What to do? 350 engine budget build! $1500 - $2000 Max

Boring swap.. Yea kind of... But so is the 455 swap... Its a common buick swap too.. For fun and having something more special he should turbo the 350.

Well but we talking bout budget..
So keeping the 350 and upgrade tranny gears carb etc seems the most reasonable anyways.



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Seems like someone outlined with links for a VERY budget friendly sbb 350 stroker that definitely WOULDN'T be boring or typical. o No:

This low compression sbb 370 stroker made 420 HP before boost with a flat tappet cam;

http://www.v8buick.com/showthread.php?200499-the-dyno-numbers-are-in&highlight=1021

Built with a bit more compression to run premium fuel if boost isn't in the future plans(which would cost the same amount) would yield a bit more than the 420 HP that they got if the OP ports his own heads and does better or even just as good as the 16 year old that ported the heads in the above thread. Spring the $100 more for the extra bore and a sonic test(around $75 to $150 depending on shop doing it) to make sure block will handle an extra .105" over bore with the crank stroked .140" extra for a 3.990" stroke and that little sbb 350 is now a sbb 383 breaking transmissions and rear ends! :Brow:


For about $500 more he could get custom 2618 pistons to handle as much boost the heads can hold and make more power than any factory block 455(yes, even one with a jock strap) ever dreamed of making reliably! But this is race car territory, a bit much for a convertible. LOL Just so people that think the sbb 350 doesn't have potential know it does


And again if anyone has ever experienced even a mild sbc 383 stroker engine in a car or truck would know that a stroker is no joke and they do deliver power! The sbb 383 vs. the BBB 462(.030" over bored) the sbb 383 that is around 350 lbs lighter than a BBB 462 would go a long way to the weight to HP ratio calculation making them closer in performance than just raw dyno numbers would lead to us to believe. Would make someone think one is much better than the other before they're installed in a car without factoring in the weight difference.

Read through the thread I linked to and see how much the torque numbers jump up on the sbb 370 stroker build even N/A, compare that to what a similar 350 has power wise, then extrapolate what power 383 cubes would have with 10:1 with a dynamic of just under 8:1 to run on premium with a tiny bit of a safety margin. Now figure what a 462 with the same compression to run the same fuel with a similar cam and factory heads. Then do the weight to HP calculations to see what the weight to HP ratio would be in a 3,600 lb car for the sbb and a 3,790 lb car for the BBB for anyone with the dyno simulation program who is curious where the 2 engines would fare. Enjoy.




Derek

 

Torque moves weight. Horsepower is how fast it can move that weight.

In a lighter car, less torque is needed if geared properly. If geared for highway, more torque helps it--a lot.

However, with better gearing, more torque is overkill and you'll end up with traction problems, making all that extra power moot.

A car with less torque can in fact be faster than a car with more torque for this very reason, not to mention better handling. There's more to a car than just straight-line performance.

Pros and cons, again.

If geared and built properly for the desired application, a Buick 350 will hold its own against most big blocks with comparable horsepower.

I've seen this time and time again at the track. Small blocks whooping up on big blocks, and vice-versa.

It just depends.

To address some of the other issues brought up, I'll start with weight comparison (and how it doesn't necessarily affect straight-line performance, but handling (stopping, going around curves, etc.))

Adding more weight to the front of the car, and placing it farther ahead of the transmission (longer engines, etc.) will directly affect how the car handles. In this regard, the Buick 350 wins hands down on the big blocks. It's a rather 'squat' engine that's nearly as wide as it is long, helping it to sit farther back closer to the firewall. This helps more than you'd think for handling. It also weighs about 100 lbs. less (some sources state 150-190 lbs. less) than the big block Buick. Again, this helps.

The Buick 350 weighs in at about 50 lbs. more than the Buick v6, and by simply adding in an aluminum intake to replace the boat anchor iron intake will make them nearly identical in weight.

You could get a 455 to weigh closer (not close) to an all iron 350 by doing similarly, but will still weigh no less than 50 lbs. more than the 350 (depending on where you get your information, this number could be as high as 150+ lbs. more than a Buick 350).

