Vortec street 355 max compression? Coolant bypass?
Moderator: Team
-
- Member
- Posts: 117
- Joined: Thu Apr 22, 2021 3:40 pm
- Location: Georgetown, Texas
Vortec street 355 max compression? Coolant bypass?
Has anyone built or ran a Vortec headed SBC with 10.1 compression on a hot street car? Literally, I live in the south. I am betting the chamber design is good enough to where I shouldn't have any problems but then again I do live in Texas and it gets HOT. I have some new 062's which are getting some bowl and valve work done as we speak that are going on a 355 with a SCAT rotator and we are looking at about 10:1 compression. DCR I suspect will be near 8:1 but I am not sure yet as Mike is still doing the cam. Am I being paranoid?
Also what is the best way to address the coolant bypass issue? These heads are on a 77 010 2 pc block which has the second water pump (to cylinder head) coolant bypass hole but Vortecs dont have that hole. Do I just simply drill the hole using the head gasket as a template? Or do I need to use the manifold coolant port and tie into the heater hose? It would seem like a better idea to just drill the passenger head. Right?
I have heard many different ways of doing this, including drilling the thermostat. I live in Texas so the cooling system HAS to be top notch.
Thanks!
Also what is the best way to address the coolant bypass issue? These heads are on a 77 010 2 pc block which has the second water pump (to cylinder head) coolant bypass hole but Vortecs dont have that hole. Do I just simply drill the hole using the head gasket as a template? Or do I need to use the manifold coolant port and tie into the heater hose? It would seem like a better idea to just drill the passenger head. Right?
I have heard many different ways of doing this, including drilling the thermostat. I live in Texas so the cooling system HAS to be top notch.
Thanks!
Re: Vortec street 355 max compression? Coolant bypass?
If you have the extra water ports on the intake back at the diz hook up the drivers side rear water port to the wP on top of the water pump.
10:1 cr wants 92 octane gas. .max wot spark timing 32-36 deg.. (you have to determine that by testing.
no drilling
10:1 cr wants 92 octane gas. .max wot spark timing 32-36 deg.. (you have to determine that by testing.
no drilling
-
- Member
- Posts: 117
- Joined: Thu Apr 22, 2021 3:40 pm
- Location: Georgetown, Texas
Re: Vortec street 355 max compression? Coolant bypass?
No coolant ports or even anything to drill on the back of the intake.
-
- Guru
- Posts: 1759
- Joined: Wed Aug 26, 2009 8:30 pm
- Location: Beautiful Southern Maryland
- Contact:
Re: Vortec street 355 max compression? Coolant bypass?
I cant say that anyone I know worries about the bypass at all. The guys run those heads on the dirt track here locally and they are very popular on street engines. I dont even know how its addressed in the factory applications. Maybe they let some flow through the heater core ? Or the thermostat allows some flow ? I can look at my 99 Tahoe over the weekend, it has a 5.7 Vortec in it. I am not even sure if it is an issue.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
www.enginerepairshop.com
Advanced Automotive Machine
Waldorf Md
www.enginerepairshop.com
Re: Vortec street 355 max compression? Coolant bypass?
I think you are right about the heater core. Pretty sure that's how the L31 truck engines accomplished "bypass", because the heater hose valve in those trucks allows full flow from WP to intake even when in the "off" position.BillK wrote: ↑Thu Jul 29, 2021 9:03 pm I cant say that anyone I know worries about the bypass at all. The guys run those heads on the dirt track here locally and they are very popular on street engines. I dont even know how its addressed in the factory applications. Maybe they let some flow through the heater core ? Or the thermostat allows some flow ? I can look at my 99 Tahoe over the weekend, it has a 5.7 Vortec in it. I am not even sure if it is an issue.
-
- Guru
- Posts: 1608
- Joined: Sat Dec 24, 2011 10:02 am
- Location: melfort saskatchewan Canada
Re: Vortec street 355 max compression? Coolant bypass?
i have a stock 350 vortec in an old deck truck that i use for hauling my race car. It has a chinese intake manifold and a 600 holley on it. I run a small coolant bypass hose from the front of the intake to the waterpump. Just like what is on a stock big block chevy. This motor and truck has worked hard for me for many years. Its not the engine in the picture, but the same idea.
You do not have the required permissions to view the files attached to this post.
The Word of God is quick and powerfull
www.therocketshop.blogspot.com
www.therocketshop.blogspot.com
Re: Vortec street 355 max compression? Coolant bypass?
Drill the hole in the head, problem solved
Tom
Tom
Re: Vortec street 355 max compression? Coolant bypass?
Vortec headed 355 at 10:1 with an advertised 276 intake lobe on a 106 ICL. DCR was in the low 8's. .040" quench. It took a full timing curve to 32 degrees with about 14 initial. Premium fuel was a must and with the vacuum advance adding timing at cruise it would rattle a little. Something I tuned around with a vacuum advance that was adjustable for both total amount and set point.
