Thread: 350 4 bolt build ????s

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I just tore a Target Crapper out of my 81 Truck, and was wondering what to use on my rebuild.

I have a 350 4 bolt at the machine shop which is a standard bore and crank. The machinest says every thing is good, no lip and crank is fine a hone and polish are all that is needed.

I have two sets of heads and do not know which ones to use. I would like to have a 350 Horsepower 350 when it is all said and done.

My confusion kicks in with the heads. One set is the 993 (big chamber heads) the others are casting #14102193. Both are 194/150. I am clueless on what compression pistons to use, cam etc.

I have not purchased any parts, would like to run on pump gas and take a 1000 mile trip if needed.

Many thanks to all that respond!

Hmmm, sounds pretty close to a motor that I am building.

Heres what I am doing with option 1

350 4 bolt block torque plate bored and honed

350 cast crank standard mains and big ends

silvolite hyperutectic flat top pistons and moy rings

Rebuilt and shot peened rods with new ARP rod bolts

block decked to .010 deck height, check piston deck with a
trial prefit before doing this !!

Use .039 compressed gasket thickness head gaskets (felpro)

Open chamber 76cc heads with new valves and reconditioned
valve guides and H11 springs Single spring and damper crower springs are good part no 68311 set to run at 118 pounds on the seat and open at 350 pounds at approx .500 lift. Valves are 1.9 and 1.5

Give heads and valves 3 angel valve and seat job to clean up
airflow path.

Performer RPM manifold with either a quadrajet based carb
a holley 4165 spread bore double pumper list 6210

Lunati cams hydraulic cam pat No 30111 grind no H220-230
Intake .465 lift 220 dur at .050 lift
exhaust .490 lift 230 dur at .050 lift
110 lobe seperation
106 lobe centrekine
running 4 degress advanced

Stock brand new oil pump

good HEI distributor with aftermarket ignition module and hig
output coil

new rocker arms and pushrods with screw in studs. You
probably dont need the screw in studs but I like them
because I am just being me

Windage tray, crank scraper and milodon rear tray baffle if
you can get that all into your style of sump


Now this engine I have described will get you into the 1 horsepower per cubic inch ballpark with good headers and a smooth flowing 2.5 inch exhaust system. It is not a serious race motor but with that cam and head combination it will be a fun car to drive with a good broad torque range up to 5000 rpm

This will have a good static and dynamic compression ratio I would give you the compression ratio calculator but am clueless to how to get it on this thread. The calculator is located at streetrod drive in under compression ratio thread. The dynamic compression ratio article gives a good insight to whats happening in the cylinder under real working conditions and how cam duration and head compression work together.

That'll be a nice motor. The only thing I might do differently is run zero deck instead of 0.010' to tighten up the squish a little, but like you, that's just being me

Thanks tech maybe you could type up the direct link to the dynamic compression ratio thread I mentioned I dont have a clue how to do that yet.

Originally posted by techinspector1
That'll be a nice motor. The only thing I might do differently is run zero deck instead of 0.010' to tighten up the squish a little,
but like you, that's just being me

OK, Guys Lets split the difference,I normally do mine at .005.

Im sure both of you are better at computing compression than me,but if you dont have 9.5 I would consider truing the heads up
and taking them down to somewhere around 70cc's.

Southerner, I like what I see, I would talk to Lunati and get their recomendation on where to put the cam in.

Thanks for the input!

You said that you were going to bore your block and I am assuming that it's a .030 over? My block will be standard bore. Do you think I will come close to the 1hp per CI with the standard bore and package you mentioned?

I also looked in my Jegs, Summitt and Herbert Catalogs. I could not find this cam, but Herbert apparently has the same grind.

Many Thanks!

[QUOTE]Originally posted by 81fleetside
[B]Thanks for the input!

You said that you were going to bore your block and I am assuming that it's a .030 over? My block will be standard bore. Do you think I will come close to the 1hp per CI with the standard bore and package you mentioned?

Your truck is no light weight. Unless You have a gear ,headers and at least a mild converter You may want to back off on the cam some.Something like a CS260H-10Comp. cam 212/212 @50
440/440 lift 110 lobe seperation.

The 5 cubic inches difference will not make more than 2 to 5 H.P. difference in that application.

The reason that I bored and torqued my block was to get it right on and to cancel out any of the factory production tolerances.

The bore was good and it had hardly any lip on it. I just want to say again that when it was bored, it was with the torque plates bolted in place to stimulate the load and distortion on the block when the heads are fully torqued down. this ensures that the bore is round when the engine is together and this gives me maximum ring sealing and therefor good cklinder pressure. The other thing to ensure while the block is getting bored and torque plate honed is that all the main caps are in place and torqued up to specs.

