Which 350 crate engine to choose.

[Jerry]

I some what have narrowed my choice down to these three crate engines by GM all are 350's.  This will be going into my 1986 Chevy K10 4x4, 4 speed trans.  I just can decide which one and its driving me crazy. I've done my home work on each but just can decide. Some help is greatly appreciated. I don't want to machine anything out, maybe a little bigger cam (if I need it) is as fare as I want to go as far as upgrading. THANKS

1. 350 HO /GM 19210007....1 piece rear seal, 4 bolt block
330hp
380ft lb

2. 350 /GM 12530282.....1 piece rear seal, 2 bolt block
255hp
330ft lb torque

3. 350 /GM 10067353-k....2 piece rear seal, 4 bolt block
300hp
356ft lb torque

[Macj1983]

1 or 3

[rich weyand]

Agreed either 1 or 3 of those choices.

The one caveat I would put in is those torque curves come on awful late, with peak torque at 3800 rpm.

A base-level stock GM 350 10067353 with a Comp 12-300-4 cam is cheaper than either of those, and will smoke both off the line, with 380 ft lbs of torque at 3000 rpm, and 300+ ft lbs from 1000 rpm on up.  No warranty once you crack it open to put the cam in though.

[Jerry]

Rich

How much HP to expect from this set up???

[zieg85]

Here is my $.02.   Keep in mind, if you are using your stock exhaust manifolds you will need the dipstick on the passenger side.  I ran into that problem on my 86.

[rich weyand]

Rich

How much HP to expect from this set up???

275 hp at 4000 rpm.  But horsepower isn't what matters on the street.  Check out this article cite from an adjacent thread:
http://www.hotrod.com/techarticles/hrdp_0401_torque_horsepower_guide/viewall.html

Note this paragraph: "Generally the rpm range that is most important is the area between peak torque rpm and peak power rpm. The car should be geared so that you shift 400-500 rpm beyond peak power, and the engine "falls back" to just beyond the peak torque point. Assuming a similar operating range, the engine with the greater area under the power curve between the power and torque rpm peak points makes for the better combination."

So looking at those engines, they have peak torque at 3800 rpm.  Peak horsepower (per the article) is always about a third higher, call it 5000 rpm.  So do you normally drive between 3300 and 5500 rpm when accelerating?  Get something with peak torque about 3000 rpm and peak horsepower about 4000 rpm, and your operating range under acceleration is 2500 to 4500 rpm.  Much better.

That's what I did with the 12-300-4 cam, after doing all the research, and I love it.  What kind of research?  I read everything on torque and horsepower on the net.  I talked to my buddy who has a beautiful '32 deuce street rod and has been doing hot rods since I was in high school -- he went with a marine (torquer) cam.  His son helped him with custom grinding that cam -- he worked at a Chicago engine builder and does semi-pro drag racing.  Another friend rebuilds and modifies Porsches and Audis, for 30 years or so.  My brother taught engine design for 30 years.  So I cheated: I called in some pros.

Anyway, when I swapped the cam I went from a claimed 290 hp to a claimed 275 hp, but that also lowered the peak hp rpms by about 1000 rpm, and the torque curve shot up and moved left (lower rpms) on the dyno curve.  Which is what you use getting off the light.  The 290 hp engine was a wind-up toy; you have to get rpms under it for it to get breathing properly.  Horsepower is fine for bragging rights, but it's how much torque you have in the rpm range that you actually drive in that matters.

I was in exactly the place you are 16 months ago when the 350 in my truck died.  I went for the horsepower number and regretted it.  Having swapped out the cam, to go for torque in my driving range rather than horsepower up high, I am much happier.

And if I came up against any of those three engines above at the stop light, I would seriously smoke them.  Not even close.

