Hi Guys, I could use some help with this. I'm planning a more complete rebuild or maybe even a crate engine, but my goal was to get the original engine running well enough to pass smog and get my registration current.

This is the original engine in the '76 and I'll summarize what I've done so far and what I found today. It started easily but ran bad and smoked heavily, blue/black smoke at idle and when revving. Plugs were wet and black so I replaced the plugs and wires since they were old and worn as well. It ran a little better but still smoked badly.

Compression is 145 on most, with the lowest at 142 and the highest at 152.

I blocked all vacuum ports including the brake booster and PCV and measured vacuum at idle of around 4-5 inches. It increases a bit when I rev it up.

I blocked the oil breathers and tested the crank case for vacuum, thinking that the intake manifold gasket may be bad. There was an inch or 2 of positive pressure, so that seems OK.

I sprayed starting fluid around the intake and it did not seem to be leaking.

I decided to replace the valve stem seals to reduce the oil burning and also the intake manifold gasket to have a fresh seal.

This is what I found!

The old plugs:



The intake manifold bolts were covered in oil:




Carbon build up around the heat riser was really bad on both sides:




It looks like the original rubber end pieces are there for the intake indicating that this may be the first time it has ever been apart.

When I put the intake on the bench a nasty blend of oil and gas poured out. No wonder it smoked so badly!

 

I have a new gasket set and plan to go to work cleaning everything to reassemble. Once the sludge is out of the way I'll clean the lifters and pushrods as well as the rockers.

It almost seems like the PCV was pulling oil from the valve train into the intake. When I put it back together I will leave the PCV port plugged and let the engine breathe through the valve cover.

Other ideas and observations? Thanks!!

 

Wow. What a stinkin' mess. How do you feel about dropping the pan?
I think I would get a can of Gunk Engine cleaner, pull all the pushrods / lifters and drench the heads letting everything run into the lifter valley and on down into the pan.
Tape off all Intake ports & water ports in the head. Scrub everything and rinse with cheap motor oil.
Reinstall lifters, pushrods, set valvelash.

The china wall gaskets could be from last builder. Some people still use those for unknown reasons.
The oil / gas slurry likely came from that baffle pan under the Intake. There is no way that was introduced into the cylinders.

You have an engine that was not vented properly. I see a faulty PCV Valve. The worst thing to do now is to plug it. Get a new one, and proper hose to the carb. For a PCV Valve to work, the engine MUST have a fresh air inlet somewhere. (other valve cover)

 

Thanks for the reply Headsup!

It sure is a mess, but I've already got a good start on cleaning it up. I also thought the slurry was coming from that baffle, but it was pouring out of the intake runners. There would be no way for gas to get into that baffle, and there is a hole in the baffle so it couldn't pool there anyway.

I need to clarify what you are suggesting for the PCV. What I have now is one baffled valve cover connected to the air cleaner and the other side has the PCV valve with a hose to the front of the carb base. I was proposing blocking that port on the carb and leaving the holes in the valve covers wide open to vent, at least to get it running. I'll add a new PCV valve at that point so I can tune with it in place.

I'll drop the pan if I need to but I'll see how well I can clean without that first.

Thanks again!

 

Put on some tunes and spent a nice couple of hours on this. It's looking better!

 

I highly recommend blocking off the heat riser and getting the spacer to delete the pass side heat riser valve if it is still there. Then convert the carb to electric choke.
Blocking the heat riser will lower temps at the manifold base about 100 degrees......to do this, use a Fel-Pro 1204 intake gasket.
You did a good job on the intake....but you need to pull the heat shield off the bottom.....the rivets are push and twist so you can remove them with a good pair of side cutters.....you will **** when you see what is behind that shield.
Use the 1/4" spacer gasket for the carb...you can get it at Cliff's. https://cliffshighperformance.com/pr...sket-250-thick.
You have a LOT of cleaning and scraping to do....and as Heads said above, it would be wise to pull the pan. From there when I do these engine in the car once overs....I replace the pump, pickup, go to a steel collar shaft and a stud to hold it on. Clean the pan all out and use an OS34509T oil pan gasket.
Now is a good time to swap to ARP stainless bolts if you budget supports it.....you will always have them. Intake bolts need a dab of sealer on them or oil will leak past some of them.
When you changed the valve seals...did you use the umbrella style?
Buy a leakdown tester from OTC and confirm the rings are bad.....145psi is ok for a low compression engine but a leakdown is the tell. Make sure your PCV system is in good shape.

Jebby

 

What a mess, that engine is 20 years overdue for a rebuild. Nothing to add that Headsup didn't already cover. A good internal/external cleaning with a "working" PCV system might get you through inspection.

 

I’m seeing lots of sludge in the engine, push rods , valve springs, top end all over. Leads me to believe that many of the piston rings are likely seized in the groove. When the rings can’t move you loose compression and oil gets past them into the combustion chamber.

I recently experienced this in a 1996 rav4 I purchased. Surprisingly seafoam in the oil worked wonders. 2 oz per qt of oil. Run 300 miles. Drain and repeat as necessary. I regained lots of compression and power and reduced oil consumption drastically. Cut open the oil filter and a ton of gunk in the filter.

