Is the TH 350 working properly

Oldsproject · December 8th, 2008, 11:26 AM

Alright guys, now that I'm road worthy and driving the car I'm into some final tweaks and I'm focused on the tranny. I've got a few questions. As a reminder I've got the following power plant pushing a 1965 F-85 Cutlass:

425 (from 1967 dynamic)
rebuilt bottom up
.030 over on Egge 10:25 pistons
Federal Mogul Sealed Gap Rings (file gapped)
C heads (unported but rebuilt)
Engle JM 20-22 Cam with 110 lobe seperation
Cloyes Double Roller TIming Chain
Edelbrock Performer Intake
Edelbrock 750CFM Carb
MSD HEI Ignition (plug and play version)
NO STALL CONVERTER (STOCK)

How I can tell if it's working properly? I modified the kick down cable bracket and vacuum hose? Manifold vacuum at the Carb is 14-15hg at 650 rpms and a solid 20 at 950RPMS. I'm getting tire burning tourque through 2nd gear but concerned that I'm not shifting properly at highway speeds. Running 65-70 miles per hour there's no downshift when I stomp on it. Is that normal? Also it doesn't seem to be downshifting correctly on the hills putting more load on the engine? Any thoughts or suggestions on what I can measure, test or do? What is normal? Sorry but looking for any tid bits that will help. Thanks.

dan2286 · December 8th, 2008, 11:53 AM

It sounds like something is up with the vacuum modulator on the trans. First make sure the vacuum line is good.

Danny Wiseley · December 8th, 2008, 07:15 PM

How did you adjust the kickdown cable?

Oldsproject · December 8th, 2008, 07:40 PM

Quote:

Originally Posted by Danny Wiseley

How did you adjust the kickdown cable?

Don't remember now as I did it some time ago. Is there an easy procedure to check adjustment?

Also, tranny is shifting better as it turns out, I did have a vacuum leak in the back of the manifold where I had a fitting blanked off. The rubber cap had a crack and the leak was sizable. It seems to be shifting well now around 28 or 30 into 3rd, When I stomp on it running about 55 it will downshift. I do not get a down shift much beyond 55 or 60 though. Is that normal?

Danny Wiseley · December 8th, 2008, 07:51 PM

Quote:

Originally Posted by Oldsproject

Don't remember now as I did it some time ago. Is there an easy procedure to check adjustment?

Also, tranny is shifting better as it turns out, I did have a vacuum leak in the back of the manifold where I had a fitting blanked off. The rubber cap had a crack and the leak was sizable. It seems to be shifting well now around 28 or 30 into 3rd, When I stomp on it running about 55 it will downshift. I do not get a down shift much beyond 55 or 60 though. Is that normal?

Sounds normal to me. With that engine, you shouldn't need to downshift to "accelerate sharply" above 60 miles per hour!

Oldsproject · December 9th, 2008, 08:59 PM

Just to close the loop, tranny is working fine. It was the vacuum leak. Thanks for your help.

Techmaven · December 31st, 2008, 03:37 PM

Don't forget, downshift speeds also take into account rear end ratio. A car with a 3.90 rear won't downshift above say, 55 where a car with 2.73's might still drop to 2nd at 70-75 or so.

December 8th, 2008, 11:26 AM	#1 (permalink)
Oldsproject 65 post sport coupe w/425 Join Date: Mar 2007 Location: Oregon City, Oregon Posts: 83	Is the TH 350 working properly Alright guys, now that I'm road worthy and driving the car I'm into some final tweaks and I'm focused on the tranny. I've got a few questions. As a reminder I've got the following power plant pushing a 1965 F-85 Cutlass: 425 (from 1967 dynamic) rebuilt bottom up .030 over on Egge 10:25 pistons Federal Mogul Sealed Gap Rings (file gapped) C heads (unported but rebuilt) Engle JM 20-22 Cam with 110 lobe seperation Cloyes Double Roller TIming Chain Edelbrock Performer Intake Edelbrock 750CFM Carb MSD HEI Ignition (plug and play version) NO STALL CONVERTER (STOCK) How I can tell if it's working properly? I modified the kick down cable bracket and vacuum hose? Manifold vacuum at the Carb is 14-15hg at 650 rpms and a solid 20 at 950RPMS. I'm getting tire burning tourque through 2nd gear but concerned that I'm not shifting properly at highway speeds. Running 65-70 miles per hour there's no downshift when I stomp on it. Is that normal? Also it doesn't seem to be downshifting correctly on the hills putting more load on the engine? Any thoughts or suggestions on what I can measure, test or do? What is normal? Sorry but looking for any tid bits that will help. Thanks.

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December 8th, 2008, 11:53 AM	#2 (permalink)
dan2286 Registered User Join Date: Mar 2008 Location: North Ridgeville, Ohio Posts: 338	It sounds like something is up with the vacuum modulator on the trans. First make sure the vacuum line is good.

December 8th, 2008, 07:15 PM	#3 (permalink)
Danny Wiseley Registered User Join Date: Mar 2007 Location: West of Lubbock, TX Posts: 160	How did you adjust the kickdown cable?

December 9th, 2008, 08:59 PM	#6 (permalink)
Oldsproject 65 post sport coupe w/425 Join Date: Mar 2007 Location: Oregon City, Oregon Posts: 83	Just to close the loop, tranny is working fine. It was the vacuum leak. Thanks for your help.

December 31st, 2008, 03:37 PM	#7 (permalink)
Techmaven Rocket Veteran Join Date: Dec 2008 Location: Long Island Posts: 40	Don't forget, downshift speeds also take into account rear end ratio. A car with a 3.90 rear won't downshift above say, 55 where a car with 2.73's might still drop to 2nd at 70-75 or so.