1998 Chev 305, will this EFI fit?

[Lenny]

Will this work on my 98 305 220hp carbed? What tuning will have to be done? I am looking to change over to fuel injection, just need some incite and a unit

Will my 1996 MP/EFI from a Vortec 350 fit these heads on the Chevy 305 above? I do not want to sell something to someone that will not work.

Thanx in advance, Lenny

[VetteLT193]

From a hazy memory I seem to remember the Vortec heads requiring a different manifold. Assuming that is what you are selling (Manifold up for a swap from carb to EFI) I think they will not work.

I could very well be wrong though!!!

[gold-n-rod]

I've wondered that too. Are the heads on a 305 the same as a 350? I know the pistons/bores are about the size of a jigger (larger shot glass). My only worry would be if the heads could flow what the intake manifold can. Oh, and will the exhaust flow the increased volume too?

Too many questions and no answers. :confused:

[VetteLT193]

I've wondered that too. Are the heads on a 305 the same as a 350? I know the pistons/bores are about the size of a jigger (larger shot glass). My only worry would be if the heads could flow what the intake manifold can. Oh, and will the exhaust flow the increased volume too?
Too many questions and no answers. :confused:


Traditionally, the difference between the 350 and 305 are minimal. Basically, the bore size is the only difference. I think 3.7something vs. the 350's 4.0. All the parts are identical, meaning, you can go back and forth on heads/cam/yady yady.

So, it's not so much the heads on a 305, it's the heads on your 305 that you have to worry about. Many times the 305 is considered to be a low cost alternative to the 350, and in order to cut costs down they put cheaper parts on (heads included).

Someone might know if the heads are the same on the merc 305 and 350 here, or have a parts book to look it up.

[mrfixxall]

Will my 1996 MP/EFI from a Vortec 350 fit these heads on the Chevy 305 above? I do not want to sell something to someone that will not work.
Thanx in advance, Lenny


Lenny,how many bolt holes are on the intake ( 8 or 12)? 12 then its not a vortech and it will work on a 305..need to ask the guy if he has a 2v carb or a 4 v, if he has a 2v then he will have to change the cam, if its a 4 v then it will work..on the 305 4v thet jet the carb richer then a 350..

[barstool]

Will my 1996 MP/EFI from a Vortec 350 fit these heads on the Chevy 305 above? I do not want to sell something to someone that will not work.
Thanx in advance, Lenny

The 305 that I have has vortec heads on it, 8 bolts total. Just to clear this up further 4 down each side. Has a 2 barrel carb.
Was wondering if the plug in the trimming cover was removable for the crank sensor? I didn't have a mirror with me tonight when I looked at it, but could feel a plug in it.
If I installed roller rockers on this what should I expect to gain over the stock stamped steel units?
What should I expect the hp increase to be with port fuel over carb?
What valve size is the 305 heads have over the 350?
Lot of questions and just as Lenny stated, want to make sure it will work before money is spent.
Thanks all for any input.

[VetteLT193]

For the roller rockers part of your question:

Assuming you go full roller rockers, and not just roller tipped, there are good gains to be had. I'd say 10 HP or so. The real benefit is that there is no negative with full rollers. The engine runs more efficient all around, oil stays cooler, etc.


If you are going to do the swap, you should also look at bumping the size up. I assume you run 1.5's, so you can go to 1.6's to 'spoof' a bigger cam. If you bump your lift, you will need to make sure the springs are strong enough so they don't bind. If you go to 1.6's I'd guess a 15 HP gain.


On the flip side, many people don't do roller rockers because for the money you can just buy a whole new cam and get some big power gains.

[mrfixxall]

The 305 that I have has vortec heads on it, 8 bolts total. Just to clear this up further 4 down each side. Has a 2 barrel carb.
Was wondering if the plug in the trimming cover was removable for the crank sensor? I didn't have a mirror with me tonight when I looked at it, but could feel a plug in it.
If I installed roller rockers on this what should I expect to gain over the stock stamped steel units?
What should I expect the hp increase to be with port fuel over carb?
What valve size is the 305 heads have over the 350?
Lot of questions and just as Lenny stated, want to make sure it will work before money is spent.
Thanks all for any input.

ask lenny for some pics,,i believe the cover has to come off to install a magnet or a efi timing gear set to trip the sensor weather it being a crank or cam sensor..it all may be in the dist..whyle your their may as well instell a hipo cam too

[Lenny]

It comes with the distributor and wires, harness and "box" and all that "stuff".

[Tank]

Hi all Back in 85or89 I had a 350 and a 305 open at the same time!
The 305 head had smaler cc.chamber, more com. But it also had smaler valves! Now we are talkining street.
Just a thought.
Tank