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Jetting
Posted: Fri Dec 18, 2009 4:43 pm
by Bob Vehring
Hope someone is around, trying to decide what to do. Looking for thoughts on jetting, the engine is ported close to the'84 spec's. and I do not want to run the air box. I will have EGT gauges but right now there on something else.
Heres what I have;
Stock 38 PJ carbs
P 40
NJ Q0
N 6DH7
S 3.0
M 290
PJ 30 ?
I'm not familiar on how to calculate for the PJ.My roughly 85 HP SRV runs 350 Mains on 39.5 carbs 290 mains seems small to me but again IDK how to figure in what the PJ is worth. Any ideas, would like to get this thing out.
BTW IDK if that's factory spec's, or if some else jetted them that way
Posted: Mon Dec 21, 2009 9:08 am
by Vmax540
Bob, Have you read some of the Articles section loads of information there including stock and modified jetting ?
1984 Update Porting Specs
1986 Service Tuning Data
1986 Update Porting
1987 Stock VMAX Evaluation and pipe Test
As you already know EGT gauges can not be beat when jetting especially, since you have porting/no airbox.
Posted: Mon Dec 21, 2009 10:55 am
by Bob Vehring
Yes, I have read all of those. I used the ' 84 specs for my porting. Its great info. When your new to a particular engine, like I am to this one, its such a help to have that info available.
As I said in a different post, I now have EGT on the sled, just not much snow left here. I'm picky about jetting and want it close to perfect all the time. Hard to do. From what I have seen with other engines, many burndowns are related in some degree to midrange and can usually be corrected by NJ and needle. The PJ makes this different.
When I see people talking about jetting here, everyone for the most part talks about the main jet, I'm trying ti find the relationship of the PJ. I do still have the copy of the Dyno teck issue that you have, I know they disconnected the PJ for their test. If all else fails, I can copy the jetting from my SRV, I think the VM should make very close to the same HP as my SRV, But I think the PJ offers some opportunity to really fine tune the jetting. I'm hoping I can find someone who's already been down that road. Bob