FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: bluef100fe on April 01, 2014, 01:22:12 PM
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The cylinder wall of a 0.030 over 390? Anybody done it? If so how well did it run? Thanks again :)
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I used a set of 2.19/1.71 valves in Edelbrock 428CJ heads on my 390 stroker engine to get to the 575HP level. That engine was .040" over, not .030" over, but I imagine that .030" over would be fine too. You could always notch the bores a little if it was too close.
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I would do that but the short block is currently in the truck and running with iron heads on it... A buddy of mine has these edelbrock heads and will borrow them to me if I have a cylinder head related problem this race season.. Thanks for the info Jay guess I should have read your book again as that info is probably in there lol
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Its not in the book, actually, Cody, but it is in the Car Craft article:
http://www.carcraft.com/techarticles/ccrp_0808_ford_390_fe/
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Thanks for the link Jay I think I have the magazine somewhere at home
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The 1.710 seems to clear on a 4.080 bore, but will leave a stripe on the wall at 4.070 even though it measures "OK".
That's the reason I've gone to 1.680 on most of our stuff.
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My bore measures 4.085 so I should be good to go if the need arises... Thanks for the insight guys
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Well plans changed for these heads...I finally got around to building my buddies .030 over 390 With these heads and I mocked up a head with checking springs and bolted it on the zero decked block... These edelbrock heads have been cut a bunch....chambers were in the mid sixties for volume last time they were checked iirc... I'm unsure what that does for valve placement in the cylinder... I think it moves the valve pierce point towards the external side of the block slightly.... But anyway the exhaust valve is leaving a witness mark on the cylinder wall and makes a dead stop at about 0.680 lift.... Goes to show always check recheck and check everything again lol... No sure thing in engine building unless you check it... I'm going to notch the tops of the cylinders and mock everything up again and recheck... Has anybody else ran into this? Wondering if the valve placement was different on the early edelbrock 6005 heads compared to the newer offerings... I think he purchased these new in 1998 or so..
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Use some thick copper gaskets to restore the original deck height. I would measure the volume of your chamber, then add the needed cc to return the head to a reasonable size. Keep in mind if the head has been milled more than .060 the surface has been compromised.
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The deck is where I want it.... I'm wondering if these heads being early edelbrock castings with 2.15/1.71 valves have a little different valve centerline or spacing than what is currently available... I've read where people have run these size valves in edelbrock heads with a 4.08 bore block and not have issues... Just wondering why I'm so special that nothing ever fits without machine work lol...
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Two things are "doing it"...
First is the cut - sound like about (assuming 66cc as a guess) .030-.035 was cut from the head.
Second is the term "dead stop" at .680 lift. Not many guys are running a net .680 lift (gross .700ish) cam in a 390 based build.
Run uncut heads and a .600 lift cam and you're over .100 away from the wall.
That said - I have usually run a 1.68 exhaust for quite a while now on our 390s.
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Thanks Barry,
The heads have been milled enough that half the "p" on performer have been erased on the end of the head... I notched the bores on the block for some extra clearance and now I get to 0.720 lift at the valve before a dead stop... My cam is suppost to be 0.600ish net lift if the rockers come in at a actual 1.76 ratio... so hopefully there is enough room now... The valve was leaving a drag mark down the cylinder wall so something had to be done... I think I should be safe now... Hope to have a high 10 second 390 when it's done.... Car it's going in is 3400 lb....
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I had a 1.72 valve drag on a 4.070 bore with about .640 gross - so I can see it getting tight...
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I would take into account the possibility of some valve float if you are going to run it hard. I have seen valves on paper that clear but under load and rpm things change quickly.
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Just goes to show ya never know until you mock things up and check... It's just a 6500 rpm bracket car deal... Suppost to be a backup engine but his good one is hurt and this one was cheaper to get together to finish the season... Well we started out thinking it would be cheaper anyway lol