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Chevrolet Performance 350/290 Crate Engine

11K views 33 replies 11 participants last post by  Hogg 
#1 ·
Is the entire Chevrolet Performance 350/290 crate engine considered a Generation 1 small block with Gen 1 style heads etc, or is it a mix of new and old?

The heads use the Gen 1 valve cover pattern, so assuming they are Gen 1 (unless frankensteined), but if they are Gen 1 - why does Chevrolet Performance not seel just the heads? I've searched and Chevrolet Performance doesn't seem to sell them - the Chevrolet Performance new gen Vortec heads always come up for sale - but not these ones.

Thanks for any info.
 
#2 ·
#3 ·
Thanks JJLT1, those first links are exactly what I was looking for - although man can't believe the price is for stripped heads! The vortecs come completely assembled for that money, so dissapointing, but exactly what I was thinking - Gen 1 heads.

The issue with the Vortecs is the more I read the more it looks like a mess to convert a Gen 1 block for those, read one forum post where a guy was drilling a hole in his actual block for the Vortec head and I think the head itself too maybe they are drilling for a sensor or something - its not a direct fit unless Im reading wrong? Then you need new manifold, then you have more overheating issues, just seems like everything I read sounds more like a negative - so thats why I wanted to stay Gen 1 if possible.
 
#8 · (Edited)
Yeah, I'm new to chevy engines, but had just read this article that seemed to say the Vortecs were not considered Gen I heads; Tech: GM 1st Gen Heads vs. Vortec Heads Reader Guide - Chevy Hardcore

Either way by Gen I I just mean the same casting size heads and having all coolant channels, intake etc. lined up - just would like something like stock - but better valves/porting/chamber basically.

That said, trust me the Vortecs would be awesome considering I can buy a rebuilt pair off ebay for like $350 - its just a matter of how much modification are we talking here? Like I said not sure if there is a coolant passage in the block itself to drill - then there is that bypass package I mentioned above that seems to need a hole; if someone knows about this would really like to know how extensive were talking.
 
#9 ·
Spent some time reading up on the Vortec issues more and finally understand; here is a pic of a vortec block - note large coolant passage between cylinders 2 and 4 at bottom area:



Then, here is a picture of a 1970 small block - its hard to see, but it has small coolant passages between 1&2 and 3&4 - but no hole between 2&3 - and the vortec heads have a large hole there; reading sounds like a lot of guys just dont know this and are running the heads with a coolant hole blocked essentially.



Then there is the other "hole" mentioned in my previous post about the bypass hole which is a whole other can of worms as drilling it possibly causes cooling issues in relation to the a/c operation.

The thing I don't know and can't find a picture of is if any later model Gen 1 small blocks ever had a coolant hole between 2&3, couldnt find any images of an early 80's block like I have to see.
 
#10 ·
Pace Performance (a GM dealer) used to sell the 260 and 290hp 350 crate heads as "take-offs" Meaning they used the brand new shortblock and put a better head on it.

For the money, you can buy a 4bolt main vortec 350 for approx $2200 with free delivery. Hard to beat; throw in a more aggressive roller cam if you like, an electric fuel pump and a vortec intake with the 650-750cfm carb of your choice. Whammo.

To really pick heads, you need to know what your pistons look like, and how far down in the bore they are. You also need to know what your camshaft is (assuming you don't want to change it).
More than likely, a 64-72cc chamber and a 180cc port head (like the IK180s or similar) is all your engine wants.
The ZZ4 heads are listed as 58cc chambers and have 165cc ports (aluminum), Vortecs are listed at 64cc chambers and 175cc ports (iron); the fastburns are 62cc chambers and 210cc ports (aluminum).
There you go, pick the performance level you want...mild to wild
 
#11 ·
It has obsolete low compression 1970 smog era heads with a 1960 era performance cam. The end result is a mixture of low compression, poor burning heads with a long duration cam with very long ramps that get the intake valve seated rather late in the compression cycle. This results in a fuel hungry engine for the power it produces which is easily 50 horses and pound feet down from what this engine could and would do with a simple change to L31 Vortec heads or an inexpensive import head like the aluminum ProComp. If you confine yourself to inexpensive heads this can be built into a decent motor for a little less money than buying crate L31, which isn't a bad deal at power per dollar.


Bogie
 
#15 ·
Your talking about the 350/290 right? 350/290 HP Small Block Crate Engine | Chevrolet Performance Its advertised as having 300hp, how is that considered "smog" heads? My actual 1980 350 engine has real "smog" heads and they are causing it to have around 200-220 horsepower according to people on this forum, so not seeing how you can use that same terminology with 350/290 heads that create 300hp?
 
