The Stovebolt Site Forums The Shop Area The HiPo Shop 383 "New build" smoking

I measured intake vacuum at 15" but given the overlap in the cam I am not sure the low reading is an indication of a problem. The engine was cold and idle was not smooth so I probably need to retest it to be sure of the reading. My vacuum gage is older and seemed stable but I didn't check it for an orifice.

The block is a 1991 Chevy 350 that was machined oversize and honed by a machine shop that has a good reputation.

Consensus seems to be that at this point the rings are not going to seal any better so I will probably run it a bit more before scheduling a time to pull the engine and tear it down.

In the past I have always used standard (not synthetic) oil and not had a break-in problem but this time I struggled to find an oil that was not a synthetic blend (probably didn't look hard enough). Engine oils are constantly changing formulations and seem to be trying to get longer and longer service intervals which is great except for break-in.

Lots of problem engines have been fixed with a slurry of Bon Ami and Marvel Mystery Oil- - - - -

www.ebay.com/itm/127479100239?

Jerry

GM used several different alloy blends for cast iron blocks, some with higher nickel content, some with higher tin content. The mid-seventies block I used to build a 383 has 10% nickel for a longer lasting bore and 10% tin for better control of expansion and contraction. The break-in procedure and type of oil is the same for all of them.

HRL - I am not sure how the "slurry of Bon Ami and Marvel Mystery Oil..." would be utilized? I do appreciate the information but just need a little more insight to be able to use it.

The grit in the abrasive cleaner will help break any glaze and provide some friction for the rings to scuff the cylinder walls.

The ad copy for Bon Ami and the logo on the package showed a newly-hatched baby chick, and the slogan "Hasn't Scratched Yet!" I believe the very mild abrasive material they used was the secret to "ring seating" on glazed cylinder walls by mixing 2-3 tablespoons of Bon Ami with half a pint of lightweight oil such as MMO or even Diesel fuel, and dribbling the slurry down the carburetor of a warmed-up engine running at fast idle. The idea was to create a little scrubbing action by the piston rings to help stubborn rings seat. Some mechanics in the 1950s swore by the procedure- - - - -others swore at it! As always, "Your results may vary!" Just thought I'd pass on a little old geezer trivia to the collective!
Jerry

The real question is, would you ever use it in one of your engines, Jerry?

And I know that you have the ability and equipment to completely tear down and rebuild an engine but let's assume for the sake of argument that you did not have that access or ability at this time. Would you try the bonami solution?

I have used that process on occasion, with mixed results. One oil-burner engine we tried to rescue after a botched rebuild by a different shop didn't work, but we found out later that one piston was missing an oil ring. Other times, the oil consumption got reduced pretty dramatically and we didn't have to open the engines up and redo the ring job. Even if the engine might need a rework later, the Bon Ami won't do any further damage.
Jerry

HRL, thanks for the details about the procedure. I was concerned that the Bon Ami was mixed with the engine oil and the affect that would have on all the bearings. Dribbling into the intake makes sense and if everything else fails I may give it a try as a last resort prior to pulling the engine for tear down.

My valve spring compressor is scheduled to be delivered today and I plan to inspect the valve stem seals on cylinder #1 to see if they offer any clues.

Follow up with a heavy dose of straight Diesel fuel trickled down the carb to flush away any residue so the polishing action doesn't get overdone. A beneficial side effect will be a drastic reduction in the local mosquito population from the cloud of exhaust smoke you'll create.
Jerry

The break in procedure I mentioned earlier will either work or not, but at least it can't hurt anything and costs only some fuel to try. I still think some plain ole' 30w non-synthetic will help.

Troman, thanks for the input. Your procedure is definitely on the list of things to try prior to pulling the engine.

No problem, I sure hope it (and/or some combination of the other procedures mentioned) reduces your oil usage enough that you may must run it.

Just to confrim what I did when I built the engine I remvoed the valve springs on both valves for cylidner #1 (used the rope method to hold valves).

Valve stem seals look as I would have expected so moving on to other action items on my list.

Well those look pretty good. Dang it! Would have been easy if you'd found this to be your problem. Looking at your spark plugs, #1 and #7 seem to have the most crud. So maybe check the seals in #7 as the others look fine.

I was now years old when I first learned of the Bon Ami procedure here in this forum, although my Dad and I did glaze break the cylinder in a lawn mower with Ajax cleanser, but that was pretty easy to get the head off and back on again! We just wiped the cylinder with it and then spun the crank.

