Vortec CT350 crate in a street car.

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F-BIRD'88
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Re: Vortec CT350 crate in a street car.

Post by F-BIRD'88 »

I am finding some others have measured the gmpp blue LS6 springs and stated coil bind at 1.190".
The gm listed spec then may be a typo. 1.185" not 1.085"
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Re: Vortec CT350 crate in a street car.

Post by rfoll »

The advertised spec for the CT350 show a static compression of 9.1. That is the advertised compression of a stock Vortec engine, making me think the engine is essentially an L31 with a nice cam. It's likely it already has a .028" head gasket making a steel shim replacement a very small improvement. A 1.6 rocker om the intake might be an easy improvement. Alex’s spring kit for Vortec heads will allow more room for lift at an affordable price.
So much to do, so little time...
ClassicRob
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Re: Vortec CT350 crate in a street car.

Post by ClassicRob »

Next question... Carburetor. Cant use any of the Quadrajets I have.

Brawler is supposed to be cheaper good stuff but I am hesitant. I don't like unknowns. Im thinking 4150 650cfm
https://www.holley.com/products/fuel_sy ... s/0-4777CE

What I really want know is, who is running without a choke? I have had a few cars that had chokes but didnt work and in Texas its not all that much of pain to start em. Would you run the above or go chokeless?
ClassicRob
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Re: Vortec CT350 crate in a street car.

Post by ClassicRob »

rfoll wrote: Wed Jun 30, 2021 5:21 pm The advertised spec for the CT350 show a static compression of 9.1. That is the advertised compression of a stock Vortec engine, making me think the engine is essentially an L31 with a nice cam. It's likely it already has a .028" head gasket making a steel shim replacement a very small improvement. A 1.6 rocker om the intake might be an easy improvement. Alex’s spring kit for Vortec heads will allow more room for lift at an affordable price.
I bought Alexs spring package for hyd. flat tappet. I am somewhat regretting it because I could have done a roller cam but as long as it breaks in with no issue I wont have any regrets.

CamKing is right on the money I think. I like those specs and they are very close to the Comp XE274-10 I also like.

Plan is to pull the heads and find someone to do some pocket porting/clean-up and VJ so I can get some more CFM out of them. I will also mill them to get the compression up. I am wanting 9.8-10.1.
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Re: Vortec CT350 crate in a street car.

Post by ClassicRob »

dynoflo
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Re: Vortec CT350 crate in a street car.

Post by dynoflo »

do not mill the heads. They are thin to begin with. Surf around and you will see how many are cracked. You cannot polish a turd too much. Just be happy with 400 tq and hp. Do not get some yoyo to port them because the intake is pretty good anyway. The exhaust is a little weak but 3 to 6 more exhaust duration helps.
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Re: Vortec CT350 crate in a street car.

Post by ClassicRob »

dynoflo wrote: Wed Jun 30, 2021 8:57 pm do not mill the heads. They are thin to begin with. Surf around and you will see how many are cracked. You cannot polish a turd too much. Just be happy with 400 tq and hp. Do not get some yoyo to port them because the intake is pretty good anyway. The exhaust is a little weak but 3 to 6 more exhaust duration helps.
I was sure you could mill them some and then use a .015" head gasket? I was going to enlist Speier to do some clean up work etc. Nothing major. Might as well since I am going to pull them off anyway.
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Re: Vortec CT350 crate in a street car.

Post by F-BIRD'88 »

Put a 750 hp style holley on it not a 650...
You're all over the map now.
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Re: Vortec CT350 crate in a street car.

Post by ClassicRob »

All over the map? I'm freaking spot on. Using the efficiency calculations/RPM/CID etc, even at 100% its 628cfm. About the only thing I think a 750 would be good for is growing. It might be better at 5500-6400 but I think drivability would benefit a 650. You dont agree?
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Re: Vortec CT350 crate in a street car.

Post by F-BIRD'88 »

No... and your method is wrong..
It will make more power, go faster and drive just as well or better with a 750.

Again, you can lead a horse to water but cannot make him drink.
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Re: Vortec CT350 crate in a street car.

Post by skinny z »

ClassicRob wrote: Sat Jun 26, 2021 9:31 pm If someone gave you a smoking deal on a new CT350 crate, what would you do to it to make it run better? This is going in a 2nd gen Camaro with a 4 speed and 3.73's.

I would love to eclipse the 400-425hp mark with a 4150. How much cam? I am simply wanting to optimize the little 350 for street usage so you can forget any rule book.

FWIW.
Speedway Motors dynos the CT350 at 350HP/390TQ.

That engine isn't too dissimilar from the 350 Vortec I put together about 20 years ago. (I think I may have even raced F-bird with it at one time).

