Question on factory B exhaust manifold

[tintr1]

I wasn’t thinking when I ordered a new Factory B pipe direct from factory. I ordered a mod system for a superjet. My problem is I have a 61x exhaust manifold ( 8 mm bolts) but I’m running a 62t cylinder (10 mm bolts). I would return and swap the manifold but I’ve already drilled and tapped it for dual cooling. I’ve been told to screw in inserts into the cylinder to accept the 61x 8mm bolts, but I’m worried about them working loose or not holding tight enough. It seems easy enough to drill out the 61x exhaust manifold to allow the use of the larger 10mm bolts that fit the 62t cylinder. What is everyone’s opinion on which route to go?? Thanks in advance!!

 

[vomitspot]

I’ve drilled for 10 mm bolts
The 2 in the center are real pia !
Easiest would be 8 10 mm/8mm time certs

 

[Jr.]

Use the Helicoils or beter yet Timecerts. They will not back out
Dont drill out the manifold for the larger bolts! You will reduce the sealing surface of the gasket and end up developing water leaks in short periods of time

 

[Tyler Zane]

I agree with both responses above. Do not drill Mani.

 

[Storbeck]

I think there are a couple of vendors that will modify the manifold for the 62t cylinder. Group k and the guy doing the 4mm stroker (don't recall the name of the company) both do it and probably more. Myself personally I'd run the inserts and "Port" the manifold to match the cylinder.

 

[Tyler Zane]

The roof of the exhaust port is a bit off but it's negligible unless the whole engine is ported and your doing every little bit.