Decisions!

[GMCBurb99]

The 0.560 is actual 0.527 with a 1.5 rocker and 0.562 with a 1.6.

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.lingenfelter.com/PDFdownloads/L210035087.pdf&ved=2ahUKEwjFsPWWxpCDAxUBHEQIHVcaA_cQFnoECA0QAQ&usg=AOvVaw3LoY5-zVwtDmAKkt_bRNVy

I would use a 9-1157 Cloyes and set it in 4* advanced. Lingenfelter cams are ground straight up, no cam advance.

The Lingenfelter cams are on a steel core, rather than a cast core as well. No special distributor gear needed, just the old melanized Vortec gear.

L31MaxExpress thanks for the info.
I’ve had some guys telling me those heads and cam might be too much for the weight of my Suburban. It does have a built 4l60e to handle basically any hp/tq i throw at it, but has a 3:42, but I figured with a good stall it should compensate for that, but I could be totally wrong on all of this. I had a local racing engine builder tell me that this combo should do well, but the 68cc combustion chambers might not work as well as if it were 64cc with the 200cc runners. I’ve just been all over the place with this thing trying to figure out the right setup. The weight and the factory fuel injection is what’s giving me problems in trying to determine what is going to be right for this thing. The thing I built was a 78 El Camino SS with a carbed 355, back in 2004 before I had an accident that left me paralyzed for over a year. My spinal cord and brain injury gets the best of me when trying to figure this stuff out anymore.lol

 

[GMCBurb99]

L31MaxExpress thanks for the info.
I’ve had some guys telling me those heads and cam might be too much for the weight of my Suburban. It does have a built 4l60e to handle basically any hp/tq i throw at it, but has a 3:42, but I figured with a good stall it should compensate for that, but I could be totally wrong on all of this. I had a local racing engine builder tell me that this combo should do well, but the 68cc combustion chambers might not work as well as if it were 64cc with the 200cc runners. I’ve just been all over the place with this thing trying to figure out the right setup. The weight and the factory fuel injection is what’s giving me problems in trying to determine what is going to be right for this thing. The last thing I built was a 78 El Camino SS with a carbed 355, back in 2004 before I had an accident that left me paralyzed for over a year. My spinal cord and brain injury gets the best of me when trying to figure this stuff out anymore.lol

 

[Komet]

AUS injection has a 30lb MPFI spider that I’m looking into if I decide on this setup.

Personally I would estimate that's the appropriate size for this application in a gasoline-only setup. My stock Vortec 350 hits about 85% DC on 24lb injectors at WOT, I figured your build here is one step up from that. The idea is to get the smallest injector you can that won't put you above 90% DC WOT so you have better minimum pulse control. If E85 is on the table, as L31MaxExpress said you'll definitely be wanting the 36s or 48s.

 

[L31MaxExpress]

Personally I would estimate that's the appropriate size for this application in a gasoline-only setup. My stock Vortec 350 hits about 85% DC on 24lb injectors at WOT, I figured your build here is one step up from that. The idea is to get the smallest injector you can that won't put you above 90% DC WOT so you have better minimum pulse control. If E85 is on the table, as L31MaxExpress said you'll definitely be wanting the 36s or 48s.

My Vortec 350 ran about 65-70% duty cycle to get 12.6:1 AFR with headers and the 6395 marine cam using stock MPFI upgrade injectors at 70 psi, 24.6 lb/hr of flow. If you are at 85% to fuel a stock engine it is either very rich or your fuel pressure is dropping off. The stock MPFI upgrade setup is 22.1 lb/hr. At a 0.450 BSFC, 85% is 333 hp worth of fuel. I personally like larger injectors running sequential to smaller units. With the larger units you do not need as much injector on time to spray the fuel. That means you can delay the injector spray until after the exhaust valve is closed or mostly closed for more of the engines operation. Waiting to spray the fuel until after the overlap period greatly reduces the unburned fuel entering the exhaust and thus wasted fuel. I have seen as much as a 25% shift in fuel trims at idle and up to ~2,500 rpm adjusting the injection timing to prevent raw fuel from being sucked into the exhaust during overlap. It is nice to have a big cam and yet not have the exhaust stink of unburned fuel. Minimum pulse is far less than the engine will idle at, even with a 48 lb/hr spider. Minimum pulse is around 0.850 msec where it will idle around ( EDIT ~4.2 msec)

 

[L31MaxExpress]

Actually hold that tought on idle being ~2 msec. I was thinking duty cycle. My idle is around 4 msec with the Ford 6.2L 41# injectors currently running my 383. That is like 5x the minimum pulse of those Ford injectors.

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[Hipster]

but the 68cc combustion chambers might not work as well as if it were 64cc with the 200cc runners.

I normally have a head milled .030 and go with .028 gaskets which will give a small amount of CR back over doing nothing and SR type gaskets @.041-.045 Most engines CR's measure out at significantly less than the advertised numbers. Small things can make a difference. 9.6 adv might measure out 9.3-4 add larger 68 cc chamber and .041 HG you might be lucky to get 9.2cr. I normally have a 3 angle w/bowl cut I can blend DIY and without question toss the springs and get them from the same manufacture as the cam for the spec'd cam.