Hello all. I have a question that I hope won't be too difficult to answer.


I bought a 305 out of a 79 camaro to put in a 4x4 project. I ordered a Summit 1102 cam and Edelbrock Performer 2101 intake on the advice of the techs at Summit (along with new springs). After tearing down the engine for the cam install I discovered it needed a full rebuild so I junked it.

I then bought a 305 HO out of an 83 Z28 (was told it was the standard engien from a truck). I ran the numbers and it works out to be the L69 engine with the aluminum manifold, etc. It has been recently rebuilt and I can only assume it is still at factory specs.

Reading up on the L69 cam specs I am not so sure I should bother replacing it with the 1102. I need the HP and torque to be best at low RPM, say under 3k mostly. I am sticking with a 4bbl Q-jet (non computer controlled one).

So my question is, should I replace the cam or not? Is it worth it or should I leave the L69 in there? I have no choice on the manifold. I was removing the factory one before I knew I had the HO motor and sheared off the bolts on the left front and right rear. I ended up having to bugger up the manifold to remove it.

Thanks for your advice,

Steve

 

Welcome aboard thirdgen.org.

What numbers did you use to determine your 305 is an L69? Both the L69 and LG4 used the exact same aluminum intake manifold (except the Canadian export LG4's got a cast iron intake), block and heads. The '83 L69 had flat top pistons while LG4 had dished, but '85 & '86 LG4's got the same pistons as the L69.

If the engine has been rebuilt, I would assume nothing. Cams, especially flat tappets, are usually replaced in a rebuild. I had an '87 LB9 which had been rebuilt (0.040"-over); should have had flat top pistons, it had full dished pistons; should have had 081 heads, one was an 081 and the other was the LO3 swirlport type.

I'd go ahead and replace the cam if it were me. Most likely your engine has an Elgin replacement cam, and I'd put the likelihood that it has L69 specs at somewhere between nil and none.

 

You are probably right about the cam.

I used the block and head casting numbers. I will have to go home and look at the block again, but I remember it was had a 1983 date on it. The heads are 14014416's. I have not removed the heads so I do't know what pistons are in there. Maybe I can tell from looking in a plug hole, but I doubt it.

 

Okay, casting numbers will only tell you it's a 305, not whether it's an L69 or LG4. They used the same castings, in case there is any doubt.

Odds are it's an LG4, but it is possible it was an L69.

You might get lucky and can tell from looking in the spark plug hole or through an open exhaust valve.

 

The LG4 had dished pistons and the L69 had the high top with valve reliefs, yes?

I think I am just going to toss in the new cam and call it good. I just hate breaking in cams...

 

Well... Dished pistons for sure. Oh well. It will be fine, though, with the new cam and intake.

Thanks for the replies!

Steve