Chevy Car Questions & Answers - Performance Q&A

Kevin McClelland May 1, 2009 0 Comment(s)

Let's get back to your TBI 350s. At McFarland we had test equipment that could record the cylinder pressure in a running engine down to 0.2 degree of crankshaft rotation. This is called engine cycle analysis. During these years, we did a ton of ignition and spark plug testing. We found that once the fire was lit in the combustion chamber, the burn speed and rate were controlled by the fuel mixture, fuel homogeneity, mixture motion, and combustion space design. Adding spark energy to a plug that fired the mixture effectively every time didn't pick up any power or economy. If you had an engine design that was prone to idle instability, lean misfire, or cylinder-to-cylinder distribution variations, you could see minor gains. Again, if you have adequate spark energy, you rarely have an issue.

Do the Pulstar plugs work? They could help an engine that has a borderline misfire condition. There have been many spark plug designs released over the years that have promised great things. We'll just have to wait and see. Maybe Pulstar would like to send us some plugs for testing.Source:

Didn't you mean Ls series?
Q What is the real, real story on the LT series of engines? Those engines seem to me to be the most advanced and best engines Chevy has ever produced. Thanks.
Kevin Hawkes Via email

A To compare the LT engines to the LS (Gen III) family is a night and day comparison. The LT1s and LT4s made very good power for their platforms; however, the LS (Gen III) small-block gives you many distinct advantages over the earlier engines. Outstanding stock cylinder head flow, all-aluminum package, aggressive camshaft profiles, stainless roller rockers, and low-friction pistons and rings are the reasons this engine shines. In my opinion, the Gen III engines will never be a small-block Chevy. However, the General has given it that tagline and it's here to stay.

The LT family of engines has basically been stepped right over. We jumped right from Gen I small-blocks to Gen III engines for swaps and performance upgrades. The Gen II engines are plentiful out in the junkyards, and almost all the Gen I engine components can be used in the Gen IIs. Pick one up and upgrade your early Chevy engine bay. The engine mounts and headers will bolt right up. Accessory drives are easily adapted from either Corvettes or Impalas.

Oil Spill
Q My '66 SS Chevelle with a 396 big-block is totally restored and beautiful. After I showed it off around town I noticed the clutch slipping. I looked under the car and saw an oil leak. It was coming from the back of the oil pan, where the main cap is. I figured I must have messed up the pan or gasket when I brought the engine home from my engine builder. I replaced the pan and gasket and it still leaked. I did a leakdown test and it seemed there was too much pressure in the crankcase. I had the engine gone through for the second time and installed Total Seal piston rings.

I put the engine back in and it still leaked. That is when I noticed the pan was touching the crossmember. My engine builder said the crossmember bends slightly on old cars and that I should put 1/4-inch plates under the motor mounts. After that, I could not close the hood, no matter what air cleaner setup I used. So I went with a low-profile oil pan from Milodon. Anyway, after all that, it still leaked, even though the pan was not touching the crossmember. I even used a one-piece gasket. I have heard from my engine builder that sometimes big-blocks just leak in that spot on the pan and there is nothing I can do.

I have spent six years and a ton of money with this so-called dream car of mine. What can I do to get the pan to stop leaking? Is there a special sealant or can it somehow be welded onto the engine? Please, any suggestions would help.
Don Way Collinsville, IL


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