Timing vs Turbo Spool

You said you used the timing pin??


But yes, as long as you figured in dwell time at TDC, and calculated the TRUE TDC, then you would be correct!

Chris
 
Well no dwell time was calculated, could that throw the cam off enough to make it run different?
 
probably not that bad, but it could definately have injection timing off... the piston stays at TDC for multiple degrees of crank rotation.

I would be concerned that the cam isn't indexed properly :eek:
 
I'm curious about that. How could it not be indexed properly if the gear is held in position with a key? I know mine was degreed using an offset key, but most cams get installed with the stock key, which is not offset. Machining error?
 
PRattenbury said:
I'm curious about that. How could it not be indexed properly if the gear is held in position with a key? I know mine was degreed using an offset key, but most cams get installed with the stock key, which is not offset. Machining error?
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I know more than one person who verifies LCA on every cam they install due to getting an improperly machined cam once and chasing their tail on them forever :eek:
 
Thanks for all the advise, I think I'll start by re-doing the timing.

Just for instance does a typical SPS62 begin to spool?

Also, is there a difference between the 12 and 24 valve Helix II? I was under the impression they are the same cam?
 
on my 98 12v with ported head, stock cam, 215 pump, and DDP4's, I would see 40-50psi around 2000rpm in 6th gear
 
schaef_12 said:
That's the main thing it's lacking, it doesn't hit hard. But so many things changed at once that its hard to pinpoint to what it is. Its very smokey on the bottom end and very clean on the top. Once it hits around 30 psi it just levels out and quits pulling. Before it would keep pulling, but I have never had any experience with an aftermarket cam or ported head so it may be normal. More smooth. Guess I'll add more fuel :rockwoot:
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You might want to slide the plate for more top end fuel, but I would take some away on the bottom end. Tune in the afc. It doesn't take much time and if you don't like it put it back where you had it.
 
IMHO the 2-3 degrees the timing pin may be off (at max in most cases unless carelessness or an acident has caused it to be bent by the cam gear) isn't going to gain or subtract 15+psi of boost. Not really sure what you had before but just saying. I've never done a cam install on one of these motors but have seen some pretty significant f'ing up on part of the cam grinder in some gas motor apps. If you can degree the cam against what the specs are supposed to be maybe you could do that and save yourself from having to remove it. Good luck!
 
I'm thinking you pulled injection timing if its more smokey on a startup than you remember. I'd check it again.
On the same fuel, no reason why it shouldn't pull as hard as before, BUT I could see it being a bit smoother with less restriction, and less of a hit.
 
Did you change head gasket thickness? If so and you went from stock to .020 over you will get more of a haze from the lower compression. Also I've seen several heads that were rebuilt and the valve stems seals were leaking.
 
I had a pdr cam years ago with similar issues. It spooled slow and the exhaust was very lazy coming out the pipe. It would hit like a 2 stroke at 2300 and pull hard as hell to 4200. I changed the cam and problem solved.
 
Bponci said:
I had a pdr cam years ago with similar issues. It spooled slow and the exhaust was very lazy coming out the pipe. It would hit like a 2 stroke at 2300 and pull hard as hell to 4200. I changed the cam and problem solved.
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I had one of those too, changed the grind and fixed it all.

Jim
 
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