I took a vacation from the Camaro. I'm back at it now.
I was getting burned out. Constantly working on it and nothing else was getting done. But now I'm back at it. It's still not running right. I had the plugs gapped at .040 and thought the spark was getting blown out so I regapped them to .025 and it still falls on its face under boost. Now I'm thinking maybe it's my cam. I'm using an XE268H Comp Cam. Might try and change that out. I'm gonna retard my timing again. It was at 8 deg BTDC I'm gonna try it at four. I got the carb jetted rich. And it is running rich by the look of the plugs. Anyone got any other suggestions? Glad to be back at it. Also one of my headers is starting to sag a bit from all the weight and exhaust pulling on it. I'm gonna have to brace that up I guess. I thought it would hold. But I guess not.
Brad...
__________________ 1986 SC TwinTurbo Camaro
Mods: Threw 2.8 in garbage, put in rebuilt
350 .060 over, XE268H Comp cam, Edelbrock
Performer RPM Intake and Edelbrock 800 CFM Carb,
Rebuilt TH350, 3.42 Rear Gears. W/ Powertrax Lockright,
LCA RLB's. B&M Mega Shifter. Vortec Heads. Best time 13.769
I made some log headers like yours out of some old headers. For support I am tacking angle iron the entire length of the top and bottom of the manifilds, this might help in your case. I was also wondering, with log type manifolds, would the exhaust create holes over time in the side of the manifolds? I used 14 gauge exhaust pipe( i think) which should last a while. I dont have pics, but hopefull you understand what i am saying.
Could it be possible that you are running too rich? On my motor (low compression, turbo cammed, 350ci), without the turbos, anything over half throtle floods it (750 holley DP). It really falls on its face bad, I am predicting that the turbos will help stop this problem, i guess i will just have to try it.
Your cam isnt the best turbo cam, but it should work decently. I would venture to say that the problem lies somewhere else, but it is a possibility.
yeah bhaas i dont think its the cam or the breathing ability of the motor...
considering your running a carb with 2 turbos bolted to home made exhaust theres plenty of room for other problems to crop up...
timing could be a huge issue, with a cam like that most people like to use a lot of advance. on my 262XE i run 15 initial, anything less and the thing doesnt have any throttle response. big cams need advance, not that yours is huge, but its much bigger than a stock one.
remember vacuum leaks can play hell with a carbs ability to meter fuel, and with a blow-thru app like yours i have no idea what that could do... check for them too!
have you tried running some race gas or octane booster? just because you cant hear detonation doesnt mean its not present. just a thought, as it would rob you of power.
you say the spark is getting blown out, but maybe your just running way to rich up top like was said above. another idea.
I've been following along with your progress for a while, considering copying your header setup simply because it look easy enough, but im waiting to see what happens to you first you are my official guiney pig, so its in my best interest to see you succeed and finish this monster.
Right on Brad, I was starting to worry you had given up! lol
I know you have EGT gauges, but do you have an o2 hooked up? Could be going lean on the secondaries..
I had a similar problem where half throttle and full boost was awesome and right around 12:1 A/F, but as soon as I opend up the secondaries, it went down to like 15:1 A/F.. Very baaaaad.. I jetted my rears up to 99's and drilled the PVCR's to 3/32 and now it's around 12:1 @ WOT...
But, alas, it was too late and I had already lifted a gasket from the testing stage where it was running too lean..
Just be very carefull while tuning, you don't want to end up like me and have to rip everything apart...
Oh yea, with a blown head gasket, 3/4 throttle, 10psi of boost and running pig rich, it will blaze the ol ET Streets like there's no tomorrow...
Good luck!
__________________
Andrew MacPherson www.ttz28.com
1982 Z28 - Twin Turbo'd 350ci 4-bolt - Holley 800 Dbl pumper - Vic Junior - 1.5 Roller Rockers - 220cc Pro Action angle plug Heads - Comp Cams Nitrous HP Cam - Pete Jackson Noisy Gear Drive - Headers - Dual 3" exhaust with side pipes - TCI 3200 Stall - 3.73 posi - MT ET Streets - N.O.S. Super Power Shot (Currently at 150)
Well, now I have another problem. I have a crack in one of the stubs. Just gonna have to weld that up. And my headers were red hot. Never seen that before. I drove the car to work last night and when I got home this morning they were red. Both sides. I also retarded my timing to 4 deg. I guess it didn't like that. So I guess I'll advance the timing and try some smaller jets. This is getting old. I want to beat on my car. Not work on it all the time. I gues it's back to the old car grind again. The fun never stops. That's too bad Bottlefed. That's a lot of work. Or just a major pain in the ***. I'm gonna try some of the suggestions you guys gave me. I want to avoid changing the cam. But if I have to, then I'll do it. Thanks.
Your cam isn't the cause of the problem you describe.. It's a fuel thing, I'm almost positive..
The biggest problem with blowthru setups like ours, is the air flow over and thru the carb..
Do you have an A/F gauge you can watch while testing? This is a MUST and I can't stress that enough.. Reading your plugs may not help at this point because it's probably running real rich at cruise and idle so you aren't really going to be able to tell what's going on at WOT thru the plugs..
Is that edelbrock carb you're running a vac secondary or a double pumper.. If it's a vac secondary, how did you boost reference the secondaries? I'm pretty sure we went over this before, but it's been a while since we last chatted...
you are my official guiney pig, so its in my best interest to see you succeed and finish this monster.
WWW.OUTLAWPERFORMANCE.COM
