LS 80Vette

I realized my stall was too low after I tried doing brake start at 2000 or so....my stall would be a pain to change it, would need to drop the rear to get the drive shaft out of the way to pull the tranny......does the low stall affect the carb ?

gkull

I had a 700R4 in my Vette for nearly 20 years. If your drive shaft was shortened to about 29 1/2 inches it gives the tail shaft some in and out movement. So to pull the tranny is pretty simple. I was doing it at home with just two floor jacks.

Remove the tail shaft ujoint
Remove the speedo cable off the side of the tranny
Remove the TV cable
Support the engine on the rear of the oil pan with one floor jack
Support the tranny at the balance point near the front of its pan.

I cut two 6X8 inch pieces of plywood to protect the pans from denting

Unbolt the tranny from the rear cross member and the cross member from the car frame and move it out of the way.

Lower the tranny and rear of the motor to give you room to get the bell housing bolts out of the block.

Many years ago I modded my cross-M to let the exhaust pass under. So I wouldn't have to screw with the exhaust ever time I pulled the tranny. I used 3500 and 3800 stall efficient converters and a 4.11 rear end

http://www.corvetteforum.net/c3/gkull/

augiedoggy

Interesting, I've always read the elelbrocks were generally lean and conservative out of the box.
Not sure how mild your 883 is but I think if you don't plan of driving over 5,500rpm you'all get a more responsive, reliable running engine if you stick with something in the 700-750 cfm range.
Its true the Holley 750 DPmay have the best WOT power but I bet for everyday driving the smaller Carb would behave a lot better
Edit went back and read op's specs and changed recommendations.

gkull

Edelbrock makes economy minded and performance minded carbs. The posters carb is super rich out of the box because they think it was going on a single plane BBC with a big cam.

http://www.edelbrock.com/automotive_...erformer.shtml

scottyp99

Most of us have never been to Alaska, and have the pre-conceived notion that it is a big, frozen tundra, but the truth is that the very southern portion of Alaska enjoys a climate similar to the Pacific northwest, if a little colder. A friend of mine drove a motorcycle to Alaska, on that "highway" going through Canada, (quotation marks meant to impart a sense of irony, as there are big parts of the "highway" that are still just a dirt road!) and he says you can't really appreciate the beauty from pictures and video, you have to be there to see it.

Gkull, the OP is using a Performer RPM Airgap, I believe, and it has a pretty good sized chunk of the divider cut out. Do you think that this will have a major effect on carb choice?

Here is something else to think about:

http://www.summitracing.com/parts/su...50vs/overview/

Scott

gkull

The key is vacuum secondary and how small the plenum and runner volume is.

Really what is 750 cfm vs 800 you would only maybe have a minor difference in primary throttle bore diameter.

I also only had single plane intakes on 355ci with my 750 Edelbrock carb. I probably put 70,000 miles on it in 10 years and 100 upon 100's of runs down the drag strip. It was just a learning curve to figure out.

To the poster do you have the 1711 carb or the thunder AVS?

LS 80Vette

the #'s on it say 1413/1423 say its a performer series 800 cfm

gkull

Okay I will do a little research. Do you have any other jets and rods? do you have a vacuum gauge and a dial back timing light?

keithinspace

Everybody wants theirs to be the biggest, most hairy-chested thing on the planet...then overlook the obvious.

A 650 Double Pump is a very solid carb for a 350 or 383 engine, volumetrically. You'll give up a very tiny amount beyond 6,000 RPM, but if your engine can't run up there, you're not giving up a thing.

Also, the Annular Boosters give even more 'spunk' to the low end because of the better atomization. If you go with a 4-corner idle circuit, there is great control and LOOOTS of low end bite when you need it.

I chose a QuickFuel 650 DP Annular Booster carb and it is an awesome piece.

terrys6t8roadster

yes it does, not smart enough to give the technical reasons why. my 69 300hp running a spreadbore with th400 trans which I presume has a low stall, hesitated all the time. fix was changing the plastic cam for the accel pump. hurray for the holley platform and it adjustability and every speed shop carries parts.

gkull

These are all true statements, but the best thing would be the $8000 8 stack EFI system.

