cam upgrade for a 1968 440 HP

[Philip Ferguson]

I've got a survivor 1968 Plymouth GTX with 85,000 original miles on the original engine and transmission (A-727). It doesn't burn any oil but the cam is worn...it won't operate the mechanical fuel pump any longer.
The original 3.23 rear end was rebuilt about 10 years ago...I haven't pulled the transmission but I'm assuming it's a stock torque converter. It's been recommended that if i'm not pulling the motor for a rebuild to go with a factory grind.
I'd like to get a little more lump vs what I currently have...it was suggested to me that the street hemi grind would be a nice solution and wouldn't damage the current valve train.

Can anybody weigh in on this? Thanks!

Phil.

 

[beanhead]

All depends on what you're wanting.. If you want to give it a slight bump in sound and power, but not enough to have to change other components, maybe look at like a comp magnum 270...or give Hughes engines a call, they have some that will work just fine with stock valve train and can recommend you a cam based on what you want and your current setup. (oh and be prepared to get like a thousand different opinions ha!)

 

[69a100]

I've got a survivor 1968 Plymouth GTX with 85,000 original miles on the original engine and transmission (A-727). It doesn't burn any oil but the cam is worn...it won't operate the mechanical fuel pump any longer.

Are you sure the cam is worn, or is it the fuel pump push rod that's worn? How can you be so sure?
I bettin on the push rod myself!
If your stuck on a cam choice, choose the smaller of the 2, you'll be a lot happier. Good Luck

 

[Philip Ferguson]

Are you sure the cam is worn, or is it the fuel pump push rod that's worn? How can you be so sure?
I bettin on the push rod myself!
If your stuck on a cam choice, choose the smaller of the 2, you'll be a lot happier. Good Luck

I thought of that as well with respect to the pushrod being worn...can that be replaced externally (through the opening for the fuel pump) or will I need to remove the intake anyways to access and remove the worn pushrod?

 

[Don Frelier]

There is a pipe plug in the block you need to remove after you take the pump off. It's pretty easy. There are other threads here where someone posted a correct length.

 

[69a100]

First thing to invest in is a FSM for your vehicle if you don't already have one! By your question, I say that you don't.

 

[wyrmrider]

Street Hemi grind used to be the answer
let's check that fuel pump pushrod first- there are better than oem solutions for the pushrod
do a compression check and report back
what gas can you run without pinging?
have you optimized your distributor curve (yet)
A GTX should have had the MAGNUM cam and the HP converter
Factory rates duration at 268 but it is a really lazy cam so a 268 aftermarket is, in fact, "bigger"
back when we did tests for chrysler the 268 Direct Connection cam helped, one size bigger hurt 60 ft times (lower low end torque)
so BVVC with those 3.23 gears and stock converter
268 Factory and Direct Connection (Mopar Performance, Purple shaft) is different than 268 aftermarket
but note how the Lunati Voodoo 268/276 cam gives a nice increase in lift to about a half inch (the .527 is with 1.6 rockers)
VD .527 .494 .329 268 226 VD 268-276 also a
VD 475/494 262/268 220/226 112lsa

as suggested above Hughes, Howards have cams that would work
the smallest Comp Mopar Cam is the XE275HL which would work but with less low end and would be happier with a looser converter and 3.55s
depends on if you want to drive like a hot rodder all the time
if you do not have headers write back when you report compression, cam suggestions will change

 

[Philip Ferguson]

First thing to invest in is a FSM for your vehicle if you don't already have one! By your question, I say that you don't.

Sorry - what does FSM stand for?

 

[Philip Ferguson]

Street Hemi grind used to be the answer
let's check that fuel pump pushrod first- there are better than oem solutions for the pushrod
do a compression check and report back
what gas can you run without pinging?
have you optimized your distributor curve (yet)
A GTX should have had the MAGNUM cam and the HP converter
Factory rates duration at 268 but it is a really lazy cam so a 268 aftermarket is, in fact, "bigger"
back when we did tests for chrysler the 268 Direct Connection cam helped, one size bigger hurt 60 ft times (lower low end torque)
so BVVC with those 3.23 gears and stock converter
268 Factory and Direct Connection (Mopar Performance, Purple shaft) is different than 268 aftermarket
but note how the Lunati Voodoo 268/276 cam gives a nice increase in lift to about a half inch (the .527 is with 1.6 rockers)
VD .527 .494 .329 268 226 VD 268-276 also a
VD 475/494 262/268 220/226 112lsa

as suggested above Hughes, Howards have cams that would work
the smallest Comp Mopar Cam is the XE275HL which would work but with less low end and would be happier with a looser converter and 3.55s
depends on if you want to drive like a hot rodder all the time
if you do not have headers write back when you report compression, cam suggestions will change

Thanks. that will be my first step to see what condition that pushrod is in before I do anything else.

 

[Philip Ferguson]

There is a pipe plug in the block you need to remove after you take the pump off. It's pretty easy. There are other threads here where someone posted a correct length.

Thanks!

 

[19polara64]

fsm=Factory service manual

 

[khryslerkid]

 

[Philip Ferguson]

View attachment 616050
View attachment 616046

awesome! thanks for this!