350 stock heads verses vortec
12-18-2003, 05:55 PM
#21
Registered
Join Date: Jul 2001
Location: SW Ohio
Posts: 770
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by 220BR
Huh?
Huh?
BH
12-19-2003, 08:10 AM
#22
Registered
Join Date: Mar 2002
Location: Irish Hills, Michigan
Posts: 108
Likes: 0
Received 0 Likes
on
0 Posts
I offed my holley for a BG demon late last season... world of difference in component quality and out of box performance... the initial cost is a bit steeper but the BG comes with all the bells and whistles that you'd spend another 50-100 bucks on adding to the holley. I'm a satisfied customer and their customer service and support are pretty good too.
i also run an rpm airgap... she runs pretty well but takes a while to build some temp in the runners so it helps to have a choke in the carb (which i don't)... makes things a bit cold blooded. performance is going to suffer ever so slightly until you begin to build some runner velocity... generally 3000 rpm or so... i've considered swapping to a single plane for some more WOT punch but from what i've seen on and off the dyno... there isn't a whole lot of variance between the RPM and a single plane under 6000 rpm... 10 hp at most on similar motors to mine...
if you are gonna do intake, carb and heads don't choke her off by neglecting the valvetrain... you'll regret the extra few hundred bucks in the long run... (ask me how i know this
) stock merc exhaust is adequate (although HEAVY) into the 350 or so hp range...
i also run an rpm airgap... she runs pretty well but takes a while to build some temp in the runners so it helps to have a choke in the carb (which i don't)... makes things a bit cold blooded. performance is going to suffer ever so slightly until you begin to build some runner velocity... generally 3000 rpm or so... i've considered swapping to a single plane for some more WOT punch but from what i've seen on and off the dyno... there isn't a whole lot of variance between the RPM and a single plane under 6000 rpm... 10 hp at most on similar motors to mine...
if you are gonna do intake, carb and heads don't choke her off by neglecting the valvetrain... you'll regret the extra few hundred bucks in the long run... (ask me how i know this
) stock merc exhaust is adequate (although HEAVY) into the 350 or so hp range...
12-19-2003, 09:51 AM
#24
Registered
Join Date: Oct 2000
Location: Spicewood, Texas USA
Posts: 1,382
Likes: 0
Received 3 Likes
on
2 Posts
Volvo uses an aluminum 4 bbl intake with a brass water jacket on their carbed Vortec 5.7 engines. Even the 2bbl version. They use an adapter to put the 2bbl carb on it. This intake looks just like an Edelbrock Performer. It has the carb mounting that will take a spread bore or square bore carb. I have one I'll sell for $150 plus shipping if anyone wants it.
Bob
Bob
12-19-2003, 10:10 AM
#25
Originally posted by bobl
Volvo uses an aluminum 4 bbl intake with a brass water jacket on their carbed Vortec 5.7 engines. Even the 2bbl version. They use an adapter to put the 2bbl carb on it. This intake looks just like an Edelbrock Performer. It has the carb mounting that will take a spread bore or square bore carb. I have one I'll sell for $150 plus shipping if anyone wants it.
Bob
Volvo uses an aluminum 4 bbl intake with a brass water jacket on their carbed Vortec 5.7 engines. Even the 2bbl version. They use an adapter to put the 2bbl carb on it. This intake looks just like an Edelbrock Performer. It has the carb mounting that will take a spread bore or square bore carb. I have one I'll sell for $150 plus shipping if anyone wants it.
Bob
12-19-2003, 11:55 AM
#26
Guest
Posts: n/a
You might be interested in the spec sheet for this engine Chevy 350 HO Vortec 330 HP . It's a standard 350 block that uses the 8060 Vortec heads, a flat hydraulic cam that Dennis Moore recommends in his book and what I believe are the stock Merc flat top pistons (the ones you should have). You can look up the parts in the GMPP catalog. The pistons look like the ones in my '92 Merc. 5.7L.
