Olds 358 build

Kelvin's80442

Greasemonkey
Apr 19, 2020
230
63
Ste Rose Manitoba
The BBO heads should be out in a month. The ultra modern chamber upgrade besides the flow improvement is why I am willing to wait for the SB head. If they are delayed, there will be some pocket porting and the chambers polished to 68cc. I would probably also use the Performer intake with the 1" open spacer with those heads.
That's the ones that Mark help design or these modified again?
 

olds307 and 403

Geezer
Thread starter
Oct 14, 2008
8,037
113
Melville,Saskatchewan
That's the ones that Mark help design or these modified again?
Yes, he has been testing them. With the same pistons and rods as my motor, Mahle 10cc coated 4032 forged with a 1mm ring pack and Molnar rods. Both internally balanced, his has a "N" crank mine has a 330 forged crank. The chamber change and spark relocation are the real ticket. With 9.2 to 1, making about the same power as your 350, pretty impressive. 87 octane would run in any conditions, no doubt in my mind. I sent my RPM intake to Mark to add bungs, rails and stand offs for multiport fuel injection. For injectors, I want something that will support 600 HP, in case 400 HP isn't enough and I want to add a Torque Storm Supercharger down the road. I added more top ring gap, so it is possible, if I choose to down the road. The EFI won't happen to probably next spring. I plan on using the Holley plug and play drop in EFI fuel pump for my stock tank. The EFI with either be Holley or AEM with boost capability. Screw you $2 a liter gas!
 
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olds307 and 403

Geezer
Thread starter
Oct 14, 2008
8,037
113
Melville,Saskatchewan
This is with a RPM, divider cut 1.5" and opening at the head, not fully matching the BBO port size. So 9.2 to 1 with this cam, a Crane 222/228@.050 Hyd roller, lift is .555 on both, 110lsa
36992d60_f76f_49a3_a220_4eb70866ca98_864b28f01ef4742dd20b50de10c2191cb058daf0.jpeg.jpg
and a 750 Brawler and full length headers. The Victor made 20 HP more, peak at 6000 rpm. Mark wanted them to shrink the port entry size closer to stock for more mild street builds and the Trans Am 403 guys who can only run the Performer but the molds were already done. I think they should add material like the RPM intake at the port entry. The ports are 198cc as cast, was never the advertised 188cc intake port, SB chamber is for a 4" bore. The BBO head is now 218cc and for a 4.155" bore.
 
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Kamloops cutlass

Master Mechanic
Jan 27, 2021
266
63
Kamloops bc
Built a 403 years 25-20 yes ago with performer rpm intake and cam , good pistons but was stuck using stock heads ,even porting them left power on the table
Some guys said use big block heads then deal with port matching problems with the intake .
Edelbrock has been a long time coming with these SBO heads
Looking forward to see how they do with your combo
 

Kelvin's80442

Greasemonkey
Apr 19, 2020
230
63
Ste Rose Manitoba
That will be impressive. Cut the divider 1.5? Cut mine 3/4.


I talked to Mark yesterday. Going to be buying a stroker crank from him and hopefully he can build my DX next year.
 
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olds307 and 403

Geezer
Thread starter
Oct 14, 2008
8,037
113
Melville,Saskatchewan
Built a 403 years 25-20 yes ago with performer rpm intake and cam , good pistons but was stuck using stock heads ,even porting them left power on the table
Some guys said use big block heads then deal with port matching problems with the intake .
Edelbrock has been a long time coming with these SBO heads
Looking forward to see how they do with your combo
The 4A are terrible on the exhaust side, Edelbrock improved the exhaust a bit over the last gen. I also want to see what they will do, sooner than later.
That will be impressive. Cut the divider 1.5? Cut mine 3/4.


I talked to Mark yesterday. Going to be buying a stroker crank from him and hopefully he can build my DX next year.
Yes, I am sure he mentioned the 1.5" divider cut. Mine is also around that 3/4" amount currently. That stroked DX should really haul *ss😎.
 

olds307 and 403

Geezer
Thread starter
Oct 14, 2008
8,037
113
Melville,Saskatchewan
No, never ever. Mine has big windows, all the rest do too. The Olds Siamese bore Nascar block is closest and can go to a 403 bore.
 

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