Heads, Gasket, Block, What Did I Blow Up?


New Member
Jul 17, 2017
Over heated the motor over the weekend and now it's a no start.
I have a mild built 351, in a fullsize bronco that races short course and pro area (Think tuff trucks)
I am not an engine gru, so I need help.
Engine is pretty much new with 3 races on it.

CAMSHSHAFT M-6250-A331 INT DUR (280) 204 @ 107ATDC LIFT .448
EXH DUR (290) [email protected] 117 BTDC LIFT .472
HEADS M-6049-Y303 64CC INT 1.94" EXH 1.54" ALUM EO# D-308-3 SVO
ROCKERS M-6564-A351 1.60:1 ROLLER

At the race this weekend, it overheated (I was in 2nd place and pushed it, I should of slowed down, but too bad so sad) to where it stalled on the track and would not re-fire.
In the pits I pulled all the plugs and sure enough, they were full of water, you could also feel the compression blowing out the radiator while I was cranking it.

I pulled the intake (Lighting lower, explorer upper) and did not find any cracks and the gaskets still looked good. I then did a compression check and had low numbers from 40-90 PSI with the intake off.
The head gaskets look 'meh' you can see some leakage at the rings, but not around the cooling ports.
I can't see any cracks at the heads, but I know you can't see a lot of them with the naked eye.
Only real way I could think of testing the rings was filling the cylinders with oil and seeing if they leaked down, they did not, is there a better way?
The piston bores don't show scoring.
I can't think of a way a cracked block would give them these symptoms, but I dunno.
All signs point to the heads, but I'm not sure I want to pay the $150 to have them looked at only to be told they are junk.
I'm very happy with the power it puts down, so I'm think either thinking flow tek heads or edelbrock heads 5023. (I'd rather put money into suspension then power)
Would it even be worth it to pay $400 (Guessing) for someone to restore these SVO heads if that's the issue?
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Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
Um...running an engine hot with aluminum heads is never a good idea.

Sounds like you don't want to spend a lot of money but you caused this...and its going to spank your wallet either way.

The heads may have warped...and the head gasket probably blew. I hope you didn't cause any other damage to it.

You'll need to pull the heads and have them checked and probably milled. The block deck will also need to be checked. These things could be done with moderate mechanical skill. You'll need a machinists straight edge. The assembly of the engine isn't too bad. There's info all over the net about torque specs and sequences.
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Apparently my ex-husband made that mistake.
15 Year Member
Jun 14, 2004
Acworth, GA
I honestly think you probably just lifted a head a little. Cracked block wouldn't dump water in the piston, it would dump it in the oil. A crack in the cylinder wall would be obvious as hell. You can check for warping with a straight edge and a feeler gauge. Just line up a very straight piece of steel with the deck of the head and see if any of the feelers will fit under the straight edge along the deck of the head. You can take it to a machinest and pay them $150 to do the exact same thing if that's what you want. You can do that with the block too if it suits your fancy, but the blocks don't warp that easy.

If the heads cracked, it's going to be between the spark plug hole and the intake valve. Most cracks are pretty obvious. If you can't see it in the combustion chamber, look inside the threads of the spark plug hole. If you don't see it there are two options. You can get a borescope camera to get a super close view. You can get one for like $20 online that plugs into your phone. The definitive check is a dye penetrant. That is what the machine shop will use since magnaflux doesn't work on aluminum.

Amazon product
View: https://www.amazon.com/CANTESCO-K801S-Penetrant-Solvent-Removable/dp/B00T46ZDLW/ref=sr_1_1?ie=UTF8&qid=1500426171&sr=8-1&keywords=dye+penetrant

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