Is it possible to use an LT4 Hotcam with stock heads? I plan on having the heads ported, but to what extent and when I'm not sure.. also, is this a good idea as a first mod, I plan on doing this at the same time as a complete engine rebuild.

 

that cam should work great with the stock heads, better if ported. you're also gonna need new springs to accept the amount of lift. good luck

 

Ahhh...don't the stock heads have press-in studs? I wouldn't run higher lift on them without converting to screw-in studs.

The cost of prepping them to work with that cam is in the ballpark of getting a good aftermarket cast iron head...with a much better design...

That is why people go to the aftermarket heads, even though it seems like a lot of $$$..

Good luck,

 

If you do the porting yourself,then all you'll need from the machine shop is a valve job,and the stud bosses tapped for screw in studs...
Valve job-$125
Tapping for studs-$100?
Porting kit-$40
Much cheaper than buying new heads....

 

You can also dress up your sister and take her to the Prom too

In the end, it depends on what you want to do and the resale value of the stock heads...cause you will probably upgrade in the future to a better head anyway.

HTH,

 

I'll have to agree .. It's almost ALWAYS cheaper to just go with aftermarket heads ... here's how my Vortec's are breaking down

$300 Vortec cores ..$250 plus shipping on ebay ...
$200 2.02/1.6's springs retainers keepers seals guide plates ..good to .600 lift..from Enginebuilder on ebay ... good stuff
$350 machine work .. cut valve seats , cut bowls , mill heads , studs tapped , milling for viton seals .... Commerce (GA) Machine , again , highly recommended !!!

$850...ouch .. too bad I already spent the money .. another $200 and I'd be running FAST BURNS !! or E-tecs etc etc ... of course my heads will be good for 500+ HP when done ... only slighly better than out of the box fastburns :\

 

Lets not forget cast iron Pro Action heads, complete for $799 from most places...

And they rule....

 

Where do ya get these pro action heads?
and the fast burn heads?

 

The fastburns are available from an GM Performance Parts outlet

Jim Pace Parts or Scoggin-Dickey

As for Pro-Action, do a search in this forum for Pro Action with my user name...there is all the info you will need on these heads. Air Flow Research is still carrying them, but is dropping them due to the fact that Pro Action is now making their heads in aluminum, which makes them a major threat to AFR.

Check the flow information....

 

Lets also Not Forget Retainer to Valve Guide interferance at about .480 Lift.

Since the Lt1 Rolls in at a niec .525 W/ 1.6 Rockers, Your going to need to adress that.

 

really ?? at .480 ?? which heads ??? we've run L98 heads and converted 305 heads up at .510 ?? with springs and flat hydralic tappets of course

roller lifters supposedly fall out at .501 .... or lift the spider retainer with every lump :\ supposedly the LT-1 guys are running .550 lift with factory lifters :\ ... sounds like the comp "R" roller lifters are the answer to that ...

let me know

TVP

 

Well.

Supposedly the Cast Iron L98 Heads w/ Stock Valves and Retainers Will Get into interferaance betwee .480-.490 Lift, At The Valve.

I think Swapmaster Measured his at .490"


You Say you have run .510" On the L98 Heads, But with Stock Springs, Valves, and retainers ?

As far as the lifter Issue, You mean the lifters rising up out of the Bores at .510" Valve lift ? I doubt it...

Same with pushing up on the spider. THe Lobes can only be as big as the cam Bearing's.

 

the lifters are held straight by a guide.. figure 8 shaped if you will ... those are held down by a large spider shaped retainer ..
there is are "flats" on the tappet to align it in the guide .. that face is only .510 high .. if you use a drop center cam .. i.e. .. the lobe drops below the factory "point" ... the lifters drop out of the bottom of the guides .. if you go beyond the .510 in height .. you'll lift the guide that is held down by the spider ... not something that'll last too long .. but apparently it works OK since
the LT-1 guys are doing it ...

Gary's ghost .. from Kent's page .. started off with L98 heads and a .510 lift cam .. t-11 springs , factory dia , good to .550 lift ..
factory retainers and keepers .. we dumped the L98 heads for some seriously worked over 305 heads ....read : SMALL chamber

here's the info on the lifters ....... from http://www.gmpartsdirect.com


This hydraulic roller tappet is used on the 5.7-liter H.O. engine assembly for ZZZ through ZZ2 engines. Use with spring P/N 10134358. The duration at lash point in degrees (intake/exhaust) is 336/336; duration at .050" tappet lift (intake/exhaust) is 235/235; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 480/480. Valve lash is zero/zero and lobe centerline is 114 degrees.

This hydraulic roller tappet is used on the 5.7-liter H.O. 350 ZZ3 & 4 engines. The duration at lash point in degrees (intake/exhaust) is 275/280; duration at .050" tappet lift (intake/exhaust) is 208/221; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 474/501. Valve lash is zero/zero and lobe centerline is 112 degrees.

 

I understand What you getting at TVP, But I Have never heard of this being an Issue.

Anyone out there running > .510 Lift on the Stock Spider assembly and stock Lifters ?

Would Definately Be One more thing to Consider.

 

So whats that Supposed to mean, Somehow The Lifters Are magically Capable of more travel on an exhuast Lobe without Contacting the Guide ?


EDIT: okay I read that again And that description is for a Cam, What the hell does that prove ?


Since when Does a lifter have a 112* Lobe Centerline ?

 

https://www.thirdgen.org/techbb2/sho...n+head+project
This is what I am talking about....
If you do the porting yourself it's FREE......
The retainers I put in my L98 heads should work fine with the LT4 Hot cam...I had to upgrade when I installed an LT1 cam and 1.6 roller tips.

 

In reference to the stock roller spider assembly, I believe you guys are forgetting that the cam doesn't have the .510 lift.

A cam with .400 lift at the cam would have .600 lift at the valve face with 1.5 ratio rockers.

A cam with .500 lift at the cam would have .750 lift at the valve face when used with 1.5 ratio rockers.

In short, you forgot about the multiplying effect of the rocker arms when figuring valve lift versus cam lift.

jms

 

I gotta stop posting when I'm this tired :\ .. way past my bedtime :\ .. the face on the lifter is about .510 .. but it has to ride on the guide/retainer which is about .180 thick .. you can't run the whole .510 in cam lift (as you point out) .. so my point ... if you look at the GM drop in cams .. they stop right about .500 lift and the .525 is made with 1.6's rockers .. so ... I'm also thinking the L98's can handle the .525 ??? I know the "ghost" had .510 I wish I had time to take a set apart and measure .. maybe in july when I get back ... hopefully you guys will have all the right answers before then ...

 

Bort, do you save everything?

The .490 is the limit on Vortec heads.

You can knock the top of the guides down with a dremel
or similar tool and use umbrella seals to get away cheap.

To really get away cheap you can cross-drill through the
stud boss with the pressed in studs in place and drive a roll
pin through them to anchor the stud in place. There have
been, and are, and will be thousands of heads with pinned
rocker studs.

The stock heads will take the lift, just pin the studs for safety.
You can do it yourself, not that big of a deal.