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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / February 2006more power in a built up 350 chevy?
hey everyone, i have a 69 camaro with a 350 in it.. i have done alot of work to it, building it from the block up. it is a four bolt main, bored 40 over with high compresion- 10.5:1. it has a set of fuelly double humper heads with a 190 intake valve. also it has a wild comp cam. for easy air flow it has a pair of hooker headers on the exhaust side, with a edelbrock 750 cfm square flange carb on top of an edelbrock rpm performer high rise manifold. the carb is jetted stock right out of the box. im am running an hei distributor for better spark. my tranny is a th400 with a small 1500 rpm stall when i drive the car, it has alot of power, but it seems to me that it should have more. i am wondering if maybe my air fuel mixture needs to be messed with or if there are other things that i can do to the engine. also i am wondering that even with the high compression and a radical cam, if i can run nitrous? any information would help tremendously, thanks 69 maro >my tranny is a th400 with a small 1500 rpm stall > when i drive the car, it has alot of power, but it seems to me that it [quoted text clipped - 6 lines] > > 69 maro One step to look into is a higher stall torque converter, you don't mention what rear gear you are running either, that will make a big difference. A "radical" camshaft is a design that will generally sacrifice low RPM torque to move the "power band" into a higher RPM range closer to peak HP. A higer stall converter and a lower rear gear will keep your engine's RPM higher and closer to the RPM where your Peak HP and torque will occur. Adding NOS will always give you "more" but whether or not your motor can stand it depends on how much and how long you use it. crazedbadboy32@msn.com wrote in article <1139987913.964671.262400@g14g2000cwa.googlegroups.com>... > hey everyone, i have a 69 camaro with a 350 in it.. i have done alot of > work to it, building it from the block up. it is a four bolt main, [quoted text clipped - 14 lines] > > 69 maro If you are like 90 percent of the guys who come by my shop looking for "more power" from the built-up engines in their street cars, your engine is "overcammed." I would bet, in the process of building this engine, you have subscribed to the philosophy that "SOME is good....MORE is better....and TOO MUCH is just right!" Well, while that certainly applies to a lot of things in life, one area in which it does NOT apply is camshafts. My guess would be that you simply have the wrong camshaft for street driving. With today's tendencey towards mail-order rather than dealing with the guys who know something at the local speed shop, this happens more often than not. The consumer buys the wildest cam listed - not knowing the consequences, and receiving little of no advice from the voice at the other end of the telephone line. Basically, the more "radical" the cam, the higher the HP comes in. Try this........ Take the car out to a straight highway. Place the transmission in "second" gear. Accelerate up through the RPM range. I'm betting that you will actually feel the car kick you in the seat of the pants somewhere between 2500 and 3500 RPM. That'll be when the camshaft comes into its power range. The fix???? A.) NEVER drive below 3000 RPM - even around town.... OR... B.) Put a less-radical camshaft in it.....bringing the power range down to a more realistic level for street driving..... Because I build "real" oval-track race cars, I often have guys like you come by with, essentially, the same problem. I send them off for a "test-drive" on the nearby Interstate, and they usually come back with a whole new look on their faces. If I sold camshafts, I could probably sell one right there and then. > Because I build "real" oval-track race cars, I often have guys like you > come by with, essentially, the same problem. got any tips to pass along for me? :) I run an Enduro (basically a pure stock) Camaro. 2bbl carb - no holleys, .450 lift cam, no vortec stuff allowed. Apart from my three main problems of breaking balljoints, blown transmissions and blown engines, I'm looking for more power. (the tranny was ran dry twice due to cut lines -> fixed, the balljoint is considered a maintenance item like spark plugs, and the first engine was overheated, the second engine lost oil pressure due to impact with something (smashed in pan) and the third engine was a free 35 year old 307 that bent the crank...) Ray >> Because I build "real" oval-track race cars, I often have guys like you >> come by with, essentially, the same problem. [quoted text clipped - 12 lines] > > Ray I used to run in a class similar to that, but we ran metric cars and one track had a no bore rule, 305 or 307 only, and another had 320 inch limit. What