Guest Anonymous Posted April 17, 2002 Share Posted April 17, 2002 Grumpyvette, Last summer I bought a ’78 280Z hybrid. Here’s what I know about the engine: Block: Chevy 350, 2 bolt main, casting 3970010 from a ’75 Camaro, flat top pistons Heads: From a ’71 Chevy pickup, casting 3973487, 76cc and 1.94” diameter valves Cam: Lunati Bracket Master 2, duration @ .060, lobe sep 110, int/exh lift .458 Intake: Edelbrock performer Carb: Edelbrock 600 Headers: Hooker With this combination, what kind of horsepower am I looking at? Quite frankly, the car doesn’t feel very fast. My "seat of the pants" estimate is that I don't have more than 200 or so horses. What do I need to change on this motor to make 275-300 horses? Plus, I really need a 700R4 tranny because with the gearing this car has, the engine is turning 4000 rpm at 70mph! I'm currently using a Chevy 3 speed automatic. Thanks! Rick Man Quote Link to comment Share on other sites More sharing options...
Tim240z Posted April 17, 2002 Share Posted April 17, 2002 Rick, Although I can't give any real specifics, I had a similar situation: My 71 truck (same heads as yours probably) was a real dog. I replaced the heads (Vortecs) and the inlet manifold (had to with the vortecs) and the L98 grind cam. HUGE difference. Those truck heads breathe about as well as a brick! The vortecs are definitely good bang for the buck!! Tim Quote Link to comment Share on other sites More sharing options...
utvolman99 Posted April 17, 2002 Share Posted April 17, 2002 Im not grumpy but I will take a crack at it. I think your running somewhere around 8.6:1 compression ratio. Putting your combo into Dyno 2000 you are looking at around 300 HP at 5000RPM and 350lb/ft of torque at 4000RPM. Now this is just guessing on the heads. Im using a stock wedge style chevrolet head from Dyno 2000. As I understand it the head flow numbers provided by the program are not a very accurate representation. If you were to add a set of Dart Iron Eagle 215cc you should be able to bump your numbers up another 50hp or so. I will be interested to see if my numbers are anywhere close to grumpy's. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted April 17, 2002 Share Posted April 17, 2002 Rick, I used to have a link that gave stock HP numbers for various engines, and if I remember correctly, the stock 70s truck engines were at around 190hp. Pretty sad for an 8 banger Tim Quote Link to comment Share on other sites More sharing options...
utvolman99 Posted April 17, 2002 Share Posted April 17, 2002 One thing to keep in mind that any computer dyno #s will be based on a new engine. The computer also assumes that carb, timing and ignition setups are perfect. Like I said above, I based my assumptions on stock "wedge" style heads and I know that the flow numbers in Dyno 2000 are a little optimistic. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted April 17, 2002 Share Posted April 17, 2002 3970010....302.....69....4...Z-28 Camaro 3970010....327.....69....2...Trucks and industrial 3970010....350...69-80...2 or 4 WELL FOR STARTERS THE BLOCKS A GOOD ONE 3973487....71-72...350..........used on 71-72 350 LT1, 75cc chamber the heads are better than some out there, but not great. the cam is more than likely the LUNATI #00016 built for lower rpm torque, now it depends on how much time and money you are willing to invest to get more hp(your at about 315hp/360 tq now) so your guess was correct. the heads and cam and intake are your problems with the heads being the biggest one but of course without the other two matching your not going to get big hp. HOW MUCH CAN YOU SPEND? HOW MUCH WORK CAN YOU DO YOURSELF? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 17, 2002 Share Posted April 17, 2002 Grumpy and guys, Thanks for your replies and help. TIM240Z, I found a link on Camaros. Get this… ’75 Camaros only had 165 advertised HP, and that was for the 4 barrel model. Could be GM was playing games with the engine specs to downplay horsepower. There was a period during the 70's and 80's when muscle cars were being penalized with high insurance premiums, so the car companies started understating horsepower specs. UTVOLMAN99, Looks like your numbers agreed pretty much with Grumpy’s, so I’m wondering whether I should eat my torque wrench with Heinz or Del Monte Ketchup?? The engine that is in my car was freshly rebuilt, and currently only has about 1000 miles on it. It is still difficult for me to accept that this engine is putting out 300 HP. Grumpy, the Lunati cam is P/N 00016, for low end torque, rpm 1500 to 5200. What do you think would be a good combination of heads/cam/intake if I were to change something? What kind of $$$ are we talking about? These are bolt on types of upgrades, right? I have a neighbor down the street that could help me with some of the engine mods. Also, I thought that the Edelbrock Performer intake was a pretty good one. Not so? If I changed heads, I would have to change the intake, too? Thanks, Rick Man Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 17, 2002 Share Posted April 17, 2002 Sounds like it needs a tune up to me. How about run a compression check. Play with the carb and ignition. Replace the wires and plugs. Also check the valve lash if it is off it will be a dog. Also pour a little water down the carb once the engine is warmed up and running. Just let it trickle in. Or use a windex spray bottle and keep sprayinf g while the engine is running. You should notice a lot of black smoke comming out the exaust. This is the carbon comming off the valves and combustion chamber. These low buck tips do work! I also be my torque wrench that the ignition timing is too low. If this does not work you have lost nothing. If it does not work put on a RMP intake and a holley 600 vac sec. The Preformer is a dog and not any better or not as good as some factory offerings. You have a good foundation. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted April 18, 2002 Share Posted April 18, 2002 ok you have a reasonably good short block from what your telling me but the heads and intake and cam are killing the hp. if you go all out your looking at about $1500 for new heads,intake and cam, that will boost your power about 100hp-110hp, if thats too much you can get about 65-70 hp more for $1100, its a P.I.T.A. but hp costs money! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 18, 2002 Share Posted April 18, 2002 TIM240Z and UTVOLMAN99, Thanks for your replies. I'm curious, too, to see what Grumpy has to say. Yes, Tim, I'm suspecting that the heads are low performance, and the cam is designed for low-end torque. UTVOLMAN99, I think your numbers are way optimistic. I'll eat my torque wrench with ketchup if I'm pulling anywhere near 300 HP! The car isn't exactly a dog, but I'm really sure that high horsepower isn't what this engine is delivering. With that kind of horsepower and the skinny tires I'm running, I'd think I could break traction any time I tromped the gas, and that ain't the case. BTW, correction on my original post. I have a '77Z, not a '78, but, of course, that doesn't have any bearing on this... Quote Link to comment Share on other sites More sharing options...
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