I recently started a different thread about a 327 I was thinking of rebuilding, but the topic diverted to so many discussions, I figured I would start a new thread and try to stay focused on topic.

I'm considering building an engine for my 67 Camaro and am interested in a Vortec 350. I understand they came stock in something like 96-99 trucks.

One possibility is to acquire a complete engine/transmission/computer etc or a doner vehicle with low mileage that I can transplant the entire setup including the EFI into my car. I'm not sure I want to get that involved with wiring and fuel systems, but this approach would be very fuel efficient.

What I'm leaning towards, is to start with a basic vortec longblock, and then add my own aftermarket intake and carb.

In either case I need input on what cams to consider, or if I go carb, what intake manifolds should I look at. I have an existing Edelbrock 1406 carb I could use.

Will the Vortec need any motor mount adapters to bolt it in my 67?

I'm sure I will have more questions, but this should get the thread started.
Thanks

If I was considering a setup for a complete swap that would be fuel efficient I would be all over a 5.3L LS. I would stay away from the factory vortec efi. I have never heard great things about the injection they use and its not cheap to modify. You would be better off swapping to a mpfi intake on it which once you start going down that road you would have been better off with the LS.

 

What I'm thinking of is finding a low mileage 350 from the late 90's, meaning one that doesn't need a cylinder bore or crank grind, maybe just a hone and polish and new rings and bearings, or maybe use it as is and reuse the pistons, rods, and lifters. If the heads are in good shape, maybe just a simple hand lap job, and whatever small items heads typically need. For the cost of a complete head rebuild, I can almost buy a new set of vortec heads, which would allow me to expand my looking to a 350 from the early 90's and just add the vortecs.

I wonder if the 350's from the early 90's were basically the same shortblock, same compression ratio, roller lifters etc, so if I bought new vortec heads, I could just as easily put them on an early 90's block. Then I would buy a new intake manifold and put on my Edlebrock 1406 600 cfm carb. Also buy a new cam unless the stock cam already had good specs.

What do you all know about the motor mounts? Are the early 90's or late 90's different them my 67 or will my existing mounts bolt right on?

Seems like the total cost of putting together a 90's vortec, carbed engine should be fairly reasonable.

 

I wonder if the 350's from the early 90's were basically the same shortblock, same compression ratio, roller lifters etc, so if I bought new vortec heads, I could just as easily put them on an early 90's block. Then I would buy a new intake manifold and put on my Edlebrock 1406 600 cfm carb. Also buy a new cam unless the stock cam already had good specs.

What do you all know about the motor mounts? Are the early 90's or late 90's different them my 67 or will my existing mounts bolt right on?

Ayuh,... The blocks changed in 86/87, 'n the Vortec heads were added in 96,...

As far as I know, SBC motor mounts are in the same spot as they were in 1957...

 

I wonder if the 350's from the early 90's were basically the same shortblock, same compression ratio, roller lifters etc, so if I bought new vortec heads, I could just as easily put them on an early 90's block.

There were some slight differences in piston rings- some had deep and some had shallow oil rings, and some were metric. There were true FT pistons used on some Gen 2 SBC engines.

There were powdered metal and forged steel rods used on different engines during this time period. By '96 when the "good" Vortec heads were on the 5.7L L31 engines, all the rods were PM as far as I know. And all the pistons were dished, around 11-12cc.

To me there doesn't seem to be any real difference in the durability of forged vs. PM rods. Others will disagree w/this, preferring the old style forged rods over the PM rods. My thoughts are, if PM rods aren't good enough then it's time to move up to a better aftermarket rod, because the rod bolts have to be changed and the rods resized at a minimum anyway. For a couple dollars per rod more, you can have sized and ready tobe balanced rods w/better bolts, etc. in an aftermarket forging. If you are on a budget, use the stock rods, resized and w/new bolts, and call it good.

