Rebuilt 290 FI engine smokes

[Stanley S.]

I drove a 60 290 FI recently that had about 30 miles on a rebuilt engine. I don't know exactly all that was done to the engine (can't communicate with the rebuilder) but upon start up with the engine cold a small amount of light blue smoke was emitted from both exhausts for about 2-3 minutes. It gradually cleared up as engine warmed. The engine idled fine and ran well at speeds up to abut40 MPH. Then after driving the car for 2-3 miles, I turned off the engine for a few minutes and then restarted and observed more smoke darker in color from the exhausts. Slightly increasing the rpm's produced even more smoke. I pulled the dipstick and a small amount of smoke flowed out of the tube. My question is this: is the smoke normal for newly rebuilt engines, will it gradually clear up after driving more miles, or could there be other problems? Thanks for any comments.

Stan

[Timothy B.]

Re: Rebuilt 290 FI engine smokes

Stanley,

Does the 283 have a road draft tube? If so, what you may think is smoke in the dipstick may just be blow by from piston rings not seated. Darker smoke on start up could be a little flooding.

If it runs OK with good oil pressure and good engine temperature don't be afraid to drive it hard, enjoy the car.

[Loren L.]

Re: Rebuilt 290 FI engine smokes

Doesn't the owner know what the engine rebuilder did/charged him for? If he doesn't, find another car. In 2013, it's hard to imagine a rebuilder using other than chrome-moly rings that virtually "seat" on the 15th stroke OR you have the only rebuilder that doesn't pay attention to valve guides and seals. In any case, it shouldn't be blowing smoke.

[Richard M.]

Re: Rebuilt 290 FI engine smokes

I agree, something sure isn't right. Any oily residue in a new exhaust system should be burned off by now, so it's likely not that. Sure sounds like valve seals to me but just rebuilt right? I've learned recently that all machine shops are not created equal.

Could be many things causing blue smoke, like rings, like mismatched manifold(FI baseplate) to heads sucking crankcase vapors, poor head rebuild, etc, etc.

Smell the exhaust for a few seconds......is it really fuel rich, or burned oil smell?

If I were you I'd request all 8 sparkplugs be pulled and numbered in sequence. Get some closeup pics of the electrodes, ground tips and porcelain and post here. I'd bet several are fouled badly with lots of black coating. Reading sparkplugs tells much about an engine.

Rich

[Joe R.]

Re: Rebuilt 290 FI engine smokes

Bottom line is about $1500.00 to $2,000.00 stand between you and a perfect rebuild on that engine. If you want to purchase the car just subtract that from the price. Rebuild the engine and enjoy the car if that's what you want.

JR

[Gene M.]

Re: Rebuilt 290 FI engine smokes

A new rebuild should not smoke. Something is not right, as mentioned rings, or guide seals. It could be as simple as the rings are all alined up and not sealing correctly. This would drip down of oil thus the smoking on start up. Same issue of oil running down valve stems with missing valve seals. Both of these are easy fix but still require tear down.

[Dennis O.]

Re: Rebuilt 290 FI engine smokes

Or the rebuilder did someone a "favor" and installed a HV pump. I had the same symptom with my' 67 and that was the problem, and I am not the only one here that has had this experience. I wonder if the fact that cost of a Mellings HV pump is 1/2 that of a standard pump has anything to do with it? "Hmmm Maybe I can 'upgrade' the build and save a little money". I would make an attempt to find detail of the rebuild. If you can't, Joe is probably got the best advice, although he may be a little bit low figuring you'll have to pull and replace the engine.

[Stanley S.]

Re: Rebuilt 290 FI engine smokes

Dennis,
What is an HV pump? High volume? The oil pressure on the gauge on the dash was reading almost 60 psi as I was driving. Stan

[Dennis O.]

Re: Rebuilt 290 FI engine smokes

There are two variables with Mellings pumps. First is you have your choice of standard, medium, or high pressure. This is determined by the relief spring in the pump. Second is standard vs. High volume. This is determined by the length of the gears in the pump. The gears in the HV pump were almost 3/8" longer than the gears in the standard pump. When I swapped mine out, it had a Mellings HV pump with a high pressure spring. Not only was my 60 lb oil gauge pegged most of the time, but the extra volume was overloading the drain back system, and after shutdown, some of that excess oil was being forced down the guides and would accumulate in the cylinder, causing the smoke at start up. I don't know much about C1 FI cars, but if you have a 60 lb gauge, you have a pressure problem as well. The Melling M55HV pump is the high volume pump; the standard pump is a Melling 10553. To make a long story short, you should have a standard volume pump. The proper spring, I don't know. The later C2 solid lifter engines used the hi pressure spring, but again, I am clueless about C1's.

