Well, we're moving right along with this one. I didn't want to turn this into a build thread but I do want to keep it alive so I can post the progress and performance of a bushed block. The one final big decision on this was the oil grooves to the cam lobe. I of course turned this into a bigger deal than it probably was but in the end Matt and I decided not to groove them. With .002" lifter to bore clearance, we're still well above a lot of stock engines on the market. I just didn't feel it was necessary in the end. Now, this could come back and bite me in the ass one way or another. The main concern running through my head is if we loose a lobe at break in, whether it was caused by the lack of grooves or not, they will still get the blame. I guess any normal person would have just grooved them as a cya (cover your ass)deal but I really don't see it being a problem and felt strongly about not wanting to sacrifice any improvements to the oil system if I don't have to.
Anyway, the block was cleaned again for mock up and more measurements. I've found the previous builder was quite bi-polar in his efforts. Most of build was done quite well, even overboard in some aspects. Then other portions were just completely overlooked or disregarded. What initially attracted me to this job was the cam bearing issue. I've also lost new cam bearings at break-in so this gave me an opportunity to scrutinize another block for comparison to my findings. That said, there were a couple other issues that I wanted to look into as well. In the very beginning I told Matt compression ratio, cam timing, and pushrod length are other portions of the build that needed to be scrutinized. It turns out I was 2 for 3.
1.c.r.: the previous buildering installed sealed power hypereutectic pistons which have a shorter compression height. The good news is that he did make up for it by taking material from the deck to account for it. The pistons are currently .015" in the hole and give this engine a compression ratio of 8.6:1. So we're good there.
2. Valve timing: I was right here. The builder installed the cam dot to dot, being ~5 degrees retarded when timed. I read a quote from a professional builder not to long ago that went something like this
"if you're not timing the cam in every build you perform then you're not qualified to work on engines."
The cams I've installed come in around 5-6 degrees retarded allowing me to advance the timing gears one tooth to provide a slightly advanced cam timing. This one was no different. Here are couple graphs from the timing data. It's a schneider 256h. The size of this cam is pushing it in a 8.6:1 304 in my opinion but he felt the most comfortable with this choice. He's running a low geared manual tranny so it should fit his needs just fine. It will definitely outperform the retarded comp 260 he had in prior to this.
Schneider 256h
204/204 on 112 lsa, intake installed @ 109
lift curve:
Velocity curve:
3. Pushrod length: right here again. Preload was border line dangerous on about every other valve. The stock pushrods had a variance in length by as much as .020". Using stock pushrods after taking off as much material as they did was big mistake. I didn't see where any were noticeably bent when rolling them on glass but the variance seemed large to me and all were shorter than their original stock length. In more than a few cases a new stock length pushrod would have pushed preload over .125
I called the guys at smith bro's to have an adjustable pushrod made. It came with the same ends that would be on the new set of pushrods once the measurements were made. They told me to take the measurement, lock it down, and then mail it back to them and they would make a set based on that measurement. While very convenient, I knew all 16 valves would have a slightly different measurement due to rocker arm wear, etc. So I jumped on ebay and found a used mitutoyo 12" dial caliper.
Once it arrived, I measured every valve twice, averaged all 16 measurements and added in .075" preload. With that new data I called smith bro.'s again and ordered a set of ball/ball heat treated pushrods, 8.910" oal. The new pushrods were beautiful and varied by just a couple thousandths.
So this engine had some critical issues to deal with. That last being a prestolite electronic distributor conversion outfitted with a pertronix one. Gear end play was .020" over spec and shaft side play was double high spec at .013"
I tested endplay at the beginning and had shims ready for those but replaceing shaft bushings was a surprise. With the exception of a groove to hold the grease cavity cap in the top bushing, they're pretty easy to make from your standard tractor supply oillite bushings.
Cleaned parts.
Stock upper bushing- 5/8" od, 1/2" id, 1" long
Makeshift lathe w/ a triangle dental file.
Ready to be cut down to size. Tractor supply bushing is 5/8 x 1/2 x 1 1/8 long.
Had to make a pilot so both bushings would install straight and on the same plane. I've outlined this procedure somewhere else so I won't go over it again. The lower bushing has been installed using a different (makeshift) pilot to be installed straight in it's bore. Now I'm piloting off the already installed lower bushing to make sure they're on the same plane.
Everything put back together but now with endplay and sideplay specs of a new distributor. I got lucky, I though I would have to broach the id for sure but that was not the case. I had to chamfer the id of the upper bushing but the shaft spins beautifully now, no id sizing needed.
Everything's finally back together and all specs are where they should be.
Main bearing's= .0025"
rods bearing's= .002"
crankshaft endplay=.004"
rod side clearance = .007"-.009"
cam bearing's= .003"
cam endplay= .006"
note re cam: there is a very critical fitment procedure that needs to be followed when installing a new camshaft on new cam bearings. I did mention it here but I've seen where Robert has gone over it more than once. The latest being in "harry's rebuild" I think it's one of the most critical lessons to learn when building one of these.
Lifters = .002"
oil pump and distributor are in spec and ready to go.
Heads have a new multi-angle valve job w/ bronze guide inserts, new intake valves, new umbrella seals, and springs @ 110#/270# vs cam open and close. Retainer to seal and spring bind are both in spec. (the guides were milled by the previous builder)
and the most important thing, everything's clean! I can't tell you how much time I spent cleaning this thing. When in doubt, I gave it bath.
I spent this weekend trying to make it look good. The prep was a pita but it was worth it in the end.
Pic cam out blue but it's just epoxy primer.
I scuffed the epoxy with red scotch-brite and then laid down some eastwood's ceramic engine paint - universal red
I've decided to break this engine in on a stand so while the paint is curing, I'll spend the next few days putting that together. I'm not going to spend 100 hours building some crazy engine stand, it's just going to get the job done and allow me to monitor all aspects of the engine while running. I've wanted one and this seems to be the perfect time to do it considering we've got some freshly prepared lifter bores in her. Plus, the owners been rewiring his truck from front to back and I just don't want to mess with all that while I'm trying to focus on the engine. Not that I think he did a poor job but we already have a lot going on here. A simple stand w/ simple wiring and everything at arms reach sound great to me. Might even have a video of it all, we'll see.
Thanks,
jason
