building a 51 chevy wagon and I have pretty much decided to use a gm crate motor #12530282 or 12530283 my question is what would changing the cam to a ram jet cam do for me and is it worth it I am not looking for super performance just good drivability
You might want to reconsider those engine choices. Those are considered replacement engines for specific year and model usage. Warranty coverage reverts to 12 months/12,000 miles when used in a "non cataloged" application, definition of non cataloged is used in a vehicle different than what the parts catalog calls for. And a camshaft change in addition may raise some red flags also for future warranty claims as those again are not considered performance engines. I've been involved in these situations as I am a dealership parts person and previously sold GM Performance Parts. If you call the GMPP customer service they will verify what I state here. You may be better off with a true GMPP engine, the warranty period of those is 2 years/50,000 miles. Get a copy of the GMPP catalog and turn to page 414 for the warranty coverage, the one under the Genuine GM Parts logo is the one that references the two engine choices you referred to. Just trying to save you some grief if a problem occurs.
thanks for the info but there is not many choices with a one piece rear main seal and vortec heads. I guess I will worry about the warrantee and try to get an answer to my question
No engine expert by any means and I take advice from others in the know. You'd need to establish your specific application and then by swapping cams over, will the valve springs work and not bind, do the spring seats need work with that cam's profile, are the locks and retainers compatible with those springs and that cam, will the cam work as designed in that engine as both are truck engines with 255hp, 1pc RMS with OEM roller cam (Lift .414" Int/.428" Exh; Duration @ .050" 191° Int/196° Ext). The difference between engines appears to be 2 bolt -v- 4 bolt mains. Ramjet cam is (Lift .460" Int/.481" Exh; Duration @ .050" 196° Int/206° Ext). A friend bought a Chevrolet Performance passenger car #12499529 350ci 290hp crate engine for his car and works well. He decided that there was no need for a cam swap and a Ram Jet was a lot more outlay. Just swapping a cam could be counter productive in an engine not designed for performance.
I've used several of the 290 horse (12499529) with good results. Excellent performance with an Edelbrock carb and headers. Guess I never worried about a warranty. I think you just need to use the right break in oil in the beginning. The first hour might be the most important in it's life?
These guys seem to know a lot about what you are talking about: https://www.thirdgen.org/forums/tbi/347093-cam-suggestions-no-tune.html
From what I'm seeing the 12530282 and 12530283 both share the same Vortec head 12558060. This head is in the GMPP 2017 issue catalog on pg. 153. The same head is used on the performance SP350/357 series engines, P/N's 12677167, 12677170 and 12677177, and on the HT 383, P/N 19332529 and HT383E, P/N 19332531. Those engines have the one piece rear main seal also. The only engine that uses a two piece rear main is the 350/290, that is based off the old "Target" universal replacement engine. Just a little more information for you.
Also that motor may or may not have a provision for a mechanical fuel pump. The earlier center bolt head one piece rear main motors had the machining done for the fuel pump push rod, but as time went on they no longer machined for that because because carbs were fazed out. 12530282 and 12530283 are both based on the 1996 - 2000 truck blocks, which do not have a provision for the mechanical pump machined into the block. yes the pump boss is cast into the block but the passage for the fuel pump push rod to reach the cam is not machined. If the original cam is used there is not a lobe on the cam to drive the fuel pump anyway. That may or may not be of concern to you, and you may be doing fuel injection and require an electric pump. but just wanted to throw that out there in case you are planning to run a carb and mechanical pump. I have used the 12530282 crate motor and the Chevrolet Performance 10067353 which is pretty much the same as the 290 horse motor just a different cam grind. I used the 165 horse motor (yeah I know) swapped out the cam for a 327 350 horse cam and I get about 300 at the rear wheels with headers and a well tuned two four set up on my 29 roadster. you can't beat the price and all old chevy stuff bolts to it.
This is an excellent choice for a mild performance crate engine. If you run a cam the heads will need new springs and the guides will need to be modified. Plenty of Hot Rod shops know just what needs to be done and you will get a real boost. There is no fuel pump provision so either an electric pump or full EFI. Fitech has about the best deal right now. Go with the four bolt option, it's worth the extra few bucks.
Ending in 283 is 4 bolt main for gvw 8600 and up. Ending in 282 is 2 bolt main is for GVW up to 8599 These engines can be made to run but they are set up for trucks. To pull heavy stuff and not bitch. Great low and mid range torque. The out of the box set up won't do well at high RPM, and it wouldn't take much to get more a little bit out of it. The ram jet cam isn't a bad upgrade or idea and super easy to do before you stick it in the truck. I've not ran one but the reviews are really good. You'll need an electric fuel pump
The other point needed to be made about these engines is the lack of cam break-in needed. This to me is the best reason to buy one over the 260 and 290 H.P. engines. With a roller cam you get a better selection and no worries about enough zink in your oil. Minor changes to the heads to accommodate a performance cam and you will outperform the 260 or 290 by a long shot.
I purchased the L31 (4 bolt) a couple months ago for my current project and pondered the same question about upgrading the cam. Decided to leave it as is. Have always been a big fan of torque and feel the stock numbers are more than adequate for a 2300 lb car. I realize your wagon weighs a bit more but I would install it as is. You can always upgrade down the road if it doesn't put a big enough smile on your face!
thanks for all the response. the gentleman who commented about having to change the valve springs if I install the ramjet cam. is that for sure because the ramjet is a low and midrange cam
I bought a GM crate 300 HP 350 engine part # 12355345 4 bolt main 9.1:1 compression , one-piece rear main seal. I like this engine in my 1940 chevy.
The Vortec heads will only clear around .450 to .460 lift with a 1.5:1 ration rocker before the valve spring retainers hit the valve guides/ seals. I say that that, there is some variation between them, but the best way is to measure each one it to be sure. The easy way to measure your clearance is to take the valve springs off the put just the retainer and keepers/locks back on, use some grease to hold it all together. Then pull up and twist a little bit to make sure the locks are seated. next take a caliper or micrometer and measure the distance between the bottom of the retainer and the top of the seal. what ever your measurement is subtract 0.050 from it for clearance. so if you have a measurement of 0.490 between the retainer and the top of the seal you would subtract the 0.050 from that, and have a clearance of 0.440 lift at that valve. If you need more clearance for your chosen cam then you can pull the heads and have the guides cut down and install new seals and all your original valves with new springs matched to the cam. just make sure your new valves springs will fit in the stock spring pocket or you'll have to have the pockets machined and buy all new retainers and locks.
· Ram jet cam · This hydraulic roller design is used on the 383 truck and Ramjet 350. · The duration at lash point in degrees (intake/exhaust) is 288/308; duration at .050" tappet lift (intake/exhaust) is 196/206 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 431/451. Valve lash is zero/zero and lobe centerline is 109 degrees. this is the specs on the ramjet cam using this cam would I have to change the retainers
also one more question any input on whether an edelbrock carb or a fitech injection unit would be more trouble free. not looking for a tire smoker just a good driving street car
If you get into the GMPP parts catalogue-you should be able to see what springs and retainers by part number are used on the Ramjet or the 383 truck or the 330HP 350 to compare to your L31 parts. Here's another option-take your stock L31 and put a ZZ4 cam in it-you will need to change the valve springs to the LT4 springs(or comparable) and a little light machine work on the Vortec spring seats-I would also have the machine shop add screw in rocker studs as you will find yourself wanting to wind it up a little every now and then. Your factory supplied L31 roller lifters will be fine-add an aluminum intake and a 600 cfm carb and you are making 350+ hp and over 400lb/ft torque. Reliable street power with a smooth idle and good gas mileage.
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