It doesn't get Texas hot where I used to live but it gets intense nonetheless.
As for the coolant lines, one from the water pump to the heater core and then back to the intake. No issues.
It doesn't get Texas hot where I used to live but it gets intense nonetheless.
As for the coolant lines, one from the water pump to the heater core and then back to the intake. No issues.
Kevin
Re: Vortec street 355 max compression? Coolant bypass?
You do not have the required permissions to view the files attached to this post.
-
- Guru
- Posts: 1481
- Joined: Thu Feb 07, 2008 1:32 pm
- Location:
Re: Vortec street 355 max compression? Coolant bypass?
Why only the driver's side? wouldn't it be best to tap both sides-the rear cylinders run hotter for sure.
Pro question poster.
Re: Vortec street 355 max compression? Coolant bypass?
You could if you had 2 spots on the water pump to connect both sides to..Bob Hollinshead wrote: ↑Sat Jul 31, 2021 11:59 amWhy only the driver's side? wouldn't it be best to tap both sides-the rear cylinders run hotter for sure.
On my 400 sbc with vortecs I just ran it to the drivers rear side... No drilling, no special gasket holes.
No thermostat serging on warm up nore overheating.
It seems to cool much better.
Re: Vortec street 355 max compression? Coolant bypass?
On my 400 with steam holes drilled, there were no problems with temperatures. I have a complete Vortec engine in my Impala, and the temperatures would swing wildly from 180 to 250 degrees at cruise speeds until I added a bypass from the intake to the radiator. More or less the same problem with the flat top 350 in my El Camino. Again, a bypass solved the problem. The 880 block in the Impala doesn't even have the bypass hole. The El Camino engine was already assembled or I would have drilled the hole in the heads. The bypass hole in the El Camino radiator is not much larger than 1/4" but it seems to do the job. The compression is 9.6 and it runs on regular. You might need to run premium at 10:1. The temperatures run right on the thermostat.
The orange bypass hose goes to the radiator. The heater circuit goes through the intake for carb heat in the winter.You do not have the required permissions to view the files attached to this post.
So much to do, so little time...
Re: Vortec street 355 max compression? Coolant bypass?
I've seen that swing at cruise. The "new" water pump had the wrong backing plate. A small bypass on both sides of the rear of the intake never hurts as it purges the air from the boil pocket. Unless you screw up the chambers, 28 degrees is about all a vortec head will like for timing, sometimes you can give it a couple more after peak torque.rfoll wrote: ↑Sun Aug 01, 2021 11:42 am On my 400 with steam holes drilled, there were no problems with temperatures. I have a complete Vortec engine in my Impala, and the temperatures would swing wildly from 180 to 250 degrees at cruise speeds until I added a bypass from the intake to the radiator. More or less the same problem with the flat top 350 in my El Camino. Again, a bypass solved the problem. The 880 block in the Impala doesn't even have the bypass hole. The El Camino engine was already assembled or I would have drilled the hole in the heads. The bypass hole in the El Camino radiator is not much larger than 1/4" but it seems to do the job. The compression is 9.6 and it runs on regular. You might need to run premium at 10:1. The temperatures run right on the thermostat. DSCN1423.JPG The orange bypass hose goes to the radiator. The heater circuit goes through the intake for carb heat in the winter.
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl
-Carl
-
- Guru
- Posts: 1481
- Joined: Thu Feb 07, 2008 1:32 pm
- Location:
Re: Vortec street 355 max compression? Coolant bypass?
You could T both sides together and still run one hose to the water pump?F-BIRD'88 wrote: ↑Sat Jul 31, 2021 6:48 pmYou could if you had 2 spots on the water pump to connect both sides to..Bob Hollinshead wrote: ↑Sat Jul 31, 2021 11:59 amWhy only the driver's side? wouldn't it be best to tap both sides-the rear cylinders run hotter for sure.
On my 400 sbc with vortecs I just ran it to the drivers rear side... No drilling, no special gasket holes.
No thermostat serging on warm up nore overheating.
It seems to cool much better.
Pro question poster.
Re: Vortec street 355 max compression? Coolant bypass?
yesBob Hollinshead wrote: ↑Mon Aug 02, 2021 2:43 pmYou could T both sides together and still run one hose to the water pump?F-BIRD'88 wrote: ↑Sat Jul 31, 2021 6:48 pmYou could if you had 2 spots on the water pump to connect both sides to..Bob Hollinshead wrote: ↑Sat Jul 31, 2021 11:59 am
Why only the driver's side? wouldn't it be best to tap both sides-the rear cylinders run hotter for sure.
On my 400 sbc with vortecs I just ran it to the drivers rear side... No drilling, no special gasket holes.
No thermostat serging on warm up nore overheating.
It seems to cool much better.