Technical > Matt Shaff's Engine Shop

Teardown surprise

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janjon:
 I bought my car with a 350 SBC roller motor not knowing many of its particulars other than aluminum rods. It started smoking a bit from #8 zoomie stack and oiling the plug a bit. The car also needed a new flexplate so out came the roller motor and in went a milder 350. Upon removing the intake I find that the intake port wall (340292 head) has a hole where some extremely industrious but hopefully talented individual ground just a little tiny bit too close to the pushrod clearance hole and the intake port was sucking oil from the valley. 'Splains why cranking pressure and leakdown % not real bad. A whole lot of handwork went into these heads, both ports and chambers, in fact, one might say a little TOO much.
 The head is removed and I am shocked to see... FLATTOPS!!! I expected to see domes of some sort.
 So a repair was attempted, (a freebie) but the repair has a similar hole. It has been suggested to me that epoxy in the runner would work to seal the leak. It would have to be in the runner because pushrod clearance to the outside is just about zero. I don't care what restriction that might cause, but am a bit concerned what might happen downstream if it came loose. Anyone have any thoughts on this?

Frontenginedragsters:
Cast iron head repair is tough.
My suggestion is to use epoxy on both sides and re-clearance the pushrod side.
By putting it on both sides it can flow thru the hole to the pushrod side and have a larger area to grab on to.
Leave some extra in the intake port side for strength.
Start with cleaning the head really good. Take a prick punch and roughen up the surfaces so the epoxy
has something to grab a hold of.
Do a little less port work and hope it works.
The nice part about a FED is you can watch those pipes and see a problem! 8)

Matt

dreracecar:
I had to switch out a couple of roller lifters to ones that had offsets in the push-rod cup in order to get clearence

JrFuel Hayden:
Yes Bruce is right, on my IRON SBC, I have .150"offset push-rod centers in my intake lifters to have more clearance and straighten the push-rods and .050" on the exhausts. I have seen a race team put so much epoxy on the push-rod side that it looked like the push-rod was going thru the intake port, all to make the intake ports even wider. They even had a cam made to move the lobe over to help straighten the push-rod. Also you made need to get offset shaft rockers to get everything to line-up.
As the saying goes "speed cost money how fast do you want to go ? "
As far as the epoxy to fix the overly ported heads, I would think just on the push-rod side would work, but check with any good head porter, they'll know. Some head porters use epoxy to change the shape of the ports to increase port air speed.

Jon

masracingtd1167:
Janjon Don't be afraid to use epoxy on the intake port. Every one of my intake ports has epoxy in the pushrod area . The best epoxy to use is called Splash Zone and you can get it from a marine supply store . It is water solable and very easy to work with . When I get a chance I will post some pictures of my heads .

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