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brainstorming an engine build

6K views 26 replies 5 participants last post by  techinspector1 
#1 ·
I bought a 350 long block in the past off craigslist, long story short, it never seemed to sound or run quite right, so I tore it down to find all the bearings were demolished by a little bit of sand (this wont happen again), and the driver side head was warped. Heads casting number showed that they were crack prone, already had other heads ordered up waiting for them to crack.

I have a few basic parts that I already have for the new engine:
------------------------------------------------------------------------
Heads:
-Comp Cams Aluminum heads with .650 grade lift springs, 2.02/1.90 valves 64cc chamber, 190cc runners, with 3/8 studs and guide plates (brand new).
-Fel Pro 1003 Head gaskets .041 compressed (brand new).
-ARP Head Bolts.

Valve Train:
-1.5 stainless full roller rockers (brand new).
-Engle EP-26/28 .520lift with 1.5 rockers, 288 advertised duration, 108 LSA, with hydraulic lifters (off old engine, looks brand new).

Intake:
-Holley 600cfm Double Pumper, mechanical secondaries/choke Aluminum Fuel Bowls, with aluminum heat sheild.
-Holley Street Dominator Open Plenum Aluminum Intake.

Going to be in a 1952 GMC long-bed pickup, manual 4spd. Saginaw tranny with Hurst shifter, Posi-traction rear (unknown gearing guessing in the low 3's), no power ANYTHING, no ac or heater. Dual 2.5in exhaust with the old cherry bomb long glass packs. Aluminum plate instead of an oak bed, apparently weighs total, less than 3500 pounds.
------------------------------------------------------------------------


Here's where the interesting stuff begins, I decided that I should just get a new short block since I do not have all the required tools other than the normal socket wrenches and torque wrenches to completely rebuild from a bare block after the machine shop, and I need something working very soon.

I not only want to use the parts that I have already bought, but I am nearly forced to by my budget of $2000. I have been browsing around after doing lots of research and have not found much of any engine blocks that will work for me.

#1: my cam states that it requires 10 - 10.5:1 compression. Blocks are either less than 9.5:1 or greater than 11:1 compression
#2: In order to get proper quench (.040), the deck clearance must be flush with the piston since my head gasket is already at .041!
#3: 383's seem to have the compression that I need, but all so far only include flexplates and no balanced flywheels for manual transmission cars.

My worst fear is to have to resort to a 190HP stock GM crate 350, crappy gas mileage and crappy power is not appealing when there are lots of big long hills and lots of trash can muffled hondas lol.

Any thoughts, opinions, advice? How can I use the parts that I already have within my budget most effectively? All comments are welcome, and all help is greatly appreciated! :thumbup:
 
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#4 ·
looks like things are moving forward :), I found a reputable private seller on ebay with a short block that was willing to respond to me with some much needed info! FINALLY, what a rare breed of a seller in this day and age!

So he has two 350 short blocks, one that will give me .030 quench, and another that will give me .040 quench, and bored .040 over. The .030 quench block will give me 10.56:1 compression, and the .040 quench block will give me 10.3:1 compression.

When I get the short block, ill be sure to inspect and double check his work.

Even though ill have better quench, with aluminum heads and 91 octane, would 10.56:1 compression still be too much? It comes with a cam, but I might use my own since it has 288 advertised duration, which apparently could help with lowering the dynamic compression.

I was reading in other places, and apparently with aluminum heads, anything below 11:1 should be ok, anyone have experience in this?
 
#6 ·
I bought a 350 long block in the past off craigslist, long story short, it never seemed to sound or run quite right, so I tore it down to find all the bearings were demolished by a little bit of sand (this wont happen again), and the driver side head was warped. Heads casting number showed that they were crack prone, already had other heads ordered up waiting for them to crack.

I have a few basic parts that I already have for the new engine:
------------------------------------------------------------------------
Heads:
-Comp Cams Aluminum heads with .650 grade lift springs, 2.02/1.90 valves 64cc chamber, 190cc runners, with 3/8 studs and guide plates (brand new).
-Fel Pro 1003 Head gaskets .041 compressed (brand new).
-ARP Head Bolts.

