Flex plate bolts witness marks on torque converter

[4spdragtop]

Getting "ready" to install 340. Prev 273/904, any reason to be concerned about witness marks? Never seen that before. 1 out of 6 bolts is different depth and head size. 3/4 head is 0.5" thread depth, 5/8 head bolts are approx 0.60" thread depth.
Head thickness 0.26 on 3/4" head, 0.28(ish) on the other 5 5/8" heads.
I have another stash of tc bolts "somewhere"
Thanks
Steve

 

[4spdragtop]

Found another stash, luckily these are the 3/4 head, which are slightly thinner heads and less thread depth.

 

[Cuda Al]

I was just about to say I have only seen the flatter style ones.


Alan

 

[69conv]

If they contact the inspection plate they will rattle like hell. You dont need me to tell you to make sure the converter seats all the way. Good luck with the install!

 

[RustyRatRod]

Yeah, you found the issue right quick. Five wrong bolts.

 

[lemondana]

Look like flywheel bolts.

 

[4spdragtop]

But only.03 difference in head thickness?? So what would the 5/8 head size bolts be for?
Yes, the tc was bottomed out, I'll make sure it is this time too.
This tc should be fine going from 273 to 340(snout size/depth)?
I'll be upgrading TC later on.
Thanks guys

If they contact the inspection plate they will rattle like hell. You dont need me to tell you to make sure the converter seats all the way. Good luck with the install!

Yeah, you found the issue right quick. Five wrong bolts.

Look like flywheel bolts.

 

[Charrlie_S]

Check the size of the converter pocket in the crank. The 340 engine will have the "large" pocket. The converter "MAY" have the small pilot. You might need to get the adapter bushing.

 

[4spdragtop]

Thanks Charlie, i will chk once 340 is off engine stand. Converter snout is approx 1.55" diameter.

Check the size of the converter pocket in the crank. The 340 engine will have the "large" pocket. The converter "MAY" have the small pilot. You might need to get the adapter bushing.

 

[Charrlie_S]

Thanks Charlie, i will chk once 340 is off engine stand. Converter snout is approx 1.55" diameter.

My memory is not what it used to be, but I think the 1.55 is the small pilot. You will need the adapter bushing. Contact member @slant six

 

[Bewy]

I would find another flex plate to compare with, it might be bent, flexed once too often......

 

[TrailBeast]

Getting "ready" to install 340. Prev 273/904, any reason to be concerned about witness marks? Never seen that before. 1 out of 6 bolts is different depth and head size. 3/4 head is 0.5" thread depth, 5/8 head bolts are approx 0.60" thread depth.
Head thickness 0.26 on 3/4" head, 0.28(ish) on the other 5 5/8" heads.
I have another stash of tc bolts "somewhere"
Thanks
Steve

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Just so you know Steve, I have seen a lot of converters with witness marks like that and it never adversely affected the converter in any of those cases.

 

[RustyRatRod]

Just so you know Steve, I have seen a lot of converters with witness marks like that and it never adversely affected the converter in any of those cases.

His could though. Since it appears from the question Charlie asked that he has a small converter hub in the large crank register, that could allow the converter to move back and forth on its axis and wear holes in the front of it from rubbing those bolts.

 

[TrailBeast]

His could though. Since it appears from the question Charlie asked that he has a small converter hub in the large crank register, that could allow the converter to move back and forth on its axis and wear holes in the front of it from rubbing those bolts.

I could see that if it was continued to run that way.

 

[4spdragtop]

Thanks for the heads up @Charrlie_S you were right, tc snout approx 1.55" and crank is 1.80" depth of 0.64....holding pattern dammit..

My memory is not what it used to be, but I think the 1.55 is the small pilot. You will need the adapter bushing. Contact member @slant six

 

[clementine]

This could be cured with a 4 speed Steve

Progress!! Inspirational!!

 

[Charrlie_S]

This could be cured with a 4 speed Steve

Progress!! Inspirational!!

Then you would need to find a flywheel with the small center hole, or again, use an adapter ring on the crank to allow use of the late model flywheel.

 

[4spdragtop]

Sidenote, I have another(unknown) TC, is there a way to visually tell if good to go or not? Can you "mix" lockup tc with non lockup trans?

Then you would need to find a flywheel with the small center hole, or again, use an adapter ring on the crank to allow use of the late model flywheel.

