Hello HAMBland, Recently, I had the pleasure of experiencing a sunken valve seat on a many-mile 327, with original heads (non-hardened seats). Many thought that was awful luck, but I preferred to think of it as the perfect opportunity to finally use some extra heads I had on the shelf, and recycle cam, lifters and timing set from a High Output Marine 305 that I was given a few months ago (in El Paso, nobody winterizes... but last year it got COLD. Block busting cold.) Here are the details to what I am working with: 1964 327, 0.030 over, 1963 327 heads 1.72/1.50, GM squarebore intake with 1964 Rochester 4Jet carb (predating the Quadrajet), Jacobs electronic iginition. Like I said, I had a reasonably low-mile/hour cam from a bad, HO 305 (225 HP, factory quadrajet, it has a tag on it says Volvo Penta AQ225E NO CU62799)... I made sure to keep the lifters in order so that they are properly paired with the correct cam lobes. My question is: Will using a cam from a sbc intended for marine use be a problem for me in my El Camino? I have done some research, but I can't find a definitive answer... I know that marine engines are cammed with less overlap. That's fine, because I believe that will improve low-end torque and also mean a smoother idle compared to a hotter cam with a smaller lobe separation angle. Visually comparing the old 327 cam to the marine 305 cam, I could tell the the ramp angle on lobes of the 305 is considerably steeper, which I think will lead to more aggressive opening and closing. My problem is that the engine as assembled pings when I stomp on it, even though it idles smooth. After 10 or 15 minutes on the road, it gets pretty hot... then the pinging gets worse. Is it my lack of tuning skills? Or is it the cam? It could just be that this is an unholy marriage of parts, compounded by my lack of insight and meager budget. This engine is in my daily driver... no burnouts or 1/4 mile runs-- I just need to get around town. And if it is a bit more torquey than horsepowery, that's fine (actually, preferred). Great, Thanks in advance (sic), acosta For those of you who feel more information would be helpful, I will describe what I have experienced so far with this hodge-podge, shoestring-budget assembly: When I first fired the engine, I set the timing to about about 4 btdc while out of the car (while I'm not saying I'm not incapable of setting up the cam or timing gear or distributor wrong, I will say that I was very conscious and sober and deliberate about getting this right, and checked everything three times. An advantage of not drinking is that I'm always super sober.). It ran rough. I first thought this would be remedied by adjusting the idle mixture on the carb, but the idle quality didn't improve too much (I set idle mixture with a vacuum gauge, adjusting to get a maximum reading). Then I advanced the timing a little, and the idle smoothed out a little. Further idle mixture adjustments would not improve the vacuum reading, but advancing the timing sure would. Ultimately I had it running really smooth, starting super easy, and 15 inches of vacuum, but this meant the timing was advanced off the tab, probably to the neighborhood of 20-30 degrees btdc. Of course, this bugs the hell out of me because I know it's not right, and when I'd drive it around it would ping on heavy acceleration. If I kept driving, it would get hot (even though I've got a new 160 thermostat, a good water pump, a clean radiator (5 years old), and a block I just flushed all the sediment out of), and when it's hot, it pings like crazy. I know I shouldn't be on the road if it's doing this, but that night there was an errand I had to run that just couldn't wait.
I put a Volvo Penta 290 (350) into my '57 Chevy truck, that thing ran great, with the T5 and 3.08 rearend I was able to knock out a stellar 14 mpg!! The shitty 307 I put into it after overheating the ever-loving beejesus out of the 350 only got 10 or 11 or so. So I had no problems with the marine 350... but that 307 was a total turd...
Hotter cams usually want more initial advance than a stock grind. That's fine but the mechanical advance needs to be limited or there will be too much total advance. That may be where your pinging is coming from. If you can get your hands on a dial-back timing light it's pretty easy to check the advance curve. Finding someone with an old fashioned distributor machine would be even better because there will be some trial and error involved in correcting it...
If you are running through transom exhaust on the el camino and you don't mind more noise, put less water in the exhaust so more goes through the engine for cooling...........
