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Discussion Starter · #1 ·
Hello all,
I am at a point of beginning to build my new engine. I have an opportunity to purchase a 350. It is said to be out of a 1961. My Elco is a 1981. will a 1961 fit into my 1981? Oh and I took all of my smog and ECM out of my elco.
Or I could also purchase a 1999 350.
The 1961 is complete and the '99 is just the block and heads.
I am looking to completely rebuild whichever I go with.
Opinions. Would it be better to go with the '61 and have the crank and block machined or go with the 99' and buy a new crank.

I will be purchasing a new big thumper cam, valves, rockers, lifters and such.

The rest would be from on my current 305.
Suggestions?
 

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The 350 SBC wasn't introduced until mid - late 60's. Be wary if the seller told you it is a 1961 350.

ANY gen 1 SBC will fit in your 1981. I purchased a L31-R ('99 4 bolt main roller cam 350) for my '87, you will have to run an electric fuel pump if you go this route, but they are good engines and are just about as reliable as you can get without going LS based.

Also, you'll need a vortec intake manifold, center bolt valve covers and a flex plate for a 1 piece rear main seal for the '99, not an issue in today's aftermarket.

Good luck with your quest.
 

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Discussion Starter · #3 ·
Ya whoops my bad. I went and looked and he said it is a '69 350.
Now the guy with the '99 did state that it was for roller cam. I guess that is a good thing to have?
 

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Ya whoops my bad. I went and looked and he said it is a '69 350.
Now the guy with the '99 did state that it was for roller cam. I guess that is a good thing to have?
Flat tappet cams like in the '69 are fine and have been around for years, roller cams are better arguably. One reason is that they wear better. The Vortec heads on the '99 flow better than almost any older style heads the General made.
 

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A 1999 GM engine might still be called a small block Chevy but that modern 1999 mill is VASTLY different than you might expect. This would be an "LS class" of engine swap and might be more trouble than you want to do. And why buy a 1999 block with only heads when well running, complete 1999 LS engines are widely available in virtually every North American junk yard for $500-800 bucks for Chevy 5.3 liter truck motors.


You might consider taking a trip to your local GM dealer parts counter to see what your dealer can do for brand new factory crate engines. Some of these carry a GM 36 month warranty with a very high mileage limit. I priced one for $2300 with free shipping but I eventually went with an LS swap motor and have not regretted it so far.


Rick
 

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A 1999 GM engine might still be called a small block Chevy but that modern 1999 mill is VASTLY different than you might expect. This would be an "LS class" of engine swap and might be more trouble than you want to do. And why buy a 1999 block with only heads when well running, complete 1999 LS engines are widely available in virtually every North American junk yard for $500-800 bucks for Chevy 5.3 liter truck motors.


Rick
The only major difference between the '69 and '99 350 is the vortec heads, 1 piece rear main seal and electric fuel pump. There is nothing close to being as complicated as an LS engine swap.

LS engines are better, and while not terribly complicated to install, will cost significantly more money to get up and running.
 

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Discussion Starter · #7 ·
I appreciate all of your input. 1st the 305 is running OK. I have done everything to this resto mod myself so far. Replace floor pans, rejuvinated the interior, did all of the body work and prep and even painted it. Oh it is not a concourse car for sure but I did it. So the next step is the engine. I can get the block and heads for 150.00 and since I want to rebuild it and increase the HP then I am going to want new parts anyway.
It sounds like I really should look more at the newer 350 engines huh?
 

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Discussion Starter · #8 ·
That being said. Will the intake and such from my 305 work with a '99 engine? If not then I may just go with the '69
 

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Do yourself a favor and skip the Thumpr line of cams for whatever you build. Even Comp’s tech advisors will try to steer you away from them if you want performance from your car.
 

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That being said. Will the intake and such from my 305 work with a '99 engine? If not then I may just go with the '69
no, for a couple of reasons. the biggest one being that the heads are for a 305 and a 350 are not the same. different design, lower compression. also, you'd be putting a pre-Vortec intake on Vortec heads.

I had a stock '99 Suburban with an L31 and it put out 250hp/350torque. It also has the good vortec heads and came with a composite manifold (but overall, it is still an SBC). I personally think you would be miles ahead with the newer block but it depends on your build timeline, how much $$ you got, and whether you mind going to the junkyard for parts or ordering new parts online.
 

