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Non-FE Discussion Forum / Re: Jegs
« on: April 22, 2024, 11:09:35 AM »
Most of the engine builders on here can get whatever Jegs/Summit can get, and probably for the same price.
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Note - Hot vs cold lash on this iron/iron 351C is the same.
As far as the quench discussion, glad to see no attempt to make it too tight. I think for most .040-.050 is plenty for the squish benefit, and I regularly run them proud with a 8554 and some even taller if we are trying to keep intake dimensions on the rare stuff. Even comparing .045 or so to .036 I'd expect no gain and only added risk.
In terms of the machining, geez Howie, Brent was right, said Ford was all over the place, and then you come back with Ford couldn't hold a spec with their tech at the time, that is EXACTLY the point. Who cares what the spec is if the machine can't hold it anyway? Brent didn't say that the machinists were evil or FOMOCO was playing a trick on us. I'll add that valve centerline, bore centers, cam bore dimensions are all over the place too once you start measuring.
Additionally, no doubt things flex with heat cycles, I am not sure what you mean by massive flexing, I don't agree with that, an FE is pretty forgiving on head gaskets even fewer head bolts than modern engines. Although anything can move, they don't change .026 from end to end and grow .010 over deck height. That's a crank centerline or deck machining issue that causes that much variance, and the numbers can tell you which it was.
Square deck a block or two, you'll see things, square deck 20, you can really see the trends.
In Brent's defense, my 361 Edsel block was off .018 across the deck and cleaned up at 10.172. It had the same quench as a '58 352 but the heads had no evidence of contact of any sort and would have had a min quench of .038.
But, Ford would NOT have release a engine with a nominal .036 quench if it would not be enough, period. 5 yrs later they built a all aluminum SBF, reliable enough to finish the Indy 500.
Now, if Ross's engine, that had a deck height of 10.155, had been assembled with a nominal .036 quench, It could not have left the assembly line so, it would have never made it to the street.
Last, it is my recollection (please correct me, if I'm wrong) that the the engine that Brent ran .035 quench on, was his JJ, 352 and he had aluminum rods in it (most high strength alum expands at 3 times the rate of steel). It didn't make any noise and didn't hurt anything, either.
Ford had trouble machining a block within .020".BS
One very interesting video he did was on flat tappet grinding. His findings made me rethink flat tappet problems. I would have posted the video but couldn't figure out how, hopefully the builders on here find it and give some feedback on their thoughts.
Thanks for all the comments , I feel much better about running it as is. I'm not a engine builder or a machinist but have been a truck mechanic for the past 40 yrs. and thought it would be interesting to assemble this engine myself, thinking it would be fairly straight forward but from the beginning its been anything but. Was planning to use my old block but it sonic tested too thin in spots and looking for a acceptable replacement took months and a few road trips. The only good block I could find was a D4TE with the extra main webbing that had already been machined. It looked great ,sonic tested good but had some pitting in one cylinder, thought I could just have a sleeve put in and didn't realize would have to bore and deck it again, 5 months at the machine shop , got it back and installing the camshaft, had to shave two cam bearings to .007 clearance to get the cam to rotate freely. Then measuring the piston skirt clearance on one cylinder .002 larger than the rest . The main clearances all measured .0025 - .0032 so that was nice but now as I'm mocking up a piston and rod on cylinder no. 4 , it measures .007 in the hole and when I used the same piston and rod in no. 1 it was .005 in the hole. Is this acceptable ? The machinist is a one man show been doing it for 50 yrs. very FE experienced and a really nice guy, he said he square decked it, maybe he's having vision problems. Also, when I torque the main caps to even 70 ft. lbs. my camshaft becomes noticeably harder to rotate. Is this normal ? It makes sense to me that if the heads torqued down distorts the cylinder bores, that the mains torqued would distort the cam tunnel. I think I'll install new cam bearings and make a cam cutter out of an old camshaft as Brent suggested and see if that helps. Should fitting the camshaft be done with the mains torqued ? I'm not looking for perfection , I realize this is a 50 yr. old truck block, just want to know what is acceptable. Even with all these issues, I am enjoying learning this process and feel very fortunate to have this forum with so many good people with so much engine knowledge and so willing to help.