430 build Part II...this time a 455!

OK, there's NO reason the valves shouldn't be sealing.

Valves can leak some, and the engine will still run. Doesn't mean the valve job was done properly.

DEMAND A VACUUM TEST OF THE VALVE SEALING from your machinist. If he can't or won't do that, you need a different machinist.

My vacuum tester will draw an 89% vacuum with the adapter blocked with a suction cup.


Connected to the exhaust port of the cylinder head so as to test the exhaust valves of that cylinder, this Lumina 4-valve DOHC head is losing only 1.5%, and that's probably air coming up the valve guides, not valve sealing per se.


I bet your valves are leaking much, much more than that. The way you describe them, I'd be surprised if they'd hold 50%.

(Don't confuse the percentage of leakage on your leakdown tester with the percentage of leakage on the vacuum tester. They're both percents, but of a totally different base number and procedure.)

 

Perhaps you can lap the valves instead of taking a head back for a valve job to make them seal for a leakdown retest?(if you have a spring compressor,or you can borrow one)By disassemling the heads you can also check for bent valves that may be the culprit from when the 430 let go?

Check for sealing after lapping valves,with kerosene(or diesel fuel) in the combustion chamber,look for gravity seepage in the intake and exuast runners.(water is to thin,and will seep to easy for this sort of test) A cheaper alternative to buying another expensive tool you'll probably only use once.(no offense Schurkey,your way is much more accurate,and probably the best way,but $$$ impracticable for a one time use if he can't find a shop to do this for him)

And as for installing an LS in your vehicle,if you have to rebuild it and use the same machine shop,you can run into the same problems as you're having now.o No: Any engine has the potenial to fail as your engine has,much much less expensive to repair what you have than doing that,me too swap.(you swap a LS in it,me too) A roller cam,and a coil on plug conversion and aluminum heads on a 455 would be WAY cooler than a "me too" swap for the cash that would go into doing the swap,probably for a lot less :dollar:.:TU:

The cylinder that is leaking in the crankcase could have a broken ring,or cracked piston that can usually be easily repaired.May not even be the machine shops fault if the part they installed failed after the fact,if that is the case,a reputable shop would make it right.(not sure if you bought the short block assembled or not?)GL


Derek

 

Thanks for the tips about checking the valve sealing. And trust me, having a built Buick motor will always be "cooler" than an LS swap, however, at some point practicality has to rear its head and for the money, thats the way to go if the heads don't pan out. As far as a "me too" factor...i dont think ive seen or met anyone else with a Boattail Riv and an LS motor. ALL the cylinders are leaking into the crankcase, not just one. I've rotated the engine with the heads off and checked the oil, there are no broken rings or pistons or metal shavings/pieces anywhere that i can see.

 

If a ring is broken,it doesn't necessarily mean that that you'll find it in the oilpan,a broken ring would get caught in the ring groove.And if a piston is cracked doesn't mean you'll see piston chunks in the oilpan either.

And WOW! All of the cylinders aren't sealing! Something majorly wrong is going on! Who built the short block?

Man I wish you were closer to help you. Prehaps the rings were all installed upsidedown?o No: That is so weird that NONE of the rings are sealing,I think I'll have to re-read from the begining of this thread to look for info of the origin of the short-block that you swapped in after the 430 died for clues of what went wrong.

Very sorry for your troubles,and I hope your settling well into your new home.GL,and I'll look for clues from earlier posts.



Derek

---------- Post added at 02:09 AM ---------- Previous post was at 12:38 AM ----------

Ok,I re-read through the couple of months of posts,and have a few questions;

First one,when you're using your leakdown gage,are you allowing the cylinder to fill to pressure with both valves open before closing the inlet pressure valve coming from the compressor?

If you have the valve closed to the heads when you fill the gage,then close the valve from the compressor before you open the valve to the heads,it will sound like you're losing pressure through the crankcase when the cylinder is filling.

Both valves need to be opened to bring the cylinder up to pressure,then the pressure feed valve is then shut,then you listen for leakage.(it wasn't mentioned that it was done this way,so thats why I'm asking)

Second question,if the leakdown tester was used properly,(I see that you assembled the short block after re-reading)do you remember when you installed the rings if they had a dot on one side,and if you put the dot towards the top? If no dot,there should of been directions on how the rings should be installed with a picture of the ring profile,are you sure they were installed in the correct orientation?