It is really up to you if you want to do this step but as I said if you want your motor to be right on then you have to pay attention to details.

The other block machining jobs are decking, besides obviously lowering the deck height it also ensures that the top of the block is paralle to the crankshaft, After I had trial fitted my pistons in the block and taken measurements for deck height I then took 1 piston and rod assembly and swapped it to the 4 outer cylinders of the block. Guess what the deck heights were out by a taper in heiht of .015". So this will automatically affect compression and valve lift. So the decking operation also trues this up.

Next get a straight edge and put it on the main bearing bores to check block streightness up the crank centreline. If straight fine if not get it alaigne honed.

A may as well say that it only makes sense to spend this amount of time and money on the motor if you plan to keep it for a long time. The motor I am building for my ute is for keeps, I am planning to hang on to it for a big chunk of the forseeable future.

I'm just trying to get this sled to be a 14 second performer. It will have headers, Edelbrock NON ERG (not required for 20 year olds in Georgia) intake and a 600 Holley.

As we speak, it has a 2:56 open rear with a 350 tranny. I am looking for a p-track/limited slip and will probably go with 3:23's and stick with the tranny so my highway time will be smooth.

Well you have a nice high hoodline on that truck, I would suggest going for the rpm performer manifold with the 600crm vac sec holley for the street and for strip work to go for a 750 cfm double pumper holley to punch it off the line and to let the engine breath at hiher revs 3/4 of the way down the strip. So all you have to do is change carbs open up the exhaust, get high premium gas and advance your timing to wring a bit more HP out of it and you should have the goods.

I will try to load up the calculator that tech originally gave to me

http://kb-silvolite.com/calc.php?action=comp

Now I will calculate the compression ratios both static and dynamic for two different head and cam combinations, but using the same basic block configeration. If you compare results you will see something interesting.

Combination 1

cylinder head volume cc 76

Piston head volume cc 6

Gasket thickness inch .039"

Gasket bore diameter inch 4.030"

Deck clearance inch +.010"

stroke inch 3.48"


STATIC COMPRESSION RATIO 8.889

Aditional information

Rod length inch 5.7

Intake closing point deg ABDC at .050
lift plus 15 degrees 36 + 15 51 deg

DYNAMIC COMPRESSION RATIO 7.796


Combination 2

Now the basic short block is left the same what will change is I will go for the 64cc double hump fuely heads 462 castings and a lunati solid lifter 00013 cam The catalogue says fair idle good performance street cam, great for saturday night drags.


Cylinder head volume cc 64

Piston head volume cc 6

gasket thickness inch .039"

gasket bore diameter inch 4.030"

Deck clearance inch +.010"

stroke inch 3.48"


STATIC COMPRESSION RATIO 10.068

Additional information

Rod length inch 5.7"

Intake closing point degrees ABDC at .050" lift
plus 15 degrees 56 + 15 71 deg

DYNAMIC COMPRESSION RATIO 7.642

So as you can see two totally diferent heads, cams and static compression ratios, but the dynamic compression ratios are the same. So this exercise derinitely points out cam and cylinder head relationships. you have the calculator available try swapping the heads and cams around and you will see how things drastically change to soggy bottom extemely low compression or detonation extremely high compression.

It is worth noting that the dynamic compression ratios cars run on pump fuel is at 7 to one and the long duration race engines run at a dynamic compression ratio of 9 to one.

So by paning heads decking the block and using diferent cylinder head gaskets you should be able to fine tune your finale compression ratio for optimum performance.

Originally posted by southerner
Thanks tech maybe you could type up the direct link to the dynamic compression ratio thread I mentioned I dont have a clue how to do that yet.

southerner, here's another shot at the calculators I gave you in case you've misplaced the thread. See the next-to-the-last post I gave you concerning the kb-silvolite calculators....
http://streetmachinesoftablerock.com...opic.php?t=124

hey i have a question this guy i work with keeps bragging cuz he has a 350 four bolt main i was wondering what the difference is between my overbored 350 and his 4 bolt main??

Originally posted by 76chev
hey i have a question this guy i work with keeps bragging cuz he has a 350 four bolt main i was wondering what the difference is between my overbored 350 and his 4 bolt main??

4-bolt/2-bolt has to do with the number of bolts used to secure the main bearing caps to the block. Most standard production blocks used 2-bolt caps because they are cheaper to manufacture and are adequate to hold the bottom end of the motor together. 4-bolt caps/blocks were used where more severe use was anticipated, such as heavy duty trucks or where higher horsepower/rpm levels were planned. The caps have nothing to do with whether the block is overbored for larger pistons or not.