darkride86T/A

I'm thinking about replacing my 86' LG4 305 with an 88-92' LO3 roller 305.
I thought about using a roller 350, like an LO5 or LM1, but I like the 305 motors, despite the fact alot of people think 305's are turds or boat anchors.
For me the 305 is a good blend of power, economy, and reliability. I just want to switch from a flat tappet LG4 to a roller LG4. I'm still going to use my Q-Jet. Well here are the questions I have:

1. Will I still be able to use my 86' LG4 ecm with the newer motor
without any problems?

2. Do I have to change my 86' distributor gear out before dropping
it in the roller motor?

3. Will my 86' alternator & A/C brackets bolt to the front of the 88-92'
305's?

4. I'm still open to using a 350, roller or not but if I use the 5.7L, who can I
contact about burning a chip for my ecm? Or will the car run okay with
the stock LG4 ecm as long as the 350 is bone stock with exception of
intake, headers, and exhaust?

Apeiron

Yes

No

Yes

Yes

darkride86T/A

Is there anything else that I will need to do the swap?

Apeiron

Not really. It's a pretty easy swap. The computer on a carbed setup does very little in terms of running the engine, so there's not much to worry about.

darkride86T/A

I'm setting my car up more for daily driving and handling rather than 1/4
mile performance(hence why I'm keeping the 2.73's),but I'm curious about
how much HP & TQ a 9.3:1 350 would produce. Do you have any ideas or
a good educated guess?

Apeiron

It would really depend on the heads and cam.

darkride86T/A

I'll probably use an Advance Auto reman. 350, you know like an 89-93
9c1 police pkg. Caprice 350. In the Caprices they had anywhere from
190hp/285lb.ft in 89' to 205hp/300lb.ft. from 91-93. I would think an
F-body's exhaust system would flow better and produce more power.

Apeiron

Those numbers would be about right if you're going to run a stock LG4 exhaust.

1320_Guy

iTrader: (3)

3rd gen exaust sucks, and if you have the ho 305 then you are already at that power level.

darkride86T/A

I plan on using Heddman Hedders or Edelbrock TES and I already have an
Edelbrock Performer intake but it's for 55-86 SBC's. I've heard you can modify
the 55-86 Performer to fit the 87 & up SBC's. How much HP & TQ do guys think with these bolt-ons and maybe an MSD 6AL?

Apeiron

The exhaust is the only thing that'll actually gain you any power there. The heads on a reman Caprice engine aren't going to be anything great. You'd be better off just getting a 350 shortblock and putting your LG4 heads on.

darkride86T/A

I thought about doing that as well but I'm concerned about the CR
being to high. I run 87 octane gas with no detonation problems, but that's with an 8.6:1 compression std 305 with 199,000 miles on it. I want to be able to still run 87 in my car.

Apeiron

If you're buying a new shortblock, you can pick something with a dished piston to keep the static compression under control if necessary.

darkride86T/A

Thanks Apeiron, you have answered alot questions I had.
You've given me some options to consider. I'll have to think
about which route I want to take. I'll let you guys know which
way I'm going to go.

five7kid

iTrader: (14)

'86 LG4 CR was 9.5:1. https://www.thirdgen.org/1986-chevy-camaro

Ditto the above heads recommendation. The Caprice engines have dished pistons, so you aren't going to have that high of compression even with the 305 heads. My pistons have 12cc dish for a streetable 87 octane 9.7:1 CR.

The odds of having an '86 HO are pretty slim - they only made 74 of them, out of 192,219 Camaros made that year.

You don't need to worry about the ECM as long as you don't go nuts on the cam overlap. If it is going to be a daily driver, you aren't going to go nuts on the cam overlap.

My ZZ3 shortblock, ported World Products 305 heads, ZZ3 intake, Hooker 2055 headers w/3" exhaust, puts out an estimated 365 HP. Daily driver. 17-22 mpg, depending upon conditions. Runs mid-13's with 2.93 gears. (I'd say, "See sig", but this information will be lost when the sig is updated with the LS1/T56 info. . . )

darkride86T/A

No, I don't have an L69 H.O. 305. Only 26 T/A's came with that motor in '86.

darkride86T/A

Okay, here's another question. What are the benefits of switching to a
roller 305 or 350 vs. putting in another flat tappet 305 or 350, assuming
that the cam profiles,duration,and compresion ratio are all similar?
(i.e. : stock camshaft/duration and CR, non H.O.)

Do the roller SBC's have better longevity than the flat tappet SBC's?

Is there a difference in HP and TQ with roller vs. flat tappet, or is it
just a diffference in RPM potential?

Apeiron

A roller lifter lets you use a cam with steeper ramps, so that the valve opens and closes faster, allowing it to stay at high lift for longer.

