About a month ago I did a cam swap.Took it to the track this weekend and only gained a tenth and my MPH went down a little.The cam is a comp cam 8-302-8 L.480/.480 D210/220 LSA112.The only things I can think of thats could be killing me is that when I changed the cam I saw a lot of carbon on the valves and stock runners are probably choking the engine.I thought the cam should have gave me about 10-20HP but my MPH in the quarter mile say's noway.What could be wrong?I adwanced the timing as high as it could go without knocking,I played with the fuel pressure tried 40psi through 50psi ran the fastest at 46psi.What do I do now?

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89 350 TPI,comp cam,edelbrock intake base,SLP headers,highflo cats,flomaster cat back,accel 300+ ign,ported plenum and runners,ported maf,auto w/shiftkit,cold air induction,AFPR,Ed wright chip,3.23 posie best ET 14.011@98.72mph without cam/New best 13.926@98.27mph

 

lm not a genius at this, but it being EFI, might it need a bit of chip programming/upgrade to take full advantage of the new cam?

Just a thought.

Clayton

 

Well, there are a lot of things to consider. What were the track conditions like before and after you did the cam swap? WHat kind of 60ft times did you have with the old cam vs the new one, things like that.

One thing to keep in mind is that TPIs are really sensitive to cam swaps. There are only a handfull of cams that are gonna give any kind of gain on a stock TPI system. Most of the time, you have to upgrade your lower intake and possibly runners as well to see any gains(like you said). I installed the small SLP cam in mine and didnt get any gain.

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L98, 3.27 9-bolt, Hooker shorty headers, custom 2.5inch Y-pipe, no cat, 3inch 2chamber flowmaster, JET AFPR, Ported MAF, Best ET: 13.86 @100mph. 1.99 60'
17 inch ROH "ZS" wheels. 17x8.5(front) and 17x9.5 (rear). Firestone Firehawk SZ50s. 245/45/zr17s and 275/40/zr17s. T56

On the way... Radar Blue 89 Formula, T56, Ram Jet 430, Ram Air, 17inch ROHs.

 

Not trying to be unsympathetic here, but look on the bright side: at least you didn't go slower. Because after my cam install, I lost one tenth and one mph. I also installed the smaller SLP cam. I even matched the springs. Since then I've gotten a custom prom from fastchip, but I haven't taken it to the track yet, although the gtech doesn't show any noticeable improvement. That SLP cam is supposed to be designed for TPI. I think that's a crock of $h*t. Especially when I hear that someone else had the same problem with the same cam. All I can say is you're not alone. I don't think the carbon would have made the difference since it was there both before and after you put the cam in.
Ya know, if I wanted to make my car slower I would have just pulled off a plug wire. I could have done that for free rather than spending all that time and money on a cam.

 

Look at it this way, you 75% of the top end of the engine apart and it still runs, thats half the battle.
Like formula joe says, i'd like to know your 60' 330' and 1/8 times/mph as well as weather conditions at the time. For example, mild wheelspin can sometimes give you a little extra MPH. Maybe there was a headwind ta the track that day. Maybe it was warmer/less barometer. Maybe you don't need to be running that muich timing. Advancing till pinging is way out, advancing for max mph is way in (if you used to read MAD magazine you'll get it.) Also, don't foregt that you could have easily ended up with agasket misalignment blocking an intake port (or a few) costing power. Maybe you have your valves adjusted on the loose side and they were on the tight side before. Your old cam was 207/213...you didn't go that much bigger so don't expect that big of a gain, and 1/2 turn of preload can give you +/- a couple more degrees. The extra lift won't do much on a stock headed engine. Maybe your throttle isn't opening all the way. Maybe you had 80 extra lbs of fuel/your CD collection in the car.
There's a lot of variables to look at, unless you can rule out everything you can't blame the cam for losing you MPH, esp. since it OBVIOUSLY runs stronger off the line.
...ed

 

E-man, time for some dyno tuning. I tell this to everyone who has extensive mods now after witnessing it myself. My friend has a 355TPI GTA. ZZ9 cam, TPIS big mouth manifold, headers, catback, intake blah blah all that crap. Well he was running 14.4. After the cam swap and manifold swap he was running 14.5. He took it to get dynoed and found out he was way to lean at WOT (186rwhp). The tuner said it was putting him out of 60-70hp. So we bumped up his fuel pressure from 49psi to 62 psi and his rwhp jumped from 186, to 219. A 33hp gain at the wheels just from bumping up fuel pressure. He has to swap to bigger injectors now to get the rest of the ponies. He doesnt plan to run 62psi long, just until the new injectors are in. Do you have stock injectors? I'm not saying this is your problem, but it very well could be. Just something to consider. Where are you located?

[This message has been edited by theformula (edited March 15, 2001).]

 

Well, you have aftermarket intake and chip, so I would venture to guess that maybe your cam timing is off a little bit. Those marks on the timing chain have to be PERFECT for the cam to run right in the motor. If your valves are dirty, that could be part of your problem and also if you didn't get new springs with your new cam that could also cause a problem. If the springs aren't right for the cam, the valve will have trouble sitting correctly in the valve seat. I would make sure your engine is in proper tune, and maybe run a few good bottles of GB44K engine treatment through the car, that should clean up those valves well enough.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!

 

I used the valve springs that the cam card said to use.The deal with the chip is I used a hyper-crap thermo master,with the fastchip I was geting knock to much advance I lowered timing 0-deg. and the computer still was pulling timing out put in hyper-crap had to lower timing to 4-deg to get rid of knocking total advance is 35.5-deg at 3200RPM.The throttle is opening all the way checked that.My old best was 60ft-2.012 **330ft-5.802**1/8ft-8.981**1/8mph-75.65**1000ft-11.706**1/4-14.011**1/4mph-98.72 temp-76,humidity-88,baro-29.47 new times 60ft-2.012**330ft-5.764**1/8-8.907**1/8mph-77.95**1000ft-11.629**1/4-13.926**1/4mph98.27 temp-53,humidity-70,baro-30.45 Old run had a lot more tire spin than new run

[This message has been edited by e-man (edited March 16, 2001).]

 

Do you think that something else is wrong that the computer is pulling the timing out? Stock timing 6BTC with the hypertech was pulling about 11deg out at 4500RPM with the fastchip it was like 21deg pulling out.