If you were closer Id borrow you a stock SB until you figure out whats wrong with yours.

Im with Vtec I think something else is going on. Does it burn oil? Smoke bad?

 

Exactly. I don't see the purpose in trashing this project and buying another car. Yes, the LS1 has more power from the get-go but once you start modding you're going to find yourself in the same position. Find a good shop or do it yourself the right way, the LT1 isn't a bad engine. I've had a number of negative experiences with mechanics and that's why I do mostly everything myself.

 

Sorry for the long post, but here goes....

I started out burning 1 quart every 1,500 miles. I called the original builder and they just said, "well that's what you're gonna get with forged pistons". So I just dealt with it for the time being, trying to get ahead of all the other problems (random dying almost every 6 months to a year, rough running, poor performance with no clear answers). Then it started burning more oil, about 1 quart a week, driving 30 miles a day. My manager and others told me they saw smoke sometimes when I accelerated, and I started noticing it too. I asked what color and my manager said it was blue-ish. I checked a plug and it was black and smelled of fuel or oil. When they did the compression test they changed all the plugs for me and said all of the plugs were fouled and saturated with oil, it had been leaking oil passed the rings for a long time they said.

Ever since I got the car, it always missed occasionally and backfired (always from the front - intake?). In the last maybe 6 months
I started noticing an audible knock and or ping when accelerating. I recently hooked it up to datamaster which revealed that I'm getting tons of knock and timing retard every time I touch the gas but even when I'm just idling. I have an LT4 knock module too. Performance is very inconsistent, usually on the slower side and it's not something that's in my head. It would sometimes run rough and shake left and right when first starting it, especially in colder weather (cold for socal). About once a year it would stumble and die. It will start right back up the first crank but only idle for about 10-45 seconds and die again. I would have it towed home and look for problems and scan it, finding nothing. I would try to get it to die again but it acted like nothing was wrong. I'd look and look and find nothing and eventually drive it again for as long as a year and it would re-occur again in almost the same way. A few times it acted similar but didn't totally die. I would pull over and wait a while and make it home somehow and again I would find no answers and it would act fine. How much of that can be attributed to lots of oil consumption and fouled plugs I don't know.

Someone asked the cam and about rocker adjustment. Here's the cam
http://www.summitracing.com/parts/CR...4&autoview=sku

The motor blew a headgasket at 12k miles. Never even came close to overheating, just slowly started noticing a lack of performance and rough running, then white smoke from the exhaust. The performance wasn't very impressive before, but I really noticed this. Funny thing is I had dropped the car off for soem twisted icm wires that was casuing stalling and I got it back and they said "ok, it's fixed and it's running great!". It ran kinda crappy, and had poor performance. I couldn't afford to have it done, so I did all of it myself. I took the heads in to be magnafluxed and then for them to do a valve job and assemble the heads. I don't have paperwork for it (i looked hard later on) but I remember pretty well one of the service writers telling me that the valve seals looked fine so they re-used them. At the time I didn't know any better that that was a bad thing to do. Being that I assembled it, I did the valve adjustment myself. I couldn't understand at all how to do it the the engine off way so i did the engine running method. I used stock preload so i doubt I tightened them too tight. I actually had one or two pop off before I finally took it to the builder to have it done professionally and had them put poly locks as a piece of mind. I should note that the valvetrain was always pretty noisy, despite being stock rockers. It wasn't any quieter or louder than my own valve adjustment. You might ask why I didn't go somewhere else. Well you'd be right to ask, but there aren't a lot of shops in my area. A lot of good shops I heard about were a few hours away. And the reason I picked this shop originally is because my dad was friends with the owner back in the day when he had a few mustangs and got work done on his cars there, so I thought I would be treated well.

The compression/leakdown test results are:
#8 - 235psi w/ 8%
#6 - 240psi w/ 5%
#4 - 230psi w/ 9%
#2 - 225psi w/ 5%
#7 - 235 psi w/ 7%
#5 - 245 psi w/ 8%
#3 - 230psi w. 8%
#1 - 240psi w/ 5%

When I picked the car up today I had hoped to talk to the main guy, but he left early for a doctors appointment, but the paperwork says "leakdown test showed pistons and oil rings. Recommend replacing rings with honing". And the thing is, they know me. They used to work at the other shop but left and started their own. He said the only thing I can do is rebuild it, but he knew that I " probably didn't want to because I had just rebuilt it". So if they even thought it might be valve seals I think they would have told me. He said he would help me out if I decided to get another motor or anything else, actually charged me half the labor for the test. Not saying you guys can't be right, just saying it doesn't look good. Based on what I just said and the results and you think it could still be valve seals, how can I find that out? Will the seals visually not look properly seated if I disassemble the heads?

