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 Need help in Swedeen with a Edelbrock 750 #1407 
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Joined: Fri May 20, 2016 5:18 am
Posts: 117
Hello everyone. I am from Sweden and is a knew member to this site sens a little over a month ago.
Need help with a stupid pig rich impossible screwed up EDI 750 1407 carb.
It,s a friends car Elcamino -66 ore something, beautifully restored of him but hi is not an engine "master"
and the engine re builder gay obviously don't know much about carbs.
Its a BBC 460 something engine 9.5:1 ovalport heads, EDI RPM performer intake, cam is a LS6 substitute
(no specs on the cam) 1.7/8 long tubes, its a street cruiser.
First ting. Tsl and ported vacuum is way of low in the throttle bore so when blades are shut closed in the bore
Tsl are exposed .075 and with idle speed screw opened 1.1/2 turn its all ready above the ported vacuum slot.
I figure,if i am going to be able to sort out this carb att all, i have to drill "idle holes" in the blades and just open
them a touch preventing them from sticking in the bore. Need sugestion on drill size to start with.
Secondly. there is no killbleed in the primary venturi cluster emulsion fuel tube, the primary boosters start to "dribble"
just under 2000 rpm in neutral whit out loading the engine, It is so sensitive that the CH side PR booster started up a little earlier just because (i guess) the fuel level on that side was aprox. 1/16 to high. Need suggestions on killbleed size.
Oh yes, the PR boosters ends about 3/8 over the smallest diam. of the venturi like Mr.Tuner pointed out in some other
forum.
Conclusion. Need advise to drill size to start with for Throttle blade "idle holes" and killbleed in PR emulsion tubes.
PR venturi cluster specs.
Idle jet .037
Idle airbl .055
Tsr. "Economy restriction" .053
Main airbl .033
Emulsion tube correction bleeds are drilled straight true both sides of the tube
1# .026
2# .026
3# .047
4# .064
1# correct. bleed the top one, is just under fuel level in the bowl and .366" up from lover end of the tube
PR jets .110 st.up rods .071/.047
Perhaps the eminent Mr.Tuner him self can give me some advise thank you.
T.Kristiansson Sweden.


Wed Jun 29, 2016 6:34 pm
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
The kill bleed is in the aluminum casting just above the brass E-tube. They often have the brass tube pressed in too far and partially blocking the bleed hole. If you need to delay the main start you can drill another orifice in the brass tube just below the aluminum casting.

I use brass tubing to make E-tubes with a few .028" bleeds for the Edelbrock and F-M carbs with the large holes in the tubes. The large holes make the nozzle flow in blobs after it starts (you may have seen it?). I generally mimic the old OE carb tubes for hole size and location. Some OE carbs had only the kill bleed, no "emulsion" bleeds, notably 300HP 327 and the 409 carbs.

The .037" idle jet is probably why it is so rich. You can use wire (or guitar string comes in .001" steps) to restrict the idle jet.

I don't know what to say about main jet, metering rod and power piston springs, you just have to tune the individual engine as it wants.


Fri Jul 01, 2016 4:20 pm
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Joined: Fri May 20, 2016 5:18 am
Posts: 117
tuner wrote:
The kill bleed is in the aluminum casting just above the brass E-tube. They often have the brass tube pressed in too far and partially blocking the bleed hole. If you need to delay the main start you can drill another orifice in the brass tube just below the aluminum casting.

I use brass tubing to make E-tubes with a few .028" bleeds for the Edelbrock and F-M carbs with the large holes in the tubes. The large holes make the nozzle flow in blobs after it starts (you may have seen it?). I generally mimic the old OE carb tubes for hole size and location. Some OE carbs had only the kill bleed, no "emulsion" bleeds, notably 300HP 327 and the 409 carbs.

The .037" idle jet is probably why it is so rich. You can use wire (or guitar string comes in .001" steps) to restrict the idle jet.

I don't know what to say about main jet, metering rod and power piston springs, you just have to tune the individual engine as it wants.

tuner wrote:
The kill bleed is in the aluminum casting just above the brass E-tube. They often have the brass tube pressed in too far and partially blocking the bleed hole. If you need to delay the main start you can drill another orifice in the brass tube just below the aluminum casting.


