Converter......something is a miss......

One of the most critical areas of a automatic race car

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maydayneal
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Converter......something is a miss......

#1 Post by maydayneal » Sun Apr 26, 2009 9:20 am

Finally got the motor running well and made it out to the track for some passes. Motor felt really strong, suspension seemed to hook well....but ET's lower than expected and it may indicate that I was blowing thru the converter. Below is my best run and the specifics.

1/4 ET: 11.79
Speed 117.49
60' - 1.747
330 - 4.965
1/8 - 7.660
1/8 mph - 91.79

Now here's the really bad news....unless I was seeing things....I'm pretty certain the RPM at the traps was around 7200....which is way high for that low speed.

The engine and trans combo is new to the car....which is a 3100# Nova (1978). The engine is a 358 SBC on a PG w/trans brake. The converter is a Hughes 6000 stall.

I left on the trans brake with a 4400 rpm chip. I shifted at 6200 rpm...which is probably a bit short. Now the motor felt like it was pulling good thru second but doing 7200 at the top has really got me concerned.

I did not get a good look at the rpm change at the shift...something I will be looking for next trip out (probably this Wednesday). And to be honest, I want to make really sure that I saw over 7000 rpm at the top....you start second guessing yourself a couple of days afterwards when your trying to analyize the run. Kind of points to having a data recorder.

One last point, the combo came out of a 2500# camaro that was running 10:30's....not sure of the speed. So this car adds some 600# to the performance....which if the combo is "right"....should be in the very low 11's or maybe even high 10's in good air.....atleast that's what the program says.

Anyway....thought I would tap Neal's expertise and get some thoughts on the numbers and opinion about what to do about the converter if I can verify the performance this week. I dont know if I just have a "way loose" converter or something is gone bad inside.

I've been a bit long winded...so thanks for taking the time to read thru.

Neal <-- Nice name huh??....spelled right too! :thumb:
Mayday (aka Neal)

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jmarkaudio
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Re: Converter......something is a miss......

#2 Post by jmarkaudio » Sun Apr 26, 2009 11:51 am

Your 60 ft is a dead giveaway that something isn't right, you need to post more engine info but sounds like more than one problem. While it may "feel" like it is hooking my guess is that it isn't, and 6000 sounds a little steep for stall but really depends on the engine combo. I had a Chevelle with a 406 and hydraulic cam that went 11.60's @115 and a 1.54 60 ft for comparison.
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maydayneal
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Re: Converter......something is a miss......

#3 Post by maydayneal » Sun Apr 26, 2009 12:43 pm

jmarkaudio wrote:Your 60 ft is a dead giveaway that something isn't right, you need to post more engine info but sounds like more than one problem. While it may "feel" like it is hooking my guess is that it isn't, and 6000 sounds a little steep for stall but really depends on the engine combo. I had a Chevelle with a 406 and hydraulic cam that went 11.60's @115 and a 1.54 60 ft for comparison.
I just bought the car and engine combo about a month ago and I really dont have the cam profile on the engine, but its a hydraulic roller valve train .....trying to get additional info on lift and duration. But what I do know (or told) is that its a .040 350 with Brodix Track 1x heads, eagle rods, engine compression is 11.5:1, Holley HP 4150 750CFM double pumper for the carb.

I should of mentioned in my first post that the rearend is a ford 9" with 4:30 (advertised) gears on a ladderbar suspension. The tires are Hoosier 29.5x11.5.

I'm going to have someone video the launch this coming week so we can see how the suspension is reacting.
Mayday (aka Neal)

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jmarkaudio
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Re: Converter......something is a miss......

#4 Post by jmarkaudio » Sun Apr 26, 2009 4:13 pm

With a hydraulic roller you are usually limited to the max RPM to around 6500 RPM, maybe a little more. I would probably look for a converter to stall between 4500-5000, a 9" would fit the bill. Weight usually translates into a little more than a tenth per hundred pounds, but if the combination of parts are wrong it may translate into more. And are you sure what it ran it the Camaro? Not that it can't be done, just unusually quick for the engine.
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maydayneal
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Re: Converter......something is a miss......