For me the ideal scenario would be to find a '96-up 5.7L Vortec long block in good shape for a good price. Add the induction system of your choice, from a carb to an aftermarket TBI EFI to whatever.

Another option you will hear is to find a good Gen 2 engine and run it w/the stock TPI set-up. The LT1 engines were never in large supply and are getting pretty long in the tooth, but if you can find a good one for the right price, it's an option that might work for you. Be sure you don't get the "baby" LT1.

There were TBI engines that used flat tappet cams, some of these blocks lack the bosses to use a factory roller valve train. This has been posted before, but not for a while, so:

350cid roller tappet blocks are casting numbers 10243880, 14011148, 14088526, and 14093638.

1986-up 350cid flat tappet (i.e. non-roller) blocks are casting number 10054727, 14079287, 14088548, and 14101148. These flat tappet blocks may have the provisions for a roller cam (i.e. bosses cast in and tapped for the spider, tapped holes for the cam plate, etc.)- but also may not be so equipped- but these blocks will have a flat tappet cam and non-roller lifters, no spider, etc. These blocks are fine if you don't care about the roller cam.

There is a flat tappet block and a roller block that both end with the numbers 148. 14101148 is a flat tappet truck block, 14011148 is a roller provisioned block.

Some blocks came machined all the way for a mechanical fuel pump. Others have either partial or no machining done to use a mechanical F/P.

A member here posted this regarding the fuel pump (sorry, I don't recall the name to give proper credit):
"All of the 638's that I've seen (not that many, 5 or 6) have had the pump rod hole drilled. I've seen 880s both ways, and both 14011148 I've seen were undrilled."

 

!

Still hard to believe that people plan projects around Gen1 engines when for the same amount of dough they can step up to an LS that is just a superior engine. I don't get it. Please! Somebody make me an offer on my ********** so I can get with the times and go LS.

 

Still hard to believe that people plan projects around Gen1 engines when for the same amount of dough they can step up to an LS that is just a superior engine. I don't get it. Please! Somebody make me an offer on my ********** so I can get with the times and go LS.

Cost, working with computer controls, etc... Otherwise I agree. My 67 c10 is getting an LQ4 6.0L

 

Pistons

Yesterday I got a deal on an 89 350TBI and a couple of 700r4's that I couldn't pass up. My tentative plan is to buy a set of Vortec heads and intake and use my 600cfm carb.

I'm thinking of reproducing the specs as found in a GM 350HO crate motor, with maybe a little better intake manifold and cam.

In my research, I'm having trouble finding pistons for this combination or for that matter any 64cc head, resulting in somewhere close to a 0.040 quench. I played with the deck height, piston compression distance and gasket thickness, but they didn't seem to matter as long as the quench height calculated right.

So I've narrowed it down to needing a set of dished pistons with a 12-16cc dome which would result in a compression ratio between 9 and 9.5. I really like the summitracing site, as I can shop for pistons by playing with the different specs, but all I come up with that matches are the Keith Black ones which seem very high priced for my budget.

Can any of you reccomend any other online sites where they have a large selection of pistons including enough details to calculate what I want. It seems like many of the sites list CR estimates that seem like they would only be correct if the piston was further away from the head as a result of a thicker gasket or compression height locating them further down in the cylinder, which from what I understand would result in a larger then desirable quench height.

Could it be that many people, even rebuilders are building engines that ignore the most efficient quench heights?

Where are the pistons to be found, that we really need?

Am I correct in targeting a CR of 9-9.5 using the Vortec heads and able to run on 87 octane gas?

Am I also correct in assuming the Vortec heads all have 64cc compression chambers?

 

5 or 6 yrs. ago popaular hotrodding mag. had a write up where they took a junkyard 4 bolt 350 roller short block an reused the pistons,rods,crank and put an EQ iron vortecs,but they had a custom grind cam from Comp cams. It made 447 hp.This is how I build my 350,except for the cam.If your interested I can get the mo. & yr.of the write up, Im sure its online.I do agree that an LS is the better way to go,but I would use an carb.intake.