OK. If one wants access to check on the killbleed you have to pull the cup plug in the cluster right?
and yes i wish to delay the main start.

tuner wrote:
I think the main problem with the carb is the miss placed Tsl and ported vacuum in conjunction with the boosters ending to far up in the venturi ( making the booster signal weaker- slower)
and with a proper adjustment to idle speed screw you will "run out of Tsl to fast and of cause with the idle running on Tsl making aidel mixscr very insensitive. Possibly why they (Edelbrock) screw the emulsion tube bleeds up getting the carb to "function" even if it is pig rich in stead of scrapping it for BAD MANUFACTURING.
"Well its a cheap carb" NO its not, its a cheap in properly function Carter carb lookalike,that takes a lot of time and money trying to tune the engine, with fouled plugs etc,
and not speaking of first all the frustration and finally anger when people look in the carb manual trying with different jets and rods and feeling enable to "fix" the rich and other problems with it.

I use brass tubing to make E-tubes with a few .028" bleeds for the Edelbrock and F-M carbs with the large holes in the tubes. The large holes make the nozzle flow in blobs after it starts (you may have seen it?). I generally mimic the old OE carb tubes for hole size and location. Some OE carbs had only the kill bleed, no "emulsion" bleeds, notably 300HP 327 and the 409 carbs.


Do the E-tubes com out fairly easy, ore you never know sort of speak. I feel that i have to start with drilling the throttle blades getting the engine idling right with the blades closed as much as possible not to expose any more of the all ready over exposed Tsl and getting in to the port vacuum slot.
Any suggestions of drill size needed to get a fair idle rpm considering the throttle blades being all closed (almost) up in the bore?

The .037" idle jet is probably why it is so rich. You can use wire (or guitar string comes in .001" steps) to restrict the idle jet.

I did my math, sticking a 0.5 mm copper wire in idle jet .037" will get me something like .0254 idle jet about 30%
area restiction. Seems to lean IMHO but i am not shore because the over exposed Tsl.

tuner wrote:
I don't know what to say about main jet, metering rod and power piston springs, you just have to tune the individual engine as it wants.


Sat Jul 02, 2016 7:27 am
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Joined: Fri May 20, 2016 5:18 am
Posts: 117
tuner wrote:
The kill bleed is in the aluminum casting just above the brass E-tube. They often have the brass tube pressed in too far and partially blocking the bleed hole. If you need to delay the main start you can drill another orifice in the brass tube just below the aluminum casting.
OK. If one wants access to check on the killbleed you have to pull the cup plug in the cluster right?
and yes i wish to delay the main start.
I think the main problem with the carb is the miss placed Tsl and ported vacuum in conjunction with the boosters ending to far up in the venturi ( making the booster signal weaker- slower)
and with a proper adjustment to idle speed screw you will "run out of Tsl to fast and of cause with the idle running on Tsl making aidel mixscr very insensitive. Possibly why they (Edelbrock) screw the emulsion tube bleeds up getting the carb to "function" even if it is pig rich in stead of scrapping it for BAD MANUFACTURING.
"Well its a cheap carb" NO its not, its a cheap in properly function Carter carb lookalike,that takes a lot of time and money trying to tune the engine, with fouled plugs etc,
and not speaking of first all the frustration and finally anger when people look in the carb manual trying with different jets and rods and feeling enable to "fix" the rich and other problems with it.

I use brass tubing to make E-tubes with a few .028" bleeds for the Edelbrock and F-M carbs with the large holes in the tubes. The large holes make the nozzle flow in blobs after it starts (you may have seen it?). I generally mimic the old OE carb tubes for hole size and location. Some OE carbs had only the kill bleed, no "emulsion" bleeds, notably 300HP 327 and the 409 carbs.
Do the E-tubes com out fairly easy, ore you never know sort of speak. I feel that i have to start with drilling the throttle blades getting the engine idling right with the blades closed as much as possible not to expose any more of the all ready over exposed Tsl and getting in to the port vacuum slot.
Any suggestions of drill size needed to get a fair idle rpm considering the throttle blades being all closed (almost) up in the bore?


The .037" idle jet is probably why it is so rich. You can use wire (or guitar string comes in .001" steps) to restrict the idle jet.
I did my math, sticking a 0.5 mm copper wire in idle jet .037" will get me something like .0254 idle jet about 30%
area resrtiction. Seems to lean IMHO but i am not shore because the over exposed Tsl.