The true answer though is to get the existing 800 working the best it can

LS 80Vette

It would be nice to get the 800 running right, if we can and save some $$...It suppose to work with my set-up, but not as it sets now because I don't use the 383 to it's full potential...so as the carb is set up now I feel it's an overkill...I just got tired of messing with it, and was looking for the easy way out...I'm wiling to give it a try with some help

Yes, I do have a Vacuum gage and a back timing light, and I have a jet and rod kit...

My Tri-Y headers are due in on Friday, So I will need to install them and the Pypes system, and mod the connection to the headers, then I can start to tune the carb to the new set-up.....

Since I work 2nd shift, I'm kinda limited to only the weekend

By the way, my name is Lee

gkull

Us guys with the nice front ends have to stick together.

Right off the bat. I think from what you said you have a hot h-flat edl cam and heads. Your max timing should end being less than 36 degrees @3200 rpm. So set your timing at 3500 rpm to 36 with the vacuum advance disconnected. Where idle falls it falls unless you recurve your dizzy to limit the max mechanical.

The hotter your cam the more initial you need. so if at 850-900 rpm idle it is 12+ great more like 18 is even better.

From the Edl. online charts do the rod and jet change to 12% less on cruise and 6% less on the full power. I'm just doing a wild *** guess
because you are 2300 miles away. If idle is gas smelling exhaust. Your have the idle screws.... engine hot vacuum gauge on the full vac port adjust your screws to max vac. like 1 turn from lightly closed is where you should end up. To get the idle correct A/F you might need to drill a .125 hole in the primary throttle blades just like all Holley carbs


I ended up making tapered rods like a Quadra jet. Edl rods are stepped and have an abrupt fuel curve AF change.

LS 80Vette

So I will do the jet and rod change 1st, and pre set the mixture screws, and if I got you right ... drill a 1/8 hole in the primary throttle blades.

gkull

If you can't get the correct A/F ratio at idle by turning the screws down. You end up having to drill the primary throttle blades. You start smaller on the drilling

keithinspace

In re-reading the original post, it appears he was throwing up the white flag as it relates to his current carb. Lars indicates that he has had minimal success with this particular carb and I think everyone agrees this is too much fuel for the engine. Seemed like he was planning on making a purchase.

I certainly am not the expert on the subject, but if a carb is oversized, does locking down the jets and idle circuit to not allow as much fuel "fix" the issue? My limited understanding says that this is true TO A DEGREE...adjustments...but if there is fundamentally too much 'carb' there, then you can't strike the stoichiometric balance between air and fuel. You'll always be chasing a rich condition.

All this comes from a person that had a Holley 750 on his LT-1 engine and it ALWAYS seemed sopping wet. Plugs were always black...pistons were black when I pulled them out...easy to flood. It was this experience that pushed me toward the 650 when I decided to 're-fuel' the car.

I'm not trying to fight back. I don't have the answers. But I am trying to speak to the other side of the coin that perhaps a Holley-based 750 isn't the answer to EVERYTHING...

v2racing

Being too rich and having too big of a carb are two separate issues. A large carb can be jetted to run the correct afr's. What too large of a carb will do is bog when you step it all the way down even when jetted right. The AFB type carbs have a weighted air valve on the secondary's that opens with engine demands. This is similar yet different to what the Quadrajet does. Anyway, what this means is the 800 Edelbrock is not too big for the engine, or even a 350 for that matter. Yes a new 750 vacuum Holley or a new 750 HP would probably run better out of the box, but the 800 Eddy can be calibrated to perform well. I've used and tuned quite a few AFB/AVS type carbs over the years and they can run very well.

George (gkull) is very experienced with tuning and giving good tech advise here. If the OP listens to him and follows his advise to a T, the car should run very well with the 800 Eddy.

LS 80Vette

I really don't mind trying to get the 800 to work if we can, ( according to the engine builder it should work ) it's just that I had so much trouble doing it myself and I always felt embarrassed or stupid to ask for help ( a stubborn man thing I guess )....If we can't succeed, no harm done...I will just purchase a smaller carb...I look at this as being a learning situation.....

LS 80Vette

I do experience the bogging, but possibly the carb is not jetted right yet...

LS 80Vette

I was wondering, do I keep the basic step up spring ( 5" ) or go to a different color, also do I keep the basic secondary jets for now, and with all the fooling around I have done with this over the years, I have forgotten which hole the pump arm rod was originally in, top, middle, bottom....Took the carb off last night, took the top off.. I think I need to do a good cleaning on this thing, it looks gunky inside and looks like it has black dirt inside....