Horespower question? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

05crewcab · 08-01-2010, 12:21 AM

Hi guys,

I have a '75 010 4-bolt 350 in my truck and am wondering what the approximate horsepower now is?

I guess the motor came out of a 75 c-20, and it has long tube headers, an edelbrock performer intake, an edelbrock 1406 carb, and HEI. I am not sure about the internals other than it appears to have factory rockers and valve springs.

So what do you think she is packing?

GASoline71 · 08-01-2010, 12:37 AM

Without knowing what cam is in it, and what heads are on it, is a crapshoot...

Stock it was prolly around 250.

Gary

05crewcab · 08-01-2010, 01:29 AM

Heads are casting # 468642 still not sure about the cam, it doesn't sound meaty or anything so i am assuming it is stock.

Irishpilot · 08-01-2010, 01:34 AM

I agree with around 250hp. However, if you have compression issues, worn rings, etc, it will be less.

05crewcab · 08-01-2010, 02:07 AM

is that 250hp stock or with the modest goodies i have on it? I dont think i have any compression issues...

cdowns · 08-01-2010, 05:51 AM

in 1975 the typical 350 was rated at 185HP so i think that 250HP quote is highly optimistic

GASoline71 · 08-01-2010, 03:22 PM

Quote:

Originally Posted by cdowns

in 1975 the typical 350 was rated at 185HP so i think that 250HP quote is highly optimistic

HAHA... well I was off a tad...

Then it MIGHT have 200 with all the "goodies" on there.

Gary

mstrav1973 · 08-01-2010, 03:43 PM

they also went from back of crank to rear wheel hp which also made the numbers go down. Im running a similar motor and would say around 220hp with those mods and an rv cam or something similar. As stated they were 165-185 stock on the 4 bolt blocks back then.

Matt

Blazer1970 · 08-01-2010, 05:52 AM

The factory rating on that motor was probably about 170 - 175 net hp.

Davetopay · 08-01-2010, 10:24 AM

If it has 642 heads it MIGHT have 8.0:1 compression.

Yeah that sucker probably doesn't make 200hp on a good day.

But.....there is good news! It really isn't that tough to swap a better set of heads on it and you already have a carb, intake, and headers!

05crewcab · 08-01-2010, 07:21 PM

Quote:

Originally Posted by Davetopay

If it has 642 heads it MIGHT have 8.0:1 compression.

Yeah that sucker probably doesn't make 200hp on a good day.

But.....there is good news! It really isn't that tough to swap a better set of heads on it and you already have a carb, intake, and headers!

Thanks for the input guys, so then here is my natural followup question cause 220 horse ain't gonna cut it!

As far as gen 1 350 heads, which ones would a) bolt right up, and b) give me the most increase in the GO pedal?

Davetopay · 08-01-2010, 07:25 PM

Quote:

Originally Posted by 05crewcab

Thanks for the input guys, so then here is my natural followup question cause 220 horse ain't gonna cut it!

As far as gen 1 350 heads, which ones would a) bolt right up, and b) give me the most increase in the GO pedal?

Here's the next question that needs to be asked. What do you want to use it for? Cruiser? Street/strip? Tow rig and work?

Does it need to rev to the moon?

05crewcab · 08-01-2010, 08:17 PM

Quote:

Originally Posted by Davetopay

Here's the next question that needs to be asked. What do you want to use it for? Cruiser? Street/strip? Tow rig and work?

Does it need to rev to the moon?

I just dont want to be embarassed when some punk blips the throttle at a stop light...what's that? street/strip??

*Dylan · 08-02-2010, 02:58 AM

With vortec heads you will need a different intake for sure. From what I have been told and have been reading a cam with a max of .480 lift will work. Have been told and have read on the Comp Cams xe268h cam, and it makes good power.

beebster · 08-02-2010, 03:54 AM

my guess would be around 200 HP.
if it was a '71 350 it would be closer to 250 HP.
with the vortec heads,intake and the comp cam xe268h you would be around 250-270

05crewcab · 08-03-2010, 01:11 AM

Quote:

Originally Posted by beebster

my guess would be around 200 HP.
if it was a '71 350 it would be closer to 250 HP.
with the vortec heads,intake and the comp cam xe268h you would be around 250-270

Ok, so if I do go vortec and this cam, I am assuming i would need different pushrods. what do i get? how do i get closer to 300hp?

sorry for all the questions. just trying to make an educated decision.

*Dylan · 08-03-2010, 01:25 AM

Quote:

Originally Posted by beebster

my guess would be around 200 HP.
if it was a '71 350 it would be closer to 250 HP.
with the vortec heads,intake and the comp cam xe268h you would be around 250-270

Is that 250-270 estimate for the motor with 165-185 HP ratings stock, or the '71 250 HP rating?

