Hipster
I'm Awesome
Some get lucky
Looking for intake and cam advice
- Thread starter BulldogSS
- Start date
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Mine is too but, it's a Mr Goodwrench block made in Meheekoe probably back in 2000.
CrustyJunker
Is STILL Here?
Also a fan of the EBL over here. I hear mixed results from the "chip," crowd. People pay a guy a decent amount of money, maybe get one revision, and your truck runs just good enough. Nobody cares more about your truck's tune than you! Open to interpretation, though.
Cam and tune would definitely be a noticeable and cost effective choice. If you're swapping heads or increasing cubic inches - then I'd recommend an intake swap.
Aftermarket intakes won't provide much gain on stock TBI heads. You'd see gains above 4,000 RPM (you probably couldn't feel, maybe see on a dyno) before the heads peter out around 5,000 RPM.
Just trying to help you guys save your money!
Cam and tune would definitely be a noticeable and cost effective choice. If you're swapping heads or increasing cubic inches - then I'd recommend an intake swap.
Aftermarket intakes won't provide much gain on stock TBI heads. You'd see gains above 4,000 RPM (you probably couldn't feel, maybe see on a dyno) before the heads peter out around 5,000 RPM.Just trying to help you guys save your money!
L31MaxExpress
I'm Awesome
Also a fan of the EBL over here. I hear mixed results from the "chip," crowd. People pay a guy a decent amount of money, maybe get one revision, and your truck runs just good enough. Nobody cares more about your truck's tune than you! Open to interpretation, though.
Cam and tune would definitely be a noticeable and cost effective choice. If you're swapping heads or increasing cubic inches - then I'd recommend an intake swap.
Just trying to help you guys save your money!
For a while I ran a 350 TBI 1-ton crate engine in my 83 G20 van with a performer rpm with the 4 center bolts slotted to fit the 87+ heads and tappered washers from Weiand with a 2" marine TBI unit on a factory marine TBI-carb adapter with the stock cam and 1.6 rockers. Stock heads with generic Z/28 springs. Had thorley tri-y headers into the factory dual 2.5" exhaust that I added a X-pipe to. Turned the EGR off in the chip. It made 208 hp and 310 tq at the wheels. The intake/TBI swap gained over 20 hp at the wheels, nearly 20 ft/lbs of torque across the whole rpm band and the stock cam pulled to 5,500 rpm. Ran the quickest ETs shifting at 5,500. With a factory 1,600 rpm torque converter in the 4L60E and 3.08 gears with a limited slip it would spin 275/60R15s fairly easily. When I got bored I put a set of pull off ZZ4 113 casting aluminum heads and the ZZ4 roller cam on it. Later swapped the cam again to a Reed custom grind and put ported vortecs with a victor jr 2bbl single plane intake on it.
Last edited:
THis is one of the best articles I have read on TBI improvements ==>> ULTIMATE TBI MODS | TBI (harristuning.com)
I did some mild mods to my tbi 350. If you want to get into the motor, you have to get a chip. First, I wanted some better fuel efficiency. I didn't really care about more power on this truck. My first tank of gas was 8.4mpg.. and it was a total turd. Zero acceleration. 1990 K2500 Silverado. HD low compression 350 rated at 190hp@4000 and 300ft/lbs at 2400. Turbo 400 trans. 4.10 gears. 245/75R16s.
I decided to make a few adjustments and track their power gains. First, I cut off the exhaust. The stock muffler was rusted out and only inhibiting flow anyway.. it was still loud but flowed like ****. I put a straight piece of 2.75" pipe in place of the cat and muffler.
After that, I saw that roller rocker arms were cheap. I got a set of 1.6 roller rockers for like $200. I installed them and it helped some. I wanted to remove the parisitic losses, whether it actually made more power or not, less friction means more power to the wheels, right?
Then I wanted to remove the 19" electric fan and install a cheap electric fan. It helped some too. Less drag on the belt.