Valve Train:
-1.5 stainless full roller rockers (brand new).
-Engle EP-26/28 .520lift with 1.5 rockers, 288 advertised duration, 108 LSA, with hydraulic lifters (off old engine, looks brand new).

Intake:
-Holley 600cfm Double Pumper, mechanical secondaries/choke Aluminum Fuel Bowls, with aluminum heat sheild.
-Holley Street Dominator Open Plenum Aluminum Intake.

Going to be in a 1952 GMC long-bed pickup, manual 4spd. Saginaw tranny with Hurst shifter, Posi-traction rear (unknown gearing guessing in the low 3's), no power ANYTHING, no ac or heater. Dual 2.5in exhaust with the old cherry bomb long glass packs. Aluminum plate instead of an oak bed, apparently weighs total, less than 3500 pounds.
------------------------------------------------------------------------


Here's where the interesting stuff begins, I decided that I should just get a new short block since I do not have all the required tools other than the normal socket wrenches and torque wrenches to completely rebuild from a bare block after the machine shop, and I need something working very soon.

I not only want to use the parts that I have already bought, but I am nearly forced to by my budget of $2000. I have been browsing around after doing lots of research and have not found much of any engine blocks that will work for me.

#1: my cam states that it requires 10 - 10.5:1 compression. Blocks are either less than 9.5:1 or greater than 11:1 compression
#2: In order to get proper quench (.040), the deck clearance must be flush with the piston since my head gasket is already at .041!
#3: 383's seem to have the compression that I need, but all so far only include flexplates and no balanced flywheels for manual transmission cars.

My worst fear is to have to resort to a 190HP stock GM crate 350, crappy gas mileage and crappy power is not appealing when there are lots of big long hills and lots of trash can muffled hondas lol.

Any thoughts, opinions, advice? How can I use the parts that I already have within my budget most effectively? All comments are welcome, and all help is greatly appreciated! :thumbup:
comp cams heads thats a new one
 
#9 · (Edited)
Comp cams doesn't make cylinder heads.

If you build an engine w/too much compression, you can run out of octane unless you want to run it on race gas or E85. So do not be tempted to run 11:1 on pump gas. Running a big cam only partially crutches the need for octane- the quench distance has to be spot on, and a big cam also requires a low rear gear, and unless you have an OD tranny to crutch that up, you'll be miserable driving any distance with =/> 4.56:1 rear gears.

In a truck I suspect strongly that you'll be a lot happier w/a 9-9.5:1 compression engine and a cam to match. If the lifters were mixed up and not placed exactly back on the same lobe they came from originally, the cam and lifters are junk, anyway.
 
#10 · (Edited)
I found this to be an excellent read during my research: Racing Engine, How to tips

cobalt brought up some good points, if it is a truck, then it should have the ability to pull something, even though I VERY highly doubt I will EVER pull anything above 500 pounds, you never know.

For a truck engine as a general rule, is it 9-9.5:1 for iron heads, and 10-10.5:1 for aluminum heads? I read that running aluminum heads allows you to increase compression by one point. I'm thinking that it would also be a good added insurance to run .035 quench since I do not expect to ever rev above 6000.

thanks for the good advice cobalt :thumbup:
 
#16 ·
I would call your estimate of "9-9.5:1 for iron heads, and 10-10.5:1 for aluminum heads", safe. I would not, however, want you to go any closer than 0.040" quench. 0.035" leaves NO room for error on the part of the machinist or the dimensions of the parts or even a missed shift or broken driveline part, there's nothing of any real substance to be gained from the extra 0.005", and the downside can be expensive.

While it's true you can usually get away w/more compression using aluminum heads, this is only because aluminum sheds heat easier into the cooling system. There are no free lunches- if you build w/alum. heads, the added compression is needed just to stay even w/an iron head- not that aluminum magically allows you to run more compression. I don't much care for aluminum heads on a SBC daily driven vehicle myself, I like good ol' cast iron. That's not to say the good aluminum heads aren't good- they are- but you do pay for the privilege.

