The Bristol Cup race is next week. A good friend of mine is a spring engineer at one of the major suppliers for our market. He is also a Jr. fan. . .good man. Anyway, he will be here from Wednesday, 25th, on so I am going to pick his brain and may have him log on here to look at the issues that this engine is running into. This engine has way to many spring failures compared to other markets, hell BBC marine engines running 4000 and 5000 rpm all day long will last 30K miles based on the hours they run.

If anyone has any specific questions you want asked, either post them or PM me. Thursday the 26 is no racing so I may log on that day with him.

Chris

 

Look at the lift and RPMs people are running in daily driver LS1 cars. It wasn't too long ago, those numbers were strictly for race engines, not daily driver cars.

 

2xLS1,
I agree. With the weight of the hyd roller and what you have mentioned I agree. Although the Ford 5.0 community approaches close to what the LS1's are running and also have a heavier lifter, but have no where near the spring issues. I don't know if it is due to the larger 1.460" OD stuff that is run or what. We shall try and find out.

Chris

 

Chris,

I thought you investigated the lock issue with a timing light and were trying to address it there??

John

 

Viper,
Our locks have been shipping since April. Everyone is happy. I would not use a stock lock, stock black oxided lock, or a lock that fits like the OEM one does in the OEM retainer on a modified engine. There is to much movement of the lock in the groove area. Compound that with a little valve float and you have a recipe that will hurt something.

Our lock must be used with an AFR retainer or Patriot retainer for Super 7.

Chris

 

I think you will find that the reason this engine has more valve-spring issues than most engine is not necessarily a problem with the engine or the springs. This is a common engine, and just as commonly, people try to test the limits of the engine...particularly how far you can rev it, and how much lift you can jam onto those springs as quickly as possible.

 

https://ls1tech.com/forums/showpost....67&postcount=3

 

how many other engines use 1.7 rockers? That makes for some wicked valve velocities...

 

I guess. It still comes down to your cam profiles and you final lift value, neither of which are too crazy stock. The 1.7 rockers are just a multiplier...based on the cam the end result is pretty much the same. Regardless of what ratio the rockers are, the cam controls all of it. The rocker is still ends up moving the same distance and lift at the tip. It's like saying:
If I have two cars and one has headers and one has a lid, and they both finish the quarter mile at the same time, which one is faster? The answer is neither. The end result (theoretically guys, I know headers and intake will create different horsepower and torque curves, blah blah blah) is the same.

 

but with wicked lobes out there today...that 1.7 multipler is a BIG factor IMHO

 

Not if you have a competent cam builder that factors this into the ramp rates.

 

Ford Cobras, 1.72" stock ratio. Marine BBC 1.7 ratio. All of which see aggressive hyd roller profiles.

Chris

 

One problem I see is the high lift and rpms like I said earlier, and people just throwing springs on the heads without checking the installed height. Who actually sets their spring height? Isn't Crane saying installed height effects the harmonics in the spring? Take a look at the broken Crane spring thread. People are saying use this shim or that shim when the only way to know what, if any shim you need it to use one of these on every valve.

 

DITTO!

Bought one for myself...money well spent

though stock valvespring heights are typically consistant so a "guesstimate" shim pack is usually sufficient.

Once you go with different valves, etc, then it becomes crucial to measure EVERY spring...my heads had .010 variance...

 

To my way of thinking, the rather small O.D. of the spring and the high lifts and RPM's is the issue. It's like sending a boy out to do a man's job. Larger O.D. springs would not be nearly as stressed. The only real issue is clearance at the underside of the rocker and the size of the spring seat pad!

 

I pointed to that fact also in some of the 918 discussions. Most folks have no idea what the above object is (for those who don't, its a valve height mic for checking setup height on your springs). Crane has obviously seen something as they upgraded the 832s. Comp has upgraded the 918s. Everyone is upgrading springs and materials. I think its a combination of poor installation practices, very agressive cam lobes, a fairly heavy valvetrain, coupled with high rpm usage. But that said, I think there are some issues that could be addressed...

 

one thing that has not been mentioned is valve weight. as you all know the ls-6 has hollow stems. allows the increase in rpm's. we have light weight 2.100 intakes at 88 grams. i don't have the ls-1 weight at hand but it may be over 100 grams. also in reference to the big block it has much larger dia. springs over my 40 years of building engines i have seen them break springs. many of you are daily driving cars with hp that 5 or 6 years ago was only found in race cars. the one lap car that we were involved in two years ago ran to 7000 rpm over the 4000 mile distance. it had titainum intake and exhaust as well as a larger diameter spring.

myron c

 

Posts like this one is why I love this site, I've learned more in 1 year of owning my LS1 from this site than I did in 6 years of owning an LT1

 

Ah, a picture of a "swifty". Yeah that is a must or a snap gauge and a mic. I agree with Tahoe. I think the larger springs on these heads would help.

Chris

 

I'm sleepy, but tomorrow, I'll see if I can find the spreadsheet TEA did with all the valve weights...

EDIT:

Here it is..
http://www.totalengineairflow.com/te...ainweights.php