One more question,did you check lifter pre-load,if not your pushrods you're using may be to long,you can get adjuststable ones to make the pre-load where you want it.Or you can buy one adjustble pushrod and order the lenght that you need.(if the pushrods are to long,your valves won't close all the wayo No:,and a compresssion test would read low)

Hopefully this helps,and you resolve your problem,let us know what you find.

Derek

 

I'll try what you say about filling the cylinder and then removing the inlet pressure but i don't think the tester works that way...if i remove the inlet pressure than the supply pressure will go down with the differential pressure.

With the Speed Pro rings, i dont recall any dimples on the rings but i honestly didn't look at them that hard either. I don't remember the directions calling out a certain way to insert them either but it could very well be.

I did not check the lifter preload as i used stock rockers and pushrods. All the pushrods can be rotated in the circular manner with no up and down movement.

 

Sorry,its been a few years since I used a leakdown tester,I forgot the inlet pressure stays on.ou:

And remeber using a leakdown tester on a new engine,you'll have more leakage past the rings until they are seated.(engine broke in) Not sure what the lesser percentage would be though?

Every ring I have ever installed calls for them to be installed a certain way,there is a top and a bottom of the ring.

And I think you mentioned that the heads were redone before?,if so, the exuast valve seat in the number 6 cylinder may of been cut deeper than the rest of the valves making the valve stem stick up higher than the rest of the valves,causing it to stay opened. On the 430,it might not of effected it if the block was never decked? Without the engine oil pressure pumping up the lifters,they would still easily spin. A staight edge across the valve stems can check to see if the heights are the same or very close with the rocker arm assemblies off.


Running out of ideas,I hope I was helpful.o No:


Derek

 

Yup, inlet pressure stays on.

There should still be no audible leakage past the valves.

Audible leakage past the rings is still no indication of QUANTITY of leakage past the rings. It doesn't take much leakage to resonate through the crankcase and sound like a tornado...while the gauge indicates acceptable leakage. Kinda depends on the engine.

Not with the rocker arms off.

It might be worthwhile to drop the piston in the bore, and then pop the intake and exhaust valve tips with a hard rubber mallet, so each valve opens a little bit and then snaps closed. If there's any carbon build-up on the valve face/valve seat, that should break it free so the valve seats again. This MIGHT improve valve seal.

 

That was refering to the compression test where he got a zero compression reading,but yeah,if the leakdown test was 100% leakage,then we could rule out the push rods(should of still been checked when assembling though). And yes,a carbon buildup could cause a valve to stick open also. But if the heads were previously rebuilt for the 430,and not ran that long,that 430 would of had to be severely out of tune to build up that much carbon,but possible?o No:

At this point(if the rubber mallet strikes don't work),disassembly of the head(s) to inspect for bent valves,carbon and other damage might be the most efficent use of time.If valves look good(not bent) with no major carbon buildup is found,lap valves for a re-test probably would be the next step to resolving this? These are 430 heads? If so,those are prone to cracking,I'm not sure where they crack,but if they crack in the right spot it could kill compression also. If the head is cracked,I would suspect it is cracked in the exaust seat area on the number 6 cylinder,or cracked form the exuast valve seat to the intake seat?

Start with the passenger side where the zero compression was found,all paths seems to point to the used heads as the culprit. Not sure on the details of the 430's demise,but that could of hurt that head.(cylinder 6 valves) Hopefully the rings were installed properly,the compression test seems very close to each other except for the # 6 reading so rings could be alright being that it is a new build.


I'm sure you could spend hours and hours more to try and track down the problem without taking the heads off and disassembling them,but after all that time to chase the problem you finally figure it out,you'll probably have to take the heads off anyway. It doesn't really look like this can be fixed without taking it apart,so...................GL



Derek

 

I've already had the heads on and off twice now and did tap all the valves with a mallet. I could disassemble the heads but barring any serious damage I really don't have the equipment to check valve guide clearance or seat sealing. At this point I'm looking for a set of heads that are known to be good to swap on and see if the engine runs properly...and if so then it'll be time for alum heads.

 

Just for the sake of being thorough, if i were to remove all the pistons and found that some or all of the rings were installed incorrectly, would i then need to de-glaze the cylinder walls before reinstall? Would I need new rings? The motor has maybe an hour of run time and less than 15 miles on it. Once it was mentioned about ring position, it made sense why a couple of the cylinders had fouled spark plugs after such little run time. I'm still trying to get the directions for the rings i used to verify install procedures but im sure it would be a safe be to assume that would be the cause of a oil in the cylinder so early after building it.