#5 Post by maydayneal » Mon Apr 27, 2009 9:26 pm

jmarkaudio wrote:With a hydraulic roller you are usually limited to the max RPM to around 6500 RPM, maybe a little more. I would probably look for a converter to stall between 4500-5000, a 9" would fit the bill. Weight usually translates into a little more than a tenth per hundred pounds, but if the combination of parts are wrong it may translate into more. And are you sure what it ran it the Camaro? Not that it can't be done, just unusually quick for the engine.
You know I better check on this....the original ad only said "roller" cam and lifters.....so it could very well be a solid roller rather than a hydraulic.

Anyway....I plan to get back out to the track this week and do some additional testing....really paying attention to the tack at the shift point and top end.
Mayday (aka Neal)

rusty
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Re: Converter......something is a miss......

#6 Post by rusty » Mon Apr 27, 2009 10:01 pm

Neal, if you can, mount a video camera on the roll bar looking at the tach. It's hard to get an accurate reading at speed(poor mans data logger)

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maydayneal
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Re: Converter......something is a miss......

#7 Post by maydayneal » Sat May 02, 2009 8:50 pm

Well I've not figured out how to mount a video yet....but I can tell you that something is sure slipping....I can only suspect that my converter is just way too loose. I moved my shift light to 6900 and in second the light flashes on just after the 1/8 mile....so I can confirm I am over 7000 rpm at the trap and only making about 118 MPH......on a 4:30 gear....oh yea its blowing thru.

Again...just to recap....the engine/trans combo came out of a 2500# camaro and my car is around 3200#. I guess adding 700# really throws this combo off. The higher stalls must work much better with lighter applications....I assume the heavier the car...a tighter and lower stall is better.

Hopefully Neal Chance can confirm that.....but I'm ready to do something with the converter....if its required.....and thats the question.

One additional thought....I'm thinking about moving the launch rev up to 5200 and see if the converter responds to a bit more.....your thoughts?
Mayday (aka Neal)

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Bob West
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Re: Converter......something is a miss......

#8 Post by Bob West » Sun May 03, 2009 12:48 pm

I think you have trans or converter problems, leaving at 4400,only a 1.74 60ft, you were spinning or something was slipping. Did you see this combo perform as you say it did in the Camaro? I leave at <1500 rpms and go 1.3x 60ft. with higher gears and a heavier car and maybe a tad more torque :mrgreen: . I like my ATI ;) The Chance boys dont like em.
72 Malibu-Nov. '08-1.329-3.995-6.280@106.94-9.988@131.62
best 60ft to date- 1.319
http://www.dragtimes.com/1972-Chevrolet ... -5251.html

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maydayneal
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Re: Converter......something is a miss......

#9 Post by maydayneal » Sun May 03, 2009 2:36 pm

Bob West wrote:I think you have trans or converter problems, leaving at 4400,only a 1.74 60ft, you were spinning or something was slipping. Did you see this combo perform as you say it did in the Camaro? I leave at <1500 rpms and go 1.3x 60ft. with higher gears and a heavier car and maybe a tad more torque :mrgreen: . I like my ATI ;) The Chance boys dont like em.
Hmmmm....possible trans?....I havent really considered trans because it seemed so "classic" for a converter issue.....always thought if it were the trans the problem would be much worse (i.e. major grinding and really bad noisy stuff). Not knowing to much about the inner workings of a PG....does anything specific come to mind that this might be in the trans?

Thx Bob.
Mayday (aka Neal)

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Re: Converter......something is a miss......

#10 Post by waterdog » Mon May 04, 2009 6:58 pm

Hey mayday, I bought one the camera mounts John mentioned in his video tech article, that thing works killer. Video has helped me figure out alot of stuff. Good luck with your converter/trans, Walt
1970 Nova SS 3580lb, Shafiroff 434 na, 9.94@135.8

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Re: Converter......something is a miss......