I don't know what to say about main jet, metering rod and power piston springs, you just have to tune the individual engine as it wants.


Sat Jul 02, 2016 7:33 am
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Joined: Fri May 20, 2016 5:18 am
Posts: 117
Did not get the Quote part right i hope you can understand which is TUNERS writing and me quoting.


Sat Jul 02, 2016 7:38 am
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
Quote:
OK. If one wants access to check on the killbleed you have to pull the cup plug in the cluster right?
and yes i wish to delay the main start.

The only reason to remove the cup plug is to enlarge the nozzle passage. The kill bleed is not behind the plug.

In this image the underside of the cluster on the left has a 45 degree (approximately) rectangular area adjacent to the main well tube in the passage through the casting to the main air bleed tube on the top. The kill bleed is an orifice drilled though the 45 degree angle to the inside of the area in the cluster above the tube. Sometimes the tube is pressed in too deep and blocks or partially blocks the orifice.

Image

Quote:
Do the E-tubes com out fairly easy, ore you never know sort of speak.
The tubes usually come out easy. Heat the casting with hot tap water, or if stubborn use propane torch (wear gloves) and grasp with thumb and finger, wiggle-pull, wiggle-pull, wiggle-pull, and they come out. Same with idle tube, usually. Sometimes grasp with drill motor chuck.
Quote:
i wish to delay the main start.
Lower the float level. Initial setting with top inverted 1.5" from gasket to bottom of float.

For the idle air bypass holes in the throttles I would start with 1.5mm or 1/16" and see the effect.

The .5mm wire in the IJ sounds good for a start.

Here are some booster pictures showing different main well tubes.
viewtopic.php?f=28&t=22


Sat Jul 02, 2016 3:49 pm
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Joined: Fri May 20, 2016 5:18 am
Posts: 117
Thanks for the info Tuner. I will start with drilling "idle holes" and see what respond i get just taking one
step a time knowing what does what, then dealing with the E-tubes.
Hopefully i will then get "carby lookalike" to respond up on normal tuning procedure.
I will let you all know how it goes along.


Sat Jul 02, 2016 4:33 pm
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Joined: Fri May 20, 2016 5:18 am
Posts: 117
OK her we go. started drilling PR. throttle blades with 2.5mm "idle holes and putting a 0.5mm wire in idle jet
2.5 mm " wasn't big enough took carby of 5 times to drill in small increments ending up with 3.6mm ore .141" -9/64"
in both th-blades which gave me a god idle rpm and right th- blade position in relation to Tsl and ported
vacuum. The engine idles fine with mix-screws 1.3/4 turn out and have normal sensitivity to mix-screws.
PR boosters still starts a little to early. Drilled one .039 hole in e-tube above fuel level didn't do much.
lowered the fuel level "aprox" 5/32" and got it right on. Car idles god in neutral and gear no off idle hesitation
and is lean when cold started as it should ( carb has no choke attached at the moment)
A slightly surge up hill on steady cruise, cured with yellow step up springs in stead of blue ones, was in carb from
rich period.
This tuning was performed with out O2 WB metering or a tach just "old school" feeling what the car likes and looking to spark plugs and sneaking up from lean on it. The owner will drive the car for a week or so to get a more complete idea of how it works out.


Sat Jul 09, 2016 4:56 pm
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
Bra jobb, är det hur du gör det.


Sat Jul 09, 2016 5:17 pm
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Joined: Fri May 20, 2016 5:18 am
Posts: 117
Thanks tuner. I didn't post the whole story because my biggest issue right now is getting my english spelling and
grammar right, it just takes to much time to write everything i really would like to do.
Beside carby problems i hade to deal with the distributor (before getting on with the carby) only having 12¤ mechanical advance.
One of the advance weights had slide up on the "pin and was lying above the other weight.
I think it is another cheap Chinese product. that came with this engine.
anyway i believe i hade the distributor of 5 times before i was satisfied with the timing changing weights and springs
from old scrapped ones they hade at their shop and using the car as a test bench.
I hade a long respond to "Tach flutter" that took me 45 min to write and i lost submitting it :| , i believe it was because i got logged out taking to long writing it.


Sat Jul 09, 2016 6:55 pm
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