Blueprint Engines carb setup - help me understand
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Intermediate
Joined: Jan 2025
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Blueprint Engines carb setup - help me understand
I recently installed a Blueprint 396 crate motor in my 71 4 speed.
Engine package came with IGN and Holley 850 carb.....supposedly fresh off the dyno.
It came with a dyno curve showing 494 HP....526 lb-ft.
I installed it, and am now mostly through the 500 mile brake-in period.
I have an Innovate O2 gauge hooked up to monitor things during break in.... with a brand new O2 sensor.
Steady state driving O2 readings are 12.8-13.0 at 60-70 mph cruise.at very light throttle and 2500-2800 RPM
Full throttle runs show 9.8-10.0 O2 readings
Am only able to get 10-12 mpg, although I think it will improve some after break-in
From the little I know about O2 readings, this seem very rich
SO:
Why would Blueprint set up the carb this rich?
Was the engine dyno'd with this carb set-up? What HP/TQ number would it make if it was set up properly ?
Did they dyno it with a different carb/setup ....then richen it up to "protect" the customer from damaging anything ?
Anyone have any thoiughts?
TIA..........Gary
Engine package came with IGN and Holley 850 carb.....supposedly fresh off the dyno.
It came with a dyno curve showing 494 HP....526 lb-ft.
I installed it, and am now mostly through the 500 mile brake-in period.
I have an Innovate O2 gauge hooked up to monitor things during break in.... with a brand new O2 sensor.
Steady state driving O2 readings are 12.8-13.0 at 60-70 mph cruise.at very light throttle and 2500-2800 RPM
Full throttle runs show 9.8-10.0 O2 readings
Am only able to get 10-12 mpg, although I think it will improve some after break-in
From the little I know about O2 readings, this seem very rich
SO:
Why would Blueprint set up the carb this rich?
Was the engine dyno'd with this carb set-up? What HP/TQ number would it make if it was set up properly ?
Did they dyno it with a different carb/setup ....then richen it up to "protect" the customer from damaging anything ?
Anyone have any thoiughts?
TIA..........Gary
Race Director
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From: Corsicana, Tx
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Which 850 carb? Surprised they went that large.
What do plugs look like? I trust that more than the O2 sensor readings. You have to give the engine what it wants.
If plugs look fat, Try taking 2 jet numbers out of each end and see what you get.
JIM
What do plugs look like? I trust that more than the O2 sensor readings. You have to give the engine what it wants.
If plugs look fat, Try taking 2 jet numbers out of each end and see what you get.
JIM
Drifting
Joined: Jun 2025
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Did your BPE engine deliver with a BPE-generated parts list that includes size descriptions of ALL carb jets, air bleeds, rods etc ?
Did motor deliver with O2 data acquired during dyno run ?
Seems BPE runs a rather high-volume assembly line; doesn't make much practical sense to repeatedly make-break fuel line connections.
The dyno results are PROBABLY achieved by using a "dyno mule" test carb; Probably NOT dyno'd with the carb you purchased. Maybe, maybe Not.
Perhaps BPE did not set-up the carb you purchased. Maybe, maybe Not.
Perhaps you ask BPE for written clarification & confirmation ?
Did motor deliver with O2 data acquired during dyno run ?
Seems BPE runs a rather high-volume assembly line; doesn't make much practical sense to repeatedly make-break fuel line connections.
The dyno results are PROBABLY achieved by using a "dyno mule" test carb; Probably NOT dyno'd with the carb you purchased. Maybe, maybe Not.
Perhaps BPE did not set-up the carb you purchased. Maybe, maybe Not.
Perhaps you ask BPE for written clarification & confirmation ?
Thread Starter
Intermediate
Joined: Jan 2025
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The Blueprint package came with a Holley 4150 850cfm double pumper carb.
Plugs, and O2 sensor end are coal black......tons of fluffy back deposits, after very little run time
It really seems like it's VERY rich.. Engine blubbers a lot, won't take throttle cleanly and stinks of unburned fuel when I park it in the garage.
I'm sure (like 427hotrod suggested) that I could re-jet the carb to make it run better, but one of the positives of the Blueprint package was that it was supposed to be a proven combination.
Wouldn't it help their marketing to publish higher HP/TQ number from a properly tuned engine.?......and give the customer a better running package?
I don't have any Holley carb parts, and really don't want to invest in them, so this puts me in a difficult situation.
Juat trying to understand Blueprints marketing strategy.
Plugs, and O2 sensor end are coal black......tons of fluffy back deposits, after very little run time
It really seems like it's VERY rich.. Engine blubbers a lot, won't take throttle cleanly and stinks of unburned fuel when I park it in the garage.
I'm sure (like 427hotrod suggested) that I could re-jet the carb to make it run better, but one of the positives of the Blueprint package was that it was supposed to be a proven combination.
Wouldn't it help their marketing to publish higher HP/TQ number from a properly tuned engine.?......and give the customer a better running package?
