Converter stall check

[MT71c-10]

Hey guys. I want to check my stall with you guys.

71 Chevy c-10, weighs in at 3700. Edel. RPM 64cc heads, RPM cam, RPM air gap manifold, roller rockers, hyper flat top, 1 5/8" headers, 3'' collector, 2.5" dual, h-pipe, Edel 750 carb, th-350, 3:73 rear gear, 275-50-17 yokohama advan s/t tires.

It has a supposed 2800 stall, but i'm getting slow launch, Hard to do standing burnouts (without the help of some gravel or water) and when it goes from park to drive it has some rpm drop 3-400 rpm. Truck runs like an ape at 3100 rpm up, a little lazy below.

Now I know the RPM stuff works best on lighter vehicles, but I like that top end scream. The Edel carb will be replaced with a Holley vac sec 750.

The converter builder wants $175 to restall, so I want to check and see what stall I really need to run, or if a stall and regear is in order.

Thanks for the help.

[ripdog28]

Would need Cam specs to give an accurate stall. I would look at other options like tune before i tear out the trans. Never know. Just a jet change could save you a lot of time and $$. A 750 carb is a bit big for your app. I would bet that a tune would do the trick.

[gchemist]

I run a 2500 stall on a heavier truck. My ZZ4 rips the tires loose at half throttle. Mechanical secondaries are a downside to Edlebrock carbs. Have you tuned the carb with a vacuum gauge?
http://www.centuryperformance.com/tu...e-spg-148.html

For a $15 tool, you get a great diagnostic tool.

[MT71c-10]

Cam spec is 234/244 .488/.510

I have rejetted this Edel. numberous times, both with the 750 and my old 1406. I have not tuned by vaccume. Tuning is not really my strongest.

I am set on getting a Holley 3310 or equivalant. Not real impressed with the Edel. so far, I have had them on the truck for 3 years ( last 2 years with the top end makeover )

I appreciate your replys, just trying to narrow down what I can, double checking I guess.

Thanks guys.

[cableguy0]

The holley is the better performance carb hands down. Your right where you need to be on gearing. converter is close enough that it should be fine. What do you have for an ignition system? Is the timing curve set properly for your setup? Proper timing will make a huge difference in how a vehicle runs.If you hold at a stop and bring the truck up on the converter what rpm are you at? Is it actually stalling to 2800rpm? It shouldnt have an issue blowing the tires off standing on the brakes and bringing it up to rpm.

[Marv D]

I agree dumping the AFB carb in favor of a 3310 or even a 4150 will be a good performance move.
Rip, the edelbrock RPM cam he's running is 234° / 244° @ 0.050, .488 / .510 lift, ground on a 107 CL with 112° LSA

I ran pretty much that same package with a B&M 2400 shelf stock convertor and it was a SLUG off the line. Like MT71 said,, around 3000ish it would come to life and even being a hydraulic,, would still be pulling at 7000-7200. It's just NOT a low end cam. I picked up nearly 1/2 a second switching to a Midwest 4800 converter, then came a back half, and then 5.43 gears and, and, and,,,, and well we know how these things are,, a constantly evolving work in progress.
But converter and carb was the two biggest changes in motor that REALLY woke things up. After 3 or 4 months and buying the Edelbrock calibration kit, and additional rods and jets not in the kit, and fighting with the lean flat spot caused by the peepoor accelerator pump design,, I gave the stinking thing away and put a Prosystems 750 on it. WORLDS of difference in throttle response, and tunability,, and it didn't really need any tuning. I ended up one jet leaner on the secondary than just straight out of the box.

So anyways,,, I would go for the carb first. The if it isn't more responsive enough for you on the low end, throw some gear and more stall at it. You will be peeling chunks of Yohokama off the rear bedside

[bigsnookmaster]

Originally Posted by Marv D

I agree dumping the AFB carb in favor of a 3310 or even a 4150 will be a good performance move.
Rip, the edelbrock RPM cam he's running is 234° / 244° @ 0.050, .488 / .510 lift, ground on a 107 CL with 112° LSA

I ran pretty much that same package with a B&M 2400 shelf stock convertor and it was a SLUG off the line. Like MT71 said,, around 3000ish it would come to life and even being a hydraulic,, would still be pulling at 7000-7200. It's just NOT a low end cam. I picked up nearly 1/2 a second switching to a Midwest 4800 converter, then came a back half, and then 5.43 gears and, and, and,,,, and well we know how these things are,, a constantly evolving work in progress.
But converter and carb was the two biggest changes in motor that REALLY woke things up. After 3 or 4 months and buying the Edelbrock calibration kit, and additional rods and jets not in the kit, and fighting with the lean flat spot caused by the peepoor accelerator pump design,, I gave the stinking thing away and put a Prosystems 750 on it. WORLDS of difference in throttle response, and tunability,, and it didn't really need any tuning. I ended up one jet leaner on the secondary than just straight out of the box.

