How much lift can stock heads take?

[gliderider06]

So I am considering this cam http://www.ebay.com/itm/201214138211?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
and with it having .513/.533 lift I was wondering how much lift can a stock #587 "J" head take? I already have the Comp 995 springs installed on them. Do the retainers hit the top of the guides with that much lift? Will I need to have the guides cut down and the viton seals installed?

 

[krazykuda]

A good head guy can check that. Mine does when I tell him that I'm going over .500" lift. If not enough clearance, they cut down the guide to get what you need and a little extra JIC....

Stock, I don't think there is enough clearance. I would get it checked JIC.


If you risk it and kiss a valve, you can put a connecting rod and piston through the side of the block - don't ask me how I know....


Much easier to make sure it's right now while it's easy to get checked and fixed. I wouldn't chance it.

 

[RustyRatRod]

It ain't that easy. If I had to answer, I would say the retainers will "probably" hit the guides with that cam. The ain't that easy part is, they might not. Chrysler had poor machining tolerances at best, so where one head will pass , another will not. The guide cutting tool is cheap. The arbor for the tool is cheap. It will chuck up in a 3/8 drill. Buy it and cut the guides down yourself. Use a simple machinist rule to get them to the right height. It's not difficult.

 

[gtsdude]

I agree with RRR, only way to know for sure is to measure.

 

[OldmanRick]

With the 995 springs already installed on them, are you sure the guides weren't already done by the previous owner of those heads?

 

[Big_Al]

I have that cam in my 360 with 1.6 rockers. I had to cut the guides down because there wasn't enough clearance. Really good cam btw!!

 

[69 Cuda 440]

Maximum Lift Camshaft

We did Performance Work for Chrysler back in the day.

Without cutting the Valve Guide Boss.

.480" to .490" Lift > Is the 'safe-point' on the 'J' Cylinder Head.
-------------------------------------------------------------------

Side Note;

Believe it or not, but the .509" Lift / 292* Duration Camshaft
just barely scrapes by in clearance, but that is 'pushing' it.

 

[gliderider06]

Crap. Come to think of it I dont have the 995 springs. I put in the 901 springs when the heads were done last winter. They are the singles withdamper. Sorry, I gave the wrong part number. I will have to look and see if my current springs are good with that cam.

 

[mderoy340]

SBM lifter pushrod geometry results in .010-.015 lift loss at the valve from cam manufacture lobe lift spec. Add the less than optimal rocker ratio of a stamped OEM rocker and you'll see how it is possible to run a 509 cam without cutting the guides down.

 

[69 Cuda 440]

SBM lifter pushrod geometry results in .010-.015 lift loss at the valve from cam manufacture lobe lift spec. Add the less than optimal rocker ratio of a stamped OEM rocker and you'll see how it is possible to run a 509 cam without cutting the guides down.

That is correct sir,

With the Geometry Angle, the Valve Lift will be effected by up to .019" on a stamped steel Rocker-Arm.

For those 'in the know', the 1966 Dodge D-Dart came thru with a Cam-Craft Camshaft 'Mechanical' with a lift of .495" Intake / .505" Exhaust, on 'Stock' 273 Cylinder Heads.

 

[ir3333]

...but doesn't the flow on stock heads stall at about .485?

 

[mderoy340]

...but doesn't the flow on stock heads stall at about .485?

Yes.

 

[gliderider06]

I wonder if I would be better with this cam instead? http://www.ebay.com/itm/141465883101?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
Has less lift and about the same duration, but it is not a split pattern cam. I have to talk to my machinist again about cutting the guides down.

 

[RustyRatRod]

Why in the hell are you so afraid of machining the guides? It's so easy a chimp can do it. Suck it up, machine them yourself, or pay to get it done and run the cam you want.

My GAWD.

 

[gliderider06]

You're right!
I Just keep second guessing myself on what I want to do with it and get confused.

 

[krazykuda]

I just tried and was able to lift one above my head.... LOL!

 

[RustyRatRod]

You're right!
I Just keep second guessing myself on what I want to do with it and get confused.

Don't second guess your own abilities. You can do it with no trouble whatsoever. It's not difficult at all......OR you can pay a machine shop if you don't want to buy the tools. They won't charge a lot to do it. If I were you , I would get the tools. You could make that money back by machining guides for other people. Basic cylinder head work is fairly simple. If you can read a mic and a machinist's rule, you can pretty much do it.