tbi intake question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cmax87v3500 · 03-04-2013, 06:52 PM

so i have a 1987 gmc v3500 with a tbi 454. it came stock with the carb intake with the gm spacer to make the tbi fit. this spacer has coolant running through it. i just got the edelbrock performer tbi intake for it, and it has the same provisions for the coolant to run into the intake just below the tbi. my question is, what is the purpose to have coolant running through the intake in this area? it seems to me that it would not help performance because it would heat up the air, and i thought a cooler, more dense air fuel mixture was better. any ides on wheather or not this is needed? i cant see any reason, except maybe on cold startup, i was planning on just plugging the coolant passage through the tbi base area off and routing the coolant like a carb 454 would have it. any info would be great, thanks in advance!

Ziegelsteinfaust · 03-04-2013, 07:52 PM

For cold weather operation to keep the intake from icing up as I understand.

rfmaster · 03-05-2013, 01:14 AM

For 87 to 90 BBC TBI GM used a stock pile of cast iron (CI) Q-jet intakes with the well known plumber delight adapter plate. For 91 to 95 GM switched to aluminum intake. Aluminum heats up faster and it was a dedicated intake for Gen 5 BBC. Rumor has it that GM had a stockpile of Q-jet intakes and when they could not emission certify BBC with a carb for 87+ models they went with a bigger TBI on top of Q-jet intake.

//RF

cmax87v3500 · 03-05-2013, 03:00 AM

maybe i have you confused, i understand the cold weather idea behind the coolant running below the tbi (thanks Ziegelsteinfaust) but what i'm wondering is, cold weather aside, would it be possible to plug this coolant passage and just plumb the coolant like like it is on a carb intake?

Tx Firefighter · 03-05-2013, 08:37 AM

I plugged all that junk on my 88 model 454. My heater hoses are now run just like traditional engines always did. No problems that I can tell.
Posted via Mobile Device

wyattglock · 03-05-2013, 10:33 AM

I bypassed the baseplate on my tbi 454. No problems at all when it is cold out. I also opened up the air cleaner so it is now a 5" tall open element filter, still no freeze up problems and it has been that way for 2 years now.

cmax87v3500 · 03-05-2013, 03:41 PM

thanks guys! thats the answer i was looking for, thats probably what im gunna do now too! thanks again!

03-04-2013, 06:52 PM	#1
cmax87v3500 Registered User Join Date: Apr 2012 Location: Wenatchee Washington Posts: 102	tbi intake question so i have a 1987 gmc v3500 with a tbi 454. it came stock with the carb intake with the gm spacer to make the tbi fit. this spacer has coolant running through it. i just got the edelbrock performer tbi intake for it, and it has the same provisions for the coolant to run into the intake just below the tbi. my question is, what is the purpose to have coolant running through the intake in this area? it seems to me that it would not help performance because it would heat up the air, and i thought a cooler, more dense air fuel mixture was better. any ides on wheather or not this is needed? i cant see any reason, except maybe on cold startup, i was planning on just plugging the coolant passage through the tbi base area off and routing the coolant like a carb 454 would have it. any info would be great, thanks in advance! __________________ 1987 GMC V3500 Sierra Classic

03-04-2013, 07:52 PM	#2
Ziegelsteinfaust Registered User Join Date: Dec 2012 Location: Temple City Posts: 3,628	Re: tbi intake question For cold weather operation to keep the intake from icing up as I understand.

03-05-2013, 01:14 AM	#3
rfmaster Registered User Join Date: Oct 2003 Location: OC CA Posts: 1,374	Re: tbi intake question For 87 to 90 BBC TBI GM used a stock pile of cast iron (CI) Q-jet intakes with the well known plumber delight adapter plate. For 91 to 95 GM switched to aluminum intake. Aluminum heats up faster and it was a dedicated intake for Gen 5 BBC. Rumor has it that GM had a stockpile of Q-jet intakes and when they could not emission certify BBC with a carb for 87+ models they went with a bigger TBI on top of Q-jet intake. //RF __________________ "The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17)

03-05-2013, 03:00 AM	#4
cmax87v3500 Registered User Join Date: Apr 2012 Location: Wenatchee Washington Posts: 102	Re: tbi intake question maybe i have you confused, i understand the cold weather idea behind the coolant running below the tbi (thanks Ziegelsteinfaust) but what i'm wondering is, cold weather aside, would it be possible to plug this coolant passage and just plumb the coolant like like it is on a carb intake? __________________ 1987 GMC V3500 Sierra Classic

03-05-2013, 08:37 AM	#5
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Re: tbi intake question I plugged all that junk on my 88 model 454. My heater hoses are now run just like traditional engines always did. No problems that I can tell. Posted via Mobile Device

03-05-2013, 10:33 AM	#6
wyattglock Registered User Join Date: Jul 2010 Location: Lafayette, IN Posts: 622	Re: tbi intake question I bypassed the baseplate on my tbi 454. No problems at all when it is cold out. I also opened up the air cleaner so it is now a 5" tall open element filter, still no freeze up problems and it has been that way for 2 years now.

03-05-2013, 03:41 PM	#7
cmax87v3500 Registered User Join Date: Apr 2012 Location: Wenatchee Washington Posts: 102	Re: tbi intake question thanks guys! thats the answer i was looking for, thats probably what im gunna do now too! thanks again! __________________ 1987 GMC V3500 Sierra Classic



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