L31 with LT1 bottom end

[L31MaxExpress]

Yeah, the idea is to run cooler to try and avoid detonation. Pretty easy to swap out later if the datalogs look good. Not sure my cam is wild enough to compensate for the increased CR. Also, im pretty sure the heads were milled .020 to clean some damage when they were rebuild. Lost the paperwork....

Shurkey the calculation I used didn't account for the top ring height but the rest of the numbers look spot on.

I am only running a cam that specs out with the 1.7 rockers at
272/284 @ 0.06,
218/228 @ .050,
.578/.578" lift,
110 LSA and 106 ICL.

Running 170°F it runs all day on 87 at 34° total advance above 3,600.

 

[Crazydavez28]

I am only running a cam that specs out with the 1.7 rockers at
272/284 @ 0.06,
218/228 @ .050,
.578/.578" lift,
110 LSA and 106 ICL.

Running 170°F it runs all day on 87 at 34° total advance above 3,600.

Are you running the factory efi?

That cams a little bigger than the one I'm gonna use but not far off. I need to come up with some 1.6 rockers...

 

[L31MaxExpress]

Are you running the factory efi?

That cams a little bigger than the one I'm gonna use but not far off. I need to come up with some 1.6 rockers...

1 meg LS PCM from a 2005 DBC Van, 24x coil near plug and an Indmar marine intake.

 

[c1500deathtrap]

So i'm confused. Are you gonna use the lt1 water pump and ignition? or try to convert it to the gen 1 stuff? If you use the stock lt1 water pump you will have to modify heads if you use the old gen 1 stuff. Where are you going with this? Can the l31 computer be set up to run optispark?

 

[Schurkey]

I am only running a cam that specs out with the 1.7 rockers

Where did you get 1.7 rockers? I slapped some Comp Cams rollers on my build, 1.6 ratio / 7/16 stud size.

Running 170°F it runs all day on 87 at 34° total advance above 3,600.

Why so little advance? I'd expect up to 40-something at light load / high intake manifold vacuum. Do I misunderstand what you mean by "total" advance?

 

[Crazydavez28]

So i'm confused. Are you gonna use the lt1 water pump and ignition? or try to convert it to the gen 1 stuff? If you use the stock lt1 water pump you will have to modify heads if you use the old gen 1 stuff. Where are you going with this? Can the l31 computer be set up to run optispark?

Im using the rotating assembly from the LT1 in my L31 Vortec build. I will try to use the Lt1 balancer spaced out to align with stock vortec assecories.

I'm saving the leftover LT1 parts for my 94 Camaro build.

 

[L31MaxExpress]

Where did you get 1.7 rockers? I slapped some Comp Cams rollers on my build, 1.6 ratio / 7/16 stud size.


Why so little advance? I'd expect up to 40-something at light load / high intake manifold vacuum. Do I misunderstand what you mean by "total" advance?

The 1.7s are Scropion 7/16" stud non self aligning since I have guideplates and hardened pushrods.

I am talking about 34* at WOT. At cruise I run up to 48-52* @ 3,000 rpm and 40-50 kpa. Thats about where it runs at 70 mph in overdrive. Lean cruise at 16:1 air/fuel ratio. Nets about 18-19 mpg.

 

[Schurkey]

The 1.7s are Scropion 7/16" stud non self aligning since I have guideplates and hardened pushrods.

OK, thanks.

I am talking about 34* at WOT. At cruise I run up to 48-52* @ 3,000 rpm and 40-50 kpa. Thats about where it runs at 70 mph in overdrive. Lean cruise at 16:1 air/fuel ratio. Nets about 18-19 mpg.

Yup, that makes a lot more sense.

 

[Crazydavez28]

Bringing this back to life. I got the short block assembled and I installed the cam at 116 intake centerline. Comp Cams XM264HR 08-416-8

I degreed it out and Intake closing is 69 ABDC. I am calculating a 7.94 Dymanic CR. Using Aluminum Vortec style heads, is this too much for daily driving with 87 octane?

 

[L31MaxExpress]

Bringing this back to life. I got the short block assembled and I installed the cam at 116 intake centerline. Comp Cams XM264HR 08-416-8

I degreed it out and Intake closing is 69 ABDC. I am calculating a 7.94 Dymanic CR. Using Aluminum Vortec style heads, is this too much for daily driving with 87 octane?

It is honestly too low IMO. I was able to run an 11:1 383 with 6" rods and a cam that was 198/208 @ 0.050 on a 110 LSA and 106 ICL when the Rhoads lifters were at low rpm on 87 octane. The cam was 218/228. Rhoads lifters chop 20° off it at low RPM.

My suggestion is you degree it in as Comp suggests. I did not run the numbers but given Comps normal method it would be 4° advanced from the LSA. 108 ICL. Put the ICLA back at 62° like the cam card shows. Actually the marine cams may only be 2° advance. Comps website is a joke compared to the full specs they once had.