350 to 454 swap...is it worth it?

[BigBlocksRule]

As long as you're going to run a carb, you really should stick with a dual plane intake. That one is better suited to either higher rpm use or a throttle body. Hang onto it, though - I'm looking to buy a late 80's regular cab dually from a buddy and if it has TBI, I'll take it off your hands.

[baclay9]

I was thinking about maybe an Edelbrock performer Air Gap manifold. Seems it would be better suited for my setup.

[BigBlocksRule]

That's the one I'd use!

[baclay9]

Let me ask you this them. I was planning on running a 750 Edelbrock carb. I was going to get the one with electric choke but noticed it is meant for "mid performance,street,towing, tuned for economy". While the manual choke is "moderate high performance" On the BB that is.

Is the only difference in these carbs the electric choke and they just have the description worded differently? Or are they actually tuned differently based on the choke they have?

[BigBlocksRule]

Actually, if you're going to stick with those heads, a Performer is a perfect port match. Those heads will never get you to the rpm's that will make the Performer RPM or Air gap work.
Edelbrock carbs tend to be problematic - snag a 750 vac sec holley and you're good to go. They'll have electric choke.

[S10Fan]

My BB has the "Peanut Port" heads, I'm running a Weiand Street Warrior intake along with a 670 Street Avenger (Holley) carb, stock manifolds, 2 1/2 exhaust, Magnaflow mufflers. The truck has plenty of power and a nice performance sound. Most importantly, I spend my weekends driving it as opposed to working on it, me like STOCK. LOL.

[baclay9]

Lol. I definately don't want something I am going to constantly have to work on. I thought a 750 carb was pretty much standard for a 454. Very interesting. So you like the magnaflows? I would like something that sounds good when I romp it but I can do without the costant loud exhuast systems.

[BigBlocksRule]

A "hot", lumpy cam is a total mismatch for peanut port heads. The cam is a performance piece, the heads are made for towing applications. It's best to build an engine where all the parts compliment each other rather than having parts with conflicting purposes.

[baclay9]

What exactly makes a head a "peanut port"? I assume that is not what I have? Are the ports shaped different or something?

[BigBlocksRule]

Intake port shape is pretty much round, it's about as tall as wide. A true oval is much taller than wide which allows a lot more airflow.

[baclay9]

So mine are peanut port then? I thought there were just two kinds. rectangle port and oval port. I guess I am kindof confused.

[baclay9]

Also, if I decide to go look at some 781's, what should I look for when checking them out. I know nothing about buying a set of heads and dont want to get my ass handed to me.

Would the springs and roller rokers off my current heads work on them or would I have to replace all of that. What all would need to be done to the heads before bolting them on and about how much is that going to cost me. Thanks again for your help and for spoon feeding me this info.

[joe231]

I wouldn't buy any heads unless the seller will allow you to have them checked out at a reputable machine shop of your choice. You will have to pay to get them checked, but that will be less money than buying a bad set of heads.

I don't know much about big blocks, but I would think you could re use your rockers and such.
I still vote that you should run it as is for now and see how it performs.... But that is just my opinion

[baclay9]

Originally Posted by joe231

I still vote that you should run it as is for now and see how it performs.... But that is just my opinion

I am going to run what I have now Joe. I have been going back and forth on it and building an all out performance motor just seems like a slippery slope for me. I think this thing will make more than enough power to keep me happy and I know it is reliable because my Dad has been driving it in his truck. I do think I will take his advice on the Edelbrock Performer manifold though as it does seem better suited for this motor.

[S10Fan]

Originally Posted by baclay9

Lol. I definately don't want something I am going to constantly have to work on. I thought a 750 carb was pretty much standard for a 454. Very interesting. So you like the magnaflows? I would like something that sounds good when I romp it but I can do without the costant loud exhuast systems.

It really is a "Paper or Plastic" kind of issue. Some folks like the all out noisy monster motor that turns every head in the parking lot. Others like the simple reliability of stock to mild built motors. There's no wrong way to go, you just need to decide on your expectations before you choose.

I like my stock BB, I like it a lot. I also like the 383 in my S-10. The BB is a daily driver, the 383 isn't, nor could I afford to drive it everyday. But, I'm getting ready to drive the 383 across the state Friday to visit my brother. LOL.

I like the Magnaflow mufflers, I also like the Flowmaster 50's I have on the S-10.

[BigBlocksRule]

Rectangle are large by huge, only needed for all-out race apps.
Ovals are better power makers for the street and can make 750hp or so with porting and a huge cam.
Peanut ports are smaller, used for high torque applications.
You really need to match the cam to the heads, yours probably needs a much smaller cam, a race cam and tow heads don't work very well together.

[baclay9]

This is my only thing, I don't know how these oval ports could be any bigger. I mean, they are the same size as the ports in the intake. I guess that is what I am not getting.

