72C3LS5

Need some advice from you all. I inherited this 72 LS5 that belonged to my Uncle who has now passed. With that being said, I can't get any information on the Cam specs. My issue is, although it sounds good and choppy, it idles down way to low when you put it in gear. It has a stock intake and heads, Holley 750 DP and 25" tall tires. I haven't had it up on a rack yet to see if I can find the gear ratio Tag, or just do the old fashion tire rotation vs. axle rotation trick, but it feels to have a rear end in the mid 3's or a 373. With that all said, what stall would you purchase for a peppy Street car/no racing and what manufacturer? I don't want to say money isn't an option, but I would like to have good quality and performance the 1st time. I attached a YouTube Video so you could get a sense of the Cam.

Street Rat

I recommend getting in touch with some of the manufacturers. They have tech lines to answer questions such as yours. I always recommend doing this as not everyone has the same set up or expectations.

ajrothm

Call FTI, tell them the BASIC combo to the best of your knowledge, they'll spec something for you that will be efficient on the street and run well at the track.

http://ftiperformance.com/Economy-Pe...erters_c80.htm


As good as it would be to have all of the info on your engine, its not entirely necessary for what you are doing..... The ball park data is that its less then 400hp, 3500 lbs (give or take without a driver), mid 3.xx for gears and a T400....Street cruising and possible drag runs, looking for a good idle in gear. They'll be able to get you close enough...

Its not like you are talking about a 700+ HP race car you are trying to run 9s with. I definitely would not take apart a good running engine to try to figure out what the cam is, just to spec a street converter...LOL...


BTW,

B&M, TCI, Summit, Jegs converters all suck.... stick with a real converter company.... FTI, PTC, Dynamic, Ultimate Converter, Coan....or if you're rich, ATI, Neal Chance etc...

I've had great luck with FTI and all my friends with fast Vettes are running them...(8.50-9.30s cars)


One other note, if you haven't checked the timing and carb adjustments, I'd do that first, that will likely help your idling in gear issue.

71vetteinnh

i had a similar issue as you described. I can validate proper carb tuning is critical. In my instance I had 2 issues. The 4150 I had was hosed and my converter was locking up immediately because of the power my engine made. Was not flashing properly

Summit helped me alot and we were able to come up with an appropriate converter for my engine combination. I knew roughly what RPM the engine started making big power at and max RPM. Rough compression ratio, transmission and rear end ratio.

I think I ended up with a Hughes and its been fantastic. 3500 stall, but its a 355 with like 500hp 13:1 compression and revs to about 7k

OldCarBum

I have the same issue with my 73 big block. The prior owner told me that the original owner installed a high lift cam, but there were no specs or cam part numbers in all the service and parts records that came with the car. My 73 runs great, but it does bother me a little shifting from park into drive and feel the rpm drop. I'm pulling the entire drive train soon so I'll live with it until the body comes off next year and the engine is gone through.

diehrd

You can not go wrong with 2600 on a basic motor with a cam.

But before you do that

What rpm does it idle at in gear ?

What is the idle timing at ?

Here are some tips on TQ converters.

Most cheap companies simply reduce the diameter 11" inch to a 9". This causes what people think is slipping , or a higher rpm to move off idle " The engine revs more"

That happens because the distance traveled to complete a single rotation is increased , JUST like rear tires affect final drive ratio. Go to a 2 inch smaller tire and take a drive. You will see higher RPM at teh same speeds when compared to the original tire size ( 27" vs 25" which causes more rpm ) Also never forget a Torque converter "Multiplies Torque" Under its STALL SPEED and a smaller TQ/converter produces less multiplication under its stall speed.

A quality converter is built for its flash stall and can remain the same size as the OEM converter. This allows for ZERO driving changes in what you feel when you pull away normal from a light.

And when you Stomp on it The flash stall delays the 1 to 1 input rpm to teh desired speed which will varry slightly from one motor to another.