In the same vein, I also never build a street engine right on the edge, compression-wise, either. The general rule of thumb on compression is one point- like going from 9:1 to 10:1- will net you about 4% more power, all else being equal. Now, that IS 16 hp on a 400 hp engine, so isn't exactly insignificant, but the down side to the added compression can be a huge loss of power if you misjudge things and you end up needing to retard the total timing from what gives you the best power- just so the engine doesn't detonate. And it has other downsides as well like less tolerance to a bad tank of fuel, or something that causes the coolant temp to rise past normal. At least in the last two cases you can stop, get out, and turn the distributor to lower the timing to limp home w/o ruining the engine- as long as you caught it soon enough.

My bottom line is: There have been a LOT of VERY strong running SBC 350/360s built using 9-9.5:1 CR. A properly spec'ed and assembled engine w/that CR can expect to make more power than you can safely use on the street. A racing engine is another animal altogether and the two (racing engine on the street) seldom meet happily in the middle, in my experience. Again, that's not to say there aren't 10:1-plus iron head or 11:1-plus aluminum head engines being driven on the street every day, w/o issue. But it IS to say that if you choose to run on the edge, it can bite you.

So I cannot in good conscience advise anyone to build a 11:1 aluminum or 10:1 iron head engine for street duty. When the parts on hand absolutely HAVE to be used, sometimes this means compromises must be made- I understand this. But if at all possible, hedge your bet to the safer side rather than the "faster" side.

Good luck.
 
#15 ·
iron makes more power hands down.
alum is easier to cast/machine/etc and why they use it..
pore the same heads in both, iron will win everytime
heat = power, alum transfers it, iron holds it..
with a fuel that not pre ign. iron all the way..
r09 engines heads where taken by nascar that where iron.. because the walked over the field
team fined 100k
 
#17 ·
Some things I forgot to say. Main thing: Stick to the fundamentals.

Insist on a torque plate final hone. A good, round cylinder w/a piston that has the correct piston to wall clearance, along w/the correct ring end gaps will do as much for performance as a LOT of other "racing" tricks. What guys fail to realize is, while a loose piston to bore clearance may have less friction, the rocking motion this allows causes the ring seal to go away.

Follow the manufacturers specs for piston clearance, ring end gap, etc. Measure the piston where the manufacturer says to measure it.

Use a three angle valve job. Backcutting the valves is sometimes a cheap way to increase flow where it'll help on a day-to-day basis (look at what GM did w/the Vortec valves- they do NOTHING "just because" :mwink:).

Break in the cam correctly.

There are other things but these are fairly important IMHO.
 
#18 ·
Some things I forgot to say. Main thing: Stick to the fundamentals.

Insist on a torque plate final hone. A good, round cylinder w/a piston that has the correct piston to wall clearance, along w/the correct ring end gaps will do as much for performance as a LOT of other "racing" tricks. What guys fail to realize is, while a loose piston to bore clearance may have less friction, the rocking motion this allows causes the ring seal to go away.

Follow the manufacturers specs for piston clearance, ring end gap, etc. Measure the piston where the manufacturer says to measure it.

Use a three angle valve job. Backcutting the valves is sometimes a cheap way to increase flow where it'll help on a day-to-day basis (look at what GM did w/the Vortec valves- they do NOTHING "just because" :mwink:).

Break in the cam correctly.

There are other things but these are fairly important IMHO.
plate hone, with bolts or studs being used on engine, and main caps torques if poss.
 
#19 ·
Ok, with a quench of .040 I will have 10.3:1 compression.