 

[Charrlie_S]

Sidenote, I have another(unknown) TC, is there a way to visually tell if good to go or not? Can you "mix" lockup tc with non lockup trans?

Without doing mods to the converter and/or the trans, this is the situation. `1960-1967 trans and converters go together. 1968 up non lockup trans/converter go together. Not sure of the 1st year of lockup, but lock up converter must be used with lock up trans. All three versions of converter and trans have splines that have a different count, and must be used with the corresponding part. It is possible to mix and match different parts, but mods are required.
PS: My 66 Barracuda race car had a early slant six (small crank pocket), a 65 cable shifted 904 with a 64 full manual valve body, and a push button shifter in a console between the bucket seats. The trans had the 68 up input shaft and related parts, and the converter was a 3200-4000 stall (depended on engine) custom made with the early small pilot, and late large spline. That way I could use the same converter with the early engine, or late engine with the crank adapter ring. Also the late non lockup trans (as is) or the early trans by swapping the input shaft. So any engine/trans combination.

 

[transman]

Maybe I'm missing something, but if the pilot of the converter measures 1.55" then it is for the early 62-67, 904 transmission, and I take it that you are going to use the early 904 transmission and converter you now have behind the 340. The 340 will have as mentioned earlier, a larger hole in the crankshaft, probably around 1.810". I know that there is a bushing available that you can install in the crank. It is a cheap, fix, and in my opinion NOT the way to go. In your Province there is a company called SMR in Bradford, 1-888-846-6603 that can correct the issue by rebuilding the 904 converter you have now, and will put the correct pilot put on it. The company I worked for in the past did a fair number of these and never had any complaints. If it were me, I'd talk to SMR, tell them what I've got, and what I planned on doing. Again, jmho. Best of luck. Do it right ONCE.

 

[toolmanmike]

And if you re using a small snout converter in a large hole crank, although it isn't right and should be corrected, it wouldn't cause the converter to stick out far enough to cause the issue. The thick headed bolts are the problem.

 

[Charrlie_S]

Maybe I'm missing something, but if the pilot of the converter measures 1.55" then it is for the early 62-67, 904 transmission, and I take it that you are going to use the early 904 transmission and converter you now have behind the 340. The 340 will have as mentioned earlier, a larger hole in the crankshaft, probably around 1.810". I know that there is a bushing available that you can install in the crank. It is a cheap, fix, and in my opinion NOT the way to go. In your Province there is a company called SMR in Bradford, 1-888-846-6603 that can correct the issue by rebuilding the 904 converter you have now, and will put the correct pilot put on it. The company I worked for in the past did a fair number of these and never had any complaints. If it were me, I'd talk to SMR, tell them what I've got, and what I planned on doing. Again, jmho. Best of luck. Do it right ONCE.

What is wrong with using the bushing?

 

[4spdragtop]

I agree with what you are saying, but I don't want to lose anymore down time. Already the middle of June, yeah I work really frickin slow lol. The future plan was to "probably" get another converter for the 340(higher stall). I believe the 273 one I have now is stock. Also getting a tc specific to the 340 allows me to shelf the 273 one for the 273 that I plan on rebuilding.
What about buying a complete 340 one from SMR? Obviously you recommend them?
Thanks
Steve

Maybe I'm missing something, but if the pilot of the converter measures 1.55" then it is for the early 62-67, 904 transmission, and I take it that you are going to use the early 904 transmission and converter you now have behind the 340. The 340 will have as mentioned earlier, a larger hole in the crankshaft, probably around 1.810". I know that there is a bushing available that you can install in the crank. It is a cheap, fix, and in my opinion NOT the way to go. In your Province there is a company called SMR in Bradford, 1-888-846-6603 that can correct the issue by rebuilding the 904 converter you have now, and will put the correct pilot put on it. The company I worked for in the past did a fair number of these and never had any complaints. If it were me, I'd talk to SMR, tell them what I've got, and what I planned on doing. Again, jmho. Best of luck. Do it right ONCE.

 

[4spdragtop]

Found their website, they look like they know what they're doing lol.
I really don't want to wait or can afford another converter right now. All machine shops here are swamped or can't be bothered with this piddly job...ffs.
I'll call SMR on Monday.
Thanks!
SMR EQUIPPED CARS

 

[Charrlie_S]

Problem with getting a converter with the large pilot, is they may not be able to give you a High stall speed with the small splines to fit your transmission (those parts are getting hard to find). So then you will need to get a later transmission, or change the front section of your trans to the later pieces.