Hey I was wanting to know what the specs are for the LT4 heads. I was wondering if I could get my heads rebuilt to those specs. Thanks for the help.

 

Exactly what are you trying to do? Its very easy to port a set of LT1 heads to outflow a stock set of LT4 heads. But that won't make them the same.... the LT4 castings are different, featuring a taller intake runner.

Look at the differences in the cross-section photos in this link:

http://www.malcams.com/legacy/misc/LT4.htm

That link also highlights the differences in valve sizes, valve types, etc.

 

LT4 heads are also NOT the holy grail the magazines and such make them out to be.

 

OK gotcha. I want to use a LT4 hotcam and need to let the machine shop know what I want. Can I get some suggestions on what I should tell them.

 

You don't have to do anything to them... just change the valvesprings over to the Hotcam springs. DONT LET THE MACHINE SHOP DO A VALVE JOB BECAUSE YOU DONT NEED IT.

Bret

 

I think what Bret is saying is the stock valvejob is better than what the vast majority of shops can give you. Milage is not the issue it once was on engines and people are far to quick to dive in and ultimately screw up a perfectly good engine. Not saying you shouldn't cam it just saying you don't need to go rebuilding things because you are camming it. The LT1 in my Roadmaster wagon has the same exact bottomend as yhe f-body at 180K I did a crank9ing compression test on a few cylinders and they came up over 185 then ran a cleaner through over the course of a few months and retested at more like 195-200. Before you say it was babied this has a base curb weight of over 4600lbs, combined with 2.93 and a 28" tire means that engine is always working even if it is not reved high.

 

So there should be no need to get bigger valves. I mean these heads are an extra pair I have so no big deal on getting the work done.

 

Bigger valve means just that bigger valves does not mean more flow or better flow. Bone stock your heads outflow the very best of the musclecar era big valve heads. Most of the good LT1 head guys only recommend replacing the valves on serious effort jobs not on your average street buildup. Stock parts are MUCH better than people give them credit for, not to say we shouldn't mod just to say do reasearch before making asumptions about what has to be done. A lot of old "wisdom" is just plain wrong and often was when it became "commom knowledge".

 

Listen to Dwayne he's right on

 

SO basicallyI should get a rebuild and a port and polish job then huh. No bigger valves and just replace my springs with the LT4 springs.

 

If you do a port and polish just don't worry about any of this and send the heads to Lloyd for a LE1 setup and you will be good to go.

Either just put the spring on the heads (NOTHING ELSE) or get the LE1 stuff done by Lloyd Elliot.

Bret

 

The HOT cam springs are meant for use with the HOT cam and the LT4s lighter valves, I would choose a differnt spring, those will work but will be just marginal so after some time could allow some valvefloat. Or I suppose you could look at lighter weight retainers to simply reduce what is asked of the springs.
This is just my opinion and I know lots of people have run the LT4 springs with the HOT cam on stock heads with no issue, I have just made enough mistakes and bought parts a second time enough times that I try to look ahead and slightly overbuild without foolishly spending money.