Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

[Fishermark]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

The Vortecs are great heads - but yes, you will then have to buy a new manifold. If funds allow, that would be by far your best bet. They will work well. Several have mentioned the "need" to buy a square bore Holley... not sure what they mean by that. The Edelbrock 1409 you mentioned originally is a square bore carb, and a good one.

BUT - if you are looking to save some cash you might be better off finding a good set of used older style heads and reworking them and keeping your original manifold and 2 barrel. That's ONLY if money is the biggest consideration. Otherwise, performance wise, a great choice is the Vortec heads and new maniold with the Edlebrock 1409 carb. Great combination!

 

[knotperfect]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

I think the best compromise might be the Edelbrock 1409, weiand stealth manifold and a set of older style heads. What hp would I be looking at?

 

[Bondo]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Ayuh,... Is that Weiand an open plenum, or dual-plane,..??

Ya want a Dual-plane...

 

[knotperfect]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Dual plane. It came with the motor that I purchased for rebuild. PO said it had an Edelbrock on it previously

 

[Bondo]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Dual plane. It came with the motor that I purchased for rebuild. PO said it had an Edelbrock on it previously
View attachment 91707View attachment 91708

Ayuh,... That'll work,... I like those AFB carbs...

 

[wca_tim]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Am I misreading this or do you plan to use the stock bore pistons in your freshly bored block? Just checking...

 

[EMC 1810SS]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Having been thru the "what heads should I use?" I would find a set of junk yard vortec heads, and a matching intake. If you go with non vortec, avoid anything from 1974 to about 1986. Most are "lightweight" castings and crack from just unbolting them from the original engine. With those pistons (probably -8cc to -10cc?) you should look for the smaller 64 cc chambers. You also need to avoid "angle plug" heads. They do not work with any of the water cooled manifolds that I have found.

 

[EMC 1810SS]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Ohhh yeah, make sure when you go to put it back together, you pay VERY close attention to ring gaps. Do not use the recommended automotive gap. You should be able to find a marine gap spec. Its a little wider to compensate for the heavy load at rpm (= heat). If you don't you take a chance of the gaps butting and best case a broken ring, worst case ripping the top land of the piston off. Neither options are desirable.

 

[knotperfect]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Am I misreading this or do you plan to use the stock bore pistons in your freshly bored block? Just checking...

No, block is only being honed. Bore is .040 and I will re-use my pistons. When I took the block with pistons to the machine shop, I had him give the pistons a quick once-over. He said they look good enough to re-use but since I have cleaned them up, I am taking them back to the shop for a better look. If I need to, I will replace them although I don't think that will be necessary.

 

[knotperfect]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

I picked up my short-block today! My original intent was to build it myself, but after doing some research I had a last minute sanity check. After I cleaned the pistons up really well, you could see a lot of scuffing on the skirts, so new pistons were in order. With pistons, bearing/rings/seals put me at $200 for parts plus shipping. Labor to swap the rods and pistons was about $60. My shop had a set of good used 40 over pistons already attached to a matched set of rods and he let me have them for $60. As far as I was concerned, that was a fair trade. He matched my online price for bearing/ring/seals and put it all together for $150. Bottom line is I have a .040 over 4 bolt main short block in hand for less than $600. Now I am looking for the heads which seem to be easy to find. All in all a great experience and a great shop to work with.

 

[Bondo]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

All in all a great experience and a great shop to work with.

Ayuh,... Ya wanta make sure that fella gets a Christmas card from now on,...

 

[RogersJetboat454]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

I picked up my short-block today! My original intent was to build it myself, but after doing some research I had a last minute sanity check. After I cleaned the pistons up really well, you could see a lot of scuffing on the skirts, so new pistons were in order. With pistons, bearing/rings/seals put me at $200 for parts plus shipping. Labor to swap the rods and pistons was about $60. My shop had a set of good used 40 over pistons already attached to a matched set of rods and he let me have them for $60. As far as I was concerned, that was a fair trade. He matched my online price for bearing/ring/seals and put it all together for $150. Bottom line is I have a .040 over 4 bolt main short block in hand for less than $600. Now I am looking for the heads which seem to be easy to find. All in all a great experience and a great shop to work with.

Are they going to balance the new slugs and rods to the crank?

 

[knotperfect]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Pistons and rods were matched already. Not sure about "balancing to rods to the crank" though. My experience is a little less advanced.

 

[fastimz]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Hey, Knot. There is a set on 350 marine vortec heads on Craigslist (Richmond). If you are interested. I saw them within the last couple days.

 

[knotperfect]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Yes, I saw them too. Not sure about the credibility of the guy selling. He has a lot of stuff listed. Bigger issue is that I am not that knowledgable about the vortecs. I think I want to stick with what I know for now and not confuse myself at this point. Thanks for looking out though. I think I have a lead of a set from guy parting out. Stay tuned....

 

[RogersJetboat454]

Re: Replacing 305 w/350, HAVE BUILD-UP QUESTIONS

Pistons and rods were matched already. Not sure about "balancing to rods to the crank" though. My experience is a little less advanced.

Ideally everything needs to be balanced together in the bottom end. The new rods and pistons you got may be a different weight than the ones you are replacing. The crank needs to be balanced accordingly.