Engine Swap (Non LS) - 305 H.O. to ...?

[g0thiac]

Are those engines carburated or TBI ?

I wouldn't think about that, you can use your old intake or get a new one and throw on the carb.

 

[64nailhead]

Finding a Vortec 350 near me that is not wiped out is demanding. With that in mind you don’t need an actual Vortec , but only the heads. 2nd on the priority list is a roller block. Once those are in place then a cam very similar to a Comp 268xe will yield 350 hp with a set of long tube headers.

This recipe has been used for more than a decade with great success. From here upgrades can be done, but they start adding to the price quickly.

If you’re not in hurry, then hunting for a complete motor will probably be most economical. But don’t be surprised to find a motor that is advertised as ‘good’ but isn’t.

What’s the budget?

 

[08Malibu]

Here are a couple of helpful links.

First is a decent 305 build up recipe you can use for your future El Camino project. GM did make Vortec style heads for 305s (L30) and they are the second highest flow factory GM heads, only beat by 350 Vortec heads. Good thing about the HO 305s is that they have pretty good CR of 9.5 :1 so they respond better to mods than most 305s along with the high flow cat. The F body version of the HO305 got dual snorkel aircleaners which alone added 10 more HP. The CCC Qjet is an excellent carburetor and don't let others tell you otherwise and the HOs have better spec Qjets.
http://montecarloss.com/SSThunder/monte_ss.html

305s are no less reliable than any other SBC and they often last to 300K. Plus they are less detonation prone than 350s which is why they often have higher CR stock. In the 80's the only Caprices to get 350s were 9C1 police package ones and even those only had 155 HP. A MCSS would blow it away, especially if the 9C1 Caprice was weighted down by heavy police equipment.

There are a couple of issues with L31s. First they lack a provision for mechanical fuel pumps so you most likely will need to convert to an electric fuel pump with in tank pumps being the preferred type. Second issue is that Vortec heads require Vortec specific intake manifolds such as this one.
https://www.summitracing.com/parts/nal-12496820

Yes, G bodies are notorious for weak flimsy frames that are as rigid as a wet noodle. The bodies are not very strong either. In the 80's GM downsized and deleted a lot of bracing from G bodies which further weakened them. Plus other shenanigan's like missing body mounts for a more comfy ride. There is a sticky thread on this forum that covers the issues and the band aids to partly fix them. The only complete fix is a aftermarket frame which are quite pricey. Next best fix is a frame off to box the stock frame which is still pricey.
https://gbodyforum.com/threads/f41-and-aftermarket-bracing-diagrams-more-pics-added.8126/

You have to remember that even back when these cars were new they were already an outdated platform. They were designed to be Granny cars first and foremost, the performance sub models were an afterthought. Weak bodies and frames, horrible 1960's derived backwards suspension geometry, undersized brakes, weak light duty rear axles, poor weight distribution, poor aerodynamics, only 2WD, optimize for the old 55 MPH national limit, thin driveshafts, lack of modern safety features, skinny weak pillars, lackluster build quality, etc. Its a tall hill to climb for G bodies and performance wise you would be better off buying that modern Camry which Driven raves about all the time here. After all, they do have 33 years of progress, AWD, and 5 more gears on their side. Plus they have modern gas saving features like DBW and stop & start systems along with superior aerodynamics. Of course comparing new cars to antique cars is a faulty comparison like comparing apples to oranges.

Considering you are talking about an HO 305, I assume your 84 Monte Carlo is an SS? The trans and rear gearing in it are already decent, a 3 speed TH350 with SS spec shift pattern and 3.42 gears. Through a 3 speed is a handicap in an era where 6 and 8 speed transmissions are the norm such as the Drivin's favorite, the Camry 😉 . In 85 Monte Carlos were upgraded to the 4 speed overdrive 2004R transmission and 3.73 rear gears. 85 and up G body frames have an extension piece welded on to mount the 2004R, 84 and older frames lack this extension but it can be added to them. However, even a OD 4 speed is still outdated by modern standards. Hotrodding boils down to how big your wallet is, those with the deepest wallets will win.

If he gets a 97 L31 it will still most likely be drilled for an oil pump pushrod. The stock cam won’t have the fuel pump drive on it though.

 

[Tynan918]

Here are a couple of helpful links.

First is a decent 305 build up recipe you can use for your future El Camino project. GM did make Vortec style heads for 305s (L30) and they are the second highest flow factory GM heads, only beat by 350 Vortec heads. Good thing about the HO 305s is that they have pretty good CR of 9.5 :1 so they respond better to mods than most 305s along with the high flow cat. The F body version of the HO305 got dual snorkel aircleaners which alone added 10 more HP. The CCC Qjet is an excellent carburetor and don't let others tell you otherwise and the HOs have better spec Qjets.
http://montecarloss.com/SSThunder/monte_ss.html

305s are no less reliable than any other SBC and they often last to 300K. Plus they are less detonation prone than 350s which is why they often have higher CR stock. In the 80's the only Caprices to get 350s were 9C1 police package ones and even those only had 155 HP. A MCSS would blow it away, especially if the 9C1 Caprice was weighted down by heavy police equipment.