I run a 11" 3600 to 4000 stall in front of my 4L80E , I have 4.11 gears and a SBC 427

The drive ability under daily driving conditions is perfect. I pull away and my motor barely revs , It idles perfectly at 750 in gear and when I let foot off break it drives forward normally and it holds on inclines.

Basically with 600hp it drives like any car with sub 400 hp ..

But when I get on it , the 1 to 1 power transfer is high enough up the rpm range to give me the RPM I need to get into and stay into my torque band.

Also when you raise the stall speed. The RPM between shifts DOES NOT DROP OFF pulling the motor down. We all know what this feels like. Go drive a basic car with an automatic. When It up shifts from first to second the motor drops alot of rpm and has to power its way back to high rpms.

A well made converter eliminates that , When i shift from 1 to 2 the rpm drop is only a few hundred rpm keeping my motor spinning hard producing its peak power from the time of the shift and all through second and into 3rd. My motor does not need "Recovery time" its always pounding out at high rpm when I run full out.

I had a few minutes..

I Hope this helps add to the discussion

I just wanted to add this. A larger or identical diameter TQ/Converter built for your stall speed will also allow the transmission to operate cooler and it maintain's the correct quantity of Fluid specified by the manufacture

ajrothm

You are right... Summit and Jegs don't make converters.... They use cheap *** companies like Boss Hogg, Freakshow, and who knows other back yard converter builders to supply their junk.

B&M and TCI are both good companies and make good products, but their converters are nothing special...basically off the shelf, inefficient junk that costs nearly the same as a quality converter.

If you haven't heard of FTI, that tells me you don't hang around the fast guys. FTI, PTC, ATI, Coan, Neal Chance, these are the GOOD converter shops... They can build you an 8" 5000 stall converter that drives just like your 2600 stall B&M Holeshot converter on the street.



There is so much bad information on this forum in regards to stall converters, its unbelievable. People stuck in the 70s-80s mentality trying to give converter advice.

HeadsU.P.

Just sayin' you shouldn't slam or bash any company on a forum unless they done you wrong. Karma comes back around you know.

Street Rat

I've used a variety of brands. None have failed. I went with Art Carr's Converter for my TH200 4R transplant.

Jebbysan

Hughes has a 2600 that would be good behind a Big Block.
Calling FTI or ATI is good advice if you want to pursue it......
I quit using TCI and B&M years ago because it seems like no two come out of the box with the same stall......just an opinion.

Jebby

ajrothm

I have used them all.... I test my stuff on the track where it counts.

I had a $200 Boss Hogg ACC 10" (2800)converter from Comp sales behind a 406" Pontiac, The converter was terribly loose, very inefficient. The car left good but wouldn't mph.... Low 1.6x 60's but would only trap 108 in the 1/4. I ran it for a year until I had some extra money and decided to "upgrade" to a TCI Super Street fighter 10" ($350)...Guess what, the car went slower, wouldn't 60' less then 1.72 and ran the same mph....

Then I put a 175 shot on the car and it blew right through the converter and wouldn't even finish the 1/4 mile (out of rpms).... Upon calling TCI, they recommended I go to a "custom race converter" for my application.....LOL Really? a mild Pontiac on a small shot? Yeah OK.... F TCI...

Learned my lesson on cheap converters long ago.


ON the contrary, the Hughes brand, GM25, (2500 stall 11") is a pretty decent converter for $250. I just installed one behind a mild 355" with 3.73 gears, its a little looser then I thought it should be around town but, its quite livable and seems to have a decent flash....I haven't beat on it much yet as its on BFGs but its a decent converter for the money, at least decent enough for my 66 year old Dad to creep around with.

Behind a real motor, it would be pretty damn loose around town....