 

When I tore apart my engine, I found the last rebuilder used Silvolite pistons with a 1.540" compression height, undecked block, and a .043" head gasket. This gave a whopping quench of .088". No wonder the previous owner had to use 93 octane even though the engine was about 8.5:1 compression! So YES engine builders more often that not ignore this dimension.

Also keep in mind Vortecs are advertised as 64cc, but in reality they are closer to 66-68. You will need to cc your own to find out. I did mine the other day after the shop milled .010" and they came out to 66cc. Also the cc dish will likely be greater than advertised, so be sure to measure your own. After you get your measurements, buy your head gasket LAST to achieve your quench and compression ratio. You are dealing with several variables: piston dish volume, head volume, and machine shop decking (or factory variance if undecked), and possibly core shift/misaligned main saddles. Measure all these, then pick the gasket.

For comparison, here is how L31 engines left the confines of the General's compound with 87 octane friendly specs:

L31 engines came in two different styles light duty (cars and trucks) and heavy duty (for HD trucks).

Bore: 4.000"
Stroke: 3.48"
Combustion Chamber Volume: 64cc (probably closer to 66cc-68cc)
Compressed Head Gasket Thickness: .015" steel shim
Deck Clearance: .025"
Squish: .040"
Piston volume: 12cc dish (for light duty)
Piston volume: 18cc (for HD)
Compression Ratio: 8.93 / 9.5 : 1 (HD / LD)
Compression Ratio: 8.68 / 9.22 : 1 (HD / LD)

I listed a range of compression ratios here based on variable head chamber size, not even counting piston dish variance, etc.

 

Still hard to believe that people plan projects around Gen1 engines when for the same amount of dough they can step up to an LS that is just a superior engine. I don't get it. Please! Somebody make me an offer on my ********* so I can get with the times and go LS.

actually in many cases its CHEAPER to go LS...

Try finding a 350 that doesn't need at least a basic rebuild, and then try to find an LS engine that does...

The only major cost associated with going LS now is headers, they are available for most cars and they are also expensive for most cars...

 

For comparison, here is how L31 engines left the confines of the General's compound with 87 octane friendly specs...

Also, take into account that those specs were only compatible w/87 octane in large part due to the ECM's ability to sense and quell detonation on the fly. These same specs, if using an analog ignition and carb, can still easily get you right into detonation if max power timing is used.

Get the quench optimized, but do not try for that last tenth of a point of compression- the gains are tiny (a rule of thumb often quoted is 4% per full point of compression, or a 16 HP gain w/a 400 HP engine for going from 9:1 to 10:1, all else being equal) especially when compared to the headaches that a detonation-prone engine combination causes. Leave leeway for a bad tank of fuel or a minor overheating condition so such an occurrence doesn't park you w/a toasted engine would be my advice.

 

I appreciate all the feedback.

I'm still have trouble finding pistons. Other then Summit, where can I look?
It seems like hypereutectic flat tops or small dishes can be found in the $10-$15 each range, but when I start looking for dishes with 12-18cc, the prices go up to $40-$60 each.

Am I looking in the wrong places?

Seems like it would be better to get a set of heads with larger combustion chambers, and pistons with less of a dish. Like maybe 72cc heads and 10cc dish pistons.

For all the hype about Vortec heads, do they all have 64-68cc chambers or are there other high flow heads available with larger chambers?

 

I appreciate all the feedback.

I'm still have trouble finding pistons. Other then Summit, where can I look?
It seems like hypereutectic flat tops or small dishes can be found in the $10-$15 each range, but when I start looking for dishes with 12-18cc, the prices go up to $40-$60 each.

Am I looking in the wrong places?

Seems like it would be better to get a set of heads with larger combustion chambers, and pistons with less of a dish. Like maybe 72cc heads and 10cc dish pistons.

