Cam questions

[SkinnyG]

I would encourage staying around 218° or smaller.  a 218° will still have a noticeable idle, but a lot less "snowball" effect of changes that you need to do to make that cam work.

If you're looking at buying aftermarket heads, look for 305-specific heads.  The combustion chambers are very small so that you can have good compression.  60cc or less, likely.  I think Edelbrock among others have a 58cc head.  Once you pick your combustion chamber size, then see what intake volume they offer in that size.  Smaller volumes keep the port velocity high which benefits torque - desireable on the street, and in a truck.

An air-gap intake will be a bit more of a challenge in winter, as there is no heat to help vapourize fuel from the TBI or carb. It will likely run poorly and burn more fuel until it's fully warmed up.  You ~can~ put TBI on an air gap (they sell TBI-to-carb-intake adapters).

[Spoonbill]

Thanks for all the help guys. She threw me for a loop yesterday. I go to do some errands, started the truck and you have to let it full warm up or it will die but this time it was much worse but I finally got it warmed up. I put it in reverse and it almost died so I throw it back to park so I can get gathered up. As soon as it got to were it would idle I shifted it into drive and same thing and this time it did die but it started right up. I went to do my errands and every time I got to where I was going same thing every time. Today, same thing. I just don't get it

[Spoonbill]

Hey skinny, what top end would you go with if you were me??

[SkinnyG]

I would leave the engine completely stock, except find a GOOD "torque" cam that the TBI computer and stock torque converter can still work with, then enjoy decent power and decent mileage.

[Spoonbill]

What cam would you suggest

[Spoonbill]

Hey guys, say you are building a top end like I am and you know intake you want so you are building your kit around it can you put in a intake that has an rpm range of 1500-6500, even though you won't take it that high can you put in a cam & heads that have an rpm range of idle-5500???



Does anyone know if this will work?

[Spoonbill]

You hear all kinds of stories about how there are a bunch of parts on a 350 that can go on a 305 and give it more performance than a 305 a part that is made for a 305. I had a conversation yesterday with a guy that told me you can put a performance 350 cam in a 305 and it will make it scream as well as a lot of other parts. I find this very hard to believe. Is there any truth to any of it?

[Rattler12]

With the exception of the roller cam generation he's is correct. A cam from a 1956 265 cu in SB will work just fine in an 86 350 and vice versa. You gotta remember the laws of physics though. A radical 350 cam put in a 305 will become even more radical. HP will peak higher in the rev range but low end torque will suffer. You also have to watch the lift. Higher the lift the more fuel to theoretically pass into the comb chamber but at a certain point w/o the right combination of pistons, heads and springs............BANG pistons hitting valves........again you can't have a low end stump puller and a high end screamer in the same vehicle

[Spoonbill]

Gotcha. Thank you

[Spoonbill]

So I'm doing the top end and know what intake I want and it has an rpm range of 1500-6500. I'm not finding any cams or heads with that range. If I put in a cam and heads with an rpm range of idle-5500 would those work with the intake or does it all have to have the same range???

[Rattler12]

Why are you dead set on an intake that makes power up to 6500 RPM ? Are you EVER going to hit 6500 rpm ? Without the pistons. rods, crank, cam,  valve springs to support 6500 rpms you're whizzin in the wind and that intake manifold will make your motor perform worse instead of better. Decide what you're going to do with the truck and go from there. People are trying to help you but you're not listening

[VileZambonie]

A common misconception is that with RPM increase comes power increase which is false. They are not linear, just look at any dyno results. Once you've hit your peak power output your gains drop off. Think of it in a simple manner and while not technical seems to help people grasp the concept, torque helps give you the push you need to get that big lump of steel moving. Power is the ability to continue pushing. Engines have a happy place where torque reaches it's peak operating range and where in your initial launch will get the most pull. The whole concept of the CVT transmission is to optimize this. Read up on them to better help understand how the whole package is what you need to think of when designing your power plant.

A cam, intake and head combo should make sense for the vehicle it's in and the powertrain it is equipped with. In most cases people go right to the wrong system first. The biggest performance gains in these trucks actually start with optimizing final drive ratio, upgrading from the old 3 speed transmissions and so on. Building a top end performance engine behind a loofy powertrain and numerically low final drive will yield negative results. So unless you've already done these things you shouldn't be aiming for 6500 RPM operating range.

[XrayTedd]

What do you think about the fitech unit? Looks pretty cool.

Fitech is a really good set up. Just as good as the "larger" brands at a lower cost. I know a few guys that run them and all of them say they would never go any other way again.

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