After that, I had an old Fram AirHog air filter. It's like Fram's version of a K&N. I installed that in the factory air cleaner. I didn't do an performance testing on that, but every little bit helps, right?
Then I found a super cheap set of ceramic coated long tube headers. They were flowtech afterburner headers. The off-sequence cylinders dump int a larger collector from the other 3 cylinders. 18436572. So the left bank had 3 cylinders dumping into a collector and cylinder 7 dumped separately into the larger collector. . and 4 did the same thing on the right bank. It is supposed to help with scavenging. . because 4 fires directly after 8 on the same bank.. and 7 fires directly after 5 on the same bank. It evens out the pulses... regardless of whether it works or not, I got them for a steal and decided to install them. I also go their accompanying y pipe to install into the stock cat and 3" single exhaust system. I feel like the stock y pipe needs work, but the factory exhaust manifolds really aren't that restrictive. If you make more than 190hp, then the headers would definitely make a bigger difference.
Then I found a cheap 3704 intake. A guy bought it for a project and never used it. I swapped it out and liked it. After everything else, the truck was definitely peppier. And my mileage had increased to about 12. The driver's side header has an O2 bung. So does the aftermarket y pipe (in the stock location). In order to fill the hole, I just used an old 4-wire O2 sensor that I had lying around. I had an old narrow band RLI gauge to tell me if I was running rich or lean. Nothing was ever rich. In fact, the gauge would show dead lean on full throttle runs. I was at the absolute max on the stock chip.. with just minor bolt-ons. Not even touching the wimpy stock cam or anemic heads.
This thing shifted at 4,000 so you know it was only getting worse if I went above there. With the perfect cam and other mods, you're only looking at about 330hp with the stock heads. With amazing heads, you're only looking at 275hp. If you get a good set of heads and mild cam, with good induction, you can easily double the stock horsepower. I opted for the smallest chamber I could find.. because with 64cc combustion chambers, my stock compression ratio was 8.4. I found some Trick Flow 305 heads with 175cc runners. They flow enough to support just shy of 500hp. My 4 bolt block was provisioned for roller right out of the box, so of course, I went with a roller cam. My thoughts are that the only applications for 4 bolt heavy duty blocks were heavy trucks and corvettes, so all 4 bolt blocks got provisioned for roller. I'm 2 for 2 with K2500 pickups. I went with a very mild comp cams roller. It's an XFI252HR. 252/264 advertised. 202/212 @/.050". 114lsa. .550"/.546" lift. I wanted instant throttle response and for it to pull past 5000. I went with a 2604 Performer Air-Gap intake. I got the heads drilled for 87-95 so I could still reuse the TBI 3704 intake if I wanted to. I'd rather have gone with the pre-86 intake pattern because their intake selection is much better. I know I can just open the center holes up, but I'd rather stick with the stock sized holes rather than big slots on 4 of the holes.
I went with a Holley 650cfm vacuum secondary carb. That combination, coupled with the headers and free-flowing exhaust, roller rockers, electric fans, and 14x3 K&N filter all added up to a pretty good power increase. The truck practically jumped off the ground from an idle. The low end torque was instant and it pulled so much harder than before through the entire rev range. One tank, I even got over 13mpg. Comp Cams estimated 406hp@5500 and 463ft/lbs@3000.
I never really liked my HEI distributor or the fact that I had to physically tune the carb. So I upgraded to Sniper TBI. Holley's tuning software is incredible. I absolutely love that I can adjust the timing or fueling on the fly. I rarely need to touch the fuel because it is self-learning. It just runs whatever I set the target AFR to.
After that, things got a little out of hand.. I installed a vortech centrifugal supercharger. I already had the tuning ability, so all I had to do was adjust a few numbers in some tables and the tuning part was done. The rest was just bolting the parts on. I thought it made power before the supercharger. This thing takes off like a rocket. . as soon as the tires quit spinning. I was going to get it dyno'd last spring.. but then covid hit so I haven't made it up there yet.