For all the hype about Vortec heads, do they all have 64-68cc chambers or are there other high flow heads available with larger chambers?

Northern Auto, RockAuto, and Competition Products are a few you might take a look at, but I don't know of a cheap inverted dome piston w/a 12-18cc dish volume.

 

Before you get hung up on the compression ratio, you mentioned that you wanted a long block and then do a cam swap.

You should determine your compression ratio after you select a cam. A mild or factory cam is going to require a lower compression ratio. This is because the intake valve closes sooner, and thus raises the dynamic compression ratio. This is why the L31 had a CR in the high 8 and low 9 range. For comparison larger/performance/radical cams have an intake valve that closes much later after BDC. At low speeds this allows air pressure to bleed off, but at higher RPM's there is a ram effect of cramming more air into the cylinder.

Also you mentioned keeping the factory computer with the L31 long block. I think there is some leaway in using a slightly better performing cam without having to modify the computer. I am not positive, but I think the cam's LSA needs to be pretty close to the original. So that all goes back to how much performance do you want/expect, and if you want a lot, you better factor in a computer retune to work with all the performance goodies.

 

Assuming you will keep the OEM 4.000" bore. Here are the numbers I come up with

bore: 4.000"
stroke: 3.48"
Head vol: 68cc
Piston dish: 10cc
Squish band*: .050"
CR: 9.12:1

* Squish band = deck clearance (which is about .025" using 1.560" compression height pistons) + head gasket compressed thickness.

Here are the pistons: http://www.summitracing.com/parts/SLP-H423ACP/
These are a manageable $15.95 a piece.
Keep in mind these are 1.540" compression height. OEM is 1.560" and these numbers are going to factor into your deck height especially since you are not decking.

Another option would be these
http://www.summitracing.com/parts/SLP-WH423NP/
at $20.99 a piece. And they are a compression height of 1.550"

Looks like Summit offers pistons with a compression height of 1.562", but these get into the $40 range. So if you are going to be a stickler about squish and cost and stuff you might be cheaper to get the block decked and throw reduced compression height pistons, assuming YOU do the tear down and assembly of the block. A machine shop will charge you extra for that labor.

 

IIRC, SP 423 pistons are a 4 valve relief, round dish piston. If that's the case, even w/an ideal quench distance, the quench is compromised by the round dish.

The 1.54" CH rebuilder specials w/a minimal 0.005" cut to the decks (for shim gaskets to seal), still will have a quench of ~0.055" (~9.020" deck height + 0.020 shorter piston compression height + 0.015 HG thickness). Or you can go ahead and cut the deck 0.020"- at more cost for the machine shop labor, plus less strength to the decks- to get a 0.040" quench figure.

Or bite the bullet and buy pistons that have an inverted dome and a CH of 1.56". Give the decks a skim for steel shim HG seal (keeping as much deck thickness as possible), and get a better quench from the D-shaped dish along w/a tight, 0.040" quench distance.

 

But I think the OP should stay away from the shim gasket unless:
1) the block is decked and the heads are milled to ensure flatness
2) the machine shop checks for warpage on both and gives the okey dokey for flatness

 

That's why block decking to ensure HG seal was accounted for in the figures I supplied. Flatness, while a requirement, is only half the equation- the surface finish is also important if using shim head gaskets. Coated shim gaskets are a little more forgiving but will still seal best w/the correct finish.

Had I also been discussing CR in that post (it was about quench, primarily), I would have said that milling the heads, while not affecting the quench, WILL slightly raise the CR. But I wasn't, so I didn't. Have to draw the line somewhere, lest the post turn into a freaking book. Like this one is fixing to do. :smash:

 

Thanks again,

The last few posts have been the most helpful so far. I started this new thread because a previous thread ended up with lots of book chapters between differing views.

At this point, my next step is to tear down my motor and see what I have to work with. Then I will get back to the detailed specs needed.

The piston combinations and recent comments on cam overlap and dynamic compression has been encouraging.

