Bad Combo?

[RangRayy]

I planned on putting a mild cam in my stock tbi 350 well one that would work well with the computer. just something to help bump up the HP from the mere 180HP out of the factory. I have not put the truck on a dyno so i am not sure on what my actual HP is but to be safe since its 28 yrs old i will assume 165-175HP.

I wanted to up the HP some but i was told with putting in edelbrock 3702 cam and lifters in the motor hooked up to a TH350 with a 3.08 rear gear it would not give me the results i am after. said i would lose 1400rpm power in the low end but would gain 1400 on the upper end. that i would feel the loss from a dead stop when punching the throttle.

which i am after a fun street truck that has decent power in all areas of the spectrum that is fun to drive on the weekends and is very responsive when i hit the throttle.

i had toyed with the idea of a supercharger but its not a lot of gain for $2109 for 25%(45hp) 225HP - 40%(72hp) 252HP. i feel as if i can spend my $$$ better and get more HP gain.

so should i look for a 700r4? and a 3.73 posi rear end?

 

[87ChevyR10]

First off, TBI's are not really designed to be flexible with power adders. The computer is specific about the range the vacuum must stay in. IMO, if you want to keep the block, but add power, you will want to switch to a carburater. Why? Carbs don't have ECU's to tell them what to do. For starters, you'll want to switch to vortech heads and intake and slap on whatever carb you want to use (within reason). While you have the heads and intake manifold off, might as well install a cam kit of your choosing.

OR, the other option would be to get a long block and build it how you want while your truck is still drivable. One other thing, you most likely have a 700r4 tranny in that R10, you'll want to get a better tranny to handle the extra power (if going over 425HP). Plenty of posts about what you want to do.

 

[RangRayy]

thats what i have found from my research but with a chip it can help an allow a milder cam.

it did come with a 700r4 but that transmission burnt up many many years ago and my grandpa had a TH350 installed. so it has the 3spd in it now

 

[MikeB]

There are some EFI-friendly aftermarket cams out there. I'd call Crane Cams or Lunati and ask for their suggestions. Perhaps a few more degrees duration with a wide LSA and a little more lift will make some more power and still make enough vacuum for EFI.

If your engine has a factory roller cam, perhaps a GM performance cam, like their Ramjet 350 cam (P/N 14097395) will work for you. Or possibly the stock cam used in 96-00 Vortec engines will be a little bigger than what was used in 87.

I'm not an EFI guy, so don't know if any EFI mods (like larger injectors) would be required.

On another note, if your truck doesn't have 2.25" or 2.50" dual exhausts, you'll be surprised at the difference that can make.

 

[87ChevyR10]

There are some EFI-friendly aftermarket cams out there. I'd call Crane Cams or Lunati and ask for their suggestions. Perhaps a few more degrees duration with a wide LSA and a little more lift will make some more power and still make enough vacuum for EFI.

If your engine has a factory roller cam, perhaps a GM performance cam, like their Ramjet 350 cam (P/N 14097395) will work for you. Or possibly the stock cam used in 96-00 Vortec engines will be a little bigger than what was used in 87.

I'm not an EFI guy, so don't know if any EFI mods (like larger injectors) would be required.

On another note, if your truck doesn't have 2.25" or 2.50" dual exhausts, you'll be surprised at the difference that can make.

I did a ton of looking around for TBI upgrades. I could only find 1 place that sold everything needed to properly upgrade a TBI and they have since closed their doors (cfm-tech).

I can also vouch for the better flowing exhaust upgrade. Get a set of long tube headers and add on your favorite muffler and you'll get a little extra punch from the motor.

*It appears CFM-Tech is still in business and changed their website addy. Go HERE.

 

[MadOgre]

If they are swirl port TBI heads they can be ported to work nicely. I like carbs too, for the reason stated earlier.

3:08s kinda makes it difficult for a street fun truck. Just simply adding some steeper gears would make it feel like you have an extra 50-100 HP

 

[87ChevyR10]

Something else to think about. The cost of a proper chip would likely be the cost of a decent carb. There is a massed produced chip made by a somewhat known company (for the life of me I can't recall the name). I have read from various forums that their stated power gains is nothing to real-world gains. I believe there is an individual on EBay who burns chips for TBI; and if I recall, they were a couple hundred bucks or more.

