Briggs High RPM Poor Boy Special
- Thread starter bowtiebutler
- Start date
- Tags briggs high poor special
Well. I figured it was about time to give an update. I broke down, and ordered a new 03-ss cam from Dyno Cams, as I wasn't having any luck finding one used. ($65 Ouch!) My $25 used ARC rod came in, and its in great shape. I also picked up a set of .010 Raptor 3 rings, as the Wiseco piston requires the thin Raptor rings. I then file fitted each of the rings to the STD bore. Top-.0025 Second- .004 Oil- .008. Not wanting to spend any money at a machine shop, I used a 1/2in. medical steel plate from a bone breaking table, which is perfectly flat to grind the head down. I just used a sheet of 80 grit to start with, and finished with a piece of 220 grit. I also machine a slot into the head with my die grinder, to aid in combustion as I milled the area above the piston completely flat. I also milled the top of the block, but just enough to give me a nice flat surface. I realize my methods aren't ideal, but the point of this build is to make as much power as possible, while sticking to a very tight budget. I'm finding it very difficult not to order a bunch of high dollar parts for it, but so far I'm behaving myself.:laugh: I'm still looking for a used billet flywheel. I realize I would probabally be ok with the stock flywheel, but there is a good chance my kids will be using this, and I'm not willing to risk it. Thanks
Matt
Matt
Nice job on the head+block :thumbsup: I've done similar machining the same way in the past, and had good results. Using whatever I had handy to get the job done.
I'm really impressed with your budget build so far :thumbsup: Even having to spend that money on the cam, your still in it pretty cheap considering what some people spend on a build.
Vic
I'm really impressed with your budget build so far :thumbsup: Even having to spend that money on the cam, your still in it pretty cheap considering what some people spend on a build.
Vic
These were the steel plate that came with an old bone breaking table that my dad had in storage. It was used for rebreaking bones that had healed wrong. It looks like some sort of torturing table!:laugh: You can put a straight edge on any of these plates, and you can't fit a .001 feeler gauge anywhere underneath.
Matt
Matt
I'm still waiting on my cam to come in, so I decided to turn my attention to making an intake to adapt my 22mm Mikuni to it. I made 1/4in. thick flanges for both the carb, and the block, although I haven't finished trimming the outside edges yet. I also made the pipe, but I still have a lot of smoothing to do inside of it, to make sure it has a smooth transition from the larger Mikuni bore, down to the Briggs port size. I will probably add a ridge underneath the intake for added strength. Thanks
Matt
Matt
It doesn't help with compression, it help with combustion. It help the flame to travel better, when these heads are milled flat like this one, or at least this is what the aftermarket racing heads say. Some of the aftermarket racing heads that have the area directly above the piston milled flat, have a slot like this machined into them, and they call it a fire slot. Honestly, I can't say for sure that it helps, but I figured maybe they know what they're talking about, and for sure it can't hurt.:thumbsup:
Matt
Matt
Horstmen used to sell the Fire Slot head. It had a similar slot cut in, and had larger cooling fins on the top . I used to use them on my open Briggs builds when I raced karts. Not sure if they still sell them or not, but they were pretty popular with the motor builders back then.
Nice job on the intake Matt .
Vic
Nice job on the intake Matt .
Vic
Got the intake mostly done today. I still have to trim down the carburetor side flange, but other than that, its done. Somehow I managed to get the carb flange clocked a little off on the pipe. The carb sits at about the 11:30 position, rather that 12:00 like it should. I don't know how it happened, as I had put marks on both the flange, and pipe, but somehow from marking it to actually welding it, I ended up off. It shouldn't hurt performance, so for the time being, I think I'll leave this way, but who knows. It may get to bugging me, and if it does, I'll just cut it, and fix it. Thanks
Matt
Matt
Well, I got some good news, and some bad news. The good news is the cam came in, and it looks great! The bad new is it going to require the longer 1.70 lifters to be able to get the valve clearance right, and I'm going to have to clearance the billet rod, as its coming in contact with the cam.:blink: I just ordered the lifters ($16.99), oh well. In the meantime, I'll get the rod clearance. Godda love all the little things that come up, when trying to build an engine far exceed its factory HP rating.:doah:
Matt
Matt
I know its been awhile since my last update, but I ran into a couple snags. I already got the longer billet lifters in, but I realized with this cams extra lift, I now only had about .002 till coil bind!:doah: I have apretty good selection of different performance valve springs for flat heads, but it didn't matter, none of them got me anywhere near enough clearance. So, once again I found myself spending more money. ($50) on a special cutting tool for machining valve spring seat area. I've always wanted one, but never really had a legitimate need. As soon as it gets here, the build will move forward. In the meantime I did pic up a frame for this engine. Its an old Sears Roper, and its UUUUUGLY!!! However, its sill solid, with only surface rust. I had several different style headers laying around that I could have used on this engine, but none of them fit this frame, so I ended up steeling the ceramic coated one off of my Raptor Clone, as it fit quite well.:thumbsup: Anyway, here are a couple pics of the engine on the frame I picked up. I'll get the frame sandblasted soon, so I can put some paint on it.
Matt
Matt
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