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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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 Posted: Sun Aug 08, 2010 8:23 pm Post subject: Cant seem to get enough fuel |
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I modified my own carbs on my jet boat after converting it to E-85 late last fall. My wideband reads 13.1-13.4 at wot and I cant seem to get it fatter. Do I need to change my boosters? Any ideas would be great.
Engine is a blown 388 sbc with twin 750 holley carbs. Aluminum heads, roller cam, yadda, yadda, yadda, you get the drift.
I have modified the metering blocks a few different ways. I have drilled out my power valve restrictors, (I have stock power valves, not high flow ones) drilled out the main jet passages and removed the orifices inside of them. The carbs have removable air bleeds.
Idle and cruise are just fine, just lean WOT. Thanks for any help. |
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murphinator
Joined: 08 Jan 2010
Posts: 93
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| Posted: Sun Aug 08, 2010 10:32 pm Post subject: |
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there are a few e85 carb gurus on this forum - hang tight and they will answer your questions 
_________________
PB's 1/4 mi 12.209, 117.75 trap ,1/8 mi 7.76 ,93.99 trap , 1.949 short time 4.53 0-60
I tune with HP Tuners software |
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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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| Posted: Mon Aug 09, 2010 7:35 am Post subject: |
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| I ordered some high flow power valves last night, hopefully they will help a little. |
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newalky
Joined: 30 Sep 2008
Posts: 84
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| Posted: Mon Aug 09, 2010 9:23 am Post subject: Re: Cant seem to get enough fuel |
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| slowboy0 wrote: |
I have modified the metering blocks a few different ways. I have drilled out my power valve restrictors, (I have stock power valves, not high flow ones) drilled out the main jet passages and removed the orifices inside of them. |
You will need E-85 specific metering blocks, they have more mods than what you have done to your GAS blocks.
I would and DID have the boosters changed also.
Mark Sullens (DragChevette) did mine and I am happy with the results.
newalky |
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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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| Posted: Mon Aug 09, 2010 11:03 am Post subject: Re: Cant seem to get enough fuel |
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| newalky wrote: |
You will need E-85 specific metering blocks, they have more mods than what you have done to your GAS blocks.
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I copied my friends e85 metering blocks. I am positive that metering blocks are not needed, all of the circuits have been modified. The only restriction I can see would be the power valves and the down leg boosters.
I was just wondering if everybody is replacing the boosters and/or high flow power valves. |
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ajcasini
Joined: 04 Mar 2009
Posts: 15
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| Posted: Mon Aug 09, 2010 8:16 pm Post subject: |
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Yes I would replace the boosters. This will give you the added fuel you need at WOT. Also if you havent done so yet I would change the air bleeds. Woudl put 026 in the HSB and 060 in the IAB for starters. If the wideband still reads lean try an 025 HSB. If still reading lean you would need to replace the boosters. I would go with .170 boosters in the carb.
AJ Casini
ajcasiniracing@hotmail.com |
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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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| Posted: Mon Aug 09, 2010 9:18 pm Post subject: |
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I was planning on messing with the air bleeds next time I take it out. Just was not sure if they are going to help enough. I really dont want to send in my carb main bodies right in the middle of boating season. I have the tool for installing larger boosters, but I cant find anybody that will sell them to me anymore. Sounds like most of the companies dont want the liability.
Thanks for the help, Ryan |
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89shortbox
Joined: 04 Nov 2007
Posts: 153
Location: Michigan
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| Posted: Mon Aug 09, 2010 10:31 pm Post subject: |
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As was said above. If you didnt go with a smaller HSB than what was in it for gasoline than you need to go smaller. .025-.028.
What is your jetting and your PVCR sizes.
_________________
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89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season. |
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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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| Posted: Tue Aug 10, 2010 7:37 am Post subject: |
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| I did change my high speed air bleeds to a smaller size, but I dont think they are as small as you are recommending. My jetting is at 99 all around, I cant remember off the top of my head what I drilled the power valve circuit restricters out to. I have that written down somewhere and will check. I know the last time I stepped that size up (by one numbered drill) it didnt make any difference in the WOT tune like it had previously. I would really like to lower my jet size a little to lean out my cruise just a little. I think changing the high speed air bleeds will help. |
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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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| Posted: Thu Aug 12, 2010 2:05 pm Post subject: |
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| The Quick Fuel high flow power valves came last night. These sure do look like they will dump alot more fuel than the stock holley ones. If the weather holds out, I will get them tested tonight. |
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89shortbox
Joined: 04 Nov 2007
Posts: 153
Location: Michigan
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| Posted: Thu Aug 12, 2010 8:09 pm Post subject: |
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I just realized you have two holleys on this setup.
99 square. Holley crap!!
Are your power valves reference below the blower?
_________________
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89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season. |
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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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| Posted: Fri Aug 13, 2010 7:41 am Post subject: |
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| 89shortbox wrote: |
Are your power valves reference below the blower? |
No they are not (at least not at this time). I dont seem to have a reason to boost reference them at this time. They seem to stay open at WOT. |
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89shortbox
Joined: 04 Nov 2007
Posts: 153
Location: Michigan
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| Posted: Fri Aug 13, 2010 10:39 am Post subject: |
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| slowboy0 wrote: | | 89shortbox wrote: |
Are your power valves reference below the blower? |
No they are not (at least not at this time). I dont seem to have a reason to boost reference them at this time. They seem to stay open at WOT. |
Ok. Maybe there isnt a restriction causing vacuum with the two carbs.
But damn I would think two dead stock holleys jetted that high would be able to cover the fuel requirement even if they werent modified.
A normal conversion for e85 on average takes 82-86 primary and 92-96 sec. jet with a .078 pvcr. Im not figuring it mathmatically here right now but it just sounds like you arent getting any PVCR fuel.
Other wise something else is wrong.
I convertered a 750 with quickfuel metering blocks and didnt change the boosters. It wasnt a complete conversion. With 72p 96s and .090 pvcr I was getting 12.5 afr with the factory HSB. With 82p 96s I got the same afr. Went smaller on the HSB bleed and got 11.5 .
_________________
----------------------
89 S10
406 SBC Twin Turbo BT
Going E85 this coming season
HAHA, the season is alreay gone to another season. |
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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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| Posted: Fri Aug 13, 2010 12:59 pm Post subject: |
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Keep in mind with two carbs the vacuum signal is going to be much worse than with a single carb.
By buddies boat has a twin turbo small block with a single carb and he didnt have near the problems that I am having. But than again, he has a single cab and it is in a blow through application.
Im also pretty sure after reading on here that the high flow power valves are going to help. |
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slowboy0
Joined: 08 Aug 2010
Posts: 14
Location: Duluth
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| Posted: Sun Aug 15, 2010 9:28 am Post subject: |
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I took the boat out yesterday afternoon for a test drive with the new high flow power valves installed. Cruise was at 10.1-10.5, WOT was at 13.1
I measured my PVCR's and they are at .080, I am going to jump them up to .091.
The HSB's are at .030, I am going to drop them down to .025's and .026's.
Hopefully this will fatten it up at WOT, then I can drop down my main jetting to get it to cruise leaner |
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