 

Finally, stopped procrastinating and dropped the heads off to check checked. Hopefully, Monday I'll here the results.

 

Did you find the paper work for your rings? What type of rings were they,maybe we can find ring oreintation on the internet if you don't have the paper work anymore.

Derek

 

I asked Summit tech if they could scan a copy and they sent me this link. http://www.dssracing.com/v/vspfiles/assets/images/ring instructions.pdf. Funny thing is, I don't remember seeing that sheet in the box when I opened it. As you can see the instructions were generic to all types of rings and gave instructions for each type so now I need to either pull a piston or get my hands on another set of the same rings to check what I have.

 

Maybe you had these rings;


4. Unidentified rings may be installed with either side up.


Would be nice to know something like that when you're installing them though with some paper work for the rings.:shock:

In the pictures of the cracked ring,is that showing both sides? I couldn't tell from the pic if there was a mark on one side,maybe the original pics are better to see if the ring has one of the marks shown in the instructions? I got my fingers crossed for you.GL


Derek

 

Spoke with the machine shop today about the heads and they magged and pressure checked the heads as SAT. That being said, they noted there was a minor crack in one of the valve spring pedestals but they said it should not be cause for concern as there was no rupture of the water jacket when they did the pressure test. I'm going to try and head over there tomorrow to take a look but in your opinions, should i even take a chance?

Well, went to take a look at the "crack" and it looks like its surface scratch. They pressurized the water jacket to 50 psi and showed my no bubbles. What do you think?

 

Just a quick update: the passenger head required a new intake/exh valve but other than that the heads are good to go. I should get them back today or Monday. I ordered another set of the rings to determine if I'm going to need to pull the engine again and the answer is yes. The middle oil ring DOES have a dimple so yeah, out comes the engine and pistons. Yay me.

 

Sorry to hear that,a very time consuming lesson,and at least you'll know its right this time,no guessing.:TU: Everything should be good to go the second time,and ready for your turbo.

You'll have a 50/50 chance that some of the rings on the pistons will be correct,hopefully most will be on in the right oreintation. The ones that are,you can just re-install them as is,the ones that aren't,you might want to hit those cylinders with a ball hone so the new rings can seat properly. Clean block and re-assemble,good to go.GL


Derek

 

* Check ring gap before install.
* Buy a ring spreader (cheap) to remove or install rings by keeping them flat.
Do not install them by hooking one end in the grove and winding them on at an angle. That can distort, weaken or crack them.
* Unmarked rings often have a bevel, notch or barrell shape on one edge. The 1st and 2nd ring will have a different shapes to determine their location. The top one seals compression, the second is a "scraper" for oil control (example inside bevel up for first, inside bevel down for second) so you can't flip these and switch places. You have to know top from bottom.
Check the difference carefully and get info off the internet or manufacturer. Extreemly important.

Head Cracks: I have a pair of 1967 "big port" heads that have cracks. After 20 years, head porting, hard driving and some overheating , they still work fine. Common problem with headwork is the machinists sink the valves all to hell and throw off the rocker geometry that is NOT fixable with adjustable rockers or push rods. You must use shims under the shafts and springs.

I'm sure you already know some of this, but I'm just thinking of the knowledge gaps that have cost me.

 

Thanks, i checked the upper rings for bevels or something to id an install direction and couldn't find anything. The second rings not only have the dimple but you can see the beveled edge. I am still deciding on whether i want to de-glaze the cylinder wall. The engine has less than an hour of run time so im not sure if id be doing more damage, but we'll see. Hopefully, i can get the engine out of the car tomorrow.

 

Well, i got the engine out today. Took me about half an hour (im getting too good at this), most of that was just maneuvering the car and hoist around my small ass garage. I had a theory going in that the pistons with the incorectly installed rings would match up to the spark plugs that were fouled so I pulled the #1 piston, whose spark plug was clean, and the rings were all installed correctly. That's the good news.

The bad news is this is what the bearings and rod journal looked like. I did find some metallic grit (and a dead ladybug) in the pickup screen sooooooo, now im at a crossroads. i can get new bearings and give it whirl or the crank and rods all go to the machinist. Sigh. I haven't pulled all the other pistons yet becuase this was enough to kill my motivation for the day.