One more example.  In 1970, Chrysler was putting the 426 Hemi engine in its street cars, mostly to homologate the race engine.  All you have to do is say "hemi" to a Mopar guy and they'll start drooling and their hands will tremble.  The 426 Hemi produced 425hp @ 5,000 rpm, and 490 lbs-ft. torque @ 4,000, which powered the Challenger through the 1/4 mile at 14.1 @ 103.2 mph.  Also in 1970, Buick put out the GSX Stage 1.  It had a 455 big block, with 350 hp at 3600 rpm and 510 lb-ft of torque at 2800 rpm.  So how did it compare to the vaunted Hemi?  A 13.38-second pass at 105.5 mph prompted Motor Trend to crown the GS 455 Stage 1 "the quickest American production car we had ever tested."

Smaller horsepower number, but higher torque, and horsepower and torque peaks about 1000 rpms lower.  Sound familiar?  That's why they called the GSX (which came out the month after I got my driver's license, so this is not hearsay) the "Hemi-killer".

Now the Hemi was a great race engine for Nascar and the like, but in the quarter-mile?  Uh-uh.  And 0-60?  Forget it.

Sorry I got up on my soapbox there, but I just put the new cam in a couple weeks back, and it has been a revelation.

[Jerry]

Rich

Which intake manifold can I use other that the 2601 air gap..Didn't want to use the two pie set up and thanks to everyone for there input. Rich, you brought everything into perspective and I will be going your recommended route hoping I can use a different intake other than the air gap intake. If you have any other recommendations for this set up you recommended  don't hesitate to let me know. THANKS

[Irish_Alley]

what about that other thread me and rich talk about engine choices? whats your budget?

[rich weyand]

Well, if you stick with the thermostatic air cleaner, you can use the air-gap manifold and pick up some additional horsepower and especially some additional torque, like 5-10 hp and 10-15 fp.  If you want to go with the open air cleaner element, which I call the two-chrome-pie-plate setup, then you cannot use the air-gap manifold.  You need carb heat to use the air-gap manifold.

The non-air-gap alternative to the 2601 is, I think, the 2701.  Same thing, but without the heat isolation between the carb and intake runners and the lifter box cover.  The oil will then keep the carb heated.  The 2601 air-gap makes sure the carb is not overheated by the engine oil, so you get a denser charge, but then you need the thermostatic air cleaner so the carb doesn't run cold.

[Jerry]

Rich


Just one last question, can u do this set up on the engine that has roller cam. I believe it the second engine that I have posted It has roller cams,vortex heads, 1 rear seal, 4 bolt.  Would I be able to put tourque cam and get the same results? If so can u suggest a cam?? Thanks

[rich weyand]

Yes, you can get a roller cam optimized for torque.  Comp's "excellent torque" cam for the rollies looks like it's the 12-464-8.  A Comp 12-464-8 with the 9.4:1 Vortec heads (which is the engine #2 above) will give you 334 hp @4500 rpm and 431 fp at 3500, which is a lot better than the 255@4600 rpm 330 fp @2800 rpm it comes with.  The torque peak is actually a little higher rpm, but the 12-464-8 cam breaks 400 fp at 2000 rpm, so the torque curve is broad and low, which is what you want.  I could smoke the stock rollie no question, but not that 12-464-8 cam.  400 fp at 2000 rpm?  Yowzah.

Now let it be said I haven't done all the research on this cam.  I ran the dyno simulator against it, and it looks good, but I would do some serious googling around for cams with the Vortec heads, and I would google that Comp part number and see if there's any first-hand experience posted, etcetcetc.  Go to Comps' simulator http://www.camquest.com/ and plug in the numbers for that engine and try some cams and play with it a bit.

[rich weyand]

Looking back, both #2 and #3 are the Vortec heads, and the #3 engine above has some better specs, with 330 HP @ 5000 RPM, 380 ft. lbs. @ 3800 RPM.  334 hp @4500 rpm and 431 fp at 3500 is better, but not as much better as it is against the #2 engine.  Probably not enough better to void the warranty and incur the extra expense.  You are already $3K into it with that engine out of the box.

If you do change out the cam, you definitely want the 4-bolt main engine for pulling those kind of torque numbers.