Guest Tom Simpson Posted June 30, 2001 Share Posted June 30, 2001 I have no idea what cam I should get or what carb. As it sits this is my setup Please make some suggestions. It is backed up by a 3.55 rear end and TH350 1980 350 4 bolt main block Dart Iron eagle heads .192 valves, 72cc performer intake edelbrock 600 carb with elec. choke short hot rod headers flat top pistons 1.5 roller rockers Very mild street cam(.443/.465/.262) not sure about those cam specs, but its a gutless cam true roller timing chain HEI ignition(have MSD stuff sitting around) Well guys....what do you think? It's the cam and carb thats killing my performance isnt it? [ June 30, 2001: Message edited by: Tom Simpson ] Quote Link to comment Share on other sites More sharing options...
z ya Posted June 30, 2001 Share Posted June 30, 2001 The cam and intake is a little small for those good flowing heads. I would suggest the comp cams 274 x energy. Also go for the eldlbrock air gap rpm intake instead of the performer. As for the carb, I think its fine. If ya got the extra cash, go for the 750cfm. Quote Link to comment Share on other sites More sharing options...
Guest Tom Simpson Posted June 30, 2001 Share Posted June 30, 2001 No room under the hood for the air-gap...darn scarab position. You think that carb will be enough? I dont mind getting another carb if it will help. Tom Quote Link to comment Share on other sites More sharing options...
fl327 Posted June 30, 2001 Share Posted June 30, 2001 youre setup sounds just like mine, but i dont have half that stuff on my car, 1.92 heads with roller rockers should be great with a 600cfm, you got a nice gently upgraded motor right there, have you done all of your interval maintainance to this point? sounds like a strong motor, your combo sounds good, also remember, the performer only makes good power from idle-5500, even if you went crazy with the bumpstick, you couldnt get its full potential, but that doesnt mean you can bump it up a notch, maybe a performer series cam, and get in that carb, hope i dont sound dumb or anything, im just not into spending money if i dont have to, and i hope you are too... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted June 30, 2001 Share Posted June 30, 2001 I think I agree with the other gents. The 600 cfm should be adequate unless you are looking for huge amounts of power. You didn't mention your expectations of the engine HP wise. For street, I'd look for a cam that has about 225 deg duration at .050 lift. You could go with more duration, but it won't be real enjoyable if its a street driven car because it won't see RPM enough to really take advantage of the duration all the time. You can use split durations on the intake and exhaust although according to Isky this does lose more bottom end. If its used more for strip use of course, you could use more duration then, as low rpm won't be as much of an issue. You didn't mention a compression ratio which will also be a factor, shoot for a tad under 10-1 with the above mentioned cam spec's and it'll put out good power (good enough for a shade over 400 - 425 hp.) IMHO. Good luck with it, Lone Quote Link to comment Share on other sites More sharing options...
Guest Tom Simpson Posted June 30, 2001 Share Posted June 30, 2001 hmmm, well I guess I'll start with a cam Anymore cam suggestions? Quote Link to comment Share on other sites More sharing options...
Guest Tom Simpson Posted June 30, 2001 Share Posted June 30, 2001 Well, I'm thinking I should go with the Comp Cams xtreme energy cam Grind: 274 Lift: .487''/.490'' RPM Range: 1800-6000 Sound about right? Quote Link to comment Share on other sites More sharing options...
