Bit of a tune up question

[silverscottsk10]

Engine has bad timing chain
So I wanna replace that here soon
Along with that I'm putting a Holley 750 and torkker 2 intake
I'm wondering if while I have the front cover off if I should switch the cam to make it a bit torqier
Low rpm high torque is what I want
What would the best possibility be to keep from changing valve springs?
And it needs to be done in a few nights too
Any tips?
First in frame like this on a 350
BBC 360s I've done in big trucks
Imagine that's much easier
Anything would be helpful

 

[Driver4r]

Are you down jetting the 750 so it doesnt overfuel and wash down your cylenders???

 

[rich weyand]

I'm running the Comp Cams 12-300-4, which is a marine/truck cam. Simulations give 422 lbft of torque at 2500 rpm, and 275 hp at 4000 in a base crate engine 350. Above 4000 rpm the power drops off, so I went to the next size heavier weight on one side of the TH350 governor to move the WOT shifts down.

If you want to keep more top end, the next two cams in order that I would recommend are the comp cams 12-235-2 (415 lbft @2500 and 290 hp at 4500), and then for a bit more on top and a touch less on the bottom, the comp cams 12-234-2 (415 lbft @2500 and 302 hp at 4500).

The peak numbers don't tell the whole story. The peaks are all about the same, but the torque curve coming off idle on the 12-300-4 is stupendous, then less with the 12-235-2, then less again with the 12-234-2. On the other hand, the horsepower is lower and drops off sooner on the high end with the 12-300-4, and the horsepower is a bit less with the 12-235-2 than the 12-234-2. With cams, it's all trade-offs.

But for big torque out of the hole and a really hard pull through 3500 rpm, it's the 12-300-4.

Lift on the 12-300-4 is only .390 on both intake and exhaust. I am running it with stock springs with no problems. The other two cams have lifts in the .450 range, and you might have problems with stock springs.

The 12-300-4 is a tremendous driver. Boatloads of torque at any rpm I drive at. Winding out a 350 in a truck just seems kind of out of place, so horsepower numbers over 4000 rpm just don't matter to me.

 

[silverscottsk10]

I can jet it
I'm in the process of planning right now
Trucks is my daily so anything to get the 3.42s moving easier is gonna help in the city
How much was the comp cam 12-300-4?

 

[rich weyand]

$200. That includes the lifters. You MUST replace the lifters when replacing a cam. The cam and lifters bed in within minutes of operation. If you put in a new cam with anything other than new lifters, the lifters will eat the cam.

http://www.amazon.com/COMP-Cams-CL1...8&qid=1402852413&sr=1-1&keywords=12-300-4+cam

 

[silverscottsk10]

Sweet
Not bad deal at all
So that with new timing chain and the 750 should make her a bit peppy?

 

[rich weyand]

I got no complaints. With that much torque, it's a hell of a street fighter considering it is otherwise just a stock low-compression 350.

 

[bucket]

Despite it's name, that is a HORRIBLE intake manifold for a heavy truck. Your butt will really feel the loss of low end torque compared to a dual plane intake.

Are you down jetting the 750 so it doesnt overfuel and wash down your cylenders???

That will not happen. The engine will take what fuel needs from a carb, not what the carb is capable of giving it, that's just how a carb works. It's not the same as say putting bigger injectors on a motor. Without changing jets, it may not run optimal, but it will not "overfuel". But the fact is, about any 750 carb comes jetted out of the box to work pretty well on a 350, it just takes a little more tuning (when compared to something like a 650) to keep it from bogging when you stomp on it.

 

[silverscottsk10]

My 650 edelbrock Boggs bad
And it's the only intake I've got clean and both are single plane so It will have to do
I'm looking at around 300$ after everything so far

 

[rich weyand]

The Edelbrock just isn't set up correctly. That's what I have, and I can give you the proper tuning parameters. Sell the Holley if you already have it and get a dual-plane manifold like the Eddy 2101.

A new accelerator pump is probably all the 1406 needs, if anything, and some tuning.

And of course, if you have the vacuum advance plugged into ported vacuum (passenger side on the Edelbrock) instead of manifold vacuum (driver side), that will cause an off-idle stumble as well.

 

[bucket]

And it's the only intake I've got clean and both are single plane so It will have to do

A stock intake will work better than a Torker.

 

[silverscottsk10]

Don't have stock
Only thing I have is two single
And I don't have the cash
That's why I asked
Gotta do with what I have

 

[silverscottsk10]

The comp cam timing set is 26.97 (except with oe roller cam)
Which means it won't work right?

 

[mtnmankev]

I'm running a Chevy stock aluminum intake and edelbrock carburetor on my mild 383 and I have never had any complaints.
If you can scrounge a chevy aluminum intake from somewhere, I think you'll be very happy with how it performs, and will save you some money instead of buying an aftermarket. If you already have the aftermarket, you could sell it and have money left over for other parts.

 

[Driver4r]

most single planes dont really produce untill 3k