Bore: 4.040 (diameter)
Stroke: 3.48
Cylinder Head Volume: 64
Effective Dome Volume: 6
Use (-) for Dome and (+) for Dish.
Deck Clearance: .025
Compressed Gasket Thickness: .015
Number of Cylinders: 8
Compression Ratio : 10.31 : 1
Total Displacement (in.3) : 356.88
Total Displacement cc's : 5850.49

2 FEL Pro Head Gaskets Rubber Coated Steel Shim 4 100" Bore 015" Comp | eBay (head gasket)
New Small Block Chevy 350 IMCA Claimer Racing Oil Pan | eBay (oil pan)
PRW SBC 305 350 Chevy Sportsman 8" Polished Harmonic Balancer | eBay (damper)
350 Chevy Short Block Assembly High Performance w Forged Pistons | eBay (they may be in the build process as we speak, they are willing to do any deck height I choose)

I can either use that .015 gasket (sounds too thin for aluminum heads) or I can tell them to deck the block to .000 for my Fel Pro 1003 .041 gasket.
 
#24 · (Edited)
The default gasket for aluminum heads is the Fel-Pro 1003. Don't use the shim gasket.

The 0.0035" variance is reasonable, considering that he may not want to spend the money to equalize rod lengths, etc. Like Cobalt said, make sure the tallest stack is at zero and the shortest is 0.0035" down in the hole.

Any used flat tappet cam and lifters are junk. You would have to re-use the very same lifter in the very same lifter bore, not in a different block. What do you think the chances are of 16 lifter bores on block #1 being bored exactly the same on the x and y axis and each one the same distance from the flywheel face of the block as 16 lifter bores on block #2?

Why would you spend 62 bucks for a Fosdick 5-quart oil pan? I doubt that it'll seal as well as a bone-stock production pan. If you want to make a difference, use a larger pan. 7-quart is a nice size for a street motor. Get the windage tray and crank scraper. Be very cautious about fitting the screen to the pan. You will need about 3/8" clearance. Less clearance can cause the pump to suck the bottom of the pan up against the screen and cut off oil supply to the pump. More clearance can cause the pump to run out of oil.
 
#20 · (Edited)
Got an interesting email from the builder.

"Just left the shop and wanted to run some things by you. The only 79 down 4 bolt at the shop is a .060 over, let me know if that's alright. Also, the owner (Barry) said that with the stock block, crank, etc. He can only guarantee a 0" - .0035" margin between cylinders on zeroing the block. Shoot me a note when you get a chance."

Usually I would think that a .0035 margin as insignificant since it is such a small number. Is that good, bad, or ugly?

I asked him if .060 will be the final bore, if it is, I don't see it as a significant issue, I have a triple pass aluminum radiator, high-flow aluminum water pump, and I assume aluminum heads will help out a tad too.
 
#22 · (Edited)
Thanks a ton, makes perfect sense, I shall let him know!

A .060 bore will bring me to 10.36:1 compression, crossing my fingers that everything will come together perfectly, all the numbers look excellent.

I will send him this: "Ok, looks good as long as the margin of error is with the piston below the deck, not out the top; Both decks match, each corner of the deck is the same, and the final cylinder bore will be .060."
 
#26 ·
Well, the weekend is coming up, the short block has arrived! Took a few weeks after it arrived to get everything situated back at my house, had to pick it up from my work in order to get the good shipping.

One final question before I begin the build and start a thread on that. For some reason I did not think to request the type of cam for the engine builders to install, so it came with an Engine Pro MC1730 with Duration @.05 = int204, exh214, and int.422, exh.444 Lift. The duration seems a little low for 10.3:1 compression, would it ping with this cam, or am I ok as I will have a good quench and aluminum heads?

For just in case that cam will not work, I purchased a comp cams, and cam assembly lube (that I can return) CS 280H-10 Duration @.05 = 230, Advertised Duration 280, valve lift .480.

I can also get an Edelbrock RPM series, and I believe that one had about 245 duration at .05 and 305 advertised, but I figured that would be a bit over-kill.

Let me know what you all think, I can return this comp cams next week for a different one with even more duration, or less, I simply got one so if it is correct I can get my pushrod length measured, and next week can have things moving along smoothly.

Thanks.
 
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