So stiffer springs on the front end would be needed, or it'll feel 'spongy' around curves and will handle like a boat.

It will also need a bigger radiator to handle the extra cubes. More power=more heat. Otherwise, you'll run into overheating issues.

If a TH400 is used, the transmission crossmember will still be usable, but will need to be placed a bit farther back (the holes exist already on the frame for this on a '68 A body car), as well as another transmission mount. The detent is solonoid activated, so this will be a direct swap over from the same setup on the ST300 (no mods needed for a TH350 cable solonoid control).

EDIT: I forgot to mention that the driveshaft will also need modification. Shortened for use with a longer transmission, as well as the larger yoke in the front for the bigger output shaft on the 400.

Even though more weight is being added to the car, the larger TH400 will help offset it by putting some of the weight further back from the engine. Handling will be improved by this vs using the smaller transmissions.

Remember the closer to the center of the car you can put the weight, the better it will handle.

The 455 engine will need new motor mounts as well as the frame pads which will bolt to the frame with holes for this already existing on the Skylark.

Different downpipes will be needed to hook to the existing system.

Unless you plan on changing out the rear end for better gearing, the big block is going to outshine the 350 in most regards.

If it's the standard gear ratio for a 350-2 in 1968 on a Skylark, it'll be a 2.56:1 open axle. A 350 will be pretty sluggish using this, especially with the ST300, unless it mimicked a big block with lower-RPM torque, which is why a big 2 barrel is the best choice for this setup, though the actual torque output in raw ft. lbs. will be significantly less, what matters more is WHERE the torque is located in the powerband (lower is better for this gearing).

(((For reference, the standard gearing for a 1968 Skylark using a 350-4 and the ST300 was a 2.73:1 open axle; the GS350 used the same ST300 but had a 3.23 limited slip. Different gearing could be optioned, but these were the default gearing for 350 A body cars in that year. The same car with a 400 big block (The GS400) came standard with the 3.42 limited slip and the ST400)))

If you bumped the compression on the 350, got a large base Rochester 2g intake and carb with no less than 500 CFM, and used a grunt type cam for maximizing torque output, this setup would be the best way to utilize a gearing ratio such as what exists already in the car.

Another great way to improve it would be to swap in a TH350 trans (or even the TH400), and build the 350 for torque using the existing rear end gearing. The aforementioned suggestion of higher compression and the Crower level 3 cam would suit this combination nicely.

You could see close to or a little over 400 ft. lbs. on a 350 Buick built this way, which comes closer to the '75 455 torque output numbers, with considerably more horsepower. You also get the added bonus of not having to change out a bunch of components under the hood to accommodate the larger (and heavier) big block, and get better gas mileage to boot. This would help offset the cost of fuel, since a low comp 455 is going to be pretty thirsty, and even though it uses regular gasoline, it'll use quite a bit more of it. lol

It's all about the combination of parts.

(((Another point of reference is that when I did the big block swap on my Lesabre, the 455's did perform better, but the handling suffered quite noticeably. It performed better as long as there were no curves involved. The 350 in that car handled way better than it did with the 455's in there. Just another FYI for those interested)))

Anyway, more thoughts from yours truly.

 

Thanks Gary that was a well thought out post with a lot of good info....

And Derek, thanks for summarizing the stroker engine builds it will be cool to see more of them done.

 

After re reading the original post. here is what I recommend and confirm what a couple others have said. Also was the existing rear ratio ever determined? Lots of PG trans cars had ratios in the 3.31 range. Could be fine with whats there.


Best bang for the buck upgrades.

#1 Quadajet $350

#2 Turbo 350 trans with cheap 2000rpm converter from Summit or other. $400

#3 3.23 or 3.42 geared rear end or gear swap. $ 400 to $600

#4 Crower level 2 cam and kit (springs), new timing chain, replace front cam bearing, cut heads .080", .080" shorter pushrods, slot intake bolt holes to save having it cut down. Valve job and open the throats to the diameter of the lowest factory machined cut. All provided the rebuilt 73 engine in sound. This will run about $1100 to $1400 with gaskets ECT.


