XR7 Dave
Registered User
Flex, that Morana set used long discontinued parts, so you can't copy that. The nice thing about that set was that the lower gear was already the correct size and it included the right chain. What Jeff is doing is the only way anymore.
Couple hints - you don't want to use a tensioner. The added abrasiveness of the roller chain vs. the stock flat link chain will chew it up and can cause catastrophic failure. It's happened.
Also, the SBF crank gear is narrower than the stock one. This will cause alignment issues if your vehicle is an 89-93 as those are very sensitive to crankshaft sensor alignment. Make a spacer so it's the correct thickness.
I'm sure you've looked at gear alignment. It's a bit tricky with SBF timing sets because there are many different iterations on the upper gear, many are designed for use with an oil pump eccentric, one piece, two piece, etc. It's annoying, but every single one is different.
Also, consider chain lubrication. The stock gear had forced oiling from the camshaft though chamfers and grooves in the machining. Getting oil to the roller chain will be a factor in long life while minimizing stretch.
Oh and on the girdle situation, consider using steel inserts since you can't use double nuts. You already machined the reliefs oversize, go ahead and put some stepped hard inserts in there so the aluminum distortion is minimized during torquing. With the ARP studs the torque values will be significantly higher than stock, so do everything you can to protect the aluminum.
Couple hints - you don't want to use a tensioner. The added abrasiveness of the roller chain vs. the stock flat link chain will chew it up and can cause catastrophic failure. It's happened.
Also, the SBF crank gear is narrower than the stock one. This will cause alignment issues if your vehicle is an 89-93 as those are very sensitive to crankshaft sensor alignment. Make a spacer so it's the correct thickness.
I'm sure you've looked at gear alignment. It's a bit tricky with SBF timing sets because there are many different iterations on the upper gear, many are designed for use with an oil pump eccentric, one piece, two piece, etc. It's annoying, but every single one is different.
Also, consider chain lubrication. The stock gear had forced oiling from the camshaft though chamfers and grooves in the machining. Getting oil to the roller chain will be a factor in long life while minimizing stretch.
Oh and on the girdle situation, consider using steel inserts since you can't use double nuts. You already machined the reliefs oversize, go ahead and put some stepped hard inserts in there so the aluminum distortion is minimized during torquing. With the ARP studs the torque values will be significantly higher than stock, so do everything you can to protect the aluminum.
Last edited: