KaP10

Hello everybody. I finished my Lt1 swap into my s10 2 years ago and have put about 10000km on the motor. I took it to the track once and ran 14's flat repeatedly but noticed that it seemed like it was falling flat on its face after 5800rpm and would make a clanking sound (suspect valve float)

After doing driving to a few shows last summer i started to notice the clanking sound all the time and the car would start to chug under load when it normally wouldn't

Took The top end apart and this is what i found



I had originally purchased comp cam 918-16 beehives(whats reccomended on Comps website) and brought them in to my engine shop to have them installed on my heads along with a valve job. The builder their said that he would have to machine the heads for them to fit and recommended 26986-16 which he had laying around instead.

This was my first engine build so i took the advice of the builder and went with what he recommended.

So what my real question is. Did my builder **** me and give me springs that were just on the edge of being compatible and keep the 918-16 beehives for himself?

Bottom is this
http://www.summitracing.com/int/part...3068/overview/

Top is this
with the CC503
and Proform 1.6rr SA
http://www.summitracing.com/int/part...6915/overview/

ACE1252

Wow, I hate to see that. Have you had a chance to look in the oil passages yet? Looks like it starved for oil for some reason(looking at spots on mains of the cam....but I'm not sure...). How do the cam bearings look? How was the oil pressure? How do the mains and rod bearings look? Any sign of oiling issues?

I had minor dip in oil pressure that was cured with a canton pickup and moroso pan.

You'll need some of the experiences engine guys here chime in as to possible sources of issues.

I'm running PAC1518 springs and didn't have to machine anything....I'm not sure what your builder saw that would make him say the heads needed machining. The PAC1518 is the same footprint as a 918.

Just looking at the spring specs, the 986 appears to be weaker than the 918.

KaP10

The oil pressure always seemed a little on the high side 30~70psi depending on rpm. never dropped below 20..

Are the stripes on the main indicative of low oil flow? Cam bearings look fine.

I have not had a look at the rod and crank bearings but suspect that they are fine as well.

This was a fresh build with less then 10,000km assembled two years ago.

96capricemgr

iTrader: (1)

If I looked up the part right the spring the "builder" used is 280lbs rate.

The 918 is 372lbs.

The 918s also fit perfectly fine without machining.

The builder is wildly incompetent and caused this damage.

KaP10

Any idea what the stripes are from on the cam shaft where the bearings are?
Its smooth all the way around and doesn't have flat spots?

bowtienut

iTrader: (1)

As was said, your builder is incompetent judging from the valvesprings he used.
There may also be another factor at play here. Where did the lifters come from? They don't look much different from several that failed for me between 50k and 150k miles on a GM Vortec crate engine (Hecho en Mexico). Very likely the same lifters that you would get as replacement LT1 lifters for a rebuild. Mine failed with a milder ZZ3 cam running sufficient spring pressure and revving to no more than 5500 rpm. I've since replaced them with a set of used LT1 lifters out of a 120k mile motor, and all is fine at 220k.

96capricemgr

iTrader: (1)

If buying new lifters I would look at the "cheap" Morel option, around $200, yes it is more than fresh OEMs but as Pat eluded to newer OEM stuff doesn't seem to be as good as original LT1.

KaP10

I re used the original lt1 lifters dumwith unknown dumkm on them. dumThey were all inspected before getting re installed. Was a running motor.dum


I've installed a new cc503 with new gmpp ls7 lifters just waiting on my comp cam 918 beehives and I should be back in action. dum( I had already ordered the lifters before I posted here)


Anyone know what the stripes are from on the cam bearings in the video?dum