By comparison, my locally built, custom 10" converter in my 71' drives basically like stock, pulls away from stop lights without throttle and pretty much feels like stock until you go 50% throttle, then it starts to loosen up as it should. Mine flashes to about 3500 rpms on dead hook launches leaving at idle and measures about 10% converter slip in the traps...Not too bad for a $300 converter.

gkull

I wold rather spend the money on high hp 9.5 inch TC,s than having to worry about if it will blow up the next time I power brake the tranny. It is so disheartening years ago when I bought a top of the line TCI TC only to have the aluminum stator shatter. It fed aluminum chunks through the tranny. So it never happened again I always bought the highest hp models and never had costly problems again

so the things you should look at are efficiency and maximum hp rating. Welded fins, anti ballooning plate, sprag or spragless

vigilante, art Carr the business not the person, continental, or maybe this 700 hp

http://ftiperformance.com/Street-Rac...0-TH400-SR.htm

gkull

aint that the truth? You shouldn't post on subjects that you have limited experience with. If you have never tried a variety of manufacturers how can you post something like getting a stall rpm lower than your highway speed. Clueless

OldCarBum

And then try to throw in the stall/lock up speed recommended buy your cam shaft manufacturer, transmission and rear end gearing.
I've been trying to learn as much as I can to set up my 73 496 BB, with a cam operating range of 2000-5800 rpm, recommended lock up of 2500 rpm and trying to run an auto overdrive with a cruising rpm of 2000 @70 mph.
I'm getting different answers every place I turn and at this point I'm about to throw in the towel and convert over to a manual 5 or 6 speed transmission.
Its frustrating.

Street Rat

PM sent OldCarBum

gkull

Lockup TC's and big motors doesn't work. The lock up is just an electrical solenoid valve applying tranny fluid to mash the clutch disk together.

In my 800 HP capable 700R4 one of the improvements was a larger high pressure 26 vane pump. The higher pressure made for more clamping force on the lockup clutches. Many year ago the quality TC companies came up with multi clutch disk lockups. My $1100 9.5 inch was a 5 disk lockup model. My tranny was setup for no auto kick down when you went to full throttle and lockup in 4th gear only and 4.11 rear end. It ran fine for years with a 383 solid roller motor and I had it built with my power level to be a 3500 stall. It was capable of very high MPH when competing in events like the Silver State classic open road race.

I got the HP bug and installed a 7500 rpm Solid roller 427 ci. I floored my Vette in lockup 4th gear and the TQ of the motor smoked my 5 disk lockup. Instead of fixing the highly efficient TC, I just drove it around for the next couple years without lockup.

when my lockup still worked I would on see a 100 - 200 rpm difference on level freeway driving when I flipped my lockup switch on. That is with a 3800 stall TC. Because of the TQ of the 427 compared to a 383 it changed me from 3500 to 3800 rpm. I had the big B&M tranny cooler and even on the over 100 degree days I never saw tranny temps exceed about 200 degrees out racing and under less load it would get down to about 160 in city driving.

My advice for a 496 ci is to forget lockup or go with a multi disk unit that unlocks if the throttle is opened up. I am pro higher stall highly efficient TC's. I have a Dodge 3500 dually and when I'm pulling my toy hauler I kick it out of OD lockup on any hill because I don't want to smoke it with 800 foot pounds or something of TQ when it gets up to 30 psi of turbo boost.

I hope this helps you.

George

diehrd

I run a lock up , with high hp

It cannot be commanded until I reach 45 in 4th gear only

And it unlocks the instant I push past 10% throttle

So you can have all the top latest greatest ideas on a high hp car. It all comes down 2 how it is built and tuned.

v2racing

I bought George's Art Carr 700R4 and converter. I had Art Carr rebuild the converter and ran it and the trans behind my 406 when it was in my 80 Vette. It drove like a stock converter until you got on it. This was in front of 3.08 gears. Very nice converter.

I remember what converters were like back in the 70's and 80's. Most of them were very loose and sloppy. Some of the inexpensive ones on the market today aren't much better. There was a local guy back in the 80's that built very inexpensive converters that worked really well. I had one in a 64 El Camino with a big block I built that worked really well, but it wasn't the norm back then.

Mike