Racing Fuel Systems

Hi All,

I have studied 15 or so threads on T slot, emulsion, and HP1000s in general. It was terrible from Holley. After a week at it, I'm close, but lost on where to go. Street/Strip truck, 454, lots of cam overlap. Maybe 8" vac at idle. 22* initial, vac adv comes in at 4" or so [It likes it].

Carb looked to be unaltered. Note- big bypass holes in all 4 throttle plates, looks to be factory. The "piss hole" in sec side was .034 ish. Closed it to .018". HP blocks with 3 holes at .029". Top hole pretty close to elevation of old 2 hole blocks. PVRCs were .063", I drilled to .073". Kill bleed is .029".

My problem is a lean sag [16 to17-1] in the 1500-1800 light throttle range on flat ground, where the manifold vacuum gets to maybe 12". More throttle brings the mains on [I assume} and it's good.

Here's where I am. Best overall driving, snappy off idle, but gives richer than ideal cruise AFR, 12s to 13s-1. Decel about the same. Above 2000, it's decent. The #75 seems good for cruise in the 2000-3000 range

.037" IFR
.020"/.021"/.021" metering block. [better than .029"/.029"/plug].
.067" IAB
.025" MAB
#75 PMJ/.073" pvrc. Richens to mid 12.xs when 8.5" PV opens [4.5" PV = big lean sag, might end up at 6.5"].
Sec throttle closed off, front has some slot showing, apx square.

I have tried:

.071" IAB. worse
.0635" and .0595 IAB. Pretty much covers lean sag, but way rich cruise, even with .033" IFR.
.028" MAB, main seems slower.
#073 PMJ = worse sag, low rpm cruise AFR pretty good.
Tried TSR at .073, didn't help, maybe worse

I fought same issues with a QFT 950 which I traded off, rather than swap baseplates. I always had affection for the old "classic" color 1000s.

I'm going to check the timing adv in the problem area to make sure it's not over advanced and lean. It doesn't surge, just goes lean until a little more throttle is applied. [I know, lean misfire gives lean reading]

I'm all ears. Thanks

Dave

p.s. - with vac, total timing is 50 couple [37 w/o]

Sorry for the novel.

Today's exercise, fwiw;

Tuner wrote on the amount of secondary T slot exposure. Mine was covered, plate not quite closed off. I opened the rear to expose T slot to square. Front t slot just covered. Had to close front a tad more to get idle down.

Otherwise, same as yesterday, except #73 main
.035"/.037" IFR
.020"/.021"/.021" metering block.
.067" IAB
.025" MAB
#73 PMJ/.073" pvrc.

Lean sag gone, rich light throttle. Really snappy. Closed rear 1/2 turn [4781 style slot screw flipped over in baseplate]. AFR better, closed another 1/8". Better yet. Still no lean sag, but part throttle afr still rich. 12s to 13s, occasional high 11s tooling around town in slow traffic 1500-2000. Not much better 2500-3000 on flat ground.

Closing idle mix screws from 1 &1/4 to 1, then 3/4, then 1/2. Each increment gets better at 1500-2500, but less than 1 and idle gets really poor. Not happy overall.

2nd lap:
Throttle plates same.
.033" ifr all around [down from .035/.037"]
.071" IAB [up from .067"].

This made light throttle low rpm and decel RICHER, even with idle mix screws 1/2 turn out [would not run at idle]. This is the first time that I've experienced this phenomenon. Interesting. I went back to .067" IAB with the throttle plates the same, will drive tomorrow.

Might have to eat crow and try some old 2 hole metering blocks.

Thanks

What was the issue with the factory Holley settings?

Helps to gauge the changes you have made up to now.

RHD,

A dozen or more threads on the later HP and XP indicate that the high ifr, too big stock air bleeds and three or five .029" hole metering block setups is bad. I didn't see much sense in trying it.

I hope to tinker more tomorrow.

Thanks

Agree that the generic calibration from Holley is less than ideal for most. Despite that I find it useful to run it factory settings to begin with to ascertain a baseline and target which circuit needs working on first. You may well end up back where you are now, but starting with factory settings and building a good tune from there one change at a time and documenting the affects of each change will be an easier path to success for your engine.

I would hazard a guess that emulsion and mab have gone too small but hard to know for sure without knowing the default condition.

I am always rebuilding and tuning Demon carbs that may well have a worse starting point than yours but I always run them first to get that baseline.

Links to the other 80514 tuning threads? I've built something similar, but my baseline settings for the yet-to-be-tested carb are "sort of" in between what you're trying and the original Holley settings.

I'm a bit surprised at how lean your jetting is, at least on the primary side. I know the factory 80514 pri was 84, and the older 9380 annular 850 w/ the standard main body was 78. Guess there's a big "It depends" here re tune and application.

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Street manners for this carb will be secondary to on-track performance... but it wouldn't hurt if it could be left on for street use. What I suspect is it's going to be too fat for typical "cruising" conditions, though.