Once you get it running may want to consider that option.

 

That is the worst sludge build up I have seen in 25 years!! Judging from the pictures I would give serious thought to a simple re-build. I would really hate to see the inside of the crankcase.

I agree with REELAV8R about the sludge removal as it is really hurting the engine it appears. I was taught by from a old Cuban mechanic how to remove sludge on Boat motors without removing the engine. We would remove the oil from a warm engine and fill it with the equal amount of Kerosene in place of the oil. Then with NO LOAD on the engine start and let it idle for 10-15 minutes and drain the kerosene mixture. It did an amazing job on removing the sludge and it won't hurt the engine as it is lubricated by the kerosene. Just do not load the engine up with the kerosene in it, idle speed only.

Another time I took a 100k mile old Ford Pickup to a Jiffy Lube and I tried their "Engine Flush" to see what they could do for the poor old 351 V8. They reverse flowed a heated Solvent (smelled something like kerosene) through the engine for about 15 minutes and when they were done the engine was so clean you could eat off the inside of the valve covers. The mechanical parts looked new and worked great for the next few years before I got rid of it. The Rock-wool Filter material was black as coal and really NASTY after the engine was flushed.

Jebbysan is also correct about doing the Leak Down test. The leak down will help you decide whether you need to rebuild now or not. I would certainly perform the leak to learn as much as you can. The leak down test tools are available from many sources and are not expensive. The down side is you need a GOOD supply of pressurized Air to perform the test. The first time I did one it took hours but I have it down to half the time now.

I wish you the very best!

 

If the rings are seized in the piston groove (likely) it will do miserably on a leakdown test. That doesn't mean that it needs a rebuild due to wear. It may be just because of sludge. In which case trying to clean it out is a worthy consideration unless a rebuild is immediately in the works regardless.

 

Clean out behind the stamped steel heat shield on bottom of intake. You'll be further amazed at its crud. It's likely You've already loosened some of it; But now, bits will likely find their way out & into your valley & oil pan. That has happened more than few times. Pull the shield off and scrub behind shield.

Carefully, carefully pry out the rivets; either reuse them or tap the holes for screws & Red Loctite.

If you completely block Each head's exhaust X-over port; with Both ports blocked, there's little need to reinstall aforementioned heat shield.

 

Thanks a million for all your responses! I really appreciate the help. You guys are completely right, a leakdown test will help me decide what I have to work with here. My hope is to have a good running engine while I plan what I want to build. I don't want to be hasty and rush into it and I also want to enjoy the car while I research and plan. I really like the idea of building a 383, and I don't rev my engines so lots of torque below 5,000 rpm is the goal.

You guys were sure right about the underside of the cover haha!!




I kept going back to it throughout the day and finally...

 

I have seen the rear seal leaking a bit when I've had it running. To do this right I would just pull the engine so I can properly clean everything and replace the full gasket set. But I'd like to save all that work for later when I have a better plan for the engine and when the rest of the car is solid. I spent the better part of the day getting the top end clean.

I used WD40 and paper towels. Lots of paper towels!

 

Jebby,

I bought both the original valve stem e ring seals and the umbrella seals. I can't really see what is under there until I start pulling springs but I suspect there are no umbrella seals.

When you recommended the ARP stainless bolts, did you mean for the intake manifold? I was planning to get a set of those, but depending on the final plan I may end up with Vortec heads so I don't want to commit just yet.

 

I have plenty of shop air, and the leakdown tester will arrive tomorrow. I'll run that test before I proceed.

So much cleaning today...

 

I love the idea of blocking that heat riser to cool the intake down. It makes sense that the oil cooks to the bottom when it has exhaust flowing through it. That intake gasket with the block off pates is also on the way!

As is a new PCV valve. I checked my old one and the spring works but it doesn't close so you can easily blow or suck air from either side. I wonder how long it has been that way. It's a full on vacuum leak like that.

Thanks again for the help! I'm reading every word and really appreciate it!

 

If you block off the heat riser passages, you also NEED to lock the heat riser valve in OPEN position. Or, better yet, cut the valve off its center shaft; then button it back up. Having the valve lock in the CLOSED position is NOT something you want to experience.

 

before reusing pushrods, clean them inside-out and then inspect all ball-ends closely for any cracks, microfractures etc.
Also, roll em on a pane of glass to check if bent. Ball-end must be shiny with no blemish; anything else is garbage.

* inspect all rockers in both their pivot cup And pushrod cup for cracks, microfractures etc; replace any non conforming.

 

Thanks 7T1!

Yeah, I was thinking about where the exhaust goes and if I block the intake ports then it is trapped in the right manifold. I can just imagine the issues. It's hard to fathom the exhaust passing through the intake and that the engine even runs like that. No wonder the heat cooks the oil.

I will try to disassemble the flapper and remove the plate so it still appears to work. I'll need the EFE valve and flapper for the smog check.

 

ebbnflow,

Thank you for your help! I have the pushrods soaking and I will give them a careful inspection along with the rockers today. I've got a good magnifier/light to really see the detail. It's crazy how much I reach for the glasses when working on stuff these days. I never used to need those!

I'll report back with more findings and pictures!