Do throttle body or carb spacers actually help?

[ucs75]

I was once told that if it didn't come with one from the manufacturer then the engineers didn't think it was necessary. Kinda like those Tornado devices for carbs years ago, waste of money.

Perhaps not a universal truth....
Those engineers also left out well over 200 HP with similar MPG, and daily driver reliability on 87 octane (IMO)

 

[Johnny Atomic]

I was once told that if it didn't come with one from the manufacturer then the engineers didn't think it was necessary. Kinda like those Tornado devices for carbs years ago, waste of money.

I think that there is a lot of truth in this, but you also need to remember it had to work in all sorts of circumstances, from Alaska to AbuDabi. Cold and Hot. And also had to deal with either a leadfoot or a granny driving it. So there definitley had to be engineering comprimises made. I doubt a spacer would make a significant difference in horsepower due to changed air flow. But I would bet money it would change heat transfer characteristics, especially when changing from a thin gasket to a thick phenolic spacer. And I could see an aluminum spacer changing heat transfer as well. Whether these changes are good or bad i'd say it probably depends on the situation. I have more summer heat problems than cold winter problems where I live, so i put a 1/2 phenolic spacer on mine, it may have made a small difference but not significant by my experience.

 

[ma3600vz]

not so much for carb spacers but for tbi one any claims of a mileage increase is BS and so is the 5-15 bump in horsepower and torque imho there is a power and torque increase but the numbers given are not right there is also a very mall increase in plenum volume as well that is most likely the best thing also there is a change in throttle response and I would say that mpgs do not change but some people will actually see a loss in mileage because they keep putting their foot in it looking for crazy gains that will never come

also for tbi get the injector pod spacer as well

as for as carb spacers go throttle response change is likely plenum volume increase is all I have never seen any carb spacer claiming to increase milage or a bump in horsepower or torque like the tbi spacers do

 

[xm20k]

All the testing I've seen was with 400Hp or greater engines turning up in the 6000+rpm range and with that they still see single digit and low 2 digit (5-20) numbers. Putting a spacer on anything street driven even if it's beat on is probably a waste of money as far as performance is concerned. Save your money and put more gas in it or change your oil.

You'll see a bigger change in the type of manifold you run before you'd ever notice a spacer. Heck freer flowing mufflers would probably make more power in the cursing/freeway speeds most people would see.

Note I'm not talking about the nonmetallic spacers used to prevent the fuel in the carb from boiling.

 

[mtbadbob]

I'm running a Helix spacer, high-pressure fuel spring, pod spacer and I ground the ridges off the air inlet ports of the TB. I'm running a super-single Flowmaster w/3" pipe from cross-over back. All this has made a moderate difference, but nothing neck-snapping or any big increases in mpg. It just runs better than stock.

 

[Casca2525]

I tend to go with the dryer duct, big factory air cleaner, but because my truck sees as much cold as hot I leave the stove doors, vacuum thermostats, etc., in place and build a stove for both sides to wrap around a header tube, but I think the only gain is winter drivability, if i do see a gain its mpg due to the faster smoother warmup

 

[Ricko1966]

Perhaps not a universal truth....
Those engineers also left out well over 200 HP with similar MPG, and daily driver reliability on 87 octane (IMO)

They left 200hp on the table on what? People won't gain 200 hp with an intake,carb and headers,most won't even with a cam change. So please tell us about this 200hp left on the table.

 

[bucket]

They left 200hp on the table on what? People won't gain 200 hp with an intake,carb and headers,most won't even with a cam change. So please tell us about this 200hp left on the table.

I'd guess more compression and much better flowing heads. Power was left on the table by not utilizing those items as well, lol.

 

[xm20k]

Perhaps not a universal truth....
Those engineers also left out well over 200 HP with similar MPG, and daily driver reliability on 87 octane (IMO)

It wasn't that they just lowered power in the early to mid 70s for no reason it was regulation and the switch to unleaded gas and lower compression ratios because of it.

 

[Frankenchevy]

I never used one, but I know they made them. All my TBI stuff got an injector pod spacer, advanced timing and then I called it good.

Assuming procedure is the same as stock, but not setting to 0—what do you set base timing to?

 

[bucket]

Assuming procedure is the same as stock, but not setting to 0—what do you set base timing to?

Anywhere from 8 to 12 degrees advanced, depending on truck use and engine health. 8* is pretty darn safe though.

 

[Frankenchevy]

Anywhere from 8 to 12 degrees advanced, depending on truck use and engine health. 8* is pretty darn safe though.

More for power, efficiency or a little of both?

I guess the factory calls for zero to reduce NOx. I wonder if the increase in HC from advancing the timing will have any ill effect on the cat?

Edit:
This thread is interesting— https://www.gmt400.com/threads/tbi-timing-advance-for-max-power.26378/

I wonder if “some other guy” has a lot of carbon buildup in the engine he was working on…

 

[Ricko1966]

More for power, efficiency or a little of both?

I guess the factory calls for zero to reduce NOx. I wonder if the increase in HC from advancing the timing will have any ill effect on the cat?

Edit:
This thread is interesting— https://www.gmt400.com/threads/tbi-timing-advance-for-max-power.26378/

I wonder if “some other guy” has a lot of carbon buildup in the engine he was working on…

People advance them,but the computer just pulls it back out if you leave it on a scanner. Whatch your knock counts. I'd try 8 I'd also try 4 and 2 and see where things felt best. TBI heads get good milage because they don't need as much total advance for a complete burn. Due to atomization and velocity. The engine has fight past the early advance so actually making negative work. For best mpg you want minimum timing that has best power. I time it. I start low and check mph at a measured distance 1/8 mile or less keep bumping the timing 2 degrees at a time and checking trap speed. You fastest mph with lowest timing setting,for best mpg and power. You can just start where ever and play with it occasionally until you find the mpg sweet spot,that will be best torque also.

 

[bucket]

More for power, efficiency or a little of both?

I guess the factory calls for zero to reduce NOx. I wonder if the increase in HC from advancing the timing will have any ill effect on the cat?

Edit:
This thread is interesting— https://www.gmt400.com/threads/tbi-timing-advance-for-max-power.26378/

I wonder if “some other guy” has a lot of carbon buildup in the engine he was working on…

Can't say on emissions, never had to deal with that.

In my experience with the TBI small block engines in in the cars and trucks, there is an obvious difference in overall power and livelyness, compared to 0* advanced. Fuel mileage may increase slightly, but not enough to accurately record. I have a hunch that it has an ill effect on emissions and that's why GM did that.