Horespower question?

[05crewcab]

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]

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

Stock it was prolly around 250.

Gary

[05crewcab]

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]

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

[05crewcab]

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

[cdowns]

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

[Blazer1970]

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

[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!

[GASoline71]

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]

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

[05crewcab]

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]

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]

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??

[Davetopay]

Street strip....on a budget...

http://www.summitracing.com/parts/SUM-162111/ (have them milled to bring up compression)

http://www.summitracing.com/parts/WND-8150/

http://www.summitracing.com/parts/LUN-00010LK/

Use the 750cfm carb of your choice.


or.............on the REAL cheap......


https://secure.pawengineparts.com/sh...6563&catid=985

https://secure.pawengineparts.com/sh...7199&catid=778

https://secure.pawengineparts.com/sh...703&catid=1469

750 carb of your choice

[72chevyk10]

isnt a 750 a bit overkill on a 350?

[Davetopay]

Originally Posted by 72chevyk10

isnt a 750 a bit overkill on a 350?

Nah. A q-jet flows 750cfm+

[05crewcab]

Thanks for the suggestions Davetopay, but i was thinking something in the get dirty at the junk yard and clean them up range on the heads

Ideally i would like to get 300-350 horse out of my setup. Is that realistic with the block I have if I change the heads to something higher compression and throw in a bigger cam?

what about vortec heads? will they just bolt right up. or do I have to change pistons, etc?

i found somewhere that the 'high power' rating on my block is 370 from the factory. which factory heads were those??

...My performance juices are now flowing

[*Dylan]

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]

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

[bMr]

Originally Posted by Davetopay

Nah. A q-jet flows 750cfm+

Isn't it that it is capable of flowing 750cfm but not necessarily dumping that much all the time? The beauty of a quadrajet is the variable CFM up to 750cfm. With the q-jets' plates over the secondaries, if the engine doesn't need that much air, it can be tuned to never see it.

[72chevyk10]

when i had my 350 the 600cfm i had got clogged. and since i was finishing up the 454 in the next few days i put the 750edel i had. and after it got moving it was great for power and what not. but off the line it was a dog. and yes i adjusted the acc. pump for best result. once i got the 454 in it was and is great to drive around

btw not saying you are wrong. its just my experience with a 750 on a 350 wasn't spectacular

[05crewcab]

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]

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]

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]

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?