Honestly, all you guys are starting to give me a little hope. I actually helped my manager remove an LS1 from the bottom out of a wrecked Z28. I was the one who convinced him to do it through the bottom, printed out a walk through for him too. He did most of the work, but that experience certainly can't hurt.

If it would help anyone to know I have a few sheets of build data like top ring gap and stuff like that, it's all greek to me.

Maybe I'll do something like this:

http://www.ebay.com/itm/Remanufactur...item3cb32acc5d

But I have zero room, I'd have to sell my 1970 camaro for space. I haven't touched it in a long time and it seems unlikely I will ever finish it.

 

Those compression figures I think are correct.
Maybe someone else can chime in on them with a good resource or confirmation.

The seals should have never been skipped it's the easiest thing to do.
The good news is you can still do them...just have to pump air into the cylinder so the valves don't fall.

You might also need a new opti and icm...that's what it sounds like anyway.
You have to get rid of any bad twistings or bad wiring this will leave way for gremlins to multiply like after 12 eatings if you don't and make you chase the wrong things.

The "forged pistons" comment merits you setting that shop on fire.

What brand pistons and what rings did they go with? Were they a matched set ?

 

as i said in the PM you sent me.............first of those are very high cranking PSI numbers...........what was the compression setup as on this motor it seems to be high......also if the cam is installed a tooth off you could've had intake valve interference which will cause the popping through the intake as well as the oil on the plug issue because its getting by the seal if the valve is bent and the guides are damaged..............with those numbers i dont think its a ring issue...........sounds like your shop has some questions to answer in cylinder head and valvetrain setup.........you will be supprised how may places hack things together only to confuse the amateur with big words and mumbo jumbo spweing from their mouth...........as a small side buisness engine builder myself it makes me sick to see cases like this where people are raped by bigger shops that shouldn't even be in buisness.......

 

JE forged pistons with JE rings according to the paperwork. Compression ratio is 10.5317. Did you read where I'm consuming 1 quart of oil a week of daily driving? Isn't that too much to not be rings? I guess I shouldn't re-use these heads since they ported them.

I'm not even going to bother to go to the other shop, they will just stonewall me. If I do anything it will be mostly by myself and a little help from this new shop.

 

give us all the #'s, let us calc the compression. need:

bore, stroke, deck height, piston cc, head cc, which head gasket used, etc.

 

This is all relatively good news...your bottom end seems fine.
You've got some questioning to do on those heads. Bent valves or bad seals.
Like quik95 said it could all point back to a bad cam sproket install.

This is amazing. This is why I do most of my work myself. Even on my beater japan stuff becuz a lot of shops just don't understand or care about what they are doing.

I don't daily drive my Z. If u want to simplify your life I would get a japan beater.

You should celebrate those compression figures...

http://youtu.be/SmM0653YvXU

 

for a 10.5:1 motor to have 250psi cranking compression the valves must not even be opening lol...........thats ALOT of pressure...........mine generates 265-270psi with 14.2:1 CR and a serious ringset/cylidner wall.........i do have a much larger cam but still

 

in inches:

Bore - 4.042
Stroke - 3.48
Deck Height - 0.025
head cc - 56
stock head gasket

top ring gap - .020 2nd - .018
oil ring data .030
piston to deck clearance - .025
main bearing clearance .010
piston to wall clearance - 4.038
thrust clearance - .003

valve diameter intake - 1.94, exhaust - 1.50

I didn't have time to call the new shop today, extremely busy work day, took a half lunch, but I'd like to soon. I'd like to believe I've found a good shop with these guys but I wonder why they wouldn't have thought it might be something other than the rings. I don't think the original shop had much experience with the LT1, they had done LS1's I was aware of but are a mostly Mustang shop. They may not have done a very good porting job either, I'm not liking the idea of re-using these heads, I think it might be smarter to start over with some LE or AI heads or even stock. But what about all the knock and timing retard, could that be caused by all of this? It would suck to still be having a lot of problems after I fix this one.