Long story short, TBI is 35+ year old technology. The computers couldn't adjust for much outside of the stock parameters. If he gets a cam, the computer won't like it. I ran an air:fuel ratio gauge on a mild bolt-on engine. The air:fuel ratio was fine, modulating back and forth between rich and lean just like it was designed to.... until you put your foot on the floor. Then it showed how far off the open loop settings had become. The stock cam is something like 170 degrees @.050" with .385"/.402" lift. Even on the stock swirl port heads, a mild RV cam will flow drastically more air. Also keep in mind that they say the stock heads aren't rated for much more than .470" lift. Just like the vortecs, the valve guide bosses are pretty big and may hit the valve retainer. That's just what I've heard. I never wasted my time on a big cam with these anemic heads. Tell your buddy to get a chip. Edelbrock will give you a chip for free if you can prove that you bought their whole top end kit for a few grand. intake, heads, cam, headers. That will net you about 325ft-lbs at the crank, maybe 240hp at 5000. I've done the mail-order custom chip thing. I was not impressed with the results. The truck belched black smoke like a "tuned" diesel. It got about 6mpg and didn't have the power that I was looking for. He needs to read up on it. Talk to tuners that have done many, many chips. Ask the tuner for his advice on a particular combo that he has a dead-nuts bang-on tune for. Go for the cam that a tuner suggests. Go for any part that the tuner suggests. And don't try to reinvent the wheel. These trucks are a minimum of 26 years old.. I guarantee it's been done before on the TBI stuff. Ask around, stick with stuff that works.. but tuning is an absolute must if you want anything more than a bone stock motor.
I decided to make a few adjustments and track their power gains. First, I cut off the exhaust. The stock muffler was rusted out and only inhibiting flow anyway.. it was still loud but flowed like ****. I put a straight piece of 2.75" pipe in place of the cat and muffler.
After that, I saw that roller rocker arms were cheap. I got a set of 1.6 roller rockers for like $200. I installed them and it helped some. I wanted to remove the parisitic losses, whether it actually made more power or not, less friction means more power to the wheels, right?
Then I wanted to remove the 19" electric fan and install a cheap electric fan. It helped some too. Less drag on the belt.
After that, I had an old Fram AirHog air filter. It's like Fram's version of a K&N. I installed that in the factory air cleaner. I didn't do an performance testing on that, but every little bit helps, right?
Then I found a super cheap set of ceramic coated long tube headers. They were flowtech afterburner headers. The off-sequence cylinders dump int a larger collector from the other 3 cylinders. 18436572. So the left bank had 3 cylinders dumping into a collector and cylinder 7 dumped separately into the larger collector. . and 4 did the same thing on the right bank. It is supposed to help with scavenging. . because 4 fires directly after 8 on the same bank.. and 7 fires directly after 5 on the same bank. It evens out the pulses... regardless of whether it works or not, I got them for a steal and decided to install them. I also go their accompanying y pipe to install into the stock cat and 3" single exhaust system. I feel like the stock y pipe needs work, but the factory exhaust manifolds really aren't that restrictive. If you make more than 190hp, then the headers would definitely make a bigger difference.
Then I found a cheap 3704 intake. A guy bought it for a project and never used it. I swapped it out and liked it. After everything else, the truck was definitely peppier. And my mileage had increased to about 12. The driver's side header has an O2 bung. So does the aftermarket y pipe (in the stock location). In order to fill the hole, I just used an old 4-wire O2 sensor that I had lying around. I had an old narrow band RLI gauge to tell me if I was running rich or lean. Nothing was ever rich. In fact, the gauge would show dead lean on full throttle runs. I was at the absolute max on the stock chip.. with just minor bolt-ons. Not even touching the wimpy stock cam or anemic heads.
