Re: 1970 L78 CKO Block from Van Nuys
 

A 4:10 in these really amps it up too.
Found a few CON VIN's beginning with 128,but nothing exact yet.

Re: 1970 L78 CKO Block from Van Nuys
 

Rick is right on the money...a 4.10 gear with an L78/TH400 makes for a lot of fun...ask me how I know [img]<<GRAEMLIN_URL>>/rolleyes.gif[/img]

Re: 1970 L78 CKO Block from Van Nuys
 

I know. I have a day 2 70 SS 396 with prepped TH400 and oval ports with big valves and stock 2240 trw 10.25 and a solid roller cam with old school weiand xcelerator with Holley 850 carb with 4.88 gears. All of it buttoned up with stock pulleys, valve covers, clutch fan etc... I can tell you a stock LS6 has no chance. That 396 with a TH400 will haul the mail my friend and it's in L34 form. In L78 piston head combo it would even be better especially on the top end.

Re: 1970 L78 CKO Block from Van Nuys
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cranberry70SSL34</div><div class="ubbcode-body">I know. I have a day 2 70 SS 396 with prepped TH400 and oval ports with big valves and stock 2240 trw 10.25 and a solid roller cam with old school weiand xcelerator with Holley 850 carb with 4.88 gears. All of it buttoned up with stock pulleys, valve covers, clutch fan etc... I can tell you a stock LS6 has no chance. That 396 with a TH400 will haul the mail my friend and it's in L34 form. In L78 piston head combo it would even be better especially on the top end. </div></div>

Might not be a popular opinion, but I figured a similarly equipped (cam, carb, intake, compression) oval port 396 would beat a rectangle port car. In a 454, where you have more cubes to support the flow and don't need as much torque, might be the opposite.

Re: 1970 L78 CKO Block from Van Nuys
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bulletpruf</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cranberry70SSL34</div><div class="ubbcode-body">I know. I have a day 2 70 SS 396 with prepped TH400 and oval ports with big valves and stock 2240 trw 10.25 and a solid roller cam with old school weiand xcelerator with Holley 850 carb with 4.88 gears. All of it buttoned up with stock pulleys, valve covers, clutch fan etc... I can tell you a stock LS6 has no chance. That 396 with a TH400 will haul the mail my friend and it's in L34 form. In L78 piston head combo it would even be better especially on the top end. </div></div>

Might not be a popular opinion, but I figured a similarly equipped (cam, carb, intake, compression) oval port 396 would beat a rectangle port car. In a 454, where you have more cubes to support the flow and don't need as much torque, might be the opposite. </div></div>

No not really. &quot;PREPPED&quot; OEM ovals (781's/049's) WILL and DO support 800+Hp. Not an &quot;auto&quot; guy, but my L34 '69 Nova when I did it to L78 spec bottom end, small roller and mildly ported &quot;840&quot; heads with Holley strip Dom intake, 800 Holley and 4.56's would run 10.40's thru muffler, slick and M-21. Just a nifty little streetcar with OEM stuff.

Re: 1970 L78 CKO Block from Van Nuys
 

Sounds like a l78 all together with the 840 square ports. I definitely like oem stuff myself. If you put 290 oval on a l78 piston with its 101 cc chamber it jumps the compression to over 12 to 1. My piston head is exactly L34 with 10.25 with solid roller cam and auto th400 with 4.88. It works real well. The only minor drawback is the trw oem pistons were not really designed for big roller cams and don't have very big reliefs. Therefore my piston to valve clearance was really tight at the suggested 104 degree spot. I had to leave it straight up at 108 in order to gain proper clearance and was borderline then. Runs super at 108 but would be a little better in heavy car if would have been able to degree it in at 104. If I were to build a L78 I'd prob go in L89 form and try to get compression above 12 with roller cam and try to get it set up at 104 and use the same cam I have in my current engine. I know what you guys mean in order for a 396 to benefit from square ports over ovals you gotta get you gains in the 6500 to 7500 range. Not sure if it is ever all round better than the ovals considering they work so well up to 6500.

Re: 1970 L78 CKO Block from Van Nuys
 

I'm not sure if you can use the 290's with the 11 to 1 pistons...I think there would be clearance issues. The oval port heads were designed to work with the different dome design of the 10.25 to 1 motors. Perhaps some of the engine gurus can chime in [img]<<GRAEMLIN_URL>>/hmmm.gif[/img]

That aside, the oval port 290's are more than enough for a strong street/strip setup...the big square ports have the edge on the high end...but, most action takes place far below that.

wilma

Re: 1970 L78 CKO Block from Van Nuys
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: EZ Nova</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bulletpruf</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cranberry70SSL34</div><div class="ubbcode-body">I know. I have a day 2 70 SS 396 with prepped TH400 and oval ports with big valves and stock 2240 trw 10.25 and a solid roller cam with old school weiand xcelerator with Holley 850 carb with 4.88 gears. All of it buttoned up with stock pulleys, valve covers, clutch fan etc... I can tell you a stock LS6 has no chance. That 396 with a TH400 will haul the mail my friend and it's in L34 form. In L78 piston head combo it would even be better especially on the top end. </div></div>

Might not be a popular opinion, but I figured a similarly equipped (cam, carb, intake, compression) oval port 396 would beat a rectangle port car. In a 454, where you have more cubes to support the flow and don't need as much torque, might be the opposite. </div></div>

No not really. &quot;PREPPED&quot; OEM ovals (781's/049's) WILL and DO support 800+Hp. Not an &quot;auto&quot; guy, but my L34 '69 Nova when I did it to L78 spec bottom end, small roller and mildly ported &quot;840&quot; heads with Holley strip Dom intake, 800 Holley and 4.56's would run 10.40's thru muffler, slick and M-21. Just a nifty little streetcar with OEM stuff. </div></div>

Mid 10's is pretty darn impressive!

Built a pretty nice 325 hp 396 for my '66 SS -- forged flat tops, stock heads with SS valves and roller rockers, moderate hydraulic flat tappet, M21 and 4.56's (originally 3.31). Stock Holley on the stock iron intake. Had a bit too much gear, I think, but should have run pretty strong. Sold it before I got to drive it; someone made me an offer I couldn't refuse. Was an Aztec Bronze car w/bronze guts. Will have to find another one some day...

Re: 1970 L78 CKO Block from Van Nuys
 

Ya funny, people think the 396/402 stuff can't run. But it's just what we had on hand. I still have the shortblock. It's a '72 402 4 bolt standard mains and piston, TRW replacements. I just upgraded the rod bolts with ARP's. With the 660 roller, I would shift that thing right at 8000.
Now I picked up another set of '69 840's with the '69 '163 intake to go back on that shortblock. I AM putting in a nice T-400 trans but I did upgrade the rear suspension now with Smith Racecraft bars and split leafs with sliders. Strange double adjustable shock on the back as well. If the ZL-1 isn't home soon, gonna put the old tired n true 402 back together and in she goes. I sure with the '163 intake the car will run right around 11.50's with a solid cam, maybe a bit better. Not sure without the roller and some more head work if I could get that into the 10's????????????????

The ZL-1, well if it goes ONLY low 10's I would be PISSED.