|10-10-2012 01:44 PM|
Talked to a couple of torque converter companies and they all recommended a 2400-2600 stall converter for my Cam specs. My local performance transmission shop recommended the same thing so I ordered a custom built 10" one for $500 bucks. Should be here early next week.
Now to the job of taking tranny out and once back together back to the disitributor and holley setup. Should also have the MSD 8365 later this week.
|10-08-2012 07:19 PM|
Hi F-Bird'88, Thank You for all the excellent info!
Now I know why the tranny guy explained to me that this was the best way to go. jeez.
I have attached a picture of what I have installed now; I could not find any info on what its specs are other than what the tranny company told me (1500 stall). I even looked at their bill and it does not list an actual model, only that it was a 'rebuilt torque converter'.
Anyway, I don't need it to be low rpm hiway cruiser, I was just wondering what I really have on my hands here. My goal all along is to build this setup the way it was meant to be; I acquired the engine as it is so now I am working towards maximizing it the way it was mean to be. If that requires putting in a 3000 stall 10" converter then that is what I will do.
Any recommendations on a torque converter company? Or maybe I should ask if there are any i should stay away from. I'll call a couple of companies and do some research. I'll call my friend who works the parts counter at the local GM dealer to see what he can get me in the GM line as well.
I have a THM-375 with a stage 2 shift kit hooked up through a BOP plate to the SBC 350.
Also, on the rear-end; I have been saving up to get that done as well; wasn't planning on doing it until later in the winter but may have to forgo that second coffee in the morning to get it in sooner. Currently it has the original rear-end in it from when the truck had a straight 6; in other words 2.73 rear end. So, what does that mean for driving it until I get that done? how will that affect the trucks driving manners?
|10-08-2012 01:10 AM|
If you want a low rpm hiway cruiser with low gears and a stock near stock low stall converter
do not use a big racey high rpm cam.
|10-08-2012 12:44 AM|
the stall of a 3000 converter is progressive relative to power input (Throttle)
yes the car will move fine with small throttle inputs. A torque converter is not a on off switch.
The max stall is not achieved untill full throttle is applyed from a stop assuming you have good traction.
The hyd coupling is loser at idle allowing a cammed up motor to idle easily in gear.
Overall part throttle low speed driving.: instead of hugging the 1300 to 2000 rpm range when driving from a stop at part throttle the engine rpm will hug the 2000 to 2500 rpm range on initial acceleration from a stop.
Heavyier throttle input results in higher engine rpm rise on acceleration, relative to throttle input.
Up to the point of full throttle. The car still move but the engine rpm is higher.
Once the vehicle reaches the desired steady cruising road speed, converter coupling is very near 1:1, much like a stock low stall converter. Engine rpm is very near normal. You only see the difference (higher engine rpm) when accelerating. It takes a few weeks driving to get used to a high stall converter, compared to a "stock" low stall converter..
Do not combine with low numerical gears. like 2.73:1 or 3.08:1.
GM th-350 and th400 torque converters.
A GM 13: converter stalls about 1300 to 1500 dehind a 350
a GM 12" converter stalls about 2100 rpm behind a 350.
A GM 11" converter stalls at 2800 behind a 350.
A GM 10" converter ( tight design) stalls about 3000-3200
a GM 10" "3500stall) stalls around 3500-3600 behind a 350
A GM 10" converter can be tuned to stall up to about 4500 behind a 350 ( race converter)
9" and 8" race converters can be tuned to stall anywhere from 3200 to 7000 rpm for a 350.
Race converters do no act like a switch and still drive well on the street as long as the gearing is agressive.
the same converter using behind a 300CID motr wil stal about 500rpm less
The same converter used behind a 454cid motor will show a higher max stall ( about 500-700rpm)
The max stall speed seen is relative to engine torque input.
If you want to know what torque converter you need, call the torque converter company.
B&M TCI, ATI Hughes. etc.
Ya get what you pay for.
A good 10" 3500 stall cost about $350-$450
A good full race converter cost $500 to $1200 (custom built)
if you ask the local trans shop what torque converter you need they will sell you what they have in stock want to sell you, not what you really need.
|10-07-2012 11:00 PM|
Thanks! I'll play with the timing tomorrow.
The torque converter is a bit trickier as I have to order one, drop to the tranny, blah blah blah, you know the deal.
I think I need to read up on the torque converter and how it works as I know the basics but not how/when it kicks in when you have a 1500 vs a 3000. i.e. does putting a 3000 in gear do nothing when the idle is at 1000 or does the car try to move (my 1500 will try to move). Do you need to be reving at 3000 (or close to that) before the car starts the move. Not that familiar, yet, with workings of the torque converter when it comes to actually when they engage. Another area for me to read up on; exciting!
There was probably a good reason why the engine/tranny combo came with a 2500 stall.
When I destroyed the tranny pump, and therefore parts of the tranny, through improper spacing of the torque converter (another lesson learnerd) the tranny shop recommended/put in a 1500 unit. But they never asked what engine setup I have. jeez.
I did not pick the specs on this engine so what's the deal with this setup F-Bird88, is it a street/strip type of setup or more agressive than that?
I do want to be able to drive the setup on the road and I'm concerned about the high stall.
Thanks for all your continued help!
Ps. the mech advance stop will be much easier when I get my MSD 8365 in
|10-07-2012 12:03 AM|
You have the wrong converter for this 224 -106 LSA cam.
That is why it drops rpm in gear so much.
The 106 LSA cam needs 24 to 26deg initial timing and a 10" 3000 stall.