Blazer1970 · 08-03-2010, 05:56 AM

Quote:

Originally Posted by *Dylan

Is that 250-270 estimate for the motor with 165-185 HP ratings stock, or the '71 250 HP rating?

Those are basically the same motor. You need to research the difference between gross and net hp.

05crewcab · 08-03-2010, 11:43 PM

Quote:

Originally Posted by Blazer1970

Those are basically the same motor. You need to research the difference between gross and net hp.

It's hard to believe the same motor will drop 75hp switching from gross to net horsepower, but then think about all the stuff running off of it on the net measure... fan, alternator, ps pump, a/c compressor, smog stuff, etc.

Anyway, regardless of gross or net hp...i just need more

can anyone answer my question in the thread above? if i go with vortec heads and that comp cam, what else do i need to complete the install?

08-01-2010, 12:21 AM	#1
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	Horsepower question? Hi guys, I have a '75 010 4-bolt 350 in my truck and am wondering what the approximate horsepower now is? I guess the motor came out of a 75 c-20, and it has long tube headers, an edelbrock performer intake, an edelbrock 1406 carb, and HEI. I am not sure about the internals other than it appears to have factory rockers and valve springs. So what do you think she is packing? __________________ 1971 C-20 350/350 Last edited by 05crewcab; 08-01-2010 at 11:33 PM.

08-01-2010, 01:29 AM	#3
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	Re: Horespower question? Heads are casting # 468642 still not sure about the cam, it doesn't sound meaty or anything so i am assuming it is stock. __________________ 1971 C-20 350/350

08-01-2010, 01:34 AM	#4
Irishpilot Registered User Join Date: Jul 2006 Location: Kunsan AB, South Korea Posts: 187	Re: Horespower question? I agree with around 250hp. However, if you have compression issues, worn rings, etc, it will be less.

08-01-2010, 02:07 AM	#5
05crewcab Registered User Join Date: Mar 2010 Location: Minnetonka, MN Posts: 409	Re: Horespower question? is that 250hp stock or with the modest goodies i have on it? I dont think i have any compression issues... __________________ 1971 C-20 350/350

08-01-2010, 05:51 AM	#6
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Horespower question? in 1975 the typical 350 was rated at 185HP so i think that 250HP quote is highly optimistic __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-01-2010, 03:43 PM	#8
mstrav1973 Registered User Join Date: Oct 2008 Location: Meridian, Idaho Posts: 321	Re: Horespower question? they also went from back of crank to rear wheel hp which also made the numbers go down. Im running a similar motor and would say around 220hp with those mods and an rv cam or something similar. As stated they were 165-185 stock on the 4 bolt blocks back then. Matt __________________ 72 chevy k-10, swb, auto, 35's, rally's, posi, 4" lift, 2.5" old style 40 series flows with headers and crossover pipe and some other stuff!!

08-01-2010, 05:52 AM	#9
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,507	Re: Horespower question? The factory rating on that motor was probably about 170 - 175 net hp. __________________ Tim

08-01-2010, 10:24 AM	#10
Davetopay Registered User Join Date: Oct 2009 Location: Leesburg, VA Posts: 424	Re: Horespower question? If it has 642 heads it MIGHT have 8.0:1 compression. Yeah that sucker probably doesn't make 200hp on a good day. But.....there is good news! It really isn't that tough to swap a better set of heads on it and you already have a carb, intake, and headers!

08-02-2010, 02:58 AM	#14
*Dylan Mean Buzzin' Half Dozen Join Date: Mar 2008 Location: Orlando, Florida Posts: 1,081	Re: Horespower question? With vortec heads you will need a different intake for sure. From what I have been told and have been reading a cam with a max of .480 lift will work. Have been told and have read on the Comp Cams xe268h cam, and it makes good power. __________________ "War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling which thinks that nothing is worth war is much worse. The person who has nothing for which he is willing to fight, nothing which is more important than his own personal safety, is a miserable creature and has no chance of being free unless made and kept so by the exertions of better men than himself." MY TRUCK (Now for sale) 1967 C10 SWB *Dylan* IIMY?

08-02-2010, 03:54 AM	#15
beebster Registered User Join Date: Jan 2009 Location: Aurora,Il ..born,raised and still live in the same house Posts: 286	Re: Horespower question? my guess would be around 200 HP. if it was a '71 350 it would be closer to 250 HP. with the vortec heads,intake and the comp cam xe268h you would be around 250-270 __________________ I love stock! Not really into the whole bagged, squished,chopped, drooped,cut, bent,lifted,twisted,split,decked,massaged,tubbed,jacked trend. (o.k. slightly lowered is fine) For the love of god, just drive it before you forget what the truck is supposed to look like !....LOL



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.