Used Braswell / Holley cast zinc HP 1.59” v x 1.75” t 2-circuit main body (marked “RYR”… from the mid-2000s? assuming Robert Yates Racing)
- QFT .160” annular booster banjos reamed to .165” to reduce step from booster entry
- QFT annular billet .600” x 12-hole inserts
- IAB .072”
- MAB .032”
- Drilled & tapped main body for 8-32 x 1/8” TSRs and installed .081” restrictions
- Accel pump nozzles .035”

Used Braswell-machined Holley cast HP base plate w/ bronze shaft bushings
- Assembled w/ QFT high-flow (slabbed) shafts, nylon shaft ribbons, Braswell screws, Holley .120”-hole plates, and BLP adjustable secondary idle bracket
- Transfer slot dimensions are .250” x .029” on all four bores (longer and wider than typical OEM Holley)
- Primary plates opened 1/2 turn to expose ~ .040” transfer slots; secondary plates opened 1/4 turn just barely uncover the transfer slots while keeping the plates from sticking on the bore
- 30 cc pumps pri & sec; pri green cam 2/2; sec orange cam 2/2

Holley SP 2C billet metering blocks (pre-drilled emulsion, but replaceable IFRs and PVCRs)
- Angle channels .160” as machined
- Tapped for lowered IFRs w/ .035” 6-32 x 1/8” restrictions
- Drilled / tapped & plugged #2 & #5 e-holes w/ 4-40 x 1/8” set screws, leaving #1 & #3 w/ original .0276” holes (a.k.a. “traditional Holley 2-emulsion config”); #4 positions were left undrilled by Holley, although I attempted to drill through one of them and snapped off the end of the pilot bit, then plugged it w/ 4-40 screw to play it safe
- Siphon breaks opened up to .026”
- Primary 4.5” 4-port power valve, secondary plugged
- Primary PVCRs .059”, secondary plugged
- Holley jets primary #82, secondary #92 on extensions

Braswell Fuel Chute Lite bowls
- .130” Braswell / QFT conventional N&S
- Braswell “Street / Strip” series standard primary & notched secondary floats

Gents,

Sorry for the delay. It's raining here [we really need rain].

RHD, I do regret trying it as from Holley, just for fun.

Brad, I have read that the large jets in later holleys are req'd because of the over-emulsify practice on them. Tuner wrote that the annular will take several jet sizes smaller for good cruise afr, vs the dropleg 80514. I have the primary PVRCs at .073", which with the pv open, is about the same as an #84 and a .067" pvrc.

Here are threads on the old board, and ST, although, none on the 80514 specifically:

https://www.tapatalk.com/groups/racingf ... 6ec50667cb
https://www.tapatalk.com/groups/racingf ... 445#p22445
https://www.tapatalk.com/groups/racingf ... -t671.html
https://www.tapatalk.com/groups/racingf ... t2463.html
https://www.tapatalk.com/groups/racingf ... t1640.html


Old 9381 annular choke horn 850 viewtopic.php?f=5&t=155

850 ultra xp
https://www.tapatalk.com/groups/racingf ... t1776.html
https://www.tapatalk.com/groups/racingf ... 703#p14703

I have links saved to threads on T-slot, emulsion in general, kill bleeds, metering blocks, 2 corner vs 4 corner, reverse idle on secondary, and other subjects. [4781s too]

I will fool with it tomorrow if it stops raining.
Thanks.
Dave

Interesting info above, thx.

Also surprised(?) that I've posted in the past on a number of those links you provided.

Finally a dry day.

Discouraged, tried an ole full choke horn 4781 to compare. Secondary disconnected.

.025"/.070" air bleeds
.033 ifrs
#77 pmj, .073" pvrc, 5.5" pv, #88 smj
3310 blocks, 3 at .029",.028" kill in pri, none in sec. Sec side converted to reverse idle.
Best with pri screws out 2+ and back side seated.[rich]

Same rich light throttle cruise 1200-1500 ish and and decel, although not as bad. Some lean sag above that at times. A lean on the mains

Went to .037" ifr, and #79 pmj.

Best throttle response yet. No lean sag. Pri screws still 1.75" out, rear seated. Dinking with t-slot exposure would change off idle afr some, but not markedly.
Note - I believe that my thinking that a larger iab made the hp1000 richer was a misconception, due to altered throttle plate position at same time]

I'm stumped. Of course, I want to, and will put the hp1000 annular back on.

Neither carb has overly long transfer slots. What to do? Try way bigger iab to see if it'll lean it in the problem area? Like .076"? [vs .070"]

Get that annular, put it back to factory settings, screw it down to the big block, put some tape over the AFR gauge and go for a drive. Just go for a good drive taking mental notes on drivability. THEN take the tape off the gauge and observe. Too rich or lean everywhere then adjust mj’s and repeat first step. When MJ is in the ballpark then start looking at what bleeds may need tweaking to improve the curve.