I notice in your photo that you're not using the O rings on the top of the valve stems, along with the positive seals. That's a good thing, as it's possible to "over-seal" the guides and wear them out for lack of lubrication. I've seen that happen on several engines. Use one or the other- - - - -not both. I like to use the positive seals on the intakes only, as the exhausts do not have intake vacuum against the bottom of the guides. O rings only on the exhausts are plenty of sealing as long as the sheet metal deflectors are used over the valve springs.
Jerry

I installed 30W break-in oil with a ZDDP additive yesterday and proceeded to run several cycles of WOT acceleration from 30 to 65-70 in 4th gear (1:1 ratio) coasting back down to 30 with the carburetor at idle. Engine speed at 65-70 is in the 3500 rpm range (just a quick glance at the tach as watching the road pretty cloase at those speeds).

It will be a while before I have enough miles on it to know if things changed or remain the same and will report back then.

Awesome! A dozen of those and some other driving will tell if it helped or not. Sounds like it does run good, tho. If the oil consumption isn't too severe and you're not daily driving it, maybe just throw a quart of oil in once in awhile and send it :-)

Short update, I have put about 70 miles on since the "break-in" procedure and oil smoke seems to be reduced but not gone entirely. Oil consumption also appears to be less but not zero. My current plan is to run another "break-in" sequence and put on some more miles before taking any other significant actions.

Great news! I just checked your Project posts and see you've got a Really nice truck. Shame it's not set up with a bumper that'd allow a few thousand lbs of trailer and load to hook up. A few miles (or hundred) miles of work would probably bring the engine around a bit quicker.

Thanks for the compliment.

I have considered adding a hitch (frame mounted) but decided that would lead down another rabbit hole for wiring, brake controller, etc. that I don't want to pursue.

I am planning to put some more high load acceleration loads on the engine to help bring it around.

A truck without a hitch is like a day without sunshine, don't let the wiring scare you, we can all help you with it. Glad to hear the engine is improving.

I'm not scared of the wiring as much as I am the inclusion of a hitch leading me to consider my '50 as a replacement for my 2024 Ram that I currently use for any towing. I know it would lead to my using the '50 more as a truck and daily driver but while that could be a good thing it does have it's limitations.

I would love to use my '57 more often and even as a daily but the fuel milage is a big draw-back. The truck weighs about 7200 lbs, and with the 6.80:1/8.20:1 gears it keeps the 283 spinning at 2800 - 3500 rpm when on the road. I haven't actually clocked the mpg but estimate 6-7 mpg based on driving. It could tow with no problem if needed. My daily driver is a 2011 Chevrolet 2500HD, 6.0 gas, 4x4, 8 ft. bed full crew cab. The 4.10 gears make it a gas hog also. If I want to conserve fuel and can do an errand on the Harley, I take it.

I've been saving gas by doing errands on one of the electric cargo bicycles that I sell. It can haul 440lbs (rider and cargo) though I've never put that much on it. Such a long wheelbase, it almost rides like a Harley!

The 51 GMC 3 ton with a 12 foot flat bed that I'm about to "restore" is going to have a gooseneck hitch and a square tube hitch receiver. It's got a 270, a SM 420, and a 2 speed vacuum shift rear axle, and part of the resto-mod is going to include a 3 speed Brownie transmission. That's 24 forward speeds and 6 in reverse- - - - -which should be adequate to tow anything I can load onto a trailer!
Jerry

Say, Jerry, can you pass on what model Brownie it is, as I’m looking
for the same for my ‘54 GMC 450 firetruck conversion.

I'll need to take a couple of pictures of the data plates. I have two- - - -a big one that I'm intending to install in my 61 American LaFrance fire truck with the 401 GMC V6 and a direct drive Clark 5 speed, and a smaller one for the 51 GMC flat bed.
Jerry

Just a quick update - drove to another car show last weekend. It was closer than the previous ones but I did note less (but not no) smoke after idling in line to enter. Oil consumption appears to be reduced although not really enough miles yet to say for certain.

Given what I now know I think we can close this thread assuming that I will still be able to refer back to it in the future.

Good to hear.

Sounds like it's coming around. If you could work in a day trip of at least a 100 miles one way with as many hills as possible (Great River Rd ?) it might make for a nice finish to the story.

If not, well there's the drive. Never regretted a long cruise in any of my rigs.

Good Luck!

I have not managed to make a 100 mile one way trip yet but I did go to another show about 40 miles one way over the weekend. I noticed smoke once while driving accelerating out of a roundabout. Oil level has dropped but my perception is that the rate is lower. I am trying to incorporate different acceleration patterns to vary loads during driving to see if that helps over time.

If rings aren't properly seated during initial break in run it might continue having oil consumption issues in my experience .

Thanks BC59, I understand that is a potential but I am trying/hoping for an outcome that will not require me to remove the engine to deglaze the bores. At this point the only problem with procrastination is consuming some oil and with the minimal miles driven it's not too bad a compromise.