This thing shifted at 4,000 so you know it was only getting worse if I went above there. With the perfect cam and other mods, you're only looking at about 330hp with the stock heads. With amazing heads, you're only looking at 275hp. If you get a good set of heads and mild cam, with good induction, you can easily double the stock horsepower. I opted for the smallest chamber I could find.. because with 64cc combustion chambers, my stock compression ratio was 8.4. I found some Trick Flow 305 heads with 175cc runners. They flow enough to support just shy of 500hp. My 4 bolt block was provisioned for roller right out of the box, so of course, I went with a roller cam. My thoughts are that the only applications for 4 bolt heavy duty blocks were heavy trucks and corvettes, so all 4 bolt blocks got provisioned for roller. I'm 2 for 2 with K2500 pickups. I went with a very mild comp cams roller. It's an XFI252HR. 252/264 advertised. 202/212 @/.050". 114lsa. .550"/.546" lift. I wanted instant throttle response and for it to pull past 5000. I went with a 2604 Performer Air-Gap intake. I got the heads drilled for 87-95 so I could still reuse the TBI 3704 intake if I wanted to. I'd rather have gone with the pre-86 intake pattern because their intake selection is much better. I know I can just open the center holes up, but I'd rather stick with the stock sized holes rather than big slots on 4 of the holes.
I went with a Holley 650cfm vacuum secondary carb. That combination, coupled with the headers and free-flowing exhaust, roller rockers, electric fans, and 14x3 K&N filter all added up to a pretty good power increase. The truck practically jumped off the ground from an idle. The low end torque was instant and it pulled so much harder than before through the entire rev range. One tank, I even got over 13mpg. Comp Cams estimated 406hp@5500 and 463ft/lbs@3000.
I never really liked my HEI distributor or the fact that I had to physically tune the carb. So I upgraded to Sniper TBI. Holley's tuning software is incredible. I absolutely love that I can adjust the timing or fueling on the fly. I rarely need to touch the fuel because it is self-learning. It just runs whatever I set the target AFR to.
After that, things got a little out of hand.. I installed a vortech centrifugal supercharger. I already had the tuning ability, so all I had to do was adjust a few numbers in some tables and the tuning part was done. The rest was just bolting the parts on. I thought it made power before the supercharger. This thing takes off like a rocket. . as soon as the tires quit spinning. I was going to get it dyno'd last spring.. but then covid hit so I haven't made it up there yet.
Long story short, TBI is 35+ year old technology. The computers couldn't adjust for much outside of the stock parameters. If he gets a cam, the computer won't like it. I ran an air:fuel ratio gauge on a mild bolt-on engine. The air:fuel ratio was fine, modulating back and forth between rich and lean just like it was designed to.... until you put your foot on the floor. Then it showed how far off the open loop settings had become. The stock cam is something like 170 degrees @.050" with .385"/.402" lift. Even on the stock swirl port heads, a mild RV cam will flow drastically more air. Also keep in mind that they say the stock heads aren't rated for much more than .470" lift. Just like the vortecs, the valve guide bosses are pretty big and may hit the valve retainer. That's just what I've heard. I never wasted my time on a big cam with these anemic heads. Tell your buddy to get a chip. Edelbrock will give you a chip for free if you can prove that you bought their whole top end kit for a few grand. intake, heads, cam, headers. That will net you about 325ft-lbs at the crank, maybe 240hp at 5000. I've done the mail-order custom chip thing. I was not impressed with the results. The truck belched black smoke like a "tuned" diesel. It got about 6mpg and didn't have the power that I was looking for. He needs to read up on it. Talk to tuners that have done many, many chips. Ask the tuner for his advice on a particular combo that he has a dead-nuts bang-on tune for. Go for the cam that a tuner suggests. Go for any part that the tuner suggests. And don't try to reinvent the wheel. These trucks are a minimum of 26 years old.. I guarantee it's been done before on the TBI stuff. Ask around, stick with stuff that works.. but tuning is an absolute must if you want anything more than a bone stock motor.
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