Shorten the timing curve to 10deg to allow this, using a screw with a bigger head diameter to restrict the advance travel more.
|10-06-2012 11:24 PM|
Thanks F-Bird'88, I'm going to check the advanced weights but since the whole distributor is new I don't think it would be warped; then again you never know.
I am more convinced now that the pro-billet (made in US of A) is the way to go. I read an article about a week ago where MSD was indicating their streetfire was chinese made and was their attempt to stay in the market they were losing to low cost alternatives. The way I read it they were pretty much apologizing for the lower quality of the unit.
Personally I don't like to scrimpt on certain things and the streetfire was a mistake so I'm going to correct that with a pro-billet. I already have a friend who will take the streetfire off my hands for a stock application and he will give me 90% of the units value so that helps.
I have multiple threads but they are not related. One is for mechanical advance (this one), one if for holley setup - transfer slot and one is for Holley setup - Choke. I guess you could say they were all related to engine tuning but I personally like to keep subjects separate as change-of-topic questions get lost in the discussion sometimes.
As for Cam shaft and torque converter specs; they are:
Cam: 450 lift, 224 duration, 206 lobe centre
Torque converter: new 1500 stall unit from GM - 2 years old now. (long story, had a 2500 in there and it went bye-bye when the transmission fried and now I have a rebuilt thm-375 tranny with 1500 staff as recommended by the tranny shop).
Thanks for the feedback, I guess my next step in this thread is to get the HEI Pro-Billet and go from there. I'll update how that goes when it comes in.
|10-06-2012 01:48 PM|
You have multiple threads on the go all related to the same issue.
What camshaft? what torque converter?
|10-06-2012 01:42 PM|
Now I know why I stick with using Good used Stock OEM GM HEI distributors. That I modify to get the curve I want.
I have never had a problem getting a smooth consistant advance curve. Usually using the stock OEM weights and just swapping the spring and establishing the mechanical advance limit with the machine head screw.
The stock weights and center piece usually allows a 20-22 deg advance curve.
In your pictures the advance weight appear warped......
|10-06-2012 11:32 AM|
Ongoing distributor saga
I tried swapping out weights with the advance kit specified from MSD for the streetfire and I didn't like it; the timing came in all at once at around 1800 (from 18 to 32 in about 200 rpm). All the different kinds of springs did was move the all-in point around but there wasn't a smooth curve so I went back to the stock setup. I have not played with shaving or changing the weights as that would be somewhat final so don't want to go there yet.
I checked the weights movement and there is no binding anywhere.
The MSD advance kit 8428 is the one I'm using now (since it is the one actually for this unit - the pro-billet kit was not)
I put a bright green line on the balancer since the day I got the engine and its still bang on.
I'm now actively saving up for a pro-billet unit but until that time I'm going to play with the Holley setup and maybe, when I have patience back, play with the ignition advance again
Thanks for all your continued help
|09-29-2012 06:33 PM|
Sorry, I forgot to mention that I had to trim the bushings to get them to fit under the e-clips that hold the weights in place with the advance kit.
|09-29-2012 06:12 PM|
Just my two cents,
Your distributor looks just like the MSD HEI Streetfire that I have laying around. I had issues with the advance mechanism not being as smooth as I thought it should be in certain positions. With no spring yours may let one weight get out in front of the other and bind(see pic,near thumb). I had to grind the end of one weight to keep it from catching. It may never have got to that position in normal use with springs. I'm just too picky(anal).
I swapped the weights out with a MSD Advance Kit PN 8428 and it seemed to be smoother.
However, I bought a MSD rev limiter module that was advertised to fit Stock and aftermarket HEI's, but low and behold it wouldn't fit in the streetfire????
I made a mod to it to get it to fit, but was still disapointed.
I decided to use an older MSD 8365 Pro Billet I had on another engine instead.
Something sure doesn't make sense with your timing being more advanced with springs vrs none. You sure the harmonic balancer outer ring isn't moving around on the hub(doubt it on a new engine)? Brush a thin line of paint across the two(from center outward) to be certain. You'll alwas know in the future if it has if the lines aren't straight.
I suspect the weights aren't as smooth as they should be, but thats just me. Might try the kit I mentioned.
|09-29-2012 09:29 AM|
Ok, I'm officially stumped and need some assistance. I'm using the MSD HEI advance medium springs. Initial is set at 17 degrees
1. with no springs and the stop advance screw in it stops at 36 degrees perfectly all the way up
2. With medium springs an NO stop advance screw I get 42 degrees at 4500
3. with medium springs and a stop advance is stops at 31 degrees all the way up.
huh? if the springs by themselves go over 36 and the stop stops it at 36 would that not have it stop at 36? I just don't get it.
I have played with over 3 different companies springs (Morose, MSD pro billet springs, MSD HEI springs and I have a mr gasket HEI kit on order). I have played with light all the way to heavy and numerous combinations of lights, mediums).
I made another screw and shaved it down to stop at 40; testing with springs showed it to stop, yup you guessed it, at 31.
I'm not sure where to look next. Any thoughts are appreciated.
I used a screw as the picture that F-Bird'88 sent, maybe another approach is needed? what are the alternatives (short of buying the pro-billet one with the built-in stop)
BTW, confirmed timing with another timing gun, a non-dial back light.
Thanks for any help
|09-28-2012 05:03 PM|
I'll pull my old light out of semi-retirement and check it out. it has no dialback feature on it.
I actually went out and bought a brand new OTC 3367 last weekend because of the concern with MSD (and I needed one that would work with an MSD ignition box for my impala restoration).
I'll update when I compare the two readings tonight.
|09-28-2012 03:40 PM|
Try a different timing light, one without a dial back function. MSD ignitions have been know to mess with lights, especially if its a dial back type.
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