The only thing that confuses me is how they get 9.1:1 with 64cc heads, flat top pistons (-3 to -7cc) and a decent quench (40 to 45 mils). I think that puts you into the tens. Maybe someone can cure my confusion.
The only thing that confuses me is how they get 9.1:1 with 64cc heads, flat top pistons (-3 to -7cc) and a decent quench (40 to 45 mils). I think that puts you into the tens. Maybe someone can cure my confusion.
12-19-2003, 12:06 PM
#27
Here are the specs on the cam in that engine, any good??? I am not really a camhead!!!!
24502476 Hydraulic Flat Tappet
This hydraulic flat tappet is used on the 350-300 and 330 HP special performance engine P/N 12355345, and 12486014. The duration at lash point in degrees (intake/exhaust) is 320/324; duration at .050" tappet lift (intake/exhaust) is 212/222 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 435/460. Valve lash is zero/zero and lobe centerline is 112.5 degrees.
24502476 Hydraulic Flat Tappet
This hydraulic flat tappet is used on the 350-300 and 330 HP special performance engine P/N 12355345, and 12486014. The duration at lash point in degrees (intake/exhaust) is 320/324; duration at .050" tappet lift (intake/exhaust) is 212/222 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 435/460. Valve lash is zero/zero and lobe centerline is 112.5 degrees.
12-19-2003, 12:10 PM
#28
Guest
Posts: n/a
It's defnitely stronger than Merc's stock 350 flat cam. Your idle shoud be fine for docking, vacuum around 13" would be my guess. Ifyou don't have Moore's book on SBC Marine performance you ought to get it. He recommends that cam for a stock to slightly modified 350.
12-19-2003, 02:44 PM
#29
Guest
Posts: n/a
Not wanting to work this afternoon, I ran the numbers in a compression calculator on Keith Black's site.
For a stock 350 (.025 deck) with a composite gasket (4.155 x 0.039) and flat top pistons with reliefs (assumed 5cc), 64 cc heads give you 9.87:1.
If you maximize your quench by using a 0.018 shim gasket, the CR jumps to 10.4:1
To get 9.1:1, you need the composite gasket and 10 to 11 cc pistons, such as the Vortec reverse dome pistons.
So, my confusion has always been that to use Vortec "quench-style" heads on a stock, non-vortec engine means you don't get much benefit from the quench. You will still get more poniesfrom the better flowing heads, but not as much as if you optimized quench/compresion.
Am I right or wrong or misguided?
For a stock 350 (.025 deck) with a composite gasket (4.155 x 0.039) and flat top pistons with reliefs (assumed 5cc), 64 cc heads give you 9.87:1.
If you maximize your quench by using a 0.018 shim gasket, the CR jumps to 10.4:1
To get 9.1:1, you need the composite gasket and 10 to 11 cc pistons, such as the Vortec reverse dome pistons.
So, my confusion has always been that to use Vortec "quench-style" heads on a stock, non-vortec engine means you don't get much benefit from the quench. You will still get more poniesfrom the better flowing heads, but not as much as if you optimized quench/compresion.
Am I right or wrong or misguided?
12-19-2003, 02:53 PM
#30
WELL,
I dont want to work either, but I have to build another 50 pieces by the end of the day(yeah right, thats not gonna happen, I will make up some excuse). But to keep it short, I dont know much about the whole quench deal, I know I will not get the full advantage, but still the best flowing head for the $$$, Just tell me what gasket to put in there, I think I have the head/cam/intake/carb deal fingered out.
I dont want to work either, but I have to build another 50 pieces by the end of the day(yeah right, thats not gonna happen, I will make up some excuse). But to keep it short, I dont know much about the whole quench deal, I know I will not get the full advantage, but still the best flowing head for the $$$, Just tell me what gasket to put in there, I think I have the head/cam/intake/carb deal fingered out.