Really, what it boils down to is cost versus gains. Sadly, TBI is a high cost and low gain system. Yeah, you could get a decent motor running with TBI; but the adaptability of a carb system is why folks choose carbs over anything for high performance applications in older vehicles. And as another member stated, there are aftermarket EFI systems which perform a heck of lot better than TBI systems; but need a lot more cash to get a working setup.

Oh, something else to wrap your brain around: the TBI system is like a 2 BBL carb which performs like a 4 BBL but needs an ECU to function correctly.

 

[RangRayy]

Thanks for the input guys. Cash rules everything haha and I am not one of the lucky ones who comes across deals of a lifetime on Craigslist or eBay or swap meets simply due to my cash funds and the deals never coincide. Oh well.

Well I have thought about converting to carb because my intake is leaking and while I have it off why not switch it out. My only concern with going carb is that carbs are getting out dated and always having to adjust it. Plus it looks like a headache switching everything over. Now before everyone rants at me if it were a DD still yeah that would be a pain to have to adjust every time I needed to go somewhere. Seeing as this is my project why not do it. Also I'm already deleting the air pump so would there's a plus.

I've searched and searched on switching tbi to carb and no where is there a list of all the parts needed.

The obvious:
•intake
•carb (650cfm)
•inline fuel regulator
•vacuum advanced? Distributor?
And that's about all I know of

 

[Joe383]

Edelbrock has a performer package for around $700 I would add about $300 to that for a few little things like valve spring, timing chain, gaskets and a few other misc parts. Should put you in the 250 HP range and wake your truck up with out loosing much in the bottom end if any. Good bang for the buck. I might do this for my big block later down the road with the same performer kit.

 

[RangRayy]

Edelbrock has a performer package for around $700 I would add about $300 to that for a few little things like valve spring, timing chain, gaskets and a few other misc parts. Should put you in the 250 HP range and wake your truck up with out loosing much in the bottom end if any. Good bang for the buck. I might do this for my big block later down the road with the same performer kit.

Do you have a link or a part number? What's included in this package? Meant for carb or tbi?

 

[Joe383]

Edelbrock#350-2104PK This is the kit I would use to make it carbureted. I would add minimum valve springs and a timing chain to this kit. Its under Jegs easy kits under the edelbrock section.

 

[RangRayy]

On another note, if your truck doesn't have 2.25" or 2.50" dual exhausts, you'll be surprised at the difference that can make.

with headers? I read that they're not meant for engines with less than 300hp. Also that a single exhaust with 3 in pipe is better than duals.

If they are swirl port TBI heads they can be ported to work nicely. I like carbs too, for the reason stated earlier.

How do I tell if they are swirl port? By a certain cast number?

 

[RangRayy]

Edelbrock#350-2104PK This is the kit I would use to make it carbureted. I would add minimum valve springs and a timing chain to this kit. Its under Jegs easy kits under the edelbrock section.

Thanks I'll look into this as well.

 

[Joe383]

I have modified quiet a few motors and duel exhaust even duel 2.25 is better than single 3 I don't care what any one says. Camaros only do this due to clearance issues. Of it was a good thing for power people would run single exhaust in racing. Duel 2.5 would be good for a mild motor. If you start to hit over the 300 HP range try to get a 2.5 kit. All I could find was a 2.25 kit for my truck. If I could have got a 2.5 kit I would have. I am making about 350 HP though. Hell my old neon came out of the factory with mandrel bent 2.25 from the factory and was only rated at 130 HP so what dose that tell ya. If it was a V8 that would be duel 2.25 for a motor making 260 HP.

 

[RangRayy]

I have modified quiet a few motors and duel exhaust even duel 2.25 is better than single 3 I don't care what any one says. Camaros only do this due to clearance issues. Of it was a good thing for power people would run single exhaust in racing. Duel 2.5 would be good for a mild motor. If you start to hit over the 300 HP range try to get a 2.5 kit. All I could find was a 2.25 kit for my truck. If I could have got a 2.5 kit I would have. I am making about 350 HP though. Hell my old neon came out of the factory with mandrel bent 2.25 from the factory and was only rated at 130 HP so what dose that tell ya. If it was a V8 that would be duel 2.25 for a motor making 260 HP.

So with headers still or stock manifolds? I've already took the air pump off and plan on leaving it off so it's either headers or plug the holes. If I go headers do i still need the O2 sensor(s)? Or can that be deleted as well if I switch it over to a carb' system?