If the problem is piston to wall clearance as it is thought to be running the engine longer is only going to promote premature wear to the pistons and possible ring damage from the accumulated aluminum. It will not "wear in" in 2, 4, 6 hrs. If it did then how would it last the next 100,000 miles.

Octania..... I know of no forged piston the likes only .004 clearance. I'll go .0045 on cast be it standard or hyperutectic. Forged usually .0055 or more. BUT......that is not across the board written in granite. There are exceptions, usually towards the looser side based on piston design and coatings. I just did a 4.250 bore engine that required .010 straight off the piston spec sheet.

As for the build in question here I'd put .005 to .0055 piston to wall and it would be very happy there.

 

Like Smitty, I found in the 1970s that .0045" at the bottom of the skirt was the absolute minimum with TRWs or stock pistons. I agree with .005" to .0055" skirt clearance at the bottom of the skirt. Now, many of today's ultra short race pistons don't want that kind of clearance. For example, Mahle recommends .003" with some of theirs.

 

Forged Icons run fine at .0035-.004.
There are lots of reasons for a hot running engine. Did you replace the water pump? Was the block thoroughly flushed after hot tanking it?
I had a water pump impeller that only slipped when it was hot, you may want to check that. Try checking the timing, adequate fuel etc.
If the pistons were too tight you might start to see compression loss due to scuffing etc. at this point. Try doing a compression test to verify but I don't think that's your problem.

 

I dont remember that part of the 1970's to open the piston to wall min .0045 for a street engine. .003 to .oo4 was more like it

 

So how do you plug the oil filter for break in? Is that really necessary? Id like to know before i start mine up. Sorry to interrupt this thread but i have never heard of that.

Steve

 

You don't. Some people will plug the bypass in the filter adaptor so that all oil is forced through the filter. But if the filter clogs you loose oil flow & volume. The bypass opens based on pressure difference across the face of the filter between inlet side and outlet side. I have never agreed with this practice and still don't. If your filter is so plugged that the bypass opens then any oil is better than reduced flow or worse yet none at all. The factory put it there as a safety mechanism and I see absolutely no reason to disable it.

 

Went to NAPA and purchased the vapor test kit for the radiator. What's 35.00 at this point? It will be in tommorrow and we'll see if there's any CO in the radiator. If so pull the heads and do head gaskets. Octania / Smitty I'm printing your post and taking it to the mechanic and go over the numbers with him also.

We did gain a little cooling by hooking the vacumn up to the heater hose valve. Finally noticed it was not hooked up. It took 30 mins at idle to reach 230 instead of 15, but it did finally creep back into the 230 range

 

Since you guys were kind enough to give all the good input thought I would give update. Vapor test was negative. Put radiator under pressure and left over night, no loss of pressure. The water pump that came on the car "appeared" to be brand new when we pulled the motor. It had not been painted and housing was bright and new, looked new inside, so we put it back on. Fan clutch appeared brand new also. Did not replace it. So I'm going to replace those two items and see where we are. If that's not it we'll start pulling the heads.
We might have missed a port that was not drilled out on a head gasket ?

 

Head gaskets are cut with a die or water jet depending on they type. You would have to be missing a lot of passages, not just one.
Good luck in your search for the issue.

 

you mentioned you were on the way to talk to the shop about the build/clearances what did they say?

 

Update. Well after hours of talking with the shop that did the machine work and going over the build process in our minds we said the hell with it and broke the motor down. WRONG head gaskets !!! Two thirds of the ports were blocked. Must have been for a 403 or a newer 455. Shame on them for not checking them at the shop and shame on us for not checking them during assembly. Thank God we didn't run it above 230 degrees. Feel like a total dumbazz !

 

It happens, at least your going in the right direction now. Most assume the correct parts were installed in a diagnosis.

 

I now know you machinist knows absolutely nothing about Oldsmobile's and their head gasket configuration. It is normal for 2/3 of the passage to be blocked by the gaskets. That is how the water is metered through the block to force it to flow everywhere. I'll go out and get you a pic to confirm this is what you saw.
Where did you get with the piston clearance issues? Does he have any idea what they actually are? When he gets new gaskets and they are exactly like what you just took off what is he going to say then?

 

Top photo is a bare 455 deck. Lots of big wide open passages for knocking the casting core material out.
Second photo is of a used Cometic head gasket laying on top of the exact same deck. Notice the bottom row of passages 1/2 to 2/3 blocked as you mentioned and the top row nothing but pin holes to prevent steam pockets and to get water every where in the block and heads.

IMG_20140729_111447_044_zpsvk89txof.jpg

IMG_20140729_111512_226_zps63gjtr3v.jpg

So unless your gaskets had even more blocked off than this we can rule that out as your problem. This passage layout is good on ALL 350/400ss/400ls/403/425/455 regardless of year.