Guest Tom Simpson Posted July 1, 2001 Share Posted July 1, 2001 just bought a comp xtreme 274, lifters, and hardened rods..... lets see if it helps Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 1, 2001 Share Posted July 1, 2001 Couldn't Hoit... Regards, Lone Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 1, 2001 Share Posted July 1, 2001 That cam choice sounds really good--not too much cam for this application. We still don't know what the compression is, though. That info would be vital. With the heads being 72cc, if the pistons are standard flat tops, the compression may be a little low. But, the cc of the Iron Eagle heads is better than stock. We know the heads have great flow, the carb (if it's functioning properly) at 600 cfm should be more than adequate to about 5500/6000 rpm. The Performer intake is ok and is at the very least matched to the carb. Try the cam swap because it's relatively cheap--but if that does not totally wake the motor up, you have too low of compression. If memory serves me right stock smog heads are 76cc and will yield about 8:1 with stock pistons. 64cc heads will yield about 9.5:1, so if your pistons are stock, then you're looking at 8.9:1 to about 9.1:1 compression. Good for streetability! Your new choice of cam seems really well suited to the engine now. It should wake that puppy up. Davy [ June 30, 2001: Message edited by: DavyZ ] Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted July 1, 2001 Share Posted July 1, 2001 Hey guys re: air-gap not fitting under hood in the scarab position. I beg to differ but mines in scarab position and Im running 355 sbc with edlebrock heads, air-gap manifold and 750 carb. I just used a low profile recessed 14 inch edlebrock air cleaner with k/n filter 2/3/4". Mike Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted July 2, 2001 Share Posted July 2, 2001 Tom, If your engine is bone stock & hasnt been bored or the block decked-then your 72cc Combustion Chamber heads w/flat top pistons would yield you @ 9.4:1; now, if your engine has been bored .030 then your comp.ratio should be @ 9.3:1 w/flat tops...yes your previous cam is a limiting factor to your max perf. race! Remember, your 600cfm carb can handle the extra perf. of your cam & heads-it will give your engine a "crispiness" in the throttling of your engine-however, you may have to tune it to the new perf. of the new cam. The duration of the cam will also determine how much air is being "compressed" on the compressions stroke as the duration determines when the intake valve closes in relation to the piston's location in the cylinder-on its upward motion within the compressions stroke; "Duration" with the cfm your intake ports in the cylinder head what cfm your heads flow at valve lift increments will determine what perf. gains are to be had. We know your cyl.heads should flow nicely; your cam, for the street, & based on the alledged 9.3:1 or 9.4:1 comp.ratio, for the street, needs to close the Intake Valve @ 46*ABDC (this needs to be the advertised "Seat to Seat" measurment-taken at .0044")! You could actually close the Intake Valve a little later-but then you'ld be hurting dinamic compression & would need a lesser "cc" combustion chamber. Let us know how your new cam works out! Kevin, (Yea,Still an Inliner) Quote Link to comment Share on other sites More sharing options...
fl327 Posted July 2, 2001 Share Posted July 2, 2001 a little nitrous wouldnt hurt either, dont tell us it wont fit, they made a v8 fit didnt they?? if it dont work, make it work!!! Leonard Quote Link to comment Share on other sites More sharing options...
DavyZ Posted July 2, 2001 Share Posted July 2, 2001 Len, he may have cast pistons which can only take a minimal hit of nitrous, and if they stock cast, I wouldn't hit them at all. If they are hypereutectic they can be hit, but forged is the best for NOS. Kevin, what do you think the compression would be if he had the nasty stock pistons? They are usually not flat-top, but are a dished kind. I should have read his post again and had seen that he did mention the pistons. I was totally winging it, but I may have been close if they were stock. I agree with you that the comp. ratio should come in right about where you say it is. Regarding the new cam: I think he has chosen wisely. Davy [ July 02, 2001: Message edited by: DavyZ ] Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 2, 2001 Share Posted July 2, 2001 Not sure what piston he has, my engine has 75cc chambers and has a lowly 8-1 compression (stock goodwrench specs), some of the smog motors could be the same way. Very likely cast like mine, which is ok for light performance use but I wouldn't go crazy spraying it or over reving it and if you use smaller chamber heads detonation really has to be monitored and dealt with, or as you might expect you may be getting a first hand look of your engines internals (possibly flying by your windshield or running over them.. ). We dropped the pan one time on a SBC and found lifters... needless to say there wasn't much point in stripping that motor down any farther... Regards, Lone Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted July 2, 2001 Share Posted July 2, 2001 Davy, Cant really say about the "Stock" set up; what is stock(?), two eyebrow valve reliefs or 4 eyebrow reliefs & how many cc's are the eyebrows adding to the cyl.head's comb.chanmbers? My calculations were made on his "Flat Top Pistons" statement and his "Iron Eagle 72cc Cyl.Head" statement. Unless he knows for sure which pistons he has-then its mostly just a crapshoot. I agree about detonation-if you're using stock pistons & smog heads! Airflow Velocity, the Mass of that airflow & the temperature of the air w/in that airflow are the basic juggling variables of any build-and the combinations of those three items either work together in a performance engine or they resist each other & hurt your output. Attempting to use a high perf. cam in a stock engine w/stock pistons & cyl.heads will only work up to a reasonable point; once you go past that point things cant get out of hand rather quickly. Quench is always a factor; the stock 350 SBC at TDC has .022" from the piston deck to the block deck (this is where a longer rod comes into play as it lessens that .022" distance) and as combustion occurs the piston (already down in the hole .022") is making it's move down the cylinder as this combustion occurs...so you're almost immediately losing cylinder pressure as your flame front is burning across the tops of the pistons. If you use a longer rods, mild pop-up pistons or deck your block close to a "0" block deck-then cylinder pressure (Quench) will actually give you a double positive wammy of extra cylinder pressure-thus the probability of detonation decreases! Isnt it fun looking at & trying to "See" what the engine is doing at a microscopic level! Ahhh, so many possibilities & so little time. Kevin, (Yea,Still an Inliner) Quote Link to comment Share on other sites More sharing options...
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