305 TPI, -will not rev.

Hi all,
I'm trying to help my brother in law with his 1990 Camaro 305 TPI, but it's been almost 15 years since i touched a V8 from the other brand and never a TPI = Help!!!
The problema is that it only makes power to about 4500 rpm, You can rev it to 6000 rpm but with out power. I was expecting power to 5500 at least. It dosent missfire the power just dies out, but power is very good below 4500 for a 305.

Specs.
5-speed and 3,73 posi.
305 TPI, stock bottom
Alu heads, 10088113 1,94/1,5 58 cc + thick Fel pros
CR is low, not measured. 7,5-8 ?? Could be a reason??
CompCams 264 HR-12 210/220° .480/.480 @112° degreed to 0°±0.5°
Trottle body 2*58 mm
Headers + 3'' single exhaust tested w/o CAT, no difference.
Injectors 24 Ib/hr. was no better than the stock 19
Modified TPI chip don't no brand.
Timing is set to 10° says the brother in law.- I'm ????
Most of the parts will go in a 350 later but this 305 must screem utill then

Dyno tuning is far away and cost $$ and will be saved to the 350 set up.
Can You mesaure timing without load on engine "the old way" ? 36°@3-4000
Maybe put 1,6 rockers on ??

Regards from SWEDEN


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4500 was just about the limit of the stock tpi intake, it was designed for low end tourque.Probably have to get different intake setup on it to make power beyond 4500 to 5000.You can check the timing with a dial back light or degreed balancer or tape to be sure the ecm is giving what it needs still should be close to 36 at 3000.

Not enough compression, too much cam, and the stock TPI intakes wussed out at 4500 anyway. Sounds like its operating correctly to me.

I`m with Curtis on this one. The stock TPI in flow terms was equal to a 2 barrell carb.

check your fuel pressure.. Or check for flow restrictions.

Is the stock 350 intake manifold better than the 305?

And is there a vacuum hose to disconect when checking timing @3000 like on a distributor?

//Stefan

Thanks Curtis
But -too much cam?? explain please.

//Stefan

You wouldn't diconnect anything to check the curve only to set base timing.There will be a connector to unplug to set base.The emission diagram on the car will show its location.As far as the 350 tpi flowing more I can't say it sounds reasonable but who knows?

Do you mean a stock 350 tpi manifold? There is no such thing, GM designed the TPI to feed a low rpm 305. The intakes on the 350 where the same.

We checked the timing with nothing disconnect and is was 12°@1000
and 32°@3500
we increased the timing by 6° to 38°@3500 and it now pulls little harder and to almost 5000 rpm.
It did not like more timing. With more timing it "missfired" on lower rpm.
I would like to have 38° + 12° for "vacuum advance" with nothing disconnected
and no load on engine???