I will add updates as I know more.

By the way, I'm planning un using a carb and not the fuel injection or computer.

 

That's why block decking to ensure HG seal was accounted for in the figures I supplied. Flatness, while a requirement, is only half the equation- the surface finish is also important if using shim head gaskets. Coated shim gaskets are a little more forgiving but will still seal best w/the correct finish.

Had I also been discussing CR in that post (it was about quench, primarily), I would have said that milling the heads, while not affecting the quench, WILL slightly raise the CR. But I wasn't, so I didn't. Have to draw the line somewhere, lest the post turn into a freaking book. Like this one is fixing to do. :smash:

My bad, I misread your post :thumbup:

 

Thanks again,

The last few posts have been the most helpful so far. I started this new thread because a previous thread ended up with lots of book chapters between differing views.

At this point, my next step is to tear down my motor and see what I have to work with. Then I will get back to the detailed specs needed.

The piston combinations and recent comments on cam overlap and dynamic compression has been encouraging.

I will add updates as I know more.

By the way, I'm planning un using a carb and not the fuel injection or computer.

What are your horsepower goals, street manner goals (low end, high end power, torque, loping idle)? That will narrow down your cam selection, and that will determine your compression ratio. Then tear down and inspect your engine, then machine work, then parts selection to get your compression ratio and squish. :thumbup:

 

What are your horsepower goals, street manner goals (low end, high end power, torque, loping idle)? That will narrow down your cam selection, and that will determine your compression ratio. Then tear down and inspect your engine, then machine work, then parts selection to get your compression ratio and squish. :thumbup:

Very good question.
Originally before I did any research I threw out a ballpark goal of 300hp, 400torque, slight lopey idle, 15mpg in 3500lb Camaro.
700r4 tranny, with appropriate rear end ratio.
Daily driver, Street use only, Good low end torque, Strong launch from a standing start, Spin tires when desired, good street manners for normal driving. No desire to wind it up to high rpm.

Initial feedback suggested a fuel injected engine, but since then I'm leaning back to using a carb. At this point I'm thinking of an L31 or 350HO as a base, but with slight improvements, which would put me in the mid 300's for power and 380-420torque.

On the subject of piston top design for good quench. Realizing that I will probably need some kind of dish, it seems the best design is the D shape where the flat top matches up with the flat portion of the head for maximum quench area. Here's the two styles suggested above available from Summit for a good price. Neither one is a tru D shaped dish.

SLP-H423ACP60

SLP-WH423NP

 

For quench in order of best to worst piston design:
flat top no valve relief
flat top 2 valve reliefs
flat top 4 valve reliefs
D-Dish
Dish and dome (not sure which is better than the other)

Why are you stuck on the d-dish? I would do everything I could with manipulating deck clearance, piston compression height and head gasket thickness so I could stick with flat tops.

 

Why are you stuck on the d-dish?.

Not stuck, just trying to learn this new myself. I just keep modifying what I think I know as I learn more.

Thank you

 

Not stuck, just trying to learn this new myself. I just keep modifying what I think I know as I learn more.

Thank you

The Vortec head has an excellent combustion chamber shape, you do not want to alter that, but there are ways to add volume to it w/o disrupting the chamber's function.

So if you want to use a FT, research reworking the combustion chambers to gain volume and see if it's something you think you can handle. You'll need grinding tools, and eye protection, and a good amount of spare time. It can be done w/nothing more specialized than a Dremel, sanding rolls and bits, a pair of goggles and a way to measure the chamber volume accurately as you work. You'll never want to do it twice, it's a dirty time consuming job. But it is an option, although getting 12cc more volume w/o running into problems might be impractical if not impossible.

BTW, the second piston above isn't a SBC piston. Post #17 describers the SP 423 pistons- round, 4 valve relief.

I believe you ought to build this engine right. That may well mean spending more than a ten spot on a piston. If you want cheap, then so be it.