Totals out around $2750 but with some parts scrounging could come in for less. Also can be done in stages.

 

Thanks Sean. I did a little basic extrapolation estimating from the 370stroker build up, first here are the N/A posted results;

"N/A it made peak torque at 4800 @ 449 ftlbs HP was at 5300 and was 422.
this thing was an animal with torque at 3500 it made 423 and never dropped below 400 until 5500 and was still 396!"

So we have seen hundreds of sbb 350 and 355(.030" over 350)builds that max out right around 400 lb ft of torque. As you can see with the extra 20 cubes the sbb 370 made 449 lb ft of torque. So that is 49/2 = 24.5 lb ft more torque per 10 extra cubes. With an extra 13 cubes on top of the 370 would get the torque up even further, 24.5/10 = 2.45 x 13 = 31.85 + 449 = 480.85 lb ft for a 383. But wait, that 449 was with a low compression engine built for boost, IIRC that engine had 8.8:1 compression so with an extra 1.2:1 more compression that number could get as high as 500 lb ft. Just so everyone knows a typical mild 9:1 compression sbc 383 stroker puts out right around 480 lb ft of max torque with the higher end ones surpassing that number by over 100 more lb ft in some cases.


And of coarse with a stroker build still being that it is still a small block it will be more efficient than a big block enabling it to get better fuel economy than a big block paying for itself from the better mileage it will get. Lets face it, the pre-election gas prices aren't going to stick around after the election, it will be back to business as usual.(my prediction anyway) :eek2:




Derek

 

And add some ported alum heads and it should be an animal!

 

I agree this would be a great combo. Lots of low end and even with piston that are .060 down hole it's about 9.4 compression. But as some of the guys have gotten good luck with the level 3 with 4 degrees advanced (set to 107.5) even on a lower 8.2 compression engine with a higher convertor making enough power to run 14s with a 2.73 gear. That's pretty good power.
And as far as Derek's suggested 370 combo making 449 lbs . That's in big block Buick torque numbers. More then adaquate to run with the big dogs and still only need pump gas.

 

Budget about 5k for that.

 

That's not MY "suggested" 370 combo, that is an actual 370 combo that was dynoed!

Here is the thread those results came from;


http://www.v8buick.com/showthread.php?200499-the-dyno-numbers-are-in&highlight=1021

Posted on the very 1st page of the thread where the rods that were used are written to have the 1.850" journal size so that would suggest a stroke of 3.990" with a bore of 3.840" to get just under 370 cubes.




Derek

 

Oh yeah!!! :Brow::Brow::Brow::Brow:




Derek

 

The stroker made some very impressive numbers. Big block territory for sure.

Maybe someone will put together a 'kit' for one so it might not look too intimidating for a broader audience (I know the 'recipe' is already there)? Could very well be the future of N/A Buick 350's. :Brow:

 

X2:3gears: Do the engine later.:TU:

 

Got a low mileage th350 transmission so far.

now I am currently deciding on either a 1970 455 engine or a 1980 gs 350 engine.
Really good prices on both and I am still under budget.

I am still concerned about the gears to get. I don't want to have to change my rear axle. The car will be painted this winter so I can do all my swaps then

 

350 trans is a good find. I suggest get a higher rpm convertor. And confirm the year of that 1980 gs350. 1968-70 are the only high compression engines from factory. And the low compression engines up to 1975 are not any different then the engine you have now. 76-80 engines are even lower compression . so do your best research on engine first

 

In defense of the Buick 350 and the use of the Crower level 3 cam, the camshaft's dimensions work well with the original engineering intent of the intake manifold, heads, and exhaust manifold air flow, and has shown to have nearly perfect synergy when matched with adequate compression for this combination. Cams larger or smaller than this show gains or losses on either end of the powerband in either horsepower or torque. Get one too small, and torque isn't affected much while horsepower suffers; get one too big, and torque suffers while horsepower gains are negligible (when used with aforementioned stock air flow parameters).

