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4150 Transition Puzzle

General engine tech -- Drag Racing to Circle Track

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63qcar
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4150 Transition Puzzle

Post by 63qcar » Mon Oct 07, 2019 6:53 pm

Carb is a BLP billet 4150 double pumper with mini annulars on an fe 482 with a fairly long cam and an MSD distributor , Ebrock CNC heads and Ebrock dual plane intake.
Problem I have been having is getting it to run smoothly from 1800 to 2500 rpm at light load ( running on transition slots at that point ) and tune goes away as water temp hits 190 F . Plugs read rich .,
Since we had 100 degree ambients last week , I decided to play some .
Carb setup was : MJ ... 76/82 P/S , IAB .... 73 P/S , HSAB .... 26 P/S , PVCR ... .061 , PV .... 10.5 , TSR .... none , IFR .... .036 P/S. Metering block are set up with 2nd , 3rd and 5th blocked and others at .026" on P/S.

First experiment was a .067 TSR . As expected , way lean and water temps skyrocketed when I ran 2700 rpm at light throttle . Went all the way up to .082 TSR before temps started looking close to normal , but even at that , they crept up in traffic at that rpm .
Took the TSR out and it ran better, but deteriorated again as I got in the 180 degree range on water temp..... and the plugs read way rich .
At a .082 TSR and .036 IFR`s , plugs are cleaning up , but it gets rougher in the 1800 to 2500 rpm range as temps increase .

Tried .077 IAB`s and overall drive-ability suffered . May try going to .070 IAB later and see what happens .

So , I can run a .075 TSR and it runs fairly clean up to 2500 rpm and then ( obviously ) starts going way lean , or I can run .082 TSR`s and it runs rough at 2500 rpm and light load as water temps hit 180 + F .
I`ve had this problem on the track also .... when I would come out of a turn at part throttle and was in the 2700 rpm rnge , the engine would miss slightly . As I rolled into WOT it cleared up .

Doesn`t make any difference if I have the PCV hooked up or not ...... suggestions welcome as I`m probably missing something that`s obvious .

mt-engines
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Re: 4150 Transition Puzzle

Post by mt-engines » Mon Oct 07, 2019 7:28 pm

long cam and a 10.5PV?
how big is the cam?

Geoff2
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Re: 4150 Transition Puzzle

Post by Geoff2 » Tue Oct 08, 2019 5:20 am

If connecting/disconnecting the PCV makes no difference, the throttle blades are probably open too far at idle.

mag2555
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Re: 4150 Transition Puzzle

Post by mag2555 » Tue Oct 08, 2019 8:03 am

What body type car is this motor in?

As under hood temps go up metering can go off base line if the fuel bowl vents are closer then 3/4 to 1 inch from the air cleaner lid or the underside of the hood, also note that today's fuel will boil at about 200 degrees and when the Carb gets that hot to start to cause the fuel to go to a vapor out the vents Tubes it gets sucked right back in to shift the once good mixture to the fat side.

63qcar
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Re: 4150 Transition Puzzle

Post by 63qcar » Tue Oct 08, 2019 10:33 am

mt-engines , I choose my PV by running vacuum , not idle vacuum . When I was road facing , I had a 3.5 pv based on 7" at idle . Car had a massive soft/lean spot at partial throttle coming out of a turn and cleared up at WOT ..... the PV was never opening since I had over 12" of vacuum at that point . Put a 10.5 PV in and problem went away .

Geoff2 .... throttle blades are at square ( about .020" ) primary and secondary .

mag2555 .... you may be on to something I hadn`t thought about . Car is a Cobra replica and tallest air cleaner I can get under the hood and still have about 1/2" clearance is a 3" Wicks . No room with that element for an insulated base gasket . I have an insulated base gasket I can put on , but will have to reduce the air cleaner height by the same amount . I`ll look later and see what I have lying around .
I have about 3/4" clearance as it is now between the vents and the lid .

Thanks for the suggestions

BobbyB
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Re: 4150 Transition Puzzle

Post by BobbyB » Tue Oct 08, 2019 12:04 pm

Just a thought... You can buy a thermocouple reader that has 4 inputs from Amazon for not much $. You can mount the reader in the car and run the tcouples to your carb...air clearer... wherever under the hood. I just tape the tcouples on with making tape or duct tape.

I have goofed with them and learned a little about underhood temps.

For example, my carb temp has been about 115 degrees F max with air temp about 90 F. My auto trans temp goes from about 165 F into the cooler and drops to 150 F out of the cooler.

My point is, Mag may really be on to something, but for a few bucks you can find out if you are at 120F or 180F. Sounds like an awesome car you have!

My427stang
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Re: 4150 Transition Puzzle

Post by My427stang » Fri Oct 11, 2019 10:38 am

I am with "start with the temp" crowd. I'd start there, If you aren't insulating the carb from the manifold on an FE, and don't have some sort of purposeful airflow, they get real hot. I ran my 489 with a 1000 HP before the EFI and it would get fussy in traffic, in my case, I put a Boss 9 scoop on the car, raised the carb and gotrid of the drop base air cleaner which acted as a heat bell and it made it better everywhere.

Is this car running turkey pan and scoop? You;d think that's keep it cooler with the carb in fresh air, if it isn't maybe that's an option.

