it has been running better after I fixed the ESC and adjusted the timing,but it still falls flat on it's face at 4000rpms. I'm going to break this down one by one and fix it right,instead of mindlessly buying performance parts that have claims to improve high rpms. I've seen this car happily rev close to 6000 stock (with gutted cat) I have a cat now,but it is a high flow and a very non-restrictive exaust system. I've checked the simple things like the air filter,thats a K&N so I shouldn't need to replace that. will blocking off the EGR flange help performance? then I may have to check out the carb,could this be caused by the secondaries leaning out the mixture after 4000rpms?the engine is a 305 HO (L69) with 8k miles on it (reman.)

 

IM no expert... but It could be weak valve springs. Did it slowing start losing top end?

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

I haven't really been too hard on this engine,it's a remanufactured longblock with 8k miles on it. I've just started to test WOT. I'm sure my ignition is ok,the carb and EGR is questionable. the engine was f-ed up for awhile because the ESC wasn't working and I had to run advanced timing to compensate. I hope this isn't a bunk engine,it has a five year/75,000mile warranty,but I don't think they care if you can't take it over 4000rpms. I'll sell this whole engine,but I want it to run good stock,I'd like to get an LS1. I might need another year or two to do that.
how can I tell if the springs are bad?

[This message has been edited by junkyarddog (edited July 01, 2001).]

 

I doubt that after only 8K that the springs are bad. Some things to confirm first... camshaft and compression. If I am reading correctly, you have had this engine to 6K once before and it was OK with that? If so, than look into carb stuff. I am also assuming you are using a Q-jet... look at Ed Mahar's tech article.

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

I would tend to think that this is an ignition problem. Did you by chance read that Hot Rod article a while back about the guy that put the 383 in the 3rd gen TA? He was having a similar problem with not being able to rev past a certain point. If I remember right, his problem was spark plug wires.

Anyways, I've heard you shouldn't use high performance wires with stock ignition, because they're too much resistance. And similarly, don't use killer ignition with stock wires. If you've got an ohmmeter handy, you can check resistance of each wire to make sure it's not too high.

Might want to check the plugs too.

 

What do you know about the reman longblock you bought, i.e. what is in it. I'd bet dollars to donuts it's a generic dish piston, generic (peanutish) cam longblock. Thus, naturally it doesn't have tthe same pull as a mighty L69. Unitl you verify (not assume) what parts went into it, assume you bought a junk engine.

The simplest explanation that fits the problem is usually right.
...ed