#12 · (Edited)
Then, here is a picture of a 1970 small block - its hard to see, but it has small coolant passages between 1&2 and 3&4 - but no hole between 2&3 - and the vortec heads have a large hole there; reading sounds like a lot of guys just dont know this and are running the heads with a coolant hole blocked essentially.
thats not just a vortec thing, its a known hot spot between the the 2 center exhaust valves..
we have been adding or enlarging that hole on every performance build
doesnt matter which heads you run, even on a gen2 motor..
some gaskets have much a bigger hole than others..

the vortecs will work as long as you have some sort of bypass to keep the water moving,,
from the WP to block like on the older blocks or a WP to intake bypass like the newer blocks,
or even the heater core will work without the heater control valve or use a bypassing heater valve..
people put vortec heads on older and newer blocks all the time..

gen1 and gen2 block and heads are very different, you can not mix and match them...
.
.
pics are a older block with the WP bypass hole, and a later block without..
 

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#28 ·
Thanks for the picsJJLT1, so the drivers side gen 1 head will have a hole in the front side which the thermastat housing routes that block bypass holes coolant into the front of the head?

I've read that a bypass has to go from the intake to the heater and then back to the pump, so just sounds like quite a lot of modification and perhaps a lot of hoses everywhere after which is not ideal. Do any aftermarket heads that are affordable keep and properly route that bypass coolant for gen 1 blocks so you don't have to go through all this?
 
#14 ·
Its a known issue, just rarely addressed because its considered a mfg fix for a long known flaw that affects performance/towing builds.

The mod isn't difficult to make but if you are not equipped to do it and don't...you end up with an engine that has all the old school flaws...thats all.

I suggest you do the mods and not worry about it, a couple hours with a die grinder and a drill is all you need...most guys don't do the WP mod because like it was said a heater core does that for you.

Don't over complicate the issue, its not the end of the world if you don't do them...lots of old school engines out there running just fine with small coolant holes in the block doing just fine. Its a good idea and helps with reliability and cooling between the valves which has always been a SBC weak spot not just the 400 version which made the issue worse because of the siamesed cylinders.

To be honest even just enlarging the block holes to get within 75% of the gasket size is close enough...doesn't have to be exact.
 
#18 ·
I have a 350/290 hp crate that's been in my truck for about 12 years. Its a decent engine, but I would not buy one again. The L31 Vortec crate is a much better deal from GM because the Vortec heads are so much better than the older iron heads on the 290HP engine, and the L31 already has a roller cam. The cam on the 290HP engine has limited low end and is not well matched to the large combustion chambers and low compression. I finally switched to a lower performance cam (similar to the one on the 260hp engine) that was much better matched to this engine.

The biggest limitations of the low end GM crate engines are the old-style heads and the lack of roller cam provisions. If your goal is performance (maybe 400 HP +) you need better heads, preferably good flowing aluminum heads, and using a roller cam gives you many more options for a more aggressive cam.

Bruce
 
#19 ·
One of the reasons many buy a crate motor is the ease and supposed reliability/warranty. I just wouldn't buy a flat tappet cam crate motor. Even if I was doing an era-correct looking car; I'd dump in a 4bolt vortec crate, and eventually switch the heads and intake out as budget allows. The only giveaways would be the dipstick on the wrong side and the lack of a mechanical fuelpump.
Im hopeful TrickFlow releases their aluminum "fuelie wringer" heads
 
#22 ·
Looking at the "fuelie" heads vs Vortec, the chamber and valve specs are almost identical, but obviously the porting and chamber design is different, so I assume that affects horsepower; can anyone tell me the difference in horsepower between some 60's fuelie heads and vortec heads?

Also, if I went the Vortec route - which seems tempting as its so cheap, does anyone know the difference between the Edelbrok 2104 and 2116 manifolds? One is slightly higher, cant see much else; these would both work with Vortecs on an 80's block with Quadrajet right?
 
#24 ·
Big difference in performance between camel humps and L31 Vortecs. The power difference is very sensitive to cam but just bolting Vortecs on will make anywhere from 20 to 60 more horsepower over camel humps for the same cam and bottom end. The porting is different the L31 Vortec repositions and reshapes the intake to where non Vortec manifolds will have sealing problems on the upper side even if you modify the bolt patter to make them fit on the head. Biggest change is in the combustion chamber where fast-burn and high swirl is the order of the day. The chamber is where the action is this is actually a return to the Ricardo chamber (Sir Harry Ricardo, look him up you'll understand why this is important).


Keep in mind the L31 Vortec needs to have the upper valve guides reworked for lifts over .45 inch. This consists of milling the guide down a little. While considered a machine shop modification all the speed stores sell a guided milling tool for this that fits into an electric drill so it cam be done at home. Also, guys have developed a thing called a Ghetto Grind which is nothing more than taking an abrasive cutoff wheel in a rightangle grinder and just chopping a part of the upper guide off the dressing the rough edges, crude but it works. There are many, many aftermarket heads that are duplicates to improvements in iron and aluminum from inexpensive imports to gold plated domestics. These tend to have both the standard and Vortec bolt pattern. They also may move the port face around so that standard intake height ports seal up better. If you live where it cold and this is a year around driver Engine Quest (EQ) makes a head with an L31 chamber, standard port positions, and exhaust cross over ports to heat the intake. In fact many racing associations will accept these as Stock Replacement heads.



