dombanks

Hi all, i have recently fitted an st170 blacktop engine to my kit car. its running jenvey throttle bodies controlled by an omex 600 and im running the vvt using a motorsport electronics controller.

The head was ported and skimmed. i was under the impression that the skim was simply to make sure the head was flat but after it was done i found out the compression was increased from 10.2 to 11:1. apparently this is quite a big skim and the engine tuner was unhappy with the tension on the cam belt. The guy who did the porting off handedly said i would need oversize tension pullies and idlers to account for the change in dimensions.

has anyone heared of this or know where to buy these oversize pulleys?

i also seem to be having issues with oil pressure in that when running i dont get more than 30PSI at best

bombero

There should be enough range in the existing tensioner to easily compensate for the amount that has been skimmed off the head! Other option is to simply use a smaller (shorter) belt. You're only talking about the cam belt, aren't you?

Unsure as why you're not getting the oil pressure .. did you do anything to the oil pump? Did you shorten your pick-up pipe and is that free from obstructions?

dombanks

are you bombero from the westy lot?

alot was taken from the head. 1.3mm infact so in effect that would be ~2.6mm to the belt. the garage couldnt find a suitable smaller one. Ive sourced a new tensioner now from the US just waiting for it to clear customs.

oil pressure is an odd one. more investigation is needed. the head is back off the engine and away to the head guy again so while its off i will investigate. in no particular order

1. ill look at the main bearings but basically they are getting replaced
2. ill check ive not cracked the pick up pipe as it needed just a fine bend to fit
3. as aim using a shortened sump from scholar who also did something to the pickup it ought to not be fouling anywhere but this was desgned for a silvertop not a blacktop so a little bit of a fettle may be needed.
4. didnt do anthing to the pump....may just replace it anyway.

bombero

Yes, one in the same!

1.3mm .. that's a LOT!!!! Are you not getting any valve/piston contact??

1. If you haven't touched the bottom end before, new main bearings would be a good move.
2&3. If the sump and pipe are from Scholar, then there shouldn't be any problems. Are they new or secondhand? Didn't think that Scholar were still doing these?
4. Most replace the pump as a matter of course.