As an added benefit, you get less friction and wear, especially considering the changes in oil additives lately. There's also no need to break-in a roller cam, you just install it and go.

darkride86T/A

I also have a question about the CR of an 86' LG4. In the techboard it states CR is 9.5:1. It also states that HP is 165. I have several manuals and books about the 3rd Gen F-Body, and some say the CR of an 86' LG4 is 9.5:1 and some say it's 8.6:1 for 1986. Some of the info I have also says the HP of an 86' LG4 in an F-Body is 155HP and 160HP. Some of my books say 87' LG4's had 165HP.

My question is, which info is correct?

91 355 z28

i would stay away from advanced auto, and pepboys too.. and deffinatley not jasper.. i would try a different route as ive had an advanced auto engine with rod knock the first 10 min it ran.. got it for free with the car so i guess u cant complain.. and everyone ive talked to has nothing but bad things to say about jasper

five7kid

iTrader: (14)

'85 & '86 LG4 had flat top pistons with 4 valve reliefs for 9.5:1 CR. '84-earlier had dished pistons for 8.6:1. '87-later had slight dish with 4 valve reliefs for 9.3:1 CR.

Apparently there were slight differences between cars that the LG4 went into so that some were 155, some 160, and some 165. I can't tell you exactly what those differences were (exhaust? air cleaner?).

darkride86T/A

five7kid, do you know what the sizes of the valves are in the 86' LG4 heads? And can I interchange 55-86 heads with 87-up roller blocks?

Apeiron

Should be 1.84/1.50

darkride86T/A

What about O'Reilly's, Auto Zone, or Napa reman engines?
----------
You can fit 1.94" intake valves in the 305 heads can't you?

darkride86T/A

I'm looking at a Jeg's catalog right as I type. I'm looking at a GM Goodwrench
350 crate engine for 87-95 Chevy/GMC 1500/2500 Light trucks. The p/n is
809-12568758, and it's $1729.99. Here are the specs:

200HP/300 LB.FT. of TQ.
9.4:1 CR
flat tappet cam .382 intake/.402 exhaust
duration @.050 : 165.9 intake/174.8 exhaust
65.3cc heads with swirl port design,and 1.94/1.50 valves
high volume oil pump


I KNOW, I KNOW, it's a truck motor. What are you guys thoughts on
this motor?

Apeiron

Yes. That's a machining operation though, of course.

five7kid

iTrader: (14)

If you thought the LG4 was lame. . .

Yes, you can put '55-'86 heads on a roller block.

Apeiron

Swirl ports get a big thumbs-down, especially in stock form and compared to your LG4 heads.

darkride86T/A

Wow! LG4 heads flow better than the late model swirl ports?

Apeiron

Just about anything does.

darkride86T/A

HA!HA!HA!HAAAAA!!!!!!!!(while I'm Rolling on the floor)

Apeiron

Power comes from the heads.

darkride86T/A

Okay, I've contained myself now. Sorry for my outburst, it's not everyday
that someone tells you that your 21 year old LG4 smogger heads are way better than newer swirl port heads.


Okay, what about this motor? :

GM Goodwrench 350 (1985-earlier w/ Rt&Lft dipstick)
260HP/350FT.LBS. of TQ.
4 bolt main 2pc RMS block
hyd.flt.tappetcam .383" intake/.401" exhaust
112 degree lobe separation
76cc heads(I know......utter)
8.5:1 CR
4 qt. oil pan
p/n :80910067353, cost $1479.99

What if I use my LG4 heads with this motor?
What would CR be and possbile HP & TQ estimates?
And would this combo work with my stock LG4 ecu?
Could I still run 87 octane?

Apeiron

LG4s aren't really "smoggers", but swirl ports are.

You'd pick up a bunch of compression with LG4 heads on that block, but you'd still be able to run 87 octane. The LG4 computer has so little control over anything that i'll run happily on just about any engine. That cam is small enough that you're in no danger of making too little vacuum for the computer. Then again you're in no danger of making power with it either.

Try finding a short block instead of those long blocks. No point paying for heads just to take them off. Check with some local machine shops for prices.

darkride86T/A

What about a ZZ4 H.O. short block with a set of World S/R Torquer heads and Crane Powermax cam : 260/272 adv.dur.&.427"/.454" gross lift




Would this mess with my ecu and 87 octane driveability?

Apeiron

That cam is still well within reason for the ECM. I'm not familiar with the heads, though.

darkride86T/A

67cc heads, .560" max lift, 170cc intake runner,and 2.02"/1.60" valves. $399.99 ea.

darkride86T/A

Well guys, you've given me some good info and ideas. I have an idea on which way I'm going to go with this swap. Now I just got to get the money together for it, hopefully Spring of '08. I'll keep you posted on my progress.
If I have questions I know where to come ask for help. Now back to finding
a good, reliable, non slipping, and cheap 700r4 so I can at least drive my
car instead of watching it sit there wasting away.