Maximum lift with stock J heads

[65D100]

Good evening all, I am wondering what the maximum lift camshaft I can run on stock J heads is. I havent been able to find much on the subject.

 

[Illahe]

Good evening all, I am wondering what the maximum lift camshaft I can run on stock J heads is. I havent been able to find much on the subject.

I'm running a SFT with .490 at the cam .462 at the valve. The cylnder heads are later oem castings, and oem valve guides. When I checked the retainer to guide clearance there is a little more lift available, say .510, but the heads have umbrella valve stem seals... With the right retainers (Crower 87049) and +.050 keepers you should be able to get a .557 SFT in there.

 

[RustyRatRod]

If someone gives you an across the board answer, that's inaccurate. This is how it is. If you want to know an exact number, you have to measure retainer to guide clearance on what you have. I've seen some go as far as .520 lift and as little as .470. That's because Chrysler was not consistent with the heights of the guides. They're going to be different head to head. So measure.

 

[Illahe]

If someone gives you an across the board answer, that's inaccurate. This is how it is. If you want to know an exact number, you have to measure retainer to guide clearance on what you have. I've seen some go as far as .520 lift and as little as .470. That's because Chrysler was not consistent with the heights of the guides. They're going to be different head to head. So measure.

Now you got me akin to go out to the shop and check my 587's against my J's...

 

[RustyRatRod]

Now you got be ackin to go out to the shop and check my 587's against my J's...

I bet it's cold as a witch's tit up there too.

 

[Illahe]

I bet it's cold as a witch's tit up there too.

Not yet, but it’s on the way!

 

[65D100]

If someone gives you an across the board answer, that's inaccurate. This is how it is. If you want to know an exact number, you have to measure retainer to guide clearance on what you have. I've seen some go as far as .520 lift and as little as .470. That's because Chrysler was not consistent with the heights of the guides. They're going to be different head to head. So measure.

Unfortunately I dont have the tools or knowledge to measure these heads. I appreciate the repy though

 

[Illahe]

Unfortunately I dont have the tools or knowledge to measure these heads. I appreciate the repy though

You can get close with a snap gauge. It’s not rocket science at the hobby level.

Happy thanksgiving.

 

[65D100]

Happy thanksgiving

 

[GTX JOHN]

If the J heads are stock ports they do not increase in flow at
more than 450/460 lift in our testing. I would focus on duration
@ 050 rather than maximum lift.

My .02 = For Free

Flame away!

 

[Illahe]

If someone gives you an across the board answer, that's inaccurate. This is how it is. If you want to know an exact number, you have to measure retainer to guide clearance on what you have. I've seen some go as far as .520 lift and as little as .470. That's because Chrysler was not consistent with the heights of the guides. They're going to be different head to head. So measure.

FWIW: Mullen’s recommendations have been accurate for me, so far.

RRR has a point, always verify. By now, most heads have been worked, and the valve seat may be on its second vale job.

increased retainer clearance effects the spring seat pressure that your camshaft requires.

 

[MOPAROFFICIAL]

Speaking for stock ....something like Valve seat depth will effect the amount of valve lift before retainer contacts the guide.....or putting the seat as far out as you can will increase the installed height , say.. .030+ ...

Now it were a small block Chevy .. each valveguide would have diff interference height...because the spring pockets are machined all over fkn place...

 

[PRH]

Imo, any 50year old heads that you’re planning on using as part of your “performance upgrade” plans should be disassembled and thoroughly inspected/evaluated…….before any parts are purchased.