heads are you running on there? Is it 305, 350 or what? And don't laugh, but those 307's are great little motors. Mine regularly turned 6,700-6,800 all year last year with cast pistons and rings. Howards cams (sorry, don't have a link handy) as well as Isky make some great lift rule cams. I ran an Isky with .465 lift last year and was really happy, and will be running another one in my new class (modifieds) this year. >>> Because I build "real" oval-track race cars, I often have guys like you >>> come by with, essentially, the same problem. [quoted text clipped - 22 lines] > really happy, and will be running another one in my new class > (modifieds) this year. I'm thinking of a GM Goodwrench crate engine for engine #4. Nothing fancy, because I can't seem to survive 200 laps without blowing something up, and to finish first, first I must finish. :) The 350 that blew up with no oil pressure had an isky cam in there, wish I woulda had a chance to see how it ran. (20 laps in I noticed the oil pressure dropping, and I shoulda parked it before it blew up...) How about exhaust manifolds? We can't run the "ram horn" ones, so I bought a set of LT1 manifolds off a 96 Camaro over the winter.... I'm hoping they'll fit. :) Ray >> I used to run in a class similar to that, but we ran metric cars and >> one track had a no bore rule, 305 or 307 only, and another had 320 [quoted text clipped - 20 lines] > > Ray I'm not a big fan of the crate motors myself, especially if you aren't allowed to work on them yourself because of the special fasteners they use in them. In reality, if you build a solid bottom end (I like to use Clevite or even better, get some King bearings, the ones made in Israel still contain lead and are better). A good oil pump (not high volume or you'll pump all your oil to the valve covers). I like the Melling 55A, it's a Z/28 replacement. I have 2 seasons on one, probably 500 laps or better. Nothing wrong with cast pistons either, but if you want the motor to really last, stick some moly rings in there. Top it off with a decent flowing set of heads, some decent valves with Z/28 or better valve springs and either screw in studs, or you can buy a pinning set out of speedways catalog for cheap and do it yourself. That should keep the top end together. The one place I do spend money is bolts. ARP's on the mains, rods and heads will really help hold it together. As for exhaust manifolds, I like the newer style from Chevy pickups, caprices, etc. They are the over the plug, log style and are supposed to flow really well. As far as the LT1's, I'm not positive, but I think those may be the newer style SB2 heads, with the even spaced exhaust ports and wouldn't work with the older heads. Good luck. Where do you race at? > I'm not a big fan of the crate motors myself, especially if you aren't > allowed to work on them yourself because of the special fasteners they [quoted text clipped - 18 lines] > Good luck. > Where do you race at? I'm thinking of the crate motor because for $1300US I can get a complete long block that meets the rules. They pull a head off the winning car, so I'm not cheating... The heads are a "problem" - if it's a 350, they must be 72cc or bigger, no vortec, no centerbolt, no aluminum. I've wondered if a set of "hi perf" stock heads on a 305 would be a better way to go... but the problem is the prices for the good stock heads is getting pretty nuts, and we're supposed to be a "beginner" class. I emailed the track owner about allowing vortec and center bolt heads in because they're now cheap compared to the "classic" small block heads. The LT1 manifolds should line up (they're same port layout) - and because it's a racecar I'm not worried about making the down pipes fit around stuff - I think you're thinking LS1 style manifolds for "ford style" spacing... What about crank scrapers? Windage trays? Fancy oil pans? I race at Victory Lane in Winnipeg. Right now the Camaro is under two feet of snow. <sigh> Ray > I'm thinking of the crate motor because for $1300US I can get a complete > long block that meets the rules. They pull a head off the winning car, [quoted text clipped - 17 lines] > > Ray OK, when I heard crate motor, I was thinking something like the 602 or 604 models that are used by some late model types. For heads, the normal high perf heads, camel humps etc. were factory 64CC heads, that rules them out. Good 305 heads are all 53-58CC's so they're out. Basically you're stuck with the smog style heads, which are definately not created equal. They almost all have a 76CC chamber in them. 487, 441, 993 and 882's are your best bets. Some also have an "X" in the casting numbers, i.e. 487X. Of the bunch, the 882's actually flow slightly better than any of them, but they tend to crack if overheated. It doesn't amount to much, but about 10 CFM more on the intake side. If you can, have