Why am I telling you this? Because I went through the same with an annular of the same size but brand ‘D’. I read all of those threads too and was convinced there was too much emulsion, mab etc, etc. I was a slave to what the AFR gauge was telling me in conflict to what my butt meter was telling me with each change. I narrowed the tune down to

MJ pri 76 sec 85
Mab .025”
Iab .071”
IFR .033”
Emulsion .025” X .020” X X
PVCR .059”
Squirt .035” pri/sec
blue cam pri orange sec
Pv 8.5

(The above and all below have .028” kill bleed)

Gauge readings were nice and steady and where ‘I’ wanted them to be.

Put it on a chassis dyno to confirm WOT AFR. Dyno operator said he didn’t have to touch a thing, great job and only changed me half price.

I then moved onto another carb to tune. Exact same carb dimensions but downleg. My plan was to tune both these carbs like the forums say and then hit the track to see what will be the best performer down the 1/4. This is a Street/Strip car like yourself.

I start with lowering the IFR on the downleg and doing some light throttle cruising to size the lower IFR in the ballpark. One step at a time scenario. All the while the .031” X .031” X .031” emulsion as factory and .031” mab were in there.
I had the main jetting in the ballpark. Went for a few drives like that and gave it a boot full a few times. I thought the AFR could look better like the annular so followed the recipe so often espoused of mab .028” and emulsion of .028” X .028” X X.
AFR certainly cleaned up. I wasn’t convinced it performed any better but the gauge told me it was better. Nice, reasonably flat and steady AFR readings. It was accomplished by

MJ pri 80 sec 89
Mab .028”
Iab .070”
IFR .031”
Emulsion .028” X .028” X X
PVCR .063”
Squirt 35 Pri/sec
Cam blue pri pink sec
Pv 8.5

I was happy because the gauge readings were happy.

I then moved onto a 750cfm downleg of the same brand and type. This was mostly due to needing something to do during so much time at home with covid lockdowns to varying degrees. The 750 ended up the same as the 850 downleg above except main jetting and pvcr. I was curious as to what it would be like if it did have a similar calibration to those Holley HP’s and XP’s that get a hard time, just for curiosities sake. So I upped the mab to 33 and added a bottom emulsion for a .028” X .028” X .028” stack. Well, one thing that was undeniable is throttle response was improved and it only needed .031” squirt and pink cams. I left the bottom e-bleed in but returned to .028” mostly because I had it in my head “33 is too big!”.

Next was a Race Demon I managed to get my hands on with a few different sized sleeves. I liked the thought of the gold 1.500” venturi sleeves. Boosters are downleg. While going through the tuning of that and questioning whether x2 or x3 emulsion is the way to go I got some good advice from a knowledgeable guy on this forum to put an over sized mab in (.050”) and then test different emulsion stacks observing AFR curve. When the combination is found that is suitable then begin trialing mab to find what size stabilizes afr best or takes the ‘chop’ out. Something absolutely undeniable is that when I had the .050” mab in there the bigger I went on emulsion the better the engine performed, especially response to throttle angle changes. For the curve I settled on emulsion of .031” X .028” X .025”. MAB .033”. It only needs squirt of .031” and pink cams both ends. This carb is dynamite and is certainly going down the quarter when it re-opens.

Because the AFR darling was the annular it was put back on for street duties. What a dud compared to the gold sleeve downleg Demon! I thought stuff it, I’m going up in mab on this sucker! As I noticed as I went up step by step on the Race Demon from .028” performance improved. Went up to .031” and then .033” on the annular and sure enough the car felt better. I then went the whole hog and replicated the same emulsion as the 975 (gold sleeve) in the annular. That woke things up!! With a little more tweaking of jets and bleeds the AFR in general is close to where it was with all the tiny bleeds but just a little more erratic on the gauge but I will take that any day for the far better performance it gives me in my Street/Strip car. Done the same with the 850 downleg and hey presto! made the previous old school type calibration seem like an old man with a walking frame.

After my life story from what I have observed is if you want to satisfy AFR readings then old school Holley calibration is the way to go, can’t deny that. All the theory of continuity of mains delivery etc is solid in practice. If you want the best performance out of your street/strip vehicle then don’t be afraid to experiment with larger emulsion and mab. You can arrive at similar AFR but what becomes clear is an AFR number alone does not always equal the same result. Same AFR number with fuel delivered to the cylinder in a different state = different outcome. It seems to me Holley, Quickfuel etc aren’t stupid with their high performance calibrations, they just need a little fine tuning to the individual application. You go to OE calibrations for engines far from OE specs and you may well be short changing that engine of its potential.

I know there will be some picking apart what I have said above but having trialed all of them there is no way you could convince me old school calibration is better than the newer in the high performance stakes.