Hey guys,

Pulling my motor today for a rebuild and port. so far the plan is:

2-piece atkins apexes, springs
atkins solid corner seals+FD springs
side seal springs
oil control springs+vitons
large street port+polish
FD exhaust inserts, ported and polished
Add 3 dowel pins per housing (corners + between the plugs)
Heat shrink tension bolts
surface grind side housings

anything Im missing here?

after i get it running im upgrading to a 42R (already got one), and shooting for 700whp race tune, 450 street (2-stage boost controller) both on 93 or 94 octane.

as it sits now the motor made 412 with totally stock block, at 14 psi (sorta, turbo was outflowed, only made 8-9psi at 6k+)

pat

 

well its out, soon as i find a big crowbar to get the flywheel off with it will be apart... its kinda sad that im getting so good at this...took me like 2 hours start to finish from driving it in the garage to setting the bare block on my build table.

 

what's the stock oil pressure on a 20B? does it still use just one regulator?

i was thinking oil mods for peace of mind at your intended power levels - you know, the usual stuff (FD regulator, race rotor bearings, multi-window mains, etc.)

maybe coatings???

either way, i'm jealous.

 

ok so i started organizing parts today, and i notice that it has the 8 window stat gear bearings, as well as shrink-wrapped tension bolts and what looks like some sort of coating on the sides of the rotors. none of that stuff is stock on an A series 20B is it?

pat

 

Yes, that is all standard on the 20B's. They use the FD style bearings, and have heat shrink on select tension bolts. I would not recommend race rotor bearings, as they have extra clearence needed for very high rpms (8500+). With the stock oil pump, it will have a hard time pumping 70psi up to 8000rpms already, and race bearings will just lower this pressure. Port the inlet in the cast iron housing for the oil pump. I dont want to throw out my opinion too harsh, but the atkins seals are very soft, and non-hardened like the factory. Just something to think about on a very very high output engine. I also dont like dowel pinning very much, as the casting gets very thin, and can crack. Maybe a stud kit would be a better investment. Do as many coolant mods as possible, as the 20b runs very high temps under high loads. Try to use a S4 waterpump as well, if you can use it with your current setup. Lapping the housings will shorten the engine life. If it was me, as long as the wear is good, I would leave as-is. But take all that with a grain of salt, just what I have learned over all the years. And everyone will have a different answer. Good luck!

 

Thanks gto,

I was planning the oil pump already, and I am running an s4 water pump. As far as pinning, It seems to me that on the early series 20B with the thinner castings this would be a decent idea, no? I cant afford to use a stud kit, so its either pins or nothing. As far as coolant mods, I'm not sure where to start on that, any recommendations? Also it looks like the coolant passages also have the coating that is on the rotors, what is it?

thanks
pat

 

I've seen 3 motors with grooves carved in the irons from atkins solid corners w/ FD springs. One ran great...just rich at idle. One hard to start. And one lost so much compression it wouldn't start.

Some motors were lapped, one was not...the hard to start one.

 

You will hear all types of opinions on if a engine needs studs, or dowel pinning, or nothing at all. Personally it would be nothing or studs for me. If you look closely where the upper dowel pin is, in relation to what degree the rotor is facing, you can see that broken dowels is from pre-ignition, more than from power. Adding more dowels to help prevent something that should'nt be there is somewhat a backward step? Then add to the fact the front cast iron plate tension bolt holes loose half their threads, from machining. With a engine as long as the 20B, I would like to have as much threads for the tension bolts as possible. I also agree with not using solid corner seals. I have seen them crack easy, and takes away bottom end, and adds more wear to the engine.

 

well, it is back together with about 100 miles on it, running great. idled at 1k 2 minutes after starting with a nice lopey idle, so i think it is going to be a good setup. I'm doing a 500 mile breakin on the s300, then i will switch to the gt42r and take it to the dyno and the track

pat

 

What parts did you decide on using?

 

same thing i originally said. by the time anyone replied it was too late to change the plan anyway. I also did new stat gear bearings and ported the oil pump and added external bearing feeds.