One more thing. You will probably get some advice here about using "Genuine Chevrolet parts". The pump GM sells may have a lighter duty casting that may break in service. (This is a Melling built pump speced by GM.) In all likelihood, your engine has a Mellings pump. Rebuilders get their parts from aftermarket supplers, not their local Chevrolet dealer.

[Joe R.]

Re: Rebuilt 290 FI engine smokes

Or the rebuilder did someone a "favor" and installed a HV pump. I had the same symptom with my' 67 and that was the problem, and I am not the only one here that has had this experience. I wonder if the fact that cost of a Mellings HV pump is 1/2 that of a standard pump has anything to do with it? "Hmmm Maybe I can 'upgrade' the build and save a little money". I would make an attempt to find detail of the rebuild. If you can't, Joe is probably got the best advice, although he may be a little bit low figuring you'll have to pull and replace the engine.

Joe does his own work so my quote would be only for machine work!

JR

[Joe L.]

Re: Rebuilt 290 FI engine smokes

There are two variables with Mellings pumps. First is you have your choice of standard, medium, or high pressure. This is determined by the relief spring in the pump. Second is standard vs. High volume. This is determined by the length of the gears in the pump. The gears in the HV pump were almost 3/8" longer than the gears in the standard pump. When I swapped mine out, it had a Mellings HV pump with a high pressure spring. Not only was my 60 lb oil gauge pegged most of the time, but the extra volume was overloading the drain back system, and after shutdown, some of that excess oil was being forced down the guides and would accumulate in the cylinder, causing the smoke at start up. I don't know much about C1 FI cars, but if you have a 60 lb gauge, you have a pressure problem as well. The Melling M55HV pump is the high volume pump; the standard pump is a Melling 10553. To make a long story short, you should have a standard volume pump. The proper spring, I don't know. The later C2 solid lifter engines used the hi pressure spring, but again, I am clueless about C1's.

One more thing. You will probably get some advice here about using "Genuine Chevrolet parts". The pump GM sells may have a lighter duty casting that may break in service. (This is a Melling built pump speced by GM.) In all likelihood, your engine has a Mellings pump. Rebuilders get their parts from aftermarket supplers, not their local Chevrolet dealer.

Dennis-----


All high volume pumps I know of are manufactured with only the high pressure spring. So, if one gets a high volume pump, one also has a high pressure pump.

Standard volume pumps may be fitted with either a standard pressure spring or a high pressure spring. GM pumps always included the relief spring installed and there were different part numbers for the standard pressure and high pressure pumps. Melling supplies a pump with various springs for installation by the user.

ALL C1 Corvettes used a standard volume, standard pressure oil pump (although pre-1959 pumps were configured slightly different than 59+).

Late 1963 thru 1965 small blocks with mechanical lifters used a standard volume, high pressure pump. 1970-72 LT-1's also used the standard volume, high pressure pump. No other Corvette small block ever used a high pressure pump. NO Corvette small block EVER originally used a high volume pump. None. Ever.

[Joe C.]

Re: Rebuilt 290 FI engine smokes

You are all misleading the OP by going off on a tangent about a HV pump. Highly unlikely, and no matter how stupid the engine builder may or may not be, he would have had to spend extra money for an item that is totally unneccessary for a mild engine such as this.

The OP had better find himself a reputable engine shop. He leaves himself wide open to predation, unless the shop comes highly recommended, or is a personal friend.

I'd be looking at intake manifold sealing, valve guides and/or seals, piston rings and/or quality and method of cylinder wall finish hone.

[Dennis O.]

Re: Rebuilt 290 FI engine smokes

You are all misleading the OP by going off on a tangent about a HV pump. Highly unlikely, and no matter how stupid the engine builder may or may not be, he would have had to spend extra money for an item that is totally unneccessary for a mild engine such as this.

The OP had better find himself a reputable engine shop. He leaves himself wide open to predation, unless the shop comes highly recommended, or is a personal friend.

I'd be looking at intake manifold sealing, valve guides and/or seals, piston rings and/or quality and method of cylinder wall finish hone.

No offense intended, but,

1. I am not the only one here that this has happened to; I know of at least two others, and I haven't been looking.

2. A Melling HV pump is half the cost of a standard pump; check it out.

3. My engine rebuilder came as a highly recommended race engine rebuilder; I think the race part is the problem.

[Joe C.]

Re: Rebuilt 290 FI engine smokes

No offense intended, but,

1. I am not the only one here that this has happened to; I know of at least two others, and I haven't been looking.

2. A Melling HV pump is half the cost of a standard pump; check it out.

3. My engine rebuilder came as a highly recommended race engine rebuilder; I think the race part is the problem.

None taken.
I'd rather work with a smart engine builder than a stupid race engine builder.
I'd rather work with a smart race engine builder than a stupid engine builder.