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Cam Swap info Needed

Hey guys I know this is an old thread but I got my new cam and lifters and intake on. Today I started and drove it for the first time and the motor sounds and feels healthy. My issue now is that the trans wont shift up into 2nd or 3rd gear. I also timed the motor by watching youtube videos and it seems to run good but how are you supposed to tell if it is timed just right? I also am leaking oil from the timing chain cover, but that should be an easy fix. When I get all these problems figured out it should be good to go. Thanks for any help!!
 
four50NCalif said:
Hey guys I know this is an old thread but I got my new cam and lifters and intake on. Today I started and drove it for the first time and the motor sounds and feels healthy. My issue now is that the trans wont shift up into 2nd or 3rd gear. I also timed the motor by watching youtube videos and it seems to run good but how are you supposed to tell if it is timed just right? I also am leaking oil from the timing chain cover, but that should be an easy fix. When I get all these problems figured out it should be good to go. Thanks for any help!!
Click to expand...

What trans?
 
Th350 and th400 are vacuum modulated, check first for a damaged or missing vacuum line.

The factory timing specs may not be ideal with the new cam. A good way is to check your timing and mixture with a vacuum gauge.
 
Even if the modulator was getting no vacuum (as in if the hose came off it),the TH350 will still upshift,but it'll have to be wound up to a lot higher rpms than usual--it might delay the shift into second gear until as high as 30 mph,and the upshift to third gear might not happen till speeds approach 50 mph,depending on the rear end gearing..and it will shift in much firmer than normally also..

You should be able to coax an upshift sooner,if you pull it down into low,and upshift it manually,if the modulator is at fault..(you'll notice no engine braking in second if you let off the throttle before it goes into third too,if the modulator is bad or not getting vacuum..

If your only getting reverse and first gear,it could be low on fluid,or the govenor gear may be stripped out,its only nylon that runs on a steel gear in the tail end of the trans..or,the valve inside the govenor may be stuck..

If the truck has just sat a long time,and was shifting OK previously,I would say its likely it is low on fluid,and or the govenor valve is stuck,or perhaps a sticking valve body piston in the valve body..kind of hard for the govenor gear to strip out when its parked..:crazy:..
 
I would not drive without the modulator, that controls the line pressure.. You'll smoke it. Go get a modulator for Lower vaccum and adjust it.. Gov and stuck valve body pistons are gonna free up as you drive it so don't expect it to fix itself in the first mile.
 
I believe the line pressure goes up when the modulator doesn't work,its kind of a fail safe feature..that's why the shifts get later and much firmer..

Another thing to check I just remembered --the detent or downshift cable adjustment may have been disturbed or it might be stuck in the "passing gear" position ,that will prevent it from upshifting out if first gear also..
 
paratrooper307 said:
Th350 and th400 are vacuum modulated, check first for a damaged or missing vacuum line.

The factory timing specs may not be ideal with the new cam. A good way is to check your timing and mixture with a vacuum gauge.
Click to expand...

Looks like I forgot to hook up the vacuum line that goes from the trans to the intake manifold right behind the carb. Would that do it? I have it apart again today to get to the timing chain cover, I also forgot that rubber U shaped gasket that goes on the bottom of the cover, do you guys use RTV when installing that rubber thing?
 
diesel4me said:
Even if the modulator was getting no vacuum (as in if the hose came off it),the TH350 will still upshift,but it'll have to be wound up to a lot higher rpms than usual--it might delay the shift into second gear until as high as 30 mph,and the upshift to third gear might not happen till speeds approach 50 mph,depending on the rear end gearing..and it will shift in much firmer than normally also..

You should be able to coax an upshift sooner,if you pull it down into low,and upshift it manually,if the modulator is at fault..(you'll notice no engine braking in second if you let off the throttle before it goes into third too,if the modulator is bad or not getting vacuum..

If your only getting reverse and first gear,it could be low on fluid,or the govenor gear may be stripped out,its only nylon that runs on a steel gear in the tail end of the trans..or,the valve inside the govenor may be stuck..

If the truck has just sat a long time,and was shifting OK previously,I would say its likely it is low on fluid,and or the govenor valve is stuck,or perhaps a sticking valve body piston in the valve body..kind of hard for the govenor gear to strip out when its parked..:crazy:..
Click to expand...



:deal:...already told you what no vacuum would do...:whistle:
 
OK got everything together and runs great!! I learned alot doing this thanks for all the advice! I did use a vacuum gauge to get the timing right, the only thing now is to tune the carb up a little with the same gauge. Stupid question what octane gas do you guys use? I know the motors are low compression so would 87 be better for it?
 
four50NCalif said:
OK got everything together and runs great!! I learned alot doing this thanks for all the advice! I did use a vacuum gauge to get the timing right, the only thing now is to tune the carb up a little with the same gauge. Stupid question what octane gas do you guys use? I know the motors are low compression so would 87 be better for it?
Click to expand...

87 octane will be fine. The vacuum gauge will make it easy to tune for mixture.
 
Hey guys I used the vacuum gauge to tune the carb mixture, I have the big 4 barrel quadrajet, seems to run the best with the mixture as rich as possible (screws turned all the way out) am I leaving power on the table? Do I need more cfm? I want to try again tomorrow I am guessing that the most vacuum that can be sustained with the screws in as much as possible would be best for gas mileage? I have yet to pull some plugs to see what they look like again my setup is:

-Comp 4x4 Cam specs say is good from 1000-5200rpm
-Full length headers/true duals
-Jegs intake manifold
-Big air filter
-Stock quadrajet carb

Thanks for any help!!
 
four50NCalif said:
Hey guys I used the vacuum gauge to tune the carb mixture, I have the big 4 barrel quadrajet, seems to run the best with the mixture as rich as possible (screws turned all the way out) am I leaving power on the table? Do I need more cfm? I want to try again tomorrow I am guessing that the most vacuum that can be sustained with the screws in as much as possible would be best for gas mileage? I have yet to pull some plugs to see what they look like again my setup is:

-Comp 4x4 Cam specs say is good from 1000-5200rpm
-Full length headers/true duals
-Jegs intake manifold
-Big air filter
-Stock quadrajet carb

Thanks for any help!!
Click to expand...

Generally for more power, you want leaner but not too lean. You have plenty of CFM, quadrajets deliver 750 CFM (800 for some big block variants) which is more than enough for a mild SBC. If you want, you can borrow my colortune, it screws into a spark plug hole and lets you see the color of the mixture as it burns.
 
Nice. :) You are encouraging me to strap the gopro to my truck and take it for a spin lol. Now that it's running decent.
 
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