'88 TBI Build

[Ricko1966]

I'd look at the head shootout link I put up a couple of posts up. You need to pick where you want your power. TBI isn't going to give you big flow numbers,and is map sensor controlled. So I'd probably stay down in the 180 port heads,and cams without lots of duration. Busy gotta go right now,I'll look at some cam profiles when I get back.

 

[Ricko1966]

The AFR's are better than vortecs in every way. Cost is almost a wash. Intake manifold is cheaper. I don't know (anybody?) if TBI has the traditional 4150 mounting flange like the carbs and aftermarket TBI?
Do a search on YouTube for the AFR vs Vortec heads. There are literally tons of demonstrations.

Should be able to use factory tbi manifold,that's part of what I like, you can spend the money on the heads you want instead of on a special purpose intake. Tbi throttle base is different bolt pattern but NBD to adapt to standard manifolds. All the afr's are not drilled for exhaust crossover,don't know if you can drill them,maybe something to investigate.

 

[Ricko1966]

@Powerhouse Ranch go to Harris tbi mods and do some investigating,he had more than 1 page and link sobprowl around. He has posts on tbi throttle body mods,pump mods,regulator mods,etc.

 

[CalSgt]

Can someone explain to me how Vortec heads are any different in this regard compared to other aftermarket heads with no heat crossover or running intake gaskets with the crossover ports blocked?

When I was younger, I daily drove my hopped up 327 with the crossover ports blocked. I had no troubles in winter.

Manifolds that fit the bolt pattern of Vortec heads don't have a heat crossover. The manifolds are designed for a "dry" system meaning they use port fuel injection. The manifolds only flow "dry" air, not air mixed with fuel like you have with TBI or carb. When wet air encounters a sharp angle, i.e. an abrupt change in direction, the fuel separates from the air due to different densities. Cold manifolds condense air/fuel mixtures. When the charge hits the bottom of the manifold it has to make a 90 degree turn. This is where the separation occurs. This is also why you will see a waffle pattern cast into the manifold at this location. A manifold with a heat crossover helps keep the fuel/air charge in a vapor (lighter) state and less prone to separation. Think filters that spin the air to separate dirt particles, same for canister vacuums. Same principle. Vortecs are ok once warm but a PITA when cold. This gets annoying on a daily driver. Hope this helps.

It doesn't help that gasoline doesn't have the vapor pressure it once had, a big federal mandate in the 90's limited the amount of vapor pressure pump gas can have. MPFI cars don't need the pressure because they atomize fuel right as it gets sucked into the hot cylinder.

Gas with higher vapor pressure evaporates faster, atomizes better and is less likely to condensate, that may explain why @bucket didn't have this problem when he was younger.

 

[Frankenchevy]

I think @Vbb199 has messed with a factory tbi quite a bit. Try searching his posts on it.

 

[AyWoSch Motors]

okay so indulge me. If you had a stock 350 TBI and wanted to upgrade it using these heads and keeping TBI, what else would you do on this motor rebuild? @bucket @SquareRoot @AyWoSch Motors give me your hypothicals as well please

Okay, for one, i wouldn't spend money on nice higher flowing new heads, and keep the stock TBI, seems like a waist.

If it were my build, with a decent stock 350 block and lower end, id personally just get set of halfway decent stock cast iron junkyard heads, edlebrock performer intake, and a nice eddy AVS or carter AFB.
Now if "I" was set on keeping the TBI, same build but either a TBI specific intake or a TBI to 4bbl adapter. Maybe with some hop up mods on the TB and fuel system.
If your set on the nice AFR heads or some other decent aluminun heads, same setup as the other too options, or maybe go to a decent TB-EFI setup..thats if you want to spend the money. Im a cheap ass, personally wouldn't spend all sort of money on a stock bottom end 350 in a relatively stock blazer/jimmy. Id build it basically stocl or a little better, and just have fun driving it. Its not going to be a race car or offroad monster. If it is...then thats a different story, haha.

Its all personal preference though, and how much you want to spend, and what you ant to do with it. Everyone is differnt. But thats my take, since you asked.

 

[SquareRoot]

Okay, for one, i wouldn't spend money on nice higher flowing new heads, and keep the stock TBI, seems like a waist.

If it were my build, with a decent stock 350 block and lower end, id personally just get set of halfway decent stock cast iron junkyard heads, edlebrock performer intake, and a nice eddy AVS or carter AFB.
Now if "I" was set on keeping the TBI, same build but either a TBI specific intake or a TBI to 4bbl adapter. Maybe with some hop up mods on the TB and fuel system.
If your set on the nice AFR heads or some other decent aluminun heads, same setup as the other too options, or maybe go to a decent TB-EFI setup..thats if you want to spend the money. Im a cheap ass, personally wouldn't spend all sort of money on a stock bottom end 350 in a relatively stock blazer/jimmy. Id build it basically stocl or a little better, and just have fun driving it. Its not going to be a race car or offroad monster. If it is...then thats a different story, haha.

