Gearing questions 7.5 rear

[Stupidquestionspro]

Have you checked your speedometer with GPS? It and or your tach may be wrong. Actually without a lock up converter like your regular TH350, add 250 to 300 rpm, so around 2100 rpm at 60 mph.

Not with gps just assumed it must be close enough based on traffic and seat feel.

Is there a specific easy way to test my tach for giggles?


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[olds307 and 403]

I test it against my dial back timing light with rpm readout.

 

[fleming442]

Here's something else to consider: your TH350 probably came from a car with a different rear gear, so your speedo drive gears are probably wrong. Use your GPS app to get the actual speed, yank the rear cover and count teeth (or just change gears), and adjust the trans gears accordingly.

 

[Stupidquestionspro]

That’s possible although my th350 isn’t from a different vehicle it’s a bop TCI street rodder I plan to check each test.


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[fleming442]

That’s possible although my th350 isn’t from a different vehicle it’s a bop TCI street rodder I plan to check each test.


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OK, did pops tell them it was a 2.41 gear when he ordered it?

 

[Stupidquestionspro]

No he ordered online from jegs and based on the part number the trans didn’t come with a speedo gear so I can only assume he swapped in the old one and the gearing is the same as stock.

I’ve downloaded a gps Speedo to my phone so I’ll check the Speedo on my way to work.


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[Stupidquestionspro]

Ok speedo seems to be dead on or within 1mph I tried to feel for my 3rd gear shift and never noticed it so that is likely the issue when I pull my cluster I’ll double check my dad moved the jumper to v8 but he was adamant he did. Now to ponder that issue. Along with all my other little issues


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[fleming442]

May have to adjust the shift linkage.......

 

[Stupidquestionspro]

Thanks I’ll have to look at that also I’ve seen multiple methods of adjusting the kick down

Do I hold the metal tab and then open the carb to WOT and that’s the correct setting for the kickdown or do I slide the insert all the way back in and open the carb to WOT and let it pull it out?


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[robert garringer]

The trans we put in was a TCI street rodder package.

TCI 311138P1 Details
GM

Transmission Part Number: 890-311138
Converter Part Number: 890-241538
Dipstick Part Number: 890-743860
Universal Kickdown Cable Part Number: 890-376900

Looks like gear ratios are

First 2.52
Second 1.52
Third 1.00

Non lock up

Apparently the converter included on a small block is between a 1500-1700 stall

Sounds like I really need to find out if I’m shifting into 3rd or if my tach is lying.




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check the resitor on the firewall above the driver side valve cover.they go out and your tack will be off.and if you have a aftermarket tack check that allso.i just went though 4 auto meter five inch super comp tachs untill i got one that read correctly.