BBC dome fitting
 

big old sealedpower dome piston fitting into the chamber of a #781 oval port/open chamber head. quite a job..the main area by the exh. valve.... any tips or other spots to check? tks.

Re: BBC dome fitting
 

check the sides of the domes for barely hitting the head. had this happen on some closed chamber heads....as you prob. know, use clay and check without head gasket. too much clearance is better than not enough, lol

Re: BBC dome fitting
 

10 o'clock area looking into the exh. port is the major interference spot. ill play/doe the sparkplug to get that clearance. usual .005'' deck and .041'' gasket. im laying back both the dome and & chamber a touch at a time. I agree, better enough room than too close...just call me the human milling machine.

Re: BBC dome fitting
 

Put the head on the empty block and scribe the head in the area of the ex. Lay the head back to the cylinder wall and then scoop the quench area out on that side to direct the flow toward the ex port/valve. The spark plug tip needs to be at least .100 away from the piston when it is positioned @ approx 36-40 degrees before TDC. .035-.040 @ TDC. I've done this on a couple of SS engines as well as shifted the heads with offset dowels (intake toward the center of the cylinder) and seen over .010 in ET & some MPH improvement .

Re: BBC dome fitting
 

lots of room everywhere else after testing. going to file a slight angle of the chambers edge at the exh. valve/dome area to be sure theres enough room at its radius. that will give us more room there being the closest and hard to measure.

Re: BBC dome fitting
 

Are you working with a 4.250 or larger bore ? I have done a couple 454 based motrs w/049 heads and big old Speed Pro open chamber pistons with good results.

Re: BBC dome fitting
 

tks everyone. tim yes it's a 4.310'' bore x 454ci stroke w/781 head. so you had relieving to do?

Re: BBC dome fitting
 

Yup, in the exh valve area, I had switched to 1.88 " valves as well. A bit off dome and a bit of chamfering on chamber as I recall.

Re: BBC dome fitting
 

tim this is parkers bbc/monty stuff. solid cam now... vast improvement over previous combo. hope your ready to go, wont be long ...sp.