I need help in determining my dcr. 3.75 stroke crank, 350 .060, flat tappet solid cam 251-259 @50 and 284-292 dur 544-547 lift, 108 LSA installed with 6 degrees advance, valve lash is .016 in and .018 exh the timing is checked at .020, 6" rods and 5cc valve relief flat tops 11:1 forged pistons, brodix track 1 alum heads milled down to 63cc, .039" x 4.10" head gasket. Any other info needed, just let me know. And Thanks

 

Anyone?

 

Do you have a piston deck clearence value?
Stock is generally accepted at .025"+/- below deck.
Based on those specs you come in at 10.73 SCR and 7.93 SCR.

 

I don't know the deck height and not on any of my paper work. Are these good numbers for a race engine and can I use pump gas with these numbers? Also, Thanks alot Skinny Z.

 

It depends.
First of all what's your definition of a race engine?
I run similar DCR values in a daily driven iron headed small block and have no trouble using 94 or 93 octane pump gas. I would think that in a drag race engine, where you have greater control over operating temperatures, you could run even higher DCR's.
That being said, if your deck height is changed from stock, ( for EXAMPLE .005" instead of .025") your DCR could be as high as 8.3 with the static ratio at 11.25.
From what I've read once you get beyond 8.5 DCR you start to get into racing fuel territory.
Others may argue however that's my personal experience.

 

Shinny Z, I just remembered that my cam is set with 6 degrees retard and not 4 degrees. Does this make a difference with my DCR assuming that the deck height is stock?

 

Absolutely. In fact it decreases the DCR which may hurt the performance depending on the application.
Here's a link to an excellent article on SCR and DCR.

http://www.empirenet.com/pkelley2/DynamicCR.html

 

Sorry for the typo, but it is installed with 6 degrees advance and not retard. What does this do to my DCR and what will the dcr be around with that info?

Thanks again Skinny Z.

 

OK. Let's reinterate.
3.75 stroke crank,
350 .060,
284-292 dur
544-547 lift,
108 LSA
installed with 6 degrees ADVANCE
5cc valve relief flat tops
heads milled down to 63cc,
.039" x 4.10" head gasket.
SCR 10.7:1
DCR 8.6:1
Now you're getting somewhere.
Those are workable numbers for a street engine providing you can keep operating temperatures under control. Maybe too much advance and too little quench for optimum however that may be splitting hairs.