Another advantage of both the L31 and aftermarket heads is they come with hardened exhaust seats which most certainly camel humps will not unless reworked in a machine shop for hard seat inserts, but none ever came from the factory like this.


The key to performance today is the acceptance of modern unleaded fuels and octane limits mostly at 91 but some places you can find 92 or 93. Working with these limitations it is found that the fast burn, high swirl chamber, mixed with careful attention to reintroduction of the wet fuel flow, along with fast lifting, high lift cams that feature short ramps ahead of their .050 duration, pretty early intake valve closing and fairly wide LSAs which demonstrate a minimum of overlap makes tons of torque and horsepower. To day it is simple to get over 400 horses out of a 350 with an engine that can run perfectly fine against a stock stall converter. Back in the camel hump days this was impossible to do as it took 11 to 1 compression ratios with very long duration cams to where the idle speed and torque and power peaks were far above what a stock stall converter could put up with. The down side of short ramp, fast and high lift cams is its hard on the lobe to lifter interface of flat tappet cams, it can be done with plenty of ZDDP additive and a proper break in but the simple solution is a roller cam. For flat tappet cam high quality aftermarket tappets are better survivors but these are going to cost from 120 to 200 dollars or more.


Bogie
 
#23 · (Edited)
When you get into the "good old days", vs "bad old days" argument....you're treading on thin ice with some folks. "Fuelie" heads have attained an almost mythic status amongst some groups. Yes 50yrs ago, they were the best factory head for a smallblock chevy, and were widely available for a reasonable price. However, porting techniques of the day involved the biggest valves you can shove in there. You can end up with a lazy port that does more harm than good for the average guy. The Vortec port; is more about speed and efficiency. Depending on the engine, it can be good for 20-30hp or more over the fuelie type head, and it has all the modern mounting provisions, and the superior (albeit ugly) centerbolt valvecovers.
Now, heres the weird part: Both heads were designed using theories/ideas from a guy named Sir Harry Ricardo. He basically designed the Vortec head back in the 1930s....Thanks to the EPA in the early 70s (after the fuelie head); the big 3 manufacturers put very little performance into street cars until probably 1985. If it wasn't for that; you probably would have seen the Vortec type head around 1973-75.

Be careful comparing engine outputs listed in the 1960s, to modern stuff. The Auto industry changed the way engines were rated for power in 1972, so YES some of the drop off in engine output is the Smog stuff, and reduced compression, but much of it is changing from SAE Gross (engine run on a test stand, with no exhaust, no powersteering/aircon/waterpump/etc); to SAE Net (Engine as delivered in the automobile). In 1971, most (if not all) car makers listed SAE gross and net. For example, the original Chevy LT-1 had 330 gross HP and 250 net HP listed in 1971. Thats approximately a 25% loss in rated HP. Now, some of THIS is a game, because car mfg would often publish HP figures at a lower RPM, in order to have a lower rating to make the insurance rates cheaper for the consumer, and more likely to buy the car.
To put that in perspective:
1965 327 with fuel injection and solid lifter cam published rating 375hp (SAE Gross). The SAE Net would be something like 290 - 295hp.
 
#26 ·
The Vortec port; is more about speed and efficiency. Depending on the engine, it can be good for 20-30hp or more over the fuelie type head, and it has all the modern mounting provisions, and the superior (albeit ugly) centerbolt valvecovers.
Thanks autogear, wow did not realize chamber design and everything would be that big of a horsepower loss, that probably removes those as an option then, good info.
 
#29 ·
There is a different spring/retainer combo that might get you .480" + a safety margin. I've never pushed a set of vortecs that high personally - but its been done plenty.
Whats your budget? We can way poetic on this stuff (you should definitely read on Harry Ricardo though) all day; but there may be an option we are missing.
 
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#33 · (Edited)
You know I should realize that my ex is a Zeelander and I sure know that their tax structure is so onerous that for her family to purchase big ticket items that it was significantly less expensive for them to fly to the States, buy washers, dryers, refrigerators, and pickup trucks then have them shipped back as personal property than to buy them new there. I guess the end cost was about the same with shipping and taxes on both ends but they got a trip to California, Oregon, and Washington to visit their American relatives out of the deal.


That said I've been negotiating with one of these Chinese foundries re making Gen I heads to my specification. Whether that ever flies I don't yet know. When I go back and look at the problems Barnes encountered with unusual Gen I heads while not to that extreme it still has given me pause because the front end cost is pretty staggering against the risk of owning a ware house full of unsellable stuff.


Bogie
 
#34 ·
I just wanted to interject that the 1996-2002 L30 305 and L31 350 was referred to as the GEN -1E SBC(aka Vortec heads with raised iuntake runners and 4 intake bolts per head)
The 1992-1997 L99-4.3 V8(3" stroke I pieces RMS crank) and alum and iron head LT1 and 1996-97 LT4 were GEN 2.
1955-1995 was GEN 1 SBC.


peace
Hog
 
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