Its all personal preference though, and how much you want to spend, and what you ant to do with it. Everyone is differnt. But thats my take, since you asked.

Good point. I wouldn't waste a dollar on TBI either. That would be like rebuilding a 305.

 

[AyWoSch Motors]

Good point. I wouldn't waste a dollar on TBI either. That would be like rebuilding a 305.

Exactly. Doable, yes, reliable, most likely, but power, eh, and worth your money, no.

 

[Ricko1966]

I agree @Vbb199 is the man too talk too on TBI. I have a pretty good plan on how I'd do it,but hate to tell someone to do something I haven't already done. My plan would be a homemade plate to put a 454 throttle body on square bore manifold,factory 5.7 computer wiring harness,map,and injectors. A better fuel pump and adjustable fuel pressure regulator. I hope Vince chimes in on this because this is my plan. In response to the above comments I disagree I think I can build a tbi system that will be better than a carb and manifold for not a lot more money and support at least 400hp.
I could just edit out my previous statement,but got thinking after I wrote it for a novice a carb and manifold would be much simpler,bolt it on and go,and less money than aftermarket efi.

 

[Ricko1966]

OR OR OR would it be feasible to just do bigger heads and intakes, but keep the TBI. I mean I had no problems with it, i had new parts for the setup. I'd hate to change it all and switch sending units and tie the truck up longer. The main question is, do they make a matching intake for the better heads still fittable for TBI?

What number heads do you have right now? Do they need rebuilt? The reason I ask go look at that cylinder head shoot out the vortecs made 20 more hp 29ft lbs of torque on the exact same motor. I wouldn't spend the money on the Vortecs for 20 hp I'd spend the money on tbi mods. Headers and under drive pulleys. That and a cam will be a big difference.

 

[AyWoSch Motors]

Heres a thought too... have your heads professionally rebuilt and modded.

You can have them decked, ported larger, and bigger valves put in. But at the very least you get like new heads, for chepaer than new prices.
You can go in there yourself and diegrind the intake ports larger by hand ive heard.

It's a thought

 

[Ricko1966]

Heres a thought too... have your heads professionally rebuilt and modded.

You can have them decked, ported larger, and bigger valves put in. But at the very least you get like new heads, for chepaer than new prices.
You can go in there yourself and diegrind the intake ports larger by hand ive heard.

It's a thought

It's a thought,but not a good idea. That's why I asked what shape his were in to see if they were a decent casting and useable as is. Just rebuilding a pair of old iron heads to stock and you've just taken a big bite of the price of better aluminum heads. Now start adding valves,seats,springs, labor to mill the heads and intake manifold. He won't really save anything.

 

[AyWoSch Motors]

It's a thought,but not a good thought. That's why I asked what shape his were in to see if they were a decent casting and useable as is. Just rebuilding a pair of old iron heads to stock and you've just taken a big bite of the price of better aluminum heads. Now start adding valves,seats,springs, labor to mill the heads and intake manifold. He won't really save anything.

Thats true too.

 

[Powerhouse Ranch]

What number heads do you have right now? Do they need rebuilt? The reason I ask go look at that cylinder head shoot out the vortecs made 20 more hp 29ft lbs of torque on the exact same motor. I wouldn't spend the money on the Vortecs for 20 hp I'd spend the money on tbi mods. Headers and under drive pulleys. That and a cam will be a big difference.

current original heads are warped due to idiot PO

 

[Powerhouse Ranch]

It's a thought,but not a good idea. That's why I asked what shape his were in to see if they were a decent casting and useable as is. Just rebuilding a pair of old iron heads to stock and you've just taken a big bite of the price of better aluminum heads. Now start adding valves,seats,springs, labor to mill the heads and intake manifold. He won't really save anything.

and @AyWoSch Motors

the main point of it is that's really causing this all, as stated in my last post, my current original heads are warped. The PO "rebuilt" the motor, had the short block sent out and it's damn good. Then he put the rest together: egr ports were clogged solid, NEW head gasket has massive leak between 3 and 5 with idle time on motor. It's clear he had no idea what he was doing. Didn't think to clean anything, guarantee he doesn't know his torque sequences. HE HAD THE EXAUST MANIFOLD RTV'd ON! Anyway I don't know why it was rebuilt but the head is definitely screwed. Perhaps he ran it on blown head gasket I DON'T KNOW.

But the MAIN thing here is i need heads now, bottom line. I wanted to do bare minimum, but the bottom end was brand new and now i need heads. That just opened the door for some upgrades and i was looking for the most reasonable, noticeable, simple upgrades while i'm here.

SO, TBI will stay and be damn near stock. Still leaving the heads question. I'm assuming AFR now, 99% of you guys are against Vortec, which a week ago was the next best thing in my book. Then again, no one knows these trucks like we do. Which i why i asked you guys.