So in the 781's the port in the heads are bigger than the intake manifold ports?

[BigBlocksRule]

What's the intake? Sounds like a regular performer. The listings I have identifies yours as peanut ports, but as with all things, there may be a mistake. Here's a pic I found on the net that compares the two, oval on top and peanut on bottom. As you can see, the oval is just about as wide as it is tall and the oval is about 1/4" taller than it is wide. Once you see 'em, you'll never forget 'em. A rectangular port is much bigger than the biggest oval.

[baclay9]

Ok, I see what you are saying. I will double check tomorrow but if memory serves
me right mine are peanut port.

So if I find a set of 781's will my springs and rockers go on them? I'm guessing they could make a big difference even in thier stock form? Any reason this motor wouldn't be just as reliable running them.

[BigBlocksRule]

All the rockers, studs, etc. are the same on all big block heads. Even in stock form, they'll outflow the peanuts and you'll make power about another 1,000 rpm in the range.
If you can find a machinist that knows what he's doing, he can open up the chambers to the head gasket line which will 1) increase flow since the chamber walls would be farther away from the edge of the valve - called "unshrouding", and 2) increase the size of the combustion chamber which will lower your compression ratio, making it more pump-gas friendly. These heads can be cut for bigger valves (stock is 2.06" intake, 1.72" exhaust, bigger valves are 2.19" intake and 1.88" exhaust) which helps flow as well.
There's not really any reason to consider the square ports, but big ovals with big valves and unshrouded chambers can make great power for the street. I can tell you from experience that if you don't spend a few bucks now, you'll always wonder what it would have been like if you'd gone ahead and done it...then you'll pull the heads and have the work done later which will cost you an extra valve job, set of head gaskets, etc. and some down time. Do it right the first time and enjoy rather than regretting. All the work with new valves and a good valve job shouldn't cost more than about $400 - $500, the unshrouding and big valve machine work is about $200 - $250 of that.
Email me direct, I can send you some links to suppliers that I've used in the past that have great prices and good parts, no offshore junk that'll fly apart

[joe231]

Did I miss something?
This engine is still together, isn't it Brandon?
So all you will be out if you swap later is the intake gasket, no?

[BlackTopMotors]

I hope it works out for you! Go with the original set up first...run premium...make sure it's tuned properly...if it won't... then make choices or adjustments from there...just another opinion...

[baclay9]

Originally Posted by joe231

Did I miss something?
This engine is still together, isn't it Brandon?
So all you will be out if you swap later is the intake gasket, no?

Yes Joe it is all together, in long block form anyway. I believe he was saying if I decide to buy the 781 heads I should go all out and go ahead and have the porting work done right off the bat.

This might sound silly but this is all I have been able to think off over the last few days. I have been everywhere from going all out and building this 454 really strong to "screw it, I'm putting the 350 back in.

I have decided I am going to put the 454 in the way it sits. I will get a Edelbrock performer intake and a 750 carb and see how I like it. Worst case senario I will pull these heads off it later and build some 781's for it.

At least I will have tried it this way and I really feel like this motor will have plenty of power to keep a grin on my face. I mean it is bound to make more power than the 350 did. So I will probably move this motor build over and combine it into my build thread. That way it will be all in one place. Thanks again for you help and opinions everyone.

[BigBlocksRule]

If you do decide to run it as-is, at least swap the cam, it's a total mismatch for those heads, at least as it was described as being too choppy for your Dad. Run a cam better suited to those heads, something around 224/230, it'll peter out at about the same time as the heads and will be a much better matched combo. Don't forget the headers, they always help!

[baclay9]

Wanted to revive this cause I have another question.

I ended up picking up a set of 781's from my Dad's neighbor for cheap. They are bone stock right now. They just need to be gone through. Since they have to be taken to the machine shop anyway I will probably open them up to 2.19 and 1.88 and have a little porting done.

I got a Edelbrock performer 2.0 along with the heads. The ports on it have been cleaned up with a grinder as well. Should this be a good intake for me or do I really need to step up to the air gap now that I am getting the head work done?

I called comp cams and got a cam reccomendation. They recommended to the XE274H for my application. They recommended that I run a 2000-2200 stall with it but on thier site it says 2500+ so I dont really know what to do there.

They said this cam would have a nice sound and give me good power from 1800-6000 RPM. He said it would make plenty of vacuum to rn my power brakes also.

WHen I pull the heads I will pull the cam that is in there and see how it compares to thier reccomendation.

Gary, you had recommended the Holley 750 w/vac secondaries. If this cam has enough vacuum to run power brakes I am assuming it would have enough to run the vacuum secondaries? I wasn't sure how this works.

I have a line on a carb and am going to pics it up in a couple of days so I just wanted to be sure. Thanks guys!!!