040" and this will allow me to deck the head a bit more, and my final CR should be somewhere in the 13.5 to 1 range. I had a lot of this stuff lying around from my SCCA racing days, so I'm currently working on such a engine, I have reduced the domes to. DIY FLYCUT PISTONS FULLThese days, not many MGBs race in the SCCA in FP in full prep trim, most MGBs are racing in vintage, and with more modest CRs, more like 12.0 -13.0 to 1, and this is very do-able with flat top piston in a MGB, so most vintage MGB. of course this sort of set with this sort of CR, meant we were doing engine refreshes (rings and bearings) about every 4-5 race weekends. With this set up, I ran Phillip 66 118 race fuel,and had to back my timing back down to 25 degrees BTDC. 055" angled sweep around the combustion chamber for the piston to not contact the cylinder head. 030 for rod stretch at rpm, so you would need with a. The idea on the head is to calculate the dome's pop up height, accounting for the head gasket compressed thickness (with a Payne black head gasket that is. All this is with a planned block to piston deck height of near zero, meaning when the piston is a TDC the entire dome is proud of the block, thus the reason forth swept relief in the head. DIY FLYCUT PISTONS MANUALNow onto the heads used with these dome pistons, you have to make sweep around the combustion chambers in the head to give the dome clearance, this was true art form, as "in the day", this was done by hand with porting tools,, some times with custom made shell mill replicating the angle of the dome piston, we made such manual cutting tool set up for the 1098, these days you can get this done with a CNC machine. These pistons originally had no valve reliefs, and. When I owned #9 Huffaker MGB, it had two dome piston engines, they were pretty mild by later standards, as for CR, later I added a higher lift Comptune cam, vs the lesser lift Delong cams used by Huffaker, then also replaced the Huffaker cylinder heads with Comptune cylinder heads, which in the end boosted CR from about 13.0 to 1 to 15.5 to 1, I also at that time had to add valve reliefs to the original Huffaker pistons, due to the higher lift cam. Here's a picture of the most common used dome piston in the MGB, this is what Huffaker used back in the mid-late 70s, and this design has been copied by many racers over the year. Oct 01 A Sad Day At The Autocross, As.Nov 18 FLBritish Invasion Car Show & F.Oct 22 ALSouth Alabama British Car Fes.This will also give the carbs plenty of time to fill the float bowls with gas. When you first start the engine, run the starter for a while without the spark plugs in to get the oil pressure up enough to make the oil light go out. Volume and mixture screws should be out about 2.5 - 3 turns to start with.ĭon't forget to put some oil in before starting. Set your carbs up to the specs in Bentley. Keep in mind that the rod rides on a cam, so you need to cut it short enough that it doesn't bang into the cover as the crankshaft rotates. You will need to cut the rod down in length a little bit. I have a homemade cover, but the inside chamber is not plugged.Īny advice for the newbie at this point? I can't wait to get this SOB in and actually use the bus this summer.ĬIP1 sells a fuel pump push rod for the 1700 - 1800 cc engine that you can use to prevent oil from gushing around in the place where the fuel pump used to be (along with possible loss of oil pressure). I'm still working on plugging or figuring out what to do with where the mechanical fuel pump used to be.
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