#11 Post by maydayneal » Tue May 05, 2009 9:03 pm

waterdog wrote:Hey mayday, I bought one the camera mounts John mentioned in his video tech article, that thing works killer. Video has helped me figure out alot of stuff. Good luck with your converter/trans, Walt
Ok I must be crazy or blind.....cant find anything from John on a camera mount. Did a search....what am I missing?
Mayday (aka Neal)

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Carolina Kid
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Re: Converter......something is a miss......

#12 Post by Carolina Kid » Wed May 06, 2009 8:59 am

maydayneal wrote:
waterdog wrote:Hey mayday, I bought one the camera mounts John mentioned in his video tech article, that thing works killer. Video has helped me figure out alot of stuff. Good luck with your converter/trans, Walt
Ok I must be crazy or blind.....cant find anything from John on a camera mount. Did a search....what am I missing?
Have a look around in here. You'll find alot of good reading.http://www.dragstuff.com/techarticles/index.html

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Re: Converter......something is a miss......

#13 Post by John_Heard » Wed May 06, 2009 10:54 am

I don't think Mike sells those mounts anymore that I'm aware of, I need to ask him. The guy that used to make them may still be though.

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Re: Converter......something is a miss......

#14 Post by Marty Chance » Thu May 07, 2009 7:11 am

NEAL sorry for the late reply,
what will the converter stall on the brake without a chip?
what does the rpm drop to after the shift?
do you run nat. asp or will you be using nitrous also?
do you have any info on the top end? cam, heads?
it sounds like the converter is just too loose, if so the good news is , you dont have to buy a new converter , you can just restall the one you have. I would be happy to talk to you in depth on this either here on this board or you can call me 316-542-9869 thanks Marty Chance
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maydayneal
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Re: Converter......something is a miss......

#15 Post by maydayneal » Thu May 07, 2009 8:36 am

Marty Chance wrote:NEAL sorry for the late reply,
what will the converter stall on the brake without a chip?
what does the rpm drop to after the shift?
do you run nat. asp or will you be using nitrous also?
do you have any info on the top end? cam, heads?
it sounds like the converter is just too loose, if so the good news is , you dont have to buy a new converter , you can just restall the one you have. I would be happy to talk to you in depth on this either here on this board or you can call me 316-542-9869 thanks Marty Chance
No appology necessary....I know your running a business...perhaps doing some racing....so no problem. I've come to really enjoy "the chase" on the combo....the stuff I'm learning thru this and other "bugs" I've fixed is pretty cool.

Anyway.....I've not pulled the chip out to see what the actual stall is....I assume if I put it on the trans brake and take it to WOT it will show me that?

On the shift....it does not drop much at all....dont have specifics (cant bring myself to stare too long during the run)...but I have my shift light on at 6800 and once I do shift its back on it very quickly...so its not falling off very much.

I'm NA...no power adders. The engine is a 358 SBC. Heads are Brodix Track 1x, HLY 4150 750cfm on a Hly single plane.... I dont have the specific cam grind...but it is a solid roller valve train. Its running 11.5:1 and the guy I bought it from said during the last "freshen up" his engine guy put in on the dyno and it made 590 HP....dont know torque or where the HP peaked out. I've played with the Comp Cams software and I have some cam profiles that seem to work for the HP range.

I think I mentioned it is a Hughes 6000 converter....really new...only about 25 passes. I gave them a call this week and talked to there tech guy and he (and like everyone else) thought it was just way too loose for this engine/car combo. If you do the numbers at the traps (7200rpm & 118 mph on 4.30 gear & 30" tire).....its slipping about 28%....which obviously is crazy ineffecient.

I've kept a good eye on the trans fluid and shows no sign of burning...the brake is solid...so I dont think its anything to do with the PG. So I've decided to pull the converter out this weekend and send it down to Hughes and have them tighten the thing up for me.

Does it seem that I'm "tracking"??....or would you have other thoughts??

Thanks for getting back to me!
Mayday (aka Neal)

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