Ok i picked up a 347 off of craigslist and i was wondering if you guys could give me some helpful hints about what to look out for while rebuilding it. Like what would be good additions to the engine. The motors going to strictly for the track. Thanks guys in advance for the help.
Tear it down and see what you have first....But... Why does it need to be rebuilt to begin with...Is it broken or just tired???
it was smoking, the guy said it needed valve seals. But i decided i wanted to rering it and freshen it up before running it. Tore it down tonight> one of the pistons was a little beaten up but all the cylinder walls look really good. Going to put new rod and main bearings in it. so far its looking like a pretty good deal. Looks to be an eagle crank with srp pistons
Heads up on the rod bearings!! If it is like my 347 then the rod journals may have a bevel on the outside edges of the journal. This makes them stronger than a 90 degree cut. I rebuilt mine using standard bearings and even plastigauged each journal/rod individually. But then once it was all assembled the motor was seized up and could not rotate the crank with a wrench. It took a while to figure out. I finally loosened the rod caps and the crank could be turned real easy. The rod bearings were binding up on the beveled edge of the cranks rod journals. Now they make special bearings that fit this type of crank and can be ordered and are expensive. After talking to my machine shop about where to buy them he suggested cuttiing the bevel into my bearings with a grinding stone on a dremel or whatever. I did that and put it back togethor and it turned smooth.
Ryan, your bearings were not the issue. You probably installed your rods backwards. You should be able to use any bearing of any make and not have it bind up. The fact yours binded up is a classic sign that rods were installed backwards on the pistons. I have seen guys even try to grind the bearings for clearance! NEVER GRIND BEARINGS!! If it doesnt fit you have a PROBLEM! Bearings sit about .050 offset in the rods. Simply turning the rods around 180 clears everything up. If your rods truely are facing the correct direction then your crank needs to be fixed.
Not true. read about it here http://forums.corral.net/forums/showthread.php?t=528948 the first build was done by the machine shop with bearings supplied by Coast high Performance with the kit. I then rebuilt the engine myself after spinning a rod bearings 1 and 5 due to an oiling issue. I used stock bearing from autozone and were not the correct ones and the needed to be chamfered bearings instead of uncut bearings. the rods were on correctly with the chamfer on the rod to the outside of the bearing. I compared the crank to the stock 302 crank and it was obviously different. stock crank was almost 90 degree cut on the edge of the journal, stroker crank had a more gradual chamfer.
Summit sells Chamferred bearings for high performance cranks. http://www.summitracing.com/search/...e/Clevite-H-Series-Rod-Bearings/?autoview=SKU Another article on Car Craft talking about Chamferred rods/bearing for a stroker. Read towards the end of the first paragraph. "The rods and bearings have been chamfered for the crank fillet" http://www.carcraft.com/techarticles/ccrp_1003_ford_347_engine_build/index.html Please don't assume you know everything when somebody else has experienced a problem first hand and offered up his experience so that somebody else does not make the same mistake. I would have thought the same os you if I hadn't experienced it myself. You can see the chamfer in this picture
76Mav77, If you want to buy new rod bearings and the cranks is standard size then you need Clevite part number CB1227H. Standard bearing are CB1227P. The thing is that the standard bearings are around $60 a set, the H bearings are $200+. Which is why guys grind or cut the P bearing when rebuilding a stroker.
The clearnancing the artical is talking about is using a grinder to cut the cylinder walls for rod clearance not for the bearings! Maybe you sent the wrong article, or I missed the part about grinding the bearings. Although its true H bearings offer more clearance, they were never designed for that reason. They were made for NASCAR and deigned for higher crush values and reving motors. I have ran P bearings with scat, eagle, FMS cranks and others with no problems 76MAV77: If your motor was burning oil , other than your heads, I would take a look at the type of pistons you have. At this point its not something to worry about but many 347's use a fairly low compression height piston which makes the piston pin cut into part of the oil ring groove. Leaking valve seals and leaking oil rings are going to show different signs when you inspect the motor. Make sure you do not clean all your parts before everything is examined
In the car craft article, towards the end of the first paragraph it states, "The rods and bearings have been chamfered for the crank fillet," The articles don't say anything about grinding the bearing, thats just what I had to do to get the motor togethor. Like the thread i listed from the Corral, nobody in town stocked the H bearings that were needed so I cut the P bearings. H bearings may not have been designed originally for stroker cranks but they were designed for High Performance use and in the intended application they probably had beveled edges in the journals. In Clevites description for the H series bearings they say, "H-Series bearings have enlarged chamfers at the sides for greater crank-fillet clearance " Most performance stroker cranks have a larger than stock bevel at the edge of the journal, some strokers may accept the P bearings but mine did not and doing a google search on the issue comes up with many instances with the same result. This may be an issue with only Coast High Performance (Probe) cranks, they may have a larger bevel than others. But the Car Craft article used an Eagle stroker kit and it stated it came with chamferred rods and bearings so it must be reccomended to replace them with the same bearing. I don't doubt that it is not ideal to grind a bearing, but waring a rebuilder of a stroker motor that he may need H bearings when putting it back togethor if he has the binding issue I and many others did.
Another article from Circle Track Magazine talking about the same issue with performance cranks and stock bearings. http://www.circletrack.com/enginetech/ctrp_1012_race_engine_rebuild_tips/rod_bearings_lifters.html
maybe the CHP kits use a Chevy based rod I just know the things don't fit. And many articles and threads reference using the H bearing with performance crankshafts because of the larger chamfer. Actually I didnt see anything in the car craft article mentioning Chevy rods, they were Eagle rods. Could they be based on a Chevy design, making then thicker and need the chamferred bearing? Oh well, hopefully the original poster don't need new bearings but if he does he has been warned of what MIGHT be needed. I don't even have a stroker motor anymore anyways, mine is still built the way it was when Ford sent it out in a Mustang.
Well I thought I was done, I was just looking on Speedway http://www.speedwaymotors.com/Ford-302-Forged-Stroker-Cranks,3182.html They list the stroker cranks as having Chevy journals. If this is standard practice then maybe the Chevy rod bearings fit better and dont need the H bearings with the chamferred edge. Brainsboy do you use chevy bearings or ford bearings part numbers since you only have had to use the P series bearing?
I have used both in the past. When I built my last 408 I actually used carrillo rods w/ forged steel crank which used the chevy bearing sizes but I used H bearings. When I build I tend to go overboard with the best products on the bottom end, so I never attempted to use P bearings with it. The current motor I am on now is a 331 stroker with P bearings with no issues but its using the ford bearing sizes. Its possible that chevy rods have less clearence than the fords. The only issues I have seen with lockup was with the rods being 180 degrees off. If not then its possible that chevy rods and certain cranks have a problem. I have never bought two scat or eagle cranks that didnt needed to be machine in some manner.