I was told the same thing.... Of course I cant swim so I keep my ass outta the lake and on the asphalt
No offence mi amigo, but the 305 would make a better boat anchor than power supply. I had a 305 in my new 87 Monte Carlo SS and it had no low end, barely enough to get a little scratch on a right hand turn out of the driveway. It ran great at 100 mph plus but I think it was due to gearing more than anything else. I personally believe that for a street motor that you should stay as close as possible to the original intended parts and not mix match. I built a 350 with earlier 350 heads, not a perfect match but ran good. The problems came at the head block point and now leaks from that junction even tho the heads and block were checked for warpage at the machine shop and within tolerance. Take your time and think it through. The guys here can give you a lot more input than I can and your a member of one of the largest data bases on earth here on the HAMB. There are thousands of tech and building articles and threads here that address this stuff so plan on spending a couple weeks researching here. Time is cheap, building engines...not so cheap if done right and unless you just love switching out motors and busting your ass...do it right the first time. Good luck.
Actually, very common for the engines to turn the same direction as our cars do. At least the single engine race boats. Twin engine race boats will have one CW engine and one CCW engine, this is so you can go straight. If both engines rotated the same directions, the boats would simply go around in a big circle. Sounds simplistic, but true. Our 4 engine Super Boat, had two CW and two CCW engines again for the same reason. Always interesting was that the reverse rotation engines ALWAYS made a few more H.P. than the conventional rotation engines, this is after 30 years of dyno testing and has never failed. Exactly the same built and blueprinted engines, same cam specs, just reverse rotation.
I always thought that boat engine were set up for max torque & not horse power being the are under more load all the time?
The cam in a marine chevy is ground for standard rotation, the reverse rotation engine used gears insted of a timing chain so the cam turns the right way (same as a car engine) while the crank turns backwards. As far as using a marine cam in a car, its basically just a truck/rv type of grind so it will give you really good low end torque and probably be all done around 5000 rpm which is perfect for a daily driver.
I have no input for you but I heard a mean sounding bad ass boat cruise thru the No wake zone . I couldn't wait for him to go by and open it up. That was a beautiful symphony of reciprocating mass. Probably the best sounding small block I've ever heard.
Sounds like balancer slipped.Time it by ear or vacuum guage.Marine cam would be all low end,good for what you want. jmho
Ok some input now. Like redline says Have you verified that the timing tab actually indicates TDC via piston stop test? I'd make sure of that before doing any more head scratching.
If your using the boat distributor theres your problem,Boat distributors have more curve built into them,Thats my guess from reading your post.And if not use a vacumn guage to set timing .Pinging is definately to much timing or wrong octane...........
Marine cam or not, it's still a SBC... Like stated above, find an advance timing light and set the total advance at 34-36deg. Good idea to check that balancer with a piston stop. Are you positive you got the cam timing correct when you installed the cam? I'm not familiar with the marine timing sets, but there can be various marks on the sprockets. Did you check for vacuum leaks around the carb and intake gaskets? If it's a factory cam, you shouldn't be having idle problems. I doubt they put anything THAT big in a factory marine engine...
I bought a brand new '95 310 hp 351W truck/marine "roller" shortblock from Ford Motorsport some years back and it came with a flat tappet marine camshaft... I pulled that one out and installed a roller cam in it... I've been wanting to try that flat tappet cam in a 302/5.0L just to see how well it does on the street.. I'll try it on my next small block Ford build..
If I remember correctly, the 2bl 157hp 302 in the mustang was using a marine cam before it went to roller, so not all marine cams may be reverse rotation. The Monte SS 305 used a Corvette cam, if memory also serves. As for a marine cam being a certain type, listening to them idle around the local dock, I'd say they can both be long duration type for high RPM, offshore running in a VSV, and "RV/truck" type for letting the boat troll around from fish hole to fish hole... as for the pinging, what compression ratio are we talking? A higher overlap cam may have bled some of that compression off, but if those higher rams aren't matching the overlap of the "older cam", having both valves closed at the same time for a longer period of time may be causing the final compression ratio to climb, and the result may be the detonation you experience. but, playing with the ignition timing could be the simple solution. oh, and the guy who went from flat tappet to roller cam...how's the distributor gear holding up?
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