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View Full Version : Raceboat Bit Me In The Butt Again!



FlatRacer, aka BarrelBack
10-08-2003, 08:57 PM
Okay, so I finally got the engine built, installed and ready to fire.

A little background:
Between getting married, having a son, and everything else that living a "normal" life requires, I haven't had much time, money or enthusiasm to spend on the raceboat. But, I still give it time and money when I have some to spare, so progress is slow, but steady.

Flashback to 2000:
I had completed a 3-year build on a 468" Kinsler injected Chevy for the boat to run in the CanAm class. I was using a pair of ported Chevy heads that I'd bought from a Dragboat racer friend who had moved up to a class that allowed aftermarket heads.
Dragged the boat up to Valleyfield, Quebec only to discover a bent exhaust valve. The motor ran fine dry on the trailer, but bent a valve when I put the hose to it. Turns out, there was a crack in the valve guide boss that was letting water leak into the combustion chamber and spray onto the valve,... ergo, bent valve.
Fine. Brought the head to my machinist to fix it. Put in a new valve guide boss, etc. Fixed.
Took it to the next race in Ville Marie, Quebec. Ran the first heat like a scalded cat. Next day, ran great for three laps and died on the fourth. Turns out, the pill I got from Kinsler that was supposed to make it run nice and fat, leaned it out and holed three pistons. So much for expert advice. Back to square one.

Fast foward to Sunday, Oct 5th, 2003:
After another three years of working on it when I could afford to, the latest incarnation of the engine was done and in the boat. No more fuel injection; I'm back to the single 4bbl 427 (Super Stock class) engine.
Since it has a solid cam, It needed to be run for 15 min. to break in the cam, change the oil, re-adjust the valve lash, and it's good to go.
After 5 minutes of running, it bent another exhaust valve! The same valve in the same head that bent before! The one that was supposedly fixed! ****!!!

My god, I am heartbroken and disgusted! I'd sell the goddamned thing, but I just can't let my bad luck beat me. The boat is such a beautiful piece of art, and the ride at speed is such an indescribable rush, that I just can't give it up.

I don't smoke, drink, gamble, or do drugs, but this raceboat thing really is my addiction. I love it. I hate it. It continually bites me in the ass, but I can't leave it alone.

FR :rolleyes: :rolleyes: :rolleyes:

http://www.donzi.net/photos/Valleyfield.jpg

MOP
10-08-2003, 09:25 PM
Kind of Bums me out being only maybe 90 miles away and can't get in to see it go in person. I had an SK boat about 40 years ago, I am sure quite a bit slower than you guys go but a Rush as you say, none better! I enjoy your shots of the flat bottoms! :)

FlatRacer, aka BarrelBack
10-08-2003, 10:06 PM
Yeehaaa!!!!
http://www.donzi.net/photos/42_Dave[1].jpg

Yeah, sometimes I bitch that I was born on the wrong coast, but hey, it could be worse. I could've been born in Iraq!

Perspective is the key to everything. wink

BUIZILLA
10-09-2003, 07:35 AM
Is, by chance, the valve hitting the piston? rocker arm geometry? pushrod length correct? what are the piston to valve clearance numbers? is thwe cam in at a *retarded* number?

just curious...

J

turbo2256
10-09-2003, 11:35 AM
#7 by chance

FlatRacer, aka BarrelBack
10-09-2003, 05:19 PM
Plenty of piston to valve. Pushrod length was checked. Cam is straight up. Rocker geometry is fine.
I haven't done a post-mortem on it yet. I'll get to that next week. But I strongly suspect a cracked guide boss. Same #8 exhaust as 3 years ago. We'll see.

FR :rolleyes:

boxy
10-11-2003, 07:24 AM
FR, my mechanical expertise stops when the key turns, but Valleyfield is less than 1.5 hours from here, and Ville Marie is only little further. When you get it cranking for next years season let me know, I'll be your Canadian crew. :D

KMLFAMILY
10-11-2003, 08:24 AM
Re- ck. valve spring pressure #"s also.I know on the drag car we had to inspect them for cracks after every run & re-adj.lash.

FlatRacer, aka BarrelBack
10-15-2003, 06:40 PM
Thanks for the offer Boxy, but since they'll be enforcing the capsule rule next season, I'm afraid my Circle Racing days are over. :mad: Nothing left to do now but some local Drags. :rolleyes:

FR :p

oldLenny
10-17-2003, 12:07 AM
Flatracer!!!, nice to "see" you...very cool. Adds a new dimension to your posts. Thanks..

Seems like the 22-24 degree deadrise is something "NEW" to you..I see in the pics you have about .5 :p

Take care, love reading 'yur posts... :)

FlatRacer, aka BarrelBack
10-23-2003, 06:36 PM
UPDATE: Pulled the engine, pulled the head. #8 exhaust valve was bent, found pitting on valve stem and in valve guide. The shop's going to pressure test the head to see where the water's coming from. This is the same valve guide boss that was replaced three years ago, so I predict the leak is in the press fit between the boss and the head.
We'll see.

FR :p

P.S. Thanks Lenny. Glad you enjoy my ranting. I don't quite look like that anymore. The strangest thing happened. I started to lose the hair in front of my head (too much testing the raceboat without a helmet). After one too many people told me I looked like David Crosby, I cut it off! :D

FlatRacer, aka BarrelBack
11-01-2003, 07:22 PM
UPDATE: Heads pressure tested okay. My machinist and I have come to the conclusion that it was caused by a steam pocket around the valve guide (the BBC exhaust valve bosses pass through the water jacket).
The transom normally sits low in the water at rest, and is of course even lower when the boat is coming on plane and the water pickup is filling the block.
Because the trailer was not hooked to the car this time, the back of the engine was higher than the front. When I ran the hose water through the engine to break in the cam, there was an air pocket created in the back of the head which soon turned into a steam pocket and superheated the valve stem so that it galled in the guide.
So far it sounds like the most plausible explanation to me. What do y'all think???

FR :p