Additionally, is the air cleaner small diameter? I like a 3 inch on my 489 but might be overkill

Now, I did one other thing too, I have fought high IFR carbs in the past, but they were Holley HPs, not sure what BLP is using. However, it's been my experience that when they shifted the IFR higher on the metering blocks, the carb got less precise with heat.
70 Mustang, 489 FE, TKO-600, Massflo SEFI, 4.11s
71 F100 SB 4x4, 445 FE, hot rod 4x4

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Re: 4150 Transition Puzzle

Post by levisnteeshirt » Sat Oct 12, 2019 8:35 pm

Is the plenum divider intact or is part of it cut out ? If not I would take it down an inch ,, if it's a billet base plate , put Holley throttle plates in it ,, most Chinese billet plates , the individual plates are not oval enough and they seem to swing by the transfer slot to quickly for them to operate correctly

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Re: 4150 Transition Puzzle

Post by Tuner » Sat Oct 12, 2019 10:42 pm

OP has BLP billet carb. The BLP base plates I have seen all are spot on, (at least with Holley butterflies, I see what you are saying about Holley vs. other butterflies) the slots are like old-school Holley, right position and right size. The APD bases I have seen were good as well.

The china stuff, eh phft, you know when you got it because the slots are too wide and too long and usually can't be tuned so the RPM and load range where the slot is most critical has the desired A/F through the whole range.

63qcar
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Re: 4150 Transition Puzzle

Post by 63qcar » Sun Oct 13, 2019 11:54 am

My427stang ... I was able to get an insulator under the carb by losing 1/2" from the Wix filter hgt. ( was 14" dia. , 3" tall ) and carb stays significantly cooler now.

Not running a turkey pan as the only filters that will fit in the pan are 8" dia and won`t flow the air I need .....already tried that. IFR`S are in the low position , however , I am running an L88 base filter housing to be able to run a Wix 2 3/4" tall element .

Intake is an E brock dual plane performer with divider intact .

I decided to put a different baseplate on it yesterday that had holes drilled in the butterflies , approx. 3/16" dia. . Vacuum at idle was in the 7" range . Adjusted idle speed and went out to play . Car ran great with only a little bucking at light throttle in the 2000 to 2500 rpm range in 3rd gear . "New" baseplate is an old Pro Systems billet one I had lying around . I checked and the TS dimensions were comparable to the BLP unit . I made no changes other than the baseplate . IAB`s still at .073 , IFR`s at .036 , TSR`s at .082" , 76/82 main jet P/S etc. Went to .078 IAB P/S and cra was much worse .

Today , I`m going to drop the IAB`s to .070 P/S and put the Wagner adjustable PCV back in and play with that some to see what effect it has . Hope to be able to dodge the thunderstorms to get enough miles on it to get a good plug read .

Really surprised me as I didn`t expect that change to have that much effect , but maybe the low vacuum is/was the culprit .I may also drop the IFR`s a thou. or so just to see what happens

BTW , exhaust has merged collectors on each side ( Cobra replica ).

63qcar
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Re: 4150 Transition Puzzle

Post by 63qcar » Sun Oct 13, 2019 11:58 am

Correction ..... holes in butterflies are 3/32" NOT 3/16" , brain fade on my part >

BigBlocksOnTop2
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Re: 4150 Transition Puzzle

Post by BigBlocksOnTop2 » Sun Oct 13, 2019 2:26 pm

What does your timing curve look like? Get the timing up at idle will help....about 26 degrees and rework the dist. for around 8-10 degrees advance. MSD distributor, better check for rotor phasing and another thing is the center electrode....they erode badly. I'm going to make one with a tungsten carbide contact to solve that problem once and for all. Higher timing at idle will increase idle rpm and vacuum because you have to lower idle rpm thus closing the butterfly and increasing vacuum, closing the transfer slot some what too...
Last edited by BigBlocksOnTop2 on Sun Oct 13, 2019 2:44 pm, edited 2 times in total.

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Re: 4150 Transition Puzzle

Post by BigBlocksOnTop2 » Sun Oct 13, 2019 2:37 pm

Pump gas mtr? I have 69 mustang, 395 cu in., 249 at .050 in., victor jr., canfields. Manifold and heads are ported but conservatively. I have an issue with a hot day with pump gas. I think it is boiling in the bowls. A Boss 9 scoop is in the future.The car gets really nasty on a hot day. I have the surge ''cruising'' down the road....you have to keep your foot very slightly in it to keep from ''trailer hitching'' (bucking). I does not do this with motor cold. I have a wide band in cylinder 5 and can move it around. Its a big cam for the street? Voodoo solid flat tappet. I think you are in the same boat as me....big cammed, pump gas motor with questionable street manners....BG annular 750 with Holley metering blocks. I done alot to this combo to help it but its as good as it gets.

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Re: 4150 Transition Puzzle

Post by levisnteeshirt » Sun Oct 13, 2019 7:19 pm

Pro systems base plates usually need Holley butterfly plates

I would cut the divider out an inch deep minimum , big motor without allot of idle vacuum , it needs idle fuel from all 4 barrels

63qcar
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Re: 4150 Transition Puzzle

Post by 63qcar » Mon Oct 14, 2019 10:48 am

Couldn`t dodge the rain yesterday , so will try today and/or tomorrow . BigBlock , your symptoms sound a lot like mine ..... and my aluminum flywheel probably doesn`t help matters .

As far as timing .... 26 degrees at idle ( 1200 rpm ) and 36 to 37 at 3500 rpm . I plan to try "locking " the distributor by some slightly stretched lightest springs MSD offers . They still pull the weights back at cutoff , but as soon as the engine fires , go to full advance . Checked with a timing light and I still have 36 degrees at idle . Yes , I know that`s not ideal , but it`s a quick and dirty way to run a test .

I may also drop the primary MJ 3 or 4 steps and increase PVCR size to see if that helps at all . When I get close , then new plugs go in to try and get some meaningful plug readings .

I also have a modified Duraspark distributor with vacuum advance I`m going to put in later this week or next . Hopefully , phasing etc were all checked out on that one when it was on the machine .

All carbs I`ve tried on this car seem to have low end problems . I`m beginning to think the merged collectors are also causing me some grief here .

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