Need help for rebuilding a 305HO
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Need help for rebuilding a 305HO
For the past week all I've been hearing is go with a 350, like as with another post here, I want the original engine. I have an 86 Firebird with a 305HO 5-speed sitting in it. I read all the comments on the TPI but I have a carb. So far I was thinking about changing the cam, intake, carb, and ignition (I have to take the computer off for the cam and carb to work). So far the car, stock, is pushing almost 200 horses, how much power increase can I expect from what I want to do? Is there any suggestions that anyone can give me on the cam size I should go to? Should I use headers instead of manifolds? I tried asking Summit and Year One but all they see is a female that knows nothing....lol
It is a daily driver but more than likely be stored in the winters from now on, and remember I to have about $2000 to play with.
It is a daily driver but more than likely be stored in the winters from now on, and remember I to have about $2000 to play with.
Junior Member
Joined: Feb 2002
Posts: 7
Likes: 0
From: Portland, OR
As I said in my original post, I want to keep the original engine and I have some tough emission standards. I'm not all that experienced at smog motors and if I spent $2500 to swap in a 350 and then couldn't pass DEQ....
And, if I can get close to 300 HP out of my 305, I'll be happy. Like rskermer, I'm more of a curvy road guy than brute speed. Although a little tire smoke never hurts!!
When I get my 305 done I'll be posting what I did.
Good luck
And, if I can get close to 300 HP out of my 305, I'll be happy. Like rskermer, I'm more of a curvy road guy than brute speed. Although a little tire smoke never hurts!!
When I get my 305 done I'll be posting what I did.
Good luck
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Don't waste your money on CC removal. It just doesn't get you any bang-for-bucks whatsoever. The compucams do a really nice job with the CC setup, and are emissions and daily-driver friendly to boot - you DO NOT have to remove the ECM to make power!
See sig for what I did. I spent right at $2400 without touching the shortblock (except changing out the cam, of course). I did get upgraded valve springs, and spent about 15 hours on the heads after they arrived (unassembled), which I'm sure helped the final results. You may be able to save a little by not changing cat or cat-back (although power would be reduced slightly if you keep the factory parts). You should also already have a dual snorkel air cleaner. Part of my expendature was for a higher stall converter, which will not be an issue for you. The intake isn't an absolute must-change, either, as a little Dremel work on it as you do the heads will save you some bucks with very little sacrificed power-wise. With those assumptions, you're looking at $1800-$1900 to do the applicable mods to your car (upgraded oil pump, rockers and ignition highly recommended). Remove the computer, and you're going to spend at least $400-$500 more (for new parts). BTW, my dollar figures include sweetheart deals on the oil pump & pan, intake, and torque converter - everything else was catalog ordered or purchased locally.
Desktop Dyno indicates 362 HP @ 6000 RPM for me (assumed 10% flow increase over World's unported numbers, 750 CFM carb, small-tube headers, 9.5:1 CR, etc.); that's probably a little optimistic, but 300 net is probably close, in a manner similar to what produced your 200 number.
You don't need a 350. A 305 will make nice power for the same money you'd have to spend on things to make the 350 work, anyway. Your T5 will be happier with a 305 as well.
See sig for what I did. I spent right at $2400 without touching the shortblock (except changing out the cam, of course). I did get upgraded valve springs, and spent about 15 hours on the heads after they arrived (unassembled), which I'm sure helped the final results. You may be able to save a little by not changing cat or cat-back (although power would be reduced slightly if you keep the factory parts). You should also already have a dual snorkel air cleaner. Part of my expendature was for a higher stall converter, which will not be an issue for you. The intake isn't an absolute must-change, either, as a little Dremel work on it as you do the heads will save you some bucks with very little sacrificed power-wise. With those assumptions, you're looking at $1800-$1900 to do the applicable mods to your car (upgraded oil pump, rockers and ignition highly recommended). Remove the computer, and you're going to spend at least $400-$500 more (for new parts). BTW, my dollar figures include sweetheart deals on the oil pump & pan, intake, and torque converter - everything else was catalog ordered or purchased locally.
Desktop Dyno indicates 362 HP @ 6000 RPM for me (assumed 10% flow increase over World's unported numbers, 750 CFM carb, small-tube headers, 9.5:1 CR, etc.); that's probably a little optimistic, but 300 net is probably close, in a manner similar to what produced your 200 number.
You don't need a 350. A 305 will make nice power for the same money you'd have to spend on things to make the 350 work, anyway. Your T5 will be happier with a 305 as well.
Joined: Jul 2000
Posts: 6,521
Likes: 91
From: Aridzona
Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Headers definitely. Random Tech's L69 catalytic converter is one of the better deals out there; I think TPIS sells it for $215.
Your car is an 86 L69 HO car w/ the 4 bolt cat flanges & 190hp stock?
You should give the car a little more cam but don't overdo it (see my sig hehe, I ran the 272 w/ the carb also); you won't regret a little more cam w/ 3.73's and a T5. The ZZ4 intake or the 3701 from Edelbrock will help a little but you should do exhaust first.
The computer carb will support everything you want to do w/ some tuning. You don't have to remove the ecm to accomplish this.
Running some combo's w/ TPI on desktop dyno, the L69 cam was hard to beat for overall tq (which is what matters) but I'm not sure on a 4bbl combo.
You could also run the ZZ4 PROM in the ECM for a little more fuel.
The dual snorkel air cleaner was a Camaro item; I believe the HO birds got a hood / cowl area induction w/ a 4 & 5/8" opening in the air cleaner lid, right?
If you're on a budget, do the shortblock properly, and do heads & intake when you can afford. Do headers now.
Matthew
Your car is an 86 L69 HO car w/ the 4 bolt cat flanges & 190hp stock?
You should give the car a little more cam but don't overdo it (see my sig hehe, I ran the 272 w/ the carb also); you won't regret a little more cam w/ 3.73's and a T5. The ZZ4 intake or the 3701 from Edelbrock will help a little but you should do exhaust first.
The computer carb will support everything you want to do w/ some tuning. You don't have to remove the ecm to accomplish this.
Running some combo's w/ TPI on desktop dyno, the L69 cam was hard to beat for overall tq (which is what matters) but I'm not sure on a 4bbl combo.
You could also run the ZZ4 PROM in the ECM for a little more fuel.
The dual snorkel air cleaner was a Camaro item; I believe the HO birds got a hood / cowl area induction w/ a 4 & 5/8" opening in the air cleaner lid, right?
If you're on a budget, do the shortblock properly, and do heads & intake when you can afford. Do headers now.
Matthew
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