Studies have shown this to be the case--in real world test scenarios as well as mathematical computations. I have personally tried to make a 'better' camshaft (on many, many occasions), using the Crower level 3 as a baseline for comparison, and while I can make one that squeezes a bit more power out of the engine, there will be other areas that suffer as a trade off, making the Crower level 3 cam one that is very difficult to beat for an overall performance cam that shows to be about as gentle on the valveltrain as it gets without cutting too heavily into performance.

I (among others) can confidently recommend this camshaft for pretty much any Buick 350 that intends on using the original factory intake and exhaust manifolds.

Crower certainly did their homework on this one.

A great combination for this engine setup would be around 10:1 static compression, 2* retard position, some head work, 3.73-3.23 gears, and a 2500 stall.

There's already a proven combination that uses essentially this setup (and the math backs it up) that runs mid 13's @ around 100 MPH in the 1/4. Pretty good street machine.

 

455 i guess..
Intake a cam and headers
Maybe a mild DIY head porting if you trust yiur skills.

The th350 as stock is better for a sbb 350.
For the bbb tq # you should have went with a th400 tranny right away, unless you planning on building the th350 sturdy.



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Just wanted to add that upon repeated comparisons between using the Crower level 3 cam and various advance/retard positions with the same DCR's, it seems the best compromise between hp and torque in the powerband is a 'straight up' position, which is to say 112/112 I/E.

Retarding it past this gives a bit more hp for a trade of some lower end and peak torque, while putting it at the default 4* 108/116 location sacrifices more hp than the few ft. lbs. it gains down low. Putting it 2* advance shows the same peak torque as 0*/0*, but loses several numbers on the upper end, so my conclusion is that 112/112 is the best place for it, which gives a 70* IVC point.

I suppose it varies/depends/etc. on what all else was done, but I noticed that it seems to want more retard if exhaust manifolds are used, while the 0*/0* is best for use with headers, and 2* advance is still good.

Not sure why Crower insisted on 'building advance' into their cams, and why the 4* was used. I guess that's the old school de-facto location for pretty much all aftermarket cams that used to use the straight pattern grinds and the 'old way' just kinda stuck; adding exhaust emphasis negates the need for this advance setting. The OEM cams show a retard position @.006 while showing advance @.050, so it makes sense that a symmetric cam put at a straight up position would work best for a symmetric design using an exhaust emphasis grind.

 

Maybe to allow for the natural retard as the chain wears or they found OE replacement timing sets were retarded.

 

Very good point you bring up Steve, and has also been the source some some confusion in the past.

I had inquired about the OEM sets from Melling and spoke with the head engineer who told me the timing sets are 0*/0* with the variances of the OEM cams 'built in' to the cam specs themselves.

Hence, the OEM timing sets have no advance built into them, as many have believed, and yes the chain does 'stretch' (more like wear-in as the miles accumulate), and along with higher RPM strain, causes the chains to 'flex' and add in a bit more retard, which makes the OEM cam's dynamics even more complex--though the valve timing events sit within a spectrum so that performance is enhanced at lower RPMs and higher RPMs as it revs.

They're asymmetric lobes, making the LSA vary depending on where you measure the lift of the lobes, which is why they sit at a retarded position @.006, then the lobe center moves over based on the ramp profile to an advanced position @.050. They're a lot more complex than symmetric lobe cams.

LSA on the FM cs647 varies from 112.75* @.050 to 114.25* @.006, if memory serves. EDIT: memory apparently didn't serve. lol Had to change it from 116.25 to 114.25. Not that anyone really gives a **** about the OEM cams. ...this shows a 1.75* retard @.006 and a 3.25* advance @.050 (109.5* ICL @.050 with 116* ICL @.006).

Modern valvetrain systems have what is known as 'variable valve timing' in which a separate timing lobe and chain alters the cam's timing events as the engine revs, and this OEM GS replica cam tries to do something similar to this with a stationary state, hence the asymmetric design with considerations made for the timing chain flex.

Very cool stuff!