You guys are awesome. I'm feeling optimistic no matter what the case is. Thanks for the help.

 

what kind of pistons? need the cc of the pistons

 

as stated earlier, an LT1 is basically just a sbc. machine shops have been working on those for 60 years.

 

ok, I assumed a 5cc piston and a felpro 1074 headgasket and I get 10.8:1, with your cam, dynamic at 9.55:1

http://www.kb-silvolite.com/calc.php?action=comp plug your values in here. the 1074 is 4.100 gasket bore with a .039.

 

Forgot to put the piston cc, you are correct it is 5. Merim123, sorry I'm a little slow with this stuff, my sheet says I have a 10.5317 ratio, is this a different ratio or my true ratio? I'm not following, I'm a newby to this. And also, what does this information reveal? Do the specs I provided show a loose build or does it just show that the bottom end is still good in relation to the compression/leakdown test results?

 

I don't know how your guys calculated it, I use that link, as you can put in a lot more variables. Not sure what your guy did.

Here's some standard stuff you can cross reference. you sure on the main bearing clearance on yours?



(ALWAYS consult your piston manufacturer for recommended clearances. Many pistons require a tighter bore)

Piston to bore 0.0055 - 0.0065" ( measured at centerline of wrist pin, perpendicular to pin)


Piston ring gap MINIMUM end clearances Top 0.022"
2nd 0.016"
Oil 0.016"

Wrist pin 0.0006 - 0.0008" in piston, 0.0008 - 0.0010" in rod for full floating pin (End play 0.0 - 0.005"

Rod bearings 0.002 - 0.025" , side clearance 0.010 - 0.020"

Main bearings 0.002 - 0.003" , 0.005 - 0.007 crankshaft end play

Piston to head clearance 0.035 MINIMUM including gasket (steel rods), 0.060" MINIMUM aluminum rods

Valve to piston clearance MINIMUM 0.020" exhaust , 0.010" intake NO VALVE FLOAT
Recommended: 0.080 intake, 0.100 Exhaust (steel rods) 0.100 intake, 0.120 Exhaust aluminum rods

 

FYI, these are not unusual leakdown test numbers, especially for a forged piston engine. You might want to look elsewhere. Here is a good article on leakdown testing:

http://www.carcraft.com/techarticles...r/viewall.html


There could be any of several things wrong, and though a lot of shops have experience with SBCs, the LT1 is quite different beyond the block. Did you change that knock module before or after you noticed engine knock? A smoky, oily engine can be a sign of a bad tune, including a knock module that is malfunctioning.

It's hard to tell what is going on in your case, but I ran into shops when I rebuilt my engine who swore up and down that they knew the LT1, then one guy told me how many CCs I had in my heads and that he mills them .030. Of course, you can do that with an SBC, but NOT with and LT1 which already has a stock compression ratio of 10.5:1. Some shops just want the business so be careful.

Deal with someone who has done LT1s. They have similarities, but are NOT the same as a SBC. I did my LT1 myself and it runs well. I sympathize with you, but I'm betting things aren't as bad as you think.

 

Thanks speedy. I'll call the new shop next week, had high hopes for them but feeling a little let down by there conclusion. I just bought a book on amazon on rebuilding LT1's so hopefully that will get me a little closer to understanding everything as I'm in the shallow part of the pool right now.

 

that book is good, i have it at home. It will give you the basics so that you can at least understand the lingo. Come here and ask the guys on the clearances that have put motors together, like quick95lt1.

It does sound like it's in your valvetrain though too (maybe it is off by a tooth)

 

im doing a lq4 swap in my 95 t/a
i was going to do a 383 stroker build on my lt1 till i got around to doing all the research
finally all the guys around my town talked me into the lq4
definatly gonna be better than those crappy lt1's
and a hell of alot more dependable.
if you need any info just pm me

 

there are lots of LT1's running around on pump gas with .030 or more cut off the heads. shoot, mine had about that much cut off of them along with .026 head gaskets.... and i was still running pump gas with nitrous at the track.


this is not rocket science. an LT1 is simple.... any competent shop can do machine work on one of these engines. i can post up some pics of a duramax..... lol