Big Cubes, OD + $$$$$

[G-Body_Vet]

I'm having a slight cam & CR disagreement between the machinist and everything all of the Pontiac builders are telling me. I want to zero deck the block and run flat tops, which would put me at 9.7 to 1 CR. The machinist is recommending dished pistons and keeping the CR around 9.0-9.5.

The heads have been ported, gasket matched on intake & exhaust, SS valves, cc'd at 93. A few people have successfully ran 10.0 to 1 on 91 octane with no detonation issues in 455's. I'm trying to focus on low lift flow and a tight quench area. The Pontiac guys are calling for a cam with 112-114 LSA, machinist wants 110 LSA. I'm walking a fine line with keeping the dynamic compression in check, which is the goal. With that in mind a RA IV style cam with more lift is what I've been leaning towards (Crower 60919) and what everyone recommends.

Don't get me wrong, the machinist knows his $hit but I'm trying to go with a tried and true combo too. On the other hand, I'm not building a strip car. Everyone I talk to is making race suggestions.

 

[whiskybent]

I checked the rpo code on my 86 regal about 2 weeks ago to see what rear gear it had and i was suprised to see that it has a 2.14 gear ratio.I have an olds 455 and a th350 in it and it will haul *ss even being geared that high because of the big block torque it makes.At 70 MPH it is turning around 2k RPM on the highway but its only getting around 12 MPG.

 

[dogsht]

Kool big Pontiac power. Yep its much easier to build a 9 or10 drag car than a reliable docile 11 second real pump gas street car. Lots of people want to give you race car build recomendations as thats what they know. I would be with you on the actual10-1 flat tops & tight quench with good dynamic compression setup. And with the Pontiac guys on the 112 to 114 LCA. But you weren't here for cam recommendations anyway. And you already know your machinists is hedging his work toward safety. You should have one ground for you when you get your flow numbers.

I ran actual 10-1 static on my big Cad motor with no detonation signs at tear down inspection after 9,000 miles. Some of which were on 89 octane and never pulled timing. IMO 10.2-1 is where you start cutting the edge with pump premium and summer heat with iron heads. Plus on those humid days where you may race or sit in stop & go traffic you can always add a gallon of Xylene.

 

[dogsht]

Hauls *ss is a relative term. Your combo leaves a lot on the table at the drag strip. Also all three mpg examples were hwy not what we would get around town or a mix.

 

[G-Body_Vet]

Kool big Pontiac power. Yep its much easier to build a 9 or10 drag car than a reliable docile 11 second real pump gas street car. Lots of people want to give you race car build recomendations as thats what they know. I would be with you on the actual10-1 flat tops & tight quench with good dynamic compression setup. And with the Pontiac guys on the 112 to 114 LCA. But you weren't here for cam recommendations anyway. And you already know your machinists is hedging his work toward safety. You should have one ground for you when you get your flow numbers.

I ran actual 10-1 static on my big Cad motor with no detonation signs at tear down inspection after 9,000 miles. Some of which were on 89 octane and never pulled timing. IMO 10.2-1 is where you start cutting the edge with pump premium and summer heat with iron heads. Plus on those humid days where you may race or sit in stop & go traffic you can always add a gallon of Xylene.

We haven't gotten into a deep discussion over this yet. I told him my idea, he shared his. I'm planning to pay him a visit tomorrow or Thurs to see what else unfolds.

 

[jrm81bu]

I actually kinda miss my 2.41 gears and th350. On the highway the rpm's are close to the same as my 3.73's and 700r4. Burnouts are slightly LESS fun with the 3.73 gears. It makes for slower wheel speed vs. rpm, unless I spin them in od. The torque I made would still move the car along nicely.