So anyways,,, I would go for the carb first. The if it isn't more responsive enough for you on the low end, throw some gear and more stall at it. You will be peeling chunks of Yohokama off the rear bedside

X-2 on the Prosystems carb!

[MT71c-10]

Cableguy, you are the man who turned me to the 3310 ( in a thread a while back ).

Ignition is a Mallory hei, crane blue/blue springs. Base time is 12*, with those springs I believe it is 34* total at 3200rpm ( I don't have tape or a light to tell me so ). As for bringing it up on the converter, I will try to take it out tomorrow and get an accurate rpm ( I haven't driven the truck for a few months, But roads are clear today ).

I also agree, she should be cooking tires easy.


Marv D, You are not kidding with the Edel. accelerator pump system. I have already drilled the .41 nozzle to .47 with a good response ( my numbers may not be exact at this time, but close ). I have more jets, rods and springs and all the accel. nozzles than any one needs.

I really don't want to be pulling chunks of tire off my bed, I think they look bad **s!!

Thanks for the help guys, I'm not the best tuner out there, but I'm trying. Anything helps me weed out the kinks.

[Super73]

What do you turn the motor too?

[MT71c-10]

6500 is all I have the peanuts for, thats at the "M" on the MPH. But she likes it and I'm sure she will take some more, but not with me, not right now. I'll need a lot more saftey done and a strip.

[cableguy0]

Put more timing in it. Try 16 at idle and see how it acts. Should put your total around 38. I assume your running 93 octane already? That cam will like the extra timing and you will steal some bottom end back. Also get a 1 inch 4 hole spacer and put it on. That will also help the bottom end power.

[Super73]

If it were me, I'd put a 4k rpm verter in it and let it rip

[MT71c-10]

So I got her out this week for a little drive, man it felt great, except for all the gravel getting thrown up.

So after it got warmed up held the brakes and hit it, it feels like the converter loads up around 2000-2200.

[cableguy0]

Do you have a tach? or are you guessing? A couple hundred rpm will be night and day in stall speed. If you just stand on the throttle without the brakes what rpm does it flash to? It really sounds like you need a higher stall converter. The things i mentioned will help a bit but if your putting that engine under load before its making any power its gonna be a dog.

[MT71c-10]

I do have an aftermarket tach. Just standing on gas from a stop I would guess in that same rpm area.

I do also think I got a little taken by converter builder.

[cableguy0]

Your stall is way to low. its definately going to be a dog. a true 2500stall in a heavy truck with some power should flash to around 2700 when you just stand on the throttle. generally you will get a range for example 24-2600 would be considered a 2500 stall 28-3200 would be a 3k stall. You get what you pay for when it comes to converters. I would personally use tci,bte boss hogg etc. I dont like the B&M junk.Theres a bunch of companies I didnt name just because i personally havent used them. Get you a 3k stall and that thing will seem like a rocket.Did you advance the timing a bit?

[Marv D]

The more power (torque) you make the more stall your going to see out of the convertor. Before you fight any further with the convertor (not saying you don't need something there) just you might get the tuneup a little tighter, try a more responsive carb, and get the timing dialed in. Advance bolsters torque in the lower rpm range. Trick is to get fuel and ignition advance to cooperate so you can step things up a little.

I made the assumption this is a 350,, when I looked back I didn't see the engine size. If so,,, You should be at 9.4:1 compression with a normal build, 64cc chambers, 6cc valve pockets, normal dect etc. With that cam you should be able to run 91 octane, have at least 10° if not 12-13° initial advance and with a tight curve setup, hold total advance at around 36. I think that would help with low end torque, and push the converter a little harder, giving you a tad more stall and launch torque. Just a thought, but before you go nuts on other things,, I'd spend some $'s at a good tuneup shop. If there is a dyno tune shop around Bozeman,, it may be $'s WELL spent.

And forget the flowers,, they just wilt and die anyways. If she's a keeper, she will understand

[MT71c-10]

Originally Posted by Marv D

And forget the flowers,, they just wilt and die anyways. If she's a keeper, she will understand

If I want to keep her, I will buy the flowers.

[MT71c-10]

Marvd, yes it is a 350. I getting ready to pull the timing cover off and check all the mech. timing ( off a tooth??? ). The carb is the first on the list to get swapped out. Were are looking at June 1st ish for that.

Thanks for all the help guys, I'm sure I will be back on looking for some more info and advice.

[63chevyll]

thats a pretty high lift, low duration cam

i run close to those specs with a 2bbl and stock intake and exhaust manifolds.

have you done a stall test?

Drop in low, Mash gasm and note when stall is before wheels spin? will king of give you an idea wherethe stall is at, no matter what was advertized