Large Vortec bowtie, Engine?

General engine tech -- Drag Racing to Circle Track

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F-BIRD'88
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Re: Large Vortec bowtie, Engine?

Post by F-BIRD'88 » Sun Sep 16, 2018 2:24 pm

Are you sure that the seeming soft pull off the corners is not really a traction problem? Chassis setup gearing.....

bigfoot584
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Re: Large Vortec bowtie, Engine?

Post by bigfoot584 » Sun Sep 16, 2018 2:56 pm

Curious going thru all the posts, I may have missed it sorry, if I did
but I didn't see anything on his LSA, that would have an effect on
the engines performance, if it's out of the ballpark from where
it should ???

88bluestar
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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Mon Sep 17, 2018 1:10 am

COMP CAMS grind #CS 6262/6263 S 108.0 PART # 12-000-47 4/7 SWAP

.020 DURATION 281 285
VALVE TIMING OPEN CLOSE
.050 INT 22 BTDC 50 ABDC
EXH 60 BBDC 16 ATDC
DURATION @ .050 252 INT 256 EXH
LOBE LIFT .361 .367 LOBE SEPERATION 108.0 (SPECS ARE 104.0 INTAKE CENTERLINE) 1.5 roller rockers

36 degrees timing, 4000 ft above sea level, 780 holley mech secondary DP built by Sean Murphy Induction. primary is 74, secondary is 82 jets with 91 pump gas. 9.5:1 comp, 355 cid

7000 max rpm rule/ currently running a 7.00 gear final. rear stays hooked up, no tire spin

F-BIRD'88
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Re: Large Vortec bowtie, Engine?

Post by F-BIRD'88 » Mon Sep 17, 2018 12:16 pm

Move the cam to a 100 deg in c/l.
Then,try reducing the gear ratio a bit.

F-BIRD'88
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Re: Large Vortec bowtie, Engine?

Post by F-BIRD'88 » Mon Sep 17, 2018 12:23 pm

Being at 4000 ft , I'd bet that the front runners are running (a lot ) more than 9.5:1 CR.

rustbucket79
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Re: Large Vortec bowtie, Engine?

Post by rustbucket79 » Mon Sep 17, 2018 9:28 pm

So are you planning to change the heads or work around what you have?

How do they enforce the rules? Do they even bother?

rocketracer380
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Re: Large Vortec bowtie, Engine?

Post by rocketracer380 » Mon Sep 17, 2018 11:32 pm

i would be interested in buying if they are 225

88bluestar
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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Tue Sep 18, 2018 2:08 am

Sometime early november is when I'm done racing this year. Plan to pull them off, clean and cced to know for sure what I have. F-BIRD88, the max is around 9.8 without being illegal, and I had wanted to run a thinner head gasket but what little cash I have is to go racing on the weekend so Im waiting off tearing into it until the season concludes. Rocketracer380 I will touch base with you once I'm done, see if you're still interested at that time, and if they are what you are looking for.

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Re: Large Vortec bowtie, Engine?

Post by 6.50camaro » Tue Sep 18, 2018 6:07 am

How do they check CR? Dan

rocketracer380
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Re: Large Vortec bowtie, Engine?

Post by rocketracer380 » Tue Sep 18, 2018 9:01 am

ok kool let me know

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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Tue Sep 18, 2018 11:56 am

6.50camaro wrote:
Tue Sep 18, 2018 6:07 am
How do they check CR? Dan
katech device for checking compression ratio.
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6.50camaro
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Re: Large Vortec bowtie, Engine?

Post by 6.50camaro » Wed Sep 19, 2018 8:02 am

Have you had your motor checked to see what the CR is with the whistler . You are giving up 5 cu.in. on engine size how much compression are you giving up. Top runners push the rules to the limit most of the time .
PS . Your cam is better suited for 11.0 to 1 CR than 9.5 and the intake runner csa is not helping you. IHMO Dan

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Re: Large Vortec bowtie, Engine?

Post by 88bluestar » Wed Sep 19, 2018 10:07 am

Wish I could run a different cam but don't really have sponsorship to do it right now. I know what you mean about rules,.....The winners always take full advantage of the gray areas but right now lack of money us hurting me. Hoping to get help in the offseason to make drastic changes.

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Re: Large Vortec bowtie, Engine?

Post by 6.50camaro » Wed Sep 19, 2018 10:46 am

I totally understand money issues. My racing has always been funded by overtime pay and buying and reselling parts .
You can start by running a little more lash on the intake ,try .005 more . If it responds positively try advancing the cam to 100° icl w/ normal lash like I think F-bird mentioned.
Then try more lash agan with the cam advanced. This will help zero in on IC position to give you better dynamic CR and better pull off the corner. It only will cost time and a few gaskets. If you can do these things before the off season it will help you know where to focuus your energies .Good Luck Dan
Don't forget to check intake PV clearance advancing the came.

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Re: Large Vortec bowtie, Engine?

Post by Tuner » Wed Sep 19, 2018 11:12 am

Anyone who has actually run these heads has no comment about the OP saying he used 36 degrees spark advance with this head which GM identifies as "Fast Burn" and advises 28 ~ 32 in the instructions they supply with the part?

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