351C Timing

Ok, now I understand what you mean about Pence's preferences. But even Rock said to keep the DCR at 8 or lower too.  One thing you have to remember when looking at DCRs from engines like the BOSS 351 and the other high compression engines from this era is they used higher octane fuels then that we don't have readily available today.  I liked Rock' recommendation of keeping DCR at 7.7-7.8 and from his math above the 69* IVC doesn't seem to do it.

I sent you a Google Drop Box download.  Not sure if you got it or it worked?  It might help you with the cam selection.

Now I know where the slight differences in pressure are! I've been using 300 ft. I'm at 450 but surrounding areas dip to 300. Weird going in because I just pulled the altitude out my head for consistent numbers.

I've made two phone calls this week and had rambling conversations with with a guy at Howard's. That cam at 112* LSA gets me to 71 IVC. My only concern there is the .611 lift on the exhaust side without the lifter bore sleeves.

a couple hydraulic rollers from George's cook book

69.5* IVC hyd-roller

https://pantera.infopop.cc/topic/looking-for-a-hyd-roller-street-cam

70* IVC hyd-roller

In the dyno2000 program I took the flat tappet Boss351 Cam and flipped the same specs to a roller cam. That alone netted a 45 Hp / 36 TQ increase. I assume it's just in the projected cam lob profiles. ? 

I did that with the Boss351 cam. Now I'm experimenting......

factor in chain stretch and i think you'll get that 3* you're looking for fairly quickly. me personally i'd target at least that 72* IVC figure i came up with, it'd be a pisser to go through it all and still be on the edge

How does it look if you retard the Howard's cam 6 degrees so it runs 2 degrees retarded?

This timing set allows for +- 8 degrees at 2 degree increments:

Can you post pics of the power curves?

I had re read your post. I'm likely going to just swap the camshaft but I'm having a lot of fun with the program.

I retarded the cam 8* (in the program!). 

It flipped the cycles on the intake and exhaust. Likely more than obvious to someone who's studied camshafts. If I understand what I'm reading it would likely cause exhaust reversion. The intake closes at 68.3 but the exhaust is closing at 64.3. Most are closing in the mid to late 70's.

It does mathematically look better in the program. 

As it sits   392HP @ 5500 / 426TQ at 4000

8* retard  407HP @ 6000 / 411TQ at 4000 and 4500  

   

The retarding helps but it seems not enough.  From the DCR calculator at 300' it shows:

Interesting seeing the power curves don't change that much between the cams.  What I actually wanted you to try was retarding the Howard's 230245-12 6 degrees instead of 3 degrees as you indicated above.  I think that might get your DCR to a safer range and not affect the power curve too much.  Runinng the Howard's 230245-12 at 3 degrees retarded seem to get the DCR close, so I thought 6 degrees might be right on the money.

Maybe Rock will have a better idea.