Stl94LT1

.520 is coil bind, take away the recommended .060 safety margin and it looks good to the stock cams .460 lift.

pgerst

si. This string has devolved into "how much safety margin is safe" to each of us kind of a thing. Looks like the lt4 hot cam could (and for one of us does) work with LT1 springs and 1.5 lifters, I just was not sure how thin the ice was. If the LT4 hot cam has .525 at the valve, looks like .035 is "safe" from GM's standpoint as the LT4 spring binds at .56? Applying that same margin in reverse, the LT1 could go to .49. Personally, i think .06 is very safe, I have run .02 on Fords (though I was not concerned if it went boom).

Edit: I am going to buy an LT1 spring and measure it.

brucer

being we're on the lt4 stuff, looking at the lt4 hotcam kit i didnt realize the kit had light weight retainers also.. seems like GM has always had less than average valve springs.

they have this spring listed for a solid lift cam, looks like it work and be a good spring for a hydraulic roller..

copied from gmpartsdirect:
3927142 - Valve Spring
This is a special performance valve spring for racing camshaft P/N 3927140. This is a good spring for mild racing engines.
Technical Notes: Single spring with damper with 1.273" O.D. and 1.16" solid height. The pressure at installed height is 110# @ 1.70" with 358" the average rate of pounds per inch. Use with retainer P/N 14003974 and seal kit P/N 10132715.

also, all the stuff i've read about the weight differences in valves.
whats the difference in weight of the stock 1.5 exhaust valve vs. 1.55 sodium filled exhaust valves, and the 1.94 vs. the 2.0 sodium filled intake valves.
i've read people saying the valve weight makes a difference, i bet theres not enough to matter when you add the larger valve diameters of the sodium filled valves.. a fairly cheap route would be to use 1.5/1.94 undercut valves plus you would improve flow quite a bit..

pgerst

They are quite a bit lighter. LT4 Intake valves weight 85 grams. LT1 Intake valves weight 110 grams. LT4 Exhaust valves weight 75 grams. LT1 Exhaust valves weight 95 grams.

http://www.malcams.com/legacy/misc/LT4.htm This is a good comparison of LT1 to LT4, so far I have found it to be well researched and reliable source.

Injuneer

That's because is was copied from here:

http://www.grandsportregistry.com/lt1vslt4.htm

John LeBlanc's "malcams" website is still a good resource, 15 years after he set it up. John ran MBA, the company that made the aluminum dress-up items for the 4th Gen. Unfortunately, long gone (MBA.... John is still with us).

pgerst

Injuneer -- what is your opinion on de-rating an lt4 hot cam with 1.5RRs and LT1 springs? I get .028 clearance before bind. To the extent the hotcam with the 1.6/LT4 spring is .035 before bind, and there are a lot of guys, running 1.6RR with LT1cam/springs, .030 before bind on exhaust, it would seem that this would be a fairly reliable swap (consistent with Griderman87's experience.)

Injuneer

The LT4 HOT cam is already pretty mild. What's the point of crippling it further with less lift? You're losing a huge amount of "area under the curve" because the cam has less lift all through its open/close cycle. Get the cam that provides the performance you want, and the valve train required to support it.

As far as the issue of coil bind, I avoided it by letting a person with a lot more experience than I have select the cam and the valve train components. Engine's been running fine, solid roller and all, 7,200rpm redline.

pgerst

I am running stock LT1 due to CA smog; if anything, I would go to 1.6 rockers but didn't want to hassle with changing it out every 2 years, no way would I do a biannual camshaft swap. I got involved in the math for the original post (who wants to do it one part at a time for money) as I had never thought about doing it cam first.

Based on the responses to the OP, there is wide range of opinion as to what is a safe margin, anywhere from .06 to .028 (by my math the GM LT4 hot cam package ends up with .035 for stock rpm LT4, though with much lighter valves.)

Jon_Esslinger

That's what I did. A custom grind cam cost me $330 shipped to my door. I'm getting power exactly where I want it and it was tailored to work with a specific valvetrain. I mean if people want to go so budget that they save $75 on a cam go for it. Do you really want to tear your motor apart after the valvetrain fails? A cam swap is more like a cam/rocker arm/spring/lifter/pushrod swap. Also how many miles are on your car?

wjogert

Sorry to resurrect an old thread, but wanted to share my $.02 for anyone else finding their way here from a topic search.
This is the post I needed to see before believing several other online posts that say LT4 Hot Cam will work with stock 1.5 rockers and valve springs.

Does it physically work? YES. Nothing broke (yet) and I've hit WOT several times. But the reason I'm even here states that something wasn't right. There is a slight "tick" that I've thought sounded like valve train. My brother argues that it sounded like noisy injectors. After reading several articles, I'm thinking it's very slight coil bind.

Before anyone rips on the decision to use stock valve train... this is a temporary setup. She's got over 150,000 and sat for many years after I tossed a stock cam lobe due to a locked up lifter roller. Planning a full motor build in a year or two, so wanted to dump as little $$ as possible into getting her rolling again. Hot Cam was cheaper than a stock cam, and online mis-information led me to believe it was a "drop in" with minimal power gains.

So now to find inexpensive valve springs...

Chimera96

...well finding "inexpensive" valve springs is easy....but not necessarily "good" ones if used with a cam other than stock

Alex springs did offer a low $ set for aluminum heads but I believe they are not available. You could check their site to see. They did have good reports

Crane 10308-1 would be a plug & play set that would work well with the hot cam

I have heard good things about Patriot springs. IIRC you would need to pull the damper spring from them though to clear valve stem seal

IMHO you never want to cheap out on valve train parts

The "tick" you hear could be valve spring binding (really never a good thing) but I suspect it is because the valve springs are just not up to the seat or open pressure needed to keep the PR from bouncing on lifter and RR cups (also not good) because of cam lift and weak springs

lt1-xjs

The Howards 98215 is a drop in spring, leave the damper out.

wjogert

Yes, inexpensive... not "cheap", lol. I had seen other mentions of the Alex springs and actually had those in mind when I mentioned "inexpensive".

Their site still shows 2 options for LT1, both for the same budget price of $130.00. The "mild to moderate" cam version, I think would be a perfect for now. LINK

wjogert

Hmmm, Summit has these for 120.00 / set. They don't come with retainers or locks though... although reviews say they work with stock hardware after removing the damper. Higher spring rate than the Alex's. Decisions.