Out of the box Vortecs on a 9.8:1 short block. (based on a 64cc chamber)
224/230 @ .050 hydraulic roller, .540" with 1.6 rockers. (Comp XR276HR)
Mid length headers and a terrible single 3"exhaust (one Flowmaster muffler).
670 vacuum secondary Holley.

It pushed a 3700 lb (race weight) 3rd Camaro to consistent 106-107 trap speeds. HP would be close to your target I would think.
The only changes of note to the heads was a Comp 26918 beehive spring upgrade and .050" offset keepers. No machining.

Car notes: 700R4 with 10" converter, 3.73 rear gear. 26" DOT slicks. No trick suspension or other gizmos. Shifted at 6000+/-.
20+ U.S. MPG highway (24 Imp MPG).
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Re: Vortec CT350 crate in a street car.

Post by ClassicRob »

skinny z wrote: Thu Jul 01, 2021 12:36 pm
ClassicRob wrote: Sat Jun 26, 2021 9:31 pm If someone gave you a smoking deal on a new CT350 crate, what would you do to it to make it run better? This is going in a 2nd gen Camaro with a 4 speed and 3.73's.

I would love to eclipse the 400-425hp mark with a 4150. How much cam? I am simply wanting to optimize the little 350 for street usage so you can forget any rule book.

FWIW.
Speedway Motors dynos the CT350 at 350HP/390TQ.

That engine isn't too dissimilar from the 350 Vortec I put together about 20 years ago. (I think I may have even raced F-bird with it at one time).

Out of the box Vortecs on a 9.8:1 short block. (based on a 64cc chamber)
224/230 @ .050 hydraulic roller, .540" with 1.6 rockers. (Comp XR276HR)
Mid length headers and a terrible single 3"exhaust (one Flowmaster muffler).
670 vacuum secondary Holley.

It pushed a 3700 lb (race weight) 3rd Camaro to consistent 106-107 trap speeds. HP would be close to your target I would think.
The only changes of note to the heads was a Comp 26918 beehive spring upgrade and .050" offset keepers. No machining.

Car notes: 700R4 with 10" converter, 3.73 rear gear. 26" DOT slicks. No trick suspension or other gizmos. Shifted at 6000+/-.
20+ U.S. MPG highway (24 Imp MPG).
I have had many third gen Camaros. Sounds like a fun car. Basically you had more compression and a roller, but a power thirsty transmission and more restrictive exhaust. I could never bring myself to get rid of the TPI on my thirdgens. It just looked too cool and drove nice.
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Re: Vortec CT350 crate in a street car.

Post by F-BIRD'88 »

The Isky 201278 hyd cam in a very plain jane flat top 350 with out of the box 062 vortecs stock rockers etc.
Dynoed at 410 hp. That motor had the low rise performer vortec intake not the more powerfull RPM hi rise intake.
It also ended up in a bratty 3 rd gen Camaro.
Th350-3500 stall 4.10's It went like a bat outa hell, Customer loved it.. Was beatin up on much more $$$ cars on the street. ha ha..
With The better RPM intake I estimate 420+ hp.

The Isky solid Z/27 cam will make even more power
Its a very good street cam for this motor .
The Isky stuff works .. Trying to give you that....
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Re: Vortec CT350 crate in a street car.

Post by ClassicRob »

F-BIRD'88 wrote: Thu Jul 01, 2021 1:12 pm The Isky 201278 hyd cam in a very plain jane flat top 350 with out of the box 062 vortecs stock rockers etc.
Dynoed at 410 hp. That motor had the low rise performer vortec intake not the more powerfull RPM hi rise intake.
It also ended up in a bratty 3 rd gen Camaro.
Th350-3500 stall 4.10's It went like a bat outa hell, Customer loved it.. Was beatin up on much more $$$ cars on the street. ha ha..
With The better RPM intake I estimate 420+ hp.

The Isky solid Z/27 cam will make even more power
Its a very good street cam for this motor .
The Isky stuff works .. Trying to give you that....
Im concerned about power brakes and that cam. Here in Texas, we have a problem with a huge influx of migrants going on and theres a bunch of NO DRIVING IDIOTS everywhere!! My car has to stop. Its also gotta turn. Im buying the expensive calipers from PTFB to use with 15" wheels and I already have a bunch of their chassis stuff. The GT suspension kit and Konis are next.
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Re: Vortec CT350 crate in a street car.

Post by F-BIRD'88 »

Both these cams work fine in cars with power brakes.
The diz has to be recurved.. If you are worried put the GM auxillary electric vacuum pump from the 80's gm V6 fwd cars on it. (junk yard sourced)
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