Hey guys,

One of the bolts on my 84 305 doesn't hold down very well anymore and I can't get a good seal on the intake. It's to the point now where it's affecting how the motor runs. I want to replace the motor next year anyway, but until I can arrange the funds I'm stuck with the 305.

My question is this. I already have a set of Vortec heads that I will be using on my new engine (will be a 383). Since I have to replace the Intake, should I just buy a stock replacement intake, OR...could I just buy a Vortec style intake and replace the heads stock heads with the Vortec's that I already have? I remember reading somewhere that the 350 size heads won't work on a 305. If that's the case, then I'll just buy a used intake and keep the stock heads. Can some one clarify this for me? Thanks!

 

Smallblock heads are interchangable but you run into a few small details...

A '350' head will generally have much larger chambers than a '305' head.

Also you have to limit the lift when using large valves on a 305 as they can and will hit the cylinder if they go too far.

 

Well, it's a completely stock motor. I was just wondering if I could juice it up a little by putting a newer vortec intake along with the Vortec heads that I already have on the motor without breaking something. Thats why I asked about the heads.

I have no idea what the lift is on a stock 305, I'll have to do some research I guess. If nothing else, I'll try and find a cheap stock replacement either here or on Ebay. /shrug

---Edit---
Ok, apparently here are the specs on the stock L69 305...

New L69 cam: L69 305 H.O.
190 hp / 240 lbft
Tach: yellow 5000
red 5500

Lift: intake .410
exhaust .423

Duration: intake 320
(crank) exhaust 320

 

I also found this Cam data, but it's from an 85 L69...so I'm not sure if there is any difference between that and the 84.

Duration
Year GM P/N Int. Exh. Int. Exh. Separation Arm Ratio
1985 (L69 and LB9)
305 AT 14088843 .403 .415 202 206 114.5 (115/-114)

 

Whats the chamber size on those vortecs? 64cc?

without a dome piston your going to end up with a rediculusly low CR.

 

Yes, they are 64cc heads.

Well, I don't want to drop my compression too low. Looks like my best option then would be to just find a used stock replacement manifold and save the vortec's for my 383 build doesn't it?

 

Well you *can* use them but your CR is going to drop from 9.5:1 to about 8.8:1

Which as i said before isnt going to help for performance but it will definately be 87oct safe!

Its not low enough its going to be a total dog but it will be lacking some power.

 

Well that's not what I want to do. Ahh well, it was just a thought. I've had them sitting in my Garage for a year waiting for my 383 to get done (MAYBE next spring money permitting). I just figured I'd put them to use but it seems I'll hurt my performance more than help it.