350 Crate Motor Teardown?

[bkeith65]

Hey..I've been reading for a while and buying up some parts....Thanks to Dan Sherwood, I got some parts for my 68 Camaro..it is a completely stock 6 cylinder with powerglide...soon to have a stock 350 with a th350....Here's the question...I just found a complete used 350 crate motor that I am picking up next weekend. It runs and sounds fine. My car is running and drivable, although slooow..should I tear down the crate motor and upgrade anything or have anything checked? I am a teacher and have the summers off. I want to paint the block anyway, so I thought this might be a good summer project. Don't know anything about the crate motor other than it is stock GM. I do not need a screamer or much more horsepower. The car's purpose is as a cruiser/driver....I can always add HP later!

Thanks,

Brian

[Adam's 55 Chevy]

If it's a crate motor try to find out if it is the 245hp 260hp or 290hp version. It's best to know where you are and go forward from there. Obviously budget dictates what you do and the initial cost of the engine as you dont want to throw away most of what you have just bought. Personally I would make sure the intake / carb & exhaust was all compatible. You will have about 8.5:1 CR on this engine so stick with a good dual plane like an RPM performer and matching 600 carb. For a budget build I would change the rockers to 1.6:1 and if funds allowed a swap to a set of Performer RPM ally heads to bring the CR up a little.

Basically what you will then have is the Edelbrock power package that should net you between 340-360hp. A cam swap so complete the package should see you heading towards the 400hp mark.

[bkeith65]

Will the bottom end stand up to 350 HP? I guess I will know more when I get a number off the block? I am only paying 1500 for a complete motor and trans...I have a better trans, so I will probably trade or sell this one....I think I am going to take it all the way down and then I can ask more specific questions....

Thanks!

[Adam's 55 Chevy]

I would imagine all the bottom ends are pretty much the same and the real difference is the cam. 350hp would be fine for this engine as long as you chose parts that produced this at a sensible RPM say 5600-5800.

[bkeith65]

Things are looking pretty good! It has an edelbrock carb..not sure what model, how can I tell? It has an edelbrock performer intake, a new msd ready to run pro billet dist. Polished aluminum edelbrock valve covers and air filter plates. underneath the flex plate were the numbers 010 all by themselves...does this mean it is a truck block? the guy said he ran it a few times and it sounded a little lopey, so it may have a cam...The heads say gm and the rocker assembly is nothing remarkable.... I have to work tomorrow and then I am off for the summer...I will try to have the rest of it torn down by the weekend....

[bkeith65]

Well I intended to have it torn down long ago..sheesh Life! Anyway..it is a truck block from 71..four bolt main 030 over and looks to be fairly clean...one concern..the bottom of the cylinders are "chipped" on four of the cylinders..like where a rod might have hit the wall..is this a big deal?

[molyorange 77]

Take the block to a machine shop and have them do a pressure test to check for cracks on the bottom of the cylinders if they look really bad.

[Adam's 55 Chevy]

When you say 'chipped' how big are you talking. The rings never get down there so it may just be the finish from the machine work as it meets the cast iron.

010 block is 4" bore. Crate engines are 4 bolt mains blocks. I think the previous owner has done basically what you needed to do with the engine. Are you sure it needs a teardown? If it ran before you bought it there is little reason to take it apart just to have a look. Maybe remove the sump and pull a bearing to see it's condition but it sounds like you have made a good deal there.

[1969CamaroRS]

While it is at the machine shop, have them check the run-out on the valve seats and valves. If they are over .001/.002 run-out a good valve job while it is apart would do wonders for the motor.

[bkeith65]

It is completely apart...chips are about 1/8 of an inch and u shaped but not clean.. kinda "chippy" :-) i should post a picture..i'll make that this weeks job...pistons are run of the mill 50 dollars a set...i want to say pro-form? the threads in the end of the crank for the pulley were jacked up completely..can they be fixed? I didn't keep track of the pistons/rods etc because my original intention was to build the bottom end stronger...have I passed the point of no return or could I reuse them...learning curve oops! thanks for the help!

[indyjps]

see if the rods are stamped with the cylinder # they came out of, if its a reman engine they might be stamped.
depends on how bad the threads are, have a machine shop take a look.
as long as the rings dont travel down to the chiped area youre OK. sounds like rough casting edges to me, nothing ot worry about.
Id reassemble the thing with new bearings, better cam, have the heads double checked and run it. depends on what kind of power you want and how much you want ot spend.
Do you have the casting #'s off the heads, this will help us determine you power possibilities. Im guessing 882 76 cc smog heads. you wont get much compression but they can run decent. Head #'s will let us know your approx compression ratio and if new pistons are needed.

[bkeith65]

Ok here are pics of the cylinders...1st one is the worst chip and the 2nd pic is a clean one.....

[bkeith65]

can anybody comment on this...is it detrimental to a rebuild?

[indyjps]

you should be able to see how far the rings traveled in the cylinders from the wear pattern. The rings should not travel as far as the chips you have, as long as it checks out OK for magnaflux and leak test at the machine shop it should not affect the rebuild at the power levels you are running.
Have the machine shop boil, magnaflux the block, install new cam bearings and freeze plugs and hone the cylinders. you should be able to reuse the pistons that were in the block and step up to some quality moly rings and / or file to fit rings. if youre looking into new pistons hypereutectic is a good compromise between cast and forged at this power level, as long as youre not planning on running nitrous you should not need forged.
A 350 hp build should not be too difficult. your cylinder heads will play a major part of being able to achieve this power level.
Can you post the casting #'s of the cylinder heads. Once we know the casting # we can give a recommendation on whether to put any additional $ into them or look into getting a different set. a set of vortec heads casting 906 or 062 will make much better power than any 1970's GM casting. you can get a set of these for around $300-500 and you may end up with more than that in rebuilding whats already on your engine.

[bkeith65]

OK... the heads have B186 stamped on them and there is a longer number that is 1407 (9) (3) (8) 261 the numbers in parentheses indicate the number in that position..it was difficult to read..so it is one of those numbers....I tried to look this up and seemed there are good things about these heads?? Thanks for the help to those who are chiming in!!

[bkeith65]

OOps..found a bit more info..the numbers are 14079261..so they are 261 heads...paper weights??