them cut for the biggest valves possible. I got a race ready set out of Sperry racing in Iowa, delivered for under $500 from ebay. They're 487 castings, 2.02/1.6 valves, all new valves, good springs, new retainers and locks, screw in studs and guide plates, and surfaced .010" to make the chambers 74CCs. A little more and you could be right at your minimum. Do your rules say anything about decking the block or what type of pistons? How about compression? You could find a 72CC head to be legal, find good flat top pistons (2 valve relief style) and deck the block to 0 and really help get your compression up there. For intakes, if you have to run cast iron, look for casting number 250 or 055, they're supposed to flow the best. Both came on Chevy and GMC trucks. Oil pans, if you have a rule stating "stock appearing" or something, look for one in speedway or Competition products under the "Claimer style" pans. Pretty cheap and they'll have built in gates and scrapers. If you can run a good one, shop around a bit and you can get something like a 7 or 8 quart with the gates and scrapers. These ones will have the bulge on the side, and you have to be careful when buying them if you're running a stock starter, some won't fit. I hear ya on the snow. I'm from Minnesota and we're supposed to have a high of around -5 tomorrow. Luckily, I'm catching a plane for Florida early in the A.M. to watch the Daytona 500 and some other racing next week. >> I'm thinking of the crate motor because for $1300US I can get a >> complete long block that meets the rules. They pull a head off the [quoted text clipped - 54 lines] > high of around -5 tomorrow. Luckily, I'm catching a plane for Florida > early in the A.M. to watch the Daytona 500 and some other racing next week. AFAIK we can run any oil pan. I'm gonna go hunting for intakes when the weather gets nicer - it's too cold to wander around the junkyard in 20 below. FWIW, flat tops and max of 9.5:1 compression, pistons can't go past top of deck. Dumb question -> but is there really power to be had by winging it up to 6 grand? I'm used to either Pontiac V8's - lotsa torque down low, or smog era Chevy's - nothing that revs to 6 grand in a "classic" small chevy. (my LS1 powered TA is a different story.) I guess I'm just used to lower revs (I still think mid 80's Camaros with max power at 4000rpm) than higher revving engines... I'm worried about blowing it up... (although I manage to do it anyway...) It's still fun, even if my Visa card melts down every now and then. :) Ray > AFAIK we can run any oil pan. I'm gonna go hunting for intakes when the > weather gets nicer - it's too cold to wander around the junkyard in 20 [quoted text clipped - 12 lines] > > Ray Sorry I couldn't get back to you sooner. Yes, there is power to be had in revving them, depending on the cam really. Most race cams will have an RPM range listed where they work best. You can find ones that work better with the lower revs but I think you'd be giving up power. Put together well, there's no reason a small block chevy can't take 6000+ easily. > hey everyone, i have a 69 camaro with a 350 in it.. i have done alot of > work to it, building it from the block up. it is a four bolt main, [quoted text clipped - 14 lines] > > 69 maro After agreeing with the too-wild cam idea, there is another place you can improve: the heads. Those double-hump heads with the 1.94 intake valves can be re-worked and 2.02 intakes installed--leaves only a fingernail-clearance between int. and exh. valves, but it WILL work.. While heads are off, there's a lot you can do with a dremel-like grinding tool. Just smoothing up the combustion chambers and runners yourself allows much more efficient flow, and if it can't get thru the valves and heads, it can't get out thru the headers and exhaust. You might wish to experiment with the distance your mufflers are from the engine--varying this distance can cause a feel-in-the-seat-of-the-pants difference in torque. There's a lot to be said about valves, heads, porting, polishing, etc. Often there is a lot overlooked here while placing more emphasis on pistons and compression and cams. HTH, & good luck. s > After agreeing with the too-wild cam idea, there is another place you > can improve: the heads. Those double-hump heads with the 1.94 intake valves > can be re-worked and 2.02 intakes installed--leaves only a > fingernail-clearance between int. and exh. valves, but it WILL work.. I agree with you up to here......and then there might be a better solution. If you are talking about the old double humperheads from the '60s, and I think you are, take them off and sell them. Then buy some modern heads. People pay crazy prices for the double humpers and new technology heads are pretty reasonable, especially for a small block Chevy. My $.02. |
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