I am just a lonely poor old high school shop teacher. The kids are building a drag car and we found a late model 350 to use. It has the center bolt valve covers. I know older small block stuff but am not up on the late model engines. We are trying to put a cam in it. I have a .509 cam but read on the web that the Vortex engines can only take up to .425. The heads do have the swirl in the intake , but the combustion camber is not the little one I saw for the Vortex engine. This engine has 4 bolt mains and I think it is a 98 truck. We are trying to keep it on the cheap, remember school teacher. Here is my question. How big can I go on a cam? Will the .509 fit with the stock heads? I also have a set of roller rockers for an older 350, will they work? The plan is to upgrade the engine every year in class. We just want something to run for now and will try to make it faster as time and money allows. I would use an older engine but have had problems finding one cheap. We do have headers and a nice manifold. Any help would be great Thanks Mick
Depending on the shop equipment you have to do things with, the more modifications the better, (for the good of the students). Of course "what's best for the faculty" will take presidence, doesn't it always? Anyhow, it will take a lot of research on your part to make sure the "goal" is met, whatever that is because if you don't accomplish the "performance objectives" you will be the goat. Good luck, and teach them something worthwhile, (and fun)!
Hey Mick. Yeah, I would for sure stay at or under .500 with those heads. However, if you look into beehive springs (competition products has them priced pretty good) you can use a cam up to .550 I believe ...
98 and up is probably a roller cam. They take different timeing componenets, cams, lifter ect. Find out what it is exactly first. You can always machine the spring pockets for a bigger spring, but a small block is happier with smaller lift and more duration.
The heads you're discribing are not VORTEC heads, although Chevrolet did refer to that truck engine as "VORTEC". Those heads won't flow much past 4500 RPM, and there's not much you can do about it. Taking the "ramp" out, used to induce swirl, will not work. Get different heads, earlier will bolt on, as will "TRUE" VORTEC HEADS; identified by their heart shaped combustion chamber, and only a total of 8 bolts holding down the intake manifold. Those heads you have are not the ticket to use. You need to step up. Butch/56sedandelivery.
If those heads have the vane cast into the intake port, they are swirl port heads and are not good for making power, or much else. I would replace the heads with an older set to open up cheap intake manifold and valvetrain availability. If you are making a super cheap drag car, I personally would try to find a set of early 80's 305HO heads - casting number 601. Second choice would be casting number 416. These are perimeter bolt heads that have good sized runners (about 160cc's) and small combustion chambers to get compression up (53cc on the 601, and 58cc on the 416 is what is listed). They have decent sized valves stock (1.84/1.50) but I usually open them up for 1.94" intake valves, and pocket port them. They will flow low 220's cfm at 28 inches with a good pocket port and filling the divot under the rocker studs with epoxy. A full port job will get them into the 240's and requires chamber relieving. Stock they flow about 190-195cfm which is better than the swirl port heads. Best part is that they are usually dirt cheap or free. Noone wants 305 parts. Stock 1.94" valves are usually dirt cheap, so all you end up being out is the cost for the machine work, unless you can regring the seats yourself. You can also use cheap Z28 springs on them, and standard intakes and valve covers.
Teach, I should have said this with my earlier posting; time to get friendly with a local automotive machine shop. Tell them who you are, what you're doing, and ask if they can help with parts/machining, and even coming to class to elaborate on their business. That would be a WIN-WIN-WIN situation. Maybe even put their name on the car. I like the idea of the small chamber 305 heads being worked over; you could probably keep the stock pistons that way, at least for a time. Good luck. Butch/6sedandelivery.
IF your cam is over 500 lift you could have some problems with the cam lobes hitting the top of the rod bolts.
myself, i LIKE this idea. maybe some of your students will take an interest in that end of the automotive world. at least in this area, we NEED good automotive machinists. i stress the "GOOD" part of that statement...
Thanks guys, I knew I could get some help here. I might have a line on an older 350. It's just a matter of cash. I'll keep you posted. Mick
Been doing a lot of research on this topic. If the heads are stock, they are probably vortec heads and can only go to .425 safely without machining. Get the head number and verify that they are vortecs though trucks after 96 usually were with 350's. Several good articles out there on making 400+ hp with the vortec heads and a cam for the stock heads. Sorry, don't have the link right here.
For a camshaft the .509 lift will not work unless you have stronger springs. The beehive comp cams springs somebody mentioned work great plus they drop right in without machining. This should be the first mod on those heads to use a better camhaft. Also newer type heads use guided rockers. The intake bolts are in different locations than older intakes manifolds. I"d stay with the block just get some older heads or if you stick with the combo you have try getting a HOT cam kit from Summit. I built a late model 350 truck block used and old comp 305 hyd .525 lift, camel humps/ bigger springs, 1.6 Erson rockers and ran very well.
heres the combo... 355 dish short block (thinking pepboys or autozone reman longblock) with a 488 lift summit cam ...off the shelf new from gm , no machine work done , no porting, bolt on....vortec heads....1.5 roller rockers (self aligning) performer rpm intake...750 double pumper....msd ignition...10" convertor...3.73's in a 70 nova street car....went 11.80's this past fall...the heads have had a set of crane bee hive style springs....i raced it one weekend ...was going 1.60's on small slicks thru the mufflers...the car without the msd & springs went 12.00's....this motor will get it done for cheap....now , on to my combo....383 flattop short block, 518/536 crane solid, and a pair of freshened up vortecs...had the bosses cut and the seats cut for 1.46 diameter springs...also went to screw in studs , to get away from the self aligning rockers...haven't got my intake yet , but leaning towards a airgap or something comperable... if the head you have are the 96-98 (think thats the years) i wouldn't put anything else on thats gm stock...they work...and work well.....i won't go into the other vortec head 355 at the shop...currently running crate motor stock class...its been in the 10.80 range with cleaned up vortecs and a dish piston short block and a 465 lift cam..... but you have to over look the 260@50 duration.......amazing how a small lift , big duration cam can hit a lick.... use your cam and make the head mods to make it work....and don't forget to check that piston to valve clearance...... brandon
My favorite cam for SBC is Comp Cams 280h Magnum (.480 lift, 230 duration @.050 lift, 108 LSA). I have run this in 3 different 350's and a '78 305 with 90k miles. This cam has a nice lopey idle and pulls good to 5500 rpm. Some of the other people had some good suggestions on the heads. The 305 H.O. heads would be nice because they flow good and will boost your compression without new pistons.
those 280 magnums work good....and they will make a 305 into a monster or alteast sound like one....one other thing....a pair of thin shim head gaskets will bump the compression as well..... brandon
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