 1103. I was on the fence, but my truck is used for towing/hauling heavy stuff and hunting/offroading, so I went with the more mild cam with the stock heads. I can post a video of it running/idling if that would help. I didn't want to go too crazy on this 350 because I have a fuel injected 454/4L80E combo that will be going in within the next year or so.

 

[Dbelk33]

I have the 1102 in my truck right now. You will NEED new lifters, just get the K1102(its the 1102 cam with the lifters included as a kit). I am still running some massaged stock heads and flat top pistons with .020 taken off the deck to get me to a 9:1 compression ratio. If you are planning on doing street only driving or want something lumpy or a little more sporty, I would recommend maybe going up to the 1103. I was on the fence, but my truck is used for towing/hauling heavy stuff and hunting/offroading, so I went with the more mild cam with the stock heads. I can post a video of it running/idling if that would help. I didn't want to go too crazy on this 350 because I have a fuel injected 454/4L80E combo that will be going in within the next year or so.

Looks like you are getting close on the motor swap! That's awesome!

I may look into the 1103. I don't mind a little extra lope. This truck will be doing no work (completely retired). I have a couple newer trucks to beat up on.

My dad had an 87 custom deluxe until I was 11. I've wanted one just like it since the day he traded it in. I also have the 1998 GMC Z71 he traded it in for and have been doing cosmetic restoration on it. Almost looks like it would have from the dealer in 1998 except with duel exhaust.

 

[akchevrolet]

I have the 1102 in my truck right now. You will NEED new lifters, just get the K1102(its the 1102 cam with the lifters included as a kit). I am still running some massaged stock heads and flat top pistons with .020 taken off the deck to get me to a 9:1 compression ratio. If you are planning on doing street only driving or want something lumpy or a little more sporty, I would recommend maybe going up to the 1103. I was on the fence, but my truck is used for towing/hauling heavy stuff and hunting/offroading, so I went with the more mild cam with the stock heads. I can post a video of it running/idling if that would help. I didn't want to go too crazy on this 350 because I have a fuel injected 454/4L80E combo that will be going in within the next year or so.

I would like to see the video.