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Discussion Starter · #11 ·
Do yourself a favor and skip the Thumpr line of cams for whatever you build. Even Comp’s tech advisors will try to steer you away from them if you want performance from your car.
Thank you for the recommendation. So what can would you go with? I am not going to be racing a track so I am wanting something to help get more HP and to make that awesome big cam sound
 

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Thank you for the recommendation. So what can would you go with? I am not going to be racing a track so I am wanting something to help get more HP and to make that awesome big cam sound
Comp Cams tech line is your best source for a recommendation. I just helped a friend yank a Mutha Thumpr out of his 454. I was trying to steer him to a 284XE but when I called Comp and gave them all his spec’s they recommended the 274XE. We fired it yesterday and it still sounds good. Much smoother than it did with the Thumpr, but still a bit lopey. No doubt that it’ll be making more power in the street-driving range now and he won’t have burning eyes from the pig-rich exhaust fumes.

Always remember that the “big cam sound” is stealing power from you in most street driven cars.
 

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Aaron
If you are driving street rather than strip, would you want a cam that provides more lower end torque?

Someone recently posted that their Big Motha Thumpr was not generating enough vacuum through their brake booster and causing braking problems.
 

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Discussion Starter · #14 ·
Aaron
If you are driving street rather than strip, would you want a cam that provides more lower end torque?

Someone recently posted that their Big Motha Thumpr was not generating enough vacuum through their brake booster and causing braking problems.
Ever since I was a young child, that was many moons ago, I have dreamt of having a ride with a big lopey sound. Even if it cost me some hp. What would you suggest for something lopey but not so much it causes issues?
 

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Discussion Starter · #15 ·
Comp Cams tech line is your best source for a recommendation. I just helped a friend yank a Mutha Thumpr out of his 454. I was trying to steer him to a 284XE but when I called Comp and gave them all his spec’s they recommended the 274XE. We fired it yesterday and it still sounds good. Much smoother than it did with the Thumpr, but still a bit lopey. No doubt that it’ll be making more power in the street-driving range now and he won’t have burning eyes from the pig-rich exhaust fumes.

Always remember that the “big cam sound” is stealing power from you in most street driven cars.
Thank you for that info. I do not have any specs yet because I have yet to tear down and rebuild. I am going to do some research to determine what I want for a can and spec the rebuild from that. So in essence build the engine around my nice new lopey cam
 

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Depending on the cam, the Vortec heads may be a problem. They are limited to about .470 lift. They can be modified for more lift. Roller cams are usually a little more expensive, but you can re-use the lifters, etc. As said, the newer engine does not have a fuel pump provision, so you will need an aftermarket electric pump. Used Vortec heads are prone to cracks between the ports, so you need to check them carefully.

If you want to start with just a block, and build what you want, I have a an L31 Roller Cam 350 block fresh back from the machine shop, bored for .040 over, that you can have for $100. Engine only had 35K miles on it when sent out for machining. PO wanted to build a drag car, and wanted max piston size.
 

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Discussion Starter · #17 ·
Depending on the cam, the Vortec heads may be a problem. They are limited to about .470 lift. They can be modified for more lift. Roller cams are usually a little more expensive, but you can re-use the lifters, etc. As said, the newer engine does not have a fuel pump provision, so you will need an aftermarket electric pump. Used Vortec heads are prone to cracks between the ports, so you need to check them carefully.

If you want to start with just a block, and build what you want, I have a an L31 Roller Cam 350 block fresh back from the machine shop, bored for .040 over, that you can have for $100. Engine only had 35K miles on it when sent out for machining. PO wanted to build a drag car, and wanted max piston size.
I would love the opportunity to buy that from you. The shipping may cost a pretty penny :)
 

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I would go with the '69 block if has 4 bolt mains. You are not going to be race competitive against the big block juiced boys, the pumped up Hemis and those 500+hp Camaros running twin turbos and super chargers, so build a nice, quick cruiser. The three things you really want to get right is the fuel delivery system, hot ignition and a good set of headers. I am running iron double hump heads on my 300hp 327, '67, but there are some nice aluminum aftermarket heads with big valves. I run a 700cfm quadrajet, but most guys like the Hollys, Edelbrock, or even a Demon on a big block. You may opt for a 750 dbl pumper, if you are into racing, but it is overkill for a less than a wild small block. If you are into racing, you can get a good 454, and one out of an older low mileage RV will already have a high lift cam. Good luck & post your progress.
 

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I would love the opportunity to buy that from you. The shipping may cost a pretty penny :)
Just pick it up. Free trip to Vegas..:rockon: Seriously though, freight might be another $100 or so....
 
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