I don't have any Holley carb parts, and really don't want to invest in them, so this puts me in a difficult situation.
Juat trying to understand Blueprints marketing strategy.
Drifting
Joined: Jun 2025
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Not doubting you when you tell us it's stank-rich & runs even worse.
Are you running the exact same fuel pump as was used to dyno motor ? Perhaps Not (same reason as dyno carb above) ? If Not; are you certain you're Not over-pressurizing (and overwhelming) the carb's needle & seat ?
Break-In: If you followed BPE break-in drill; At near 500 miles, the rings & cylinder walls were broken-in Long ago. Rings & cylinder walls produce vast majority of motors' friction.
Why not ask BPE why it is what it is ? AND, ask Exactly What BPE will do to remediate this ?
Trust but Verify; while Courteous but Firm. If it's legal in Your Jurisdiction, surreptitiously record & archive any telecon.
Read your BPE warranty closely (it's online: too bad more don't do so Pre-purchase). But, Unless you reside in State of Nebraska, BPE KNOWS few non-residents sue for less than $5-$15K. Typically, the same applies whenever there's an interstate claim; when defendant has no physical presence in claimants' home State. Often, the juice ain't worth the squeeze; Ask Your attorney.
Are you running the exact same fuel pump as was used to dyno motor ? Perhaps Not (same reason as dyno carb above) ? If Not; are you certain you're Not over-pressurizing (and overwhelming) the carb's needle & seat ?
Break-In: If you followed BPE break-in drill; At near 500 miles, the rings & cylinder walls were broken-in Long ago. Rings & cylinder walls produce vast majority of motors' friction.
Why not ask BPE why it is what it is ? AND, ask Exactly What BPE will do to remediate this ?
Trust but Verify; while Courteous but Firm. If it's legal in Your Jurisdiction, surreptitiously record & archive any telecon.
Read your BPE warranty closely (it's online: too bad more don't do so Pre-purchase). But, Unless you reside in State of Nebraska, BPE KNOWS few non-residents sue for less than $5-$15K. Typically, the same applies whenever there's an interstate claim; when defendant has no physical presence in claimants' home State. Often, the juice ain't worth the squeeze; Ask Your attorney.
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Joined: Jan 2000
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From: Corsicana, Tx
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I agree with you.....I'd ck with Blueprint before tearing into the carb. Maybe they'll send you another one?
Otherwise it's fixing what you have which won't be too terrible unless something like a main body is warped or something.
I was just cking their site and the show a 530 HP version with a 950 carb now? That one has a pretty healthy cam in it at 252/259 on a 114 LSA....but it should be tuneable just fine.
Also interesting...they say their 396 is actually a 389" due to 4" bore and 3.875" stroke. And their "383" is actually a 377"......Weird advertising.
And that 396 one says it's supposed to use 100 octane race fuel...even though it's only 10.4 compression? More weirdness.
What are the spec's on your engine?
Blueprint makes some good parts from the ones I've looked at...but haven't dug into their combos yet.
JIM
Otherwise it's fixing what you have which won't be too terrible unless something like a main body is warped or something.
I was just cking their site and the show a 530 HP version with a 950 carb now? That one has a pretty healthy cam in it at 252/259 on a 114 LSA....but it should be tuneable just fine.
Also interesting...they say their 396 is actually a 389" due to 4" bore and 3.875" stroke. And their "383" is actually a 377"......Weird advertising.
And that 396 one says it's supposed to use 100 octane race fuel...even though it's only 10.4 compression? More weirdness.
What are the spec's on your engine?
Blueprint makes some good parts from the ones I've looked at...but haven't dug into their combos yet.
JIM
Last edited by 427Hotrod; Nov 25, 2025 at 12:57 AM.
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Did it have a bit of oil in it and did the carb smell of gas. Usually they will build and dyno one combination and use those numbers for the rest of the copies. 4psi is too low somting wong.
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Thanks for all the suggestions.
Let me sort out this fuel pressure issue, and I'll get back to you.
Re: Air Cleaner question: I'm runing the big block 2' drop base with 3 1/2" paper element from Summit and a normal 1" domed top......gives 3/8" hood clearance and keeps lid a bit over 2" above carb top.
Best I could do.with 71 base hood.and 2101 Edelbrock manifold.
Let me sort out this fuel pressure issue, and I'll get back to you.
Re: Air Cleaner question: I'm runing the big block 2' drop base with 3 1/2" paper element from Summit and a normal 1" domed top......gives 3/8" hood clearance and keeps lid a bit over 2" above carb top.
Best I could do.with 71 base hood.and 2101 Edelbrock manifold.
Melting Slicks
Joined: Apr 2021
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From: Minnesota
Air cleaner doesn’t sound like the issue then. Like everyone else has said, replace the fuel pump. The chances of new parts being bad right out of the box is higher than it’s ever been nowadays.