There are a couple of issues with L31s. First they lack a provision for mechanical fuel pumps so you most likely will need to convert to an electric fuel pump with in tank pumps being the preferred type. Second issue is that Vortec heads require Vortec specific intake manifolds such as this one.
https://www.summitracing.com/parts/nal-12496820

Yes, G bodies are notorious for weak flimsy frames that are as rigid as a wet noodle. The bodies are not very strong either. In the 80's GM downsized and deleted a lot of bracing from G bodies which further weakened them. Plus other shenanigan's like missing body mounts for a more comfy ride. There is a sticky thread on this forum that covers the issues and the band aids to partly fix them. The only complete fix is a aftermarket frame which are quite pricey. Next best fix is a frame off to box the stock frame which is still pricey.
https://gbodyforum.com/threads/f41-and-aftermarket-bracing-diagrams-more-pics-added.8126/

You have to remember that even back when these cars were new they were already an outdated platform. They were designed to be Granny cars first and foremost, the performance sub models were an afterthought. Weak bodies and frames, horrible 1960's derived backwards suspension geometry, undersized brakes, weak light duty rear axles, poor weight distribution, poor aerodynamics, only 2WD, optimize for the old 55 MPH national limit, thin driveshafts, lack of modern safety features, skinny weak pillars, lackluster build quality, etc. Its a tall hill to climb for G bodies and performance wise you would be better off buying that modern Camry which Driven raves about all the time here. After all, they do have 33 years of progress, AWD, and 5 more gears on their side. Plus they have modern gas saving features like DBW and stop & start systems along with superior aerodynamics. Of course comparing new cars to antique cars is a faulty comparison like comparing apples to oranges.

Considering you are talking about an HO 305, I assume your 84 Monte Carlo is an SS? The trans and rear gearing in it are already decent, a 3 speed TH350 with SS spec shift pattern and 3.42 gears. Through a 3 speed is a handicap in an era where 6 and 8 speed transmissions are the norm such as the Drivin's favorite, the Camry 😉 . In 85 Monte Carlos were upgraded to the 4 speed overdrive 2004R transmission and 3.73 rear gears. 85 and up G body frames have an extension piece welded on to mount the 2004R, 84 and older frames lack this extension but it can be added to them. However, even a OD 4 speed is still outdated by modern standards. Hotrodding boils down to how big your wallet is, those with the deepest wallets will win.

Great info and links, I'll look into all of this before considering a swap...

Not a true SS, base MC with SS body parts...the VIN reads it originally came with a V6, this 305 H.O. is swapped in.

 

[Tynan918]

Finding a Vortec 350 near me that is not wiped out is demanding. With that in mind you don’t need an actual Vortec , but only the heads. 2nd on the priority list is a roller block. Once those are in place then a cam very similar to a Comp 268xe will yield 350 hp with a set of long tube headers.

This recipe has been used for more than a decade with great success. From hear upgrades can be done, but they start adding to the price quickly.

If you’re not in hurry, then hunting for a complete motor will probably be most economical. But don’t be surprised to find a motor that is advertised as ‘good’ but isn’t.

What’s the budget?

I want to teardown and completely rebuild another big engine (327,350,355, etc.) and swap this 305 H.O. engine with it...so as long as the engine is good enough for teardown and rebuild, thats good enough for me.

 

[64nailhead]

Do yourself a favor and don’t buy any parts until the new motor is torn down and inspected.

 

[565bbchevy]

I would probably just save up and go with a crate engine in your case, it will be a quick swap with minimal tools dropping in a 355. 383 etc.
Building your own engine requires a lot of specialized tools that can be costly and unless this is something you plan on doing as a job or a serious hobby it is probably not worth the investment.
For me the number one issue of building your own engine from scratch is you must have a machine shop that you trust to do the work correctly and is priced reasonable enough to be worthwhile over an engine that is already built.
And with lack of experience all it takes is one assembly mistake to ruin an engine that you just dumped a bunch of money into and I have seen this happen many times and sometimes it is the simplest thing that does it.

 

[Tynan918]

Do yourself a favor and don’t buy any parts until the new motor is torn down and inspected.

Most definitely, nothing I want to rush...

 

[Tynan918]

I would probably just save up and go with a crate engine in your case, it will be a quick swap with minimal tools dropping in a 355. 383 etc.
Building your own engine requires a lot of specialized tools that can be costly and unless this is something you plan on doing as a job or a serious hobby it is probably not worth the investment.
For me the number one issue of building your own engine from scratch is you must have a machine shop that you trust to do the work correctly and is priced reasonable enough to be worthwhile over an engine that is already built.
And with lack of experience all it takes is one assembly mistake to ruin an engine that you just dumped a bunch of money into and I have seen this happen many times and sometimes it is the simplest thing that does it.

Crate engine... I'll look into it, but I'm willing to learn.

 

[Tynan918]

This should be very informative...