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Author Topic:   Plug & Flywheel Question
Dirt Full Roller

Total posts: 56
posted May 23, 2001 09:31 AM
When I bought my car it was race ready and ever so often I run across things that I have questions about. Heres one of those things...This past weekend after the feature my wife said, about the motor, "It Don't Sound Right" It sounded OK to me, but to make her happy I pulled all the plugs to run a compression check. It was then that I found that the #2 spark plug was missing the center portion of the plug(insiede). I went ahead and checked the compression and all of the holes pumped 190 except #2 which pumped 170. All the other other plugs looked fine and I don't beleive it's a lean problem. Any thoughts???

Issue #2...I pulled the motor (406) to take to the shop and when I removed the flywheel there was a fixture that was behind the flywheel (looks like some sort of counter balance) my question is this, I run a bert transmission and don't know if the flywheel is for a 350 or 400. I know that the 400 are externally balanced but now that counter balance has me wondering if they use 350 flywheels. I am putting a back-up 355 in it and was wondering how do I tell which flywheel it is, and do I use the counter balance.


Dirt Full Roller

Total posts: 75
posted May 23, 2001 05:49 PM
If you can get a borescope and look into #2 cyl, you could have some detonation going on. Did it look like the insulation broke or was it burnt or peppered?... As for your flywheel.. the balance plate is for the 400 sbc so you can run the 350 flywheel...don't use the plate with your 355, the stock 400 flywheel has weights welded on it. the plate compensates for this....

Dirt Full Roller

Total posts: 56
posted May 23, 2001 06:23 PM
It's not burnt at all, It looks like it was brittle & just broke..I've gone ahead and pulled the motor out..I let ya know what my builder determines happened...

Thanks for the info on the flywheel..

Dirt Maniac

Total posts: 168
posted June 06, 2001 10:26 PM
One thing I would suggest in the future is to buy yourself a cylinder leak down tester. You can tell much more about the condition of your individual cylinders with it and can diagnose cylinder problems. A compression guage has its place but even a cam that is going flat could cause the problem described and could have been repaired without pulling the engine. Borrow one someday and mess with it , you will see what I mean.

Dirt Freak

Total posts: 219
posted June 08, 2001 03:08 AM
I TOTALLY AGREE ON THE LEAK DOWN TESTER....I leak our motors every few night of racing...this is a great way to keep on top the valve terrain.......You may find a broken spring, but if you are loosing compression the leak down will tell you how much and could just hook a air hose to the cyclinder and blow air in...if you hear air comming out the intake there is a intake valve problem....out the exhaust there is a exhaust valve problem....on a 400 block you will find a blown head gasket because the air will go into the cylinder next to the one you are filling with air.........also, take the radiator cap off while doing this lead down and you will see air bubbles if head gasket is out or cracked somewhere else.....
for $65 this is one of the most important tools to have in the shop.........Jeff

Dirt Full Roller

Total posts: 56
posted June 08, 2001 08:51 AM

I'll get me one..Never have used one but sounds like a good idea to me.

Dirt Full Roller

Total posts: 66
posted June 12, 2001 04:54 PM
The plug problem you have is new to me, sounds like you just got a bad plug.
KK17 is exactly right about your flywheel problems.

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