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Bret
Yoda
Offline
Hey gang,
Ok nothing firm yet – but I’m going over some of my options for upgrading my 78B’s head & valve train.
While I know I won’t see any huge gains especially considering that I have to retain my original single Zenith Stromberg set-up for emissions requirements. But I plan on up-rating as much as I can without breaking the law. Minimum. However, I figure I’ll be ready for future modifications down the road, when I move out of the Republic of Kalifornia with it’s nanny-ish emissions laws.
For starters topping the wish list; I am looking at acquiring an aluminum head and possibly ported & polished and a mild street came. I might even try larger intake valves.
Next I plan on addressing the valve train. Up-rated lifters with tubular pushrods possibly installing a set of Roller Rockers. I know that the pre-manufactured sets from VB & Moss ain’t cheap, with an asking price of about $1000 for the set. But as an alternative I’ve found that there are at least two sellers on eBay that sell individual roller rockers in sets, that can be used with the standard rocker arm shaft, in with a ratio of 1.5+ for about $265 for the set. And for ~$14 more you can get them in the higher ratio of 1.625. Both would be an improvement over the stock ratio of 1.41:1.
Anyway doing some reading in Peter Burgess’ “How to Power Tune MGB 4-Cylinder Engines”. When talking on Roller Rockers - he mentions the expected stuff like – “checking the valve springs for coil bind under full lift (min 10 thou)” & “increasing the rocker (tappet) clearance by 14%”. But he also mentions – “checking to make sure that the exhaust valve will not hit the block at full lift. And that if it hasn’t already been done to cutout the bore is necessary”.
I can see checking the springs and perhaps making a change to the tappet clearance Example: 13mm (hot) to say 15mm. But I was of the understanding that I shouldn’t need to make any other modifications. Is there a problem with exhaust valve making contact with the block?
So if anybody undertaken this endeavor on the late model B engine would like to share their thoughts and findings on this I’d be very interested.
Ok nothing firm yet – but I’m going over some of my options for upgrading my 78B’s head & valve train.
While I know I won’t see any huge gains especially considering that I have to retain my original single Zenith Stromberg set-up for emissions requirements. But I plan on up-rating as much as I can without breaking the law. Minimum. However, I figure I’ll be ready for future modifications down the road, when I move out of the Republic of Kalifornia with it’s nanny-ish emissions laws.
For starters topping the wish list; I am looking at acquiring an aluminum head and possibly ported & polished and a mild street came. I might even try larger intake valves.
Next I plan on addressing the valve train. Up-rated lifters with tubular pushrods possibly installing a set of Roller Rockers. I know that the pre-manufactured sets from VB & Moss ain’t cheap, with an asking price of about $1000 for the set. But as an alternative I’ve found that there are at least two sellers on eBay that sell individual roller rockers in sets, that can be used with the standard rocker arm shaft, in with a ratio of 1.5+ for about $265 for the set. And for ~$14 more you can get them in the higher ratio of 1.625. Both would be an improvement over the stock ratio of 1.41:1.
Anyway doing some reading in Peter Burgess’ “How to Power Tune MGB 4-Cylinder Engines”. When talking on Roller Rockers - he mentions the expected stuff like – “checking the valve springs for coil bind under full lift (min 10 thou)” & “increasing the rocker (tappet) clearance by 14%”. But he also mentions – “checking to make sure that the exhaust valve will not hit the block at full lift. And that if it hasn’t already been done to cutout the bore is necessary”.
I can see checking the springs and perhaps making a change to the tappet clearance Example: 13mm (hot) to say 15mm. But I was of the understanding that I shouldn’t need to make any other modifications. Is there a problem with exhaust valve making contact with the block?
So if anybody undertaken this endeavor on the late model B engine would like to share their thoughts and findings on this I’d be very interested.