 

OK took heads and gaskets to machine shop. All look to be fine. He will look over them again today and maybe magna flux again. He is looking up info on piston to wall clearance used but he is confident it is in the .004- .005 range (forged pistons). Cylinder walls are pristine and show no scuffs or damage. Going to double check balancer (original, not new or replacement) and make sure it lines up with marker when #1 is at TDC. If it's not exact then timing may be low and I know that will generate heat. If we have to pull motor I will check skirt to wall w feeler gauge, but like I said the cylinder walls are very clean and show cross hatching with no scuffs or marks

 

My builder was concerned about the
larger clearance on my build.
The Speed Pro listing and what everybody here said to do were very different.
Encouraging that the walls look good!

Hoping all goes well with your engine.

 

Put a bore gage in and measure a cylinder

 

if you dont have maybe the shop will let you borrow one along with a 4-5 micrometer

 

You have other issues besides piston clearance. Keep an open mind.

 

Still have not found clear and obvious reason as to why motor would be running hot. Checked balancer at TDC, dead on the money. Heads gone thru completely and cannot find any issues. No mixing of fluids at all. Coolant perfect, oil clean and clear. Even drug a magnet through some of the oil and no metal. Pulled water pump and looks brand new, turns nice and no play in shaft. Measured depth of gauge sensor in manifold. Pretty damn close to bottom of intake (may have been touching). Going to put brass bushing in to raise it up slightly when we reassemble. All I know to do is put the damn thing back together and see what happens.
Machine shop "cleaned " the heads before I picked them up and in doing so knocked about half the paint off !! I'm waiting correct color paint from OPGI before we reassemble. So I have a couple of days to mull this over

 

Check your thermostat while you have everything apart. Mine ran hot on the initial break in. New 185 deg thermostat. Removed the thermostat and put it in a pot of boiling water. It would open, but just a little. It did not open enough for full flow. Installed new thermo and no more issues.

 

any update?

 

I feel like we found the issue. Repop W30 intake (which I was told was cast from the original). Rear ports were closed off with a thin sheet of aluminum flashing from the casting. Opened them up with a die grinder in about 2 mins. Reassembling this weekend.

 

Did you take pics of this? Not sure what you are talking about. Rear water ports on the intake?

 

Rear water ports do little or nothing
RH one goes to heater
LH one usually blocked off until the smog era put a sensor there.
used for "four corner" cooling sometimes.

Say you don't have a reverse rotation V6 diesel water pump perhaps??

What is the WP casting ID?
Photo of it?

 

That was what was confusing to me. Seems only one has water flowing through it to the heater. The other should be blocked off.

 

The heater delete option blocked those intake water ports as well. I blocked mine to bypass heater w no issues.

 

First thanks to all for your input on this. FINALLY got problem figured out. It was the timing. Long story short the lower timing chain gear was off. The three marker dots were not marked (TDC, 10 degrees adv.,10 degrees retarded) as all others I have ever seen were. We obviously were not at TDC mark like we thought we were when we installed the timing chain.
Using the light to set the timing it ran hot (230)every time after 15 mins or so. Setting the timing by ear it runs at 195 degrees and should decrease even more as the motor breaks in. NO MORE PROBLEM. Geeze what a long strange trip it's been

 

Curious Pro Comp T-chain?

 

Truthfully I don't remember (project build time is 2 years plus) but I will check when I return from out of town trip

 

So was the camshaft degreed during installation? Sounds like it was not.

 

My buddy and I did the build in my shop. We thought it was but obviously we were wrong...

 

Timing marks on the gear aren't plus or minus 10, they're plus or minus 4. That wasn't your problem. Problem was most likely incorrect ignition timing, not valve timing.
But glad you got it sorted out.

 

Sorry but this doesn't make any sense. Degreeing the cam involves attaching a degree wheel to the crank, determining TDC, and measuring valve lift with a dial indicator to verify valve timing events vs. the cam card specs.

You either did the above or the cam was not degreed when it was installed. It's probably immaterial based on what cutlassefi posted above, though.

 

Back in the 60s and earlier, the owners manual gave instructions on engine break-in. I don't have an Old manual in front of me, but I do have a 1970 Pontiac owners manual. It cautions to drive it gently. "First 200 miles limit speed to 50mph. Second 200 miles, limit speed to 60mph. Third 200 miles limit speed to 70mph." Also, "avoid high engine speeds in lower gears." Engine break-in for an Olds isn't much different than for a Pontiac.


I don't think 200-210 is too hot for a new engine, especially a new build. Actually, it's not too hot for an engine that is broken in. And idiot lights don't come on until close to 250 degrees. My guess is the temps will drop as you get some miles on it.