Inliners International Forums General Discussion Engines Tearing into my 250 for the first time.

Let me first introuce myself. My names Thomas, i'm a 23 year old studying automotive tech out here in Seattle. Im a long time reader short time member here. I have a 1968 Chevy c10 stepside shortbed with a 250 in it.





I got this truck from my grandfather when i was 15. Im never getting rid of this thing. The only bad thing about it is the rust. My rockers are pretty bad. Anyways im restoring it little by little. Ive redone the suspension, now tis time for the engine(because thats what class im taking).

My goal is to rebuild the 250 for daily use. I did a leak test and everything that can leak did. compression is around 110 across thr board. My pocket isnt that deep because im paying for school out of my own pocket.

My first question is who do you guys recommend for rebuild kits. I was looking into rock auto but i wanted to get peoples opinions with who they have experience with and how was it. Of course an opinion on the parts used would be awesome as well.

I'll be doing all the machining myself(with help of course). If we put aside the cost of machining what are some upgrades i can do. I was reading something on a bigger valve? Ive also read a bit of the lump kit.

idk if i will have the money for it but i was told a clifford heated manifold with a holly 390 is great for daily use. Opinions?

Anyways feel free to toss out any advice with anything mentioned.

Thomas

Upgrading to larger valves and lumps would be a good start, you will need to also install a performance camshaft as well to get the most benefit from the head mods.

IF YOU HAVE 110 IN ALL CYLINDERS IT STILL HAS ALOT OF LIFE LEFT, RUN IT TILL YOU GET OUT OF SCHOOL. AND FOR YOUR USE STOCK IS BEST AS ALL MODS WILL EFFECY MPG. JMO
BOB

P/S
NICE TRUCK ! I HAVE A 1970 AND 1972 C-10'S

Nice truck. What kind of wheels are those?

Nice '68 C10. I had one once myself and yes I had to replace the rockers. If I understand correctly your 250 will be your personal training engine in class. That means you'll have good guidance(I hope.) from your instructor(s). Rock Auto has good prices if you don't mind paying shipping and the time wait. I bet your local auto supply can price just as well and get same day delivery. Also, I would ask your instructor about obtaining parts through the school. Sometimes they strike deals with a supplier.
Welcome and Good Luck with your C10 project. Hope you share your progress here.

Cnc - what cam would you be suggesting? For street use i heard 1.94 valves are to big right?

bcowan - I've already set up the rebuild this quarter. im pretty set on it.

Jstew - Im not sure to be honest

Drew - yes my 250 will be my block to work on. This instructor i trust (unlike some others). Autozone is the only place i get a discount. Maybe orielys.

I wish my '68 looked that good. I have new rockers and cab corners ready to go when I am. I agree with everything above. If it is now your driver getting another engine to build would be nice. You need to build one while you have this opportunity. Northern has kits at good prices and I think you can still upgrade components like cams. The head work, a good intake/carb, cam, and exhaust will be the most improvement for the money. A GM HEI distributer will be good but can easily be added later. All of this done in moderation will still give you a dependable and efficient driver.

FYI, look around theres alot of 250's around, build one of those and leave the one in your truck alone jmo. p/s expect to have close th 1k in it done modestly when done not counting machine work.

My truck isnt a daily driver. I just want it to run like one just incase it needs to be. I drive a 65 bug and every now and then an 05 mini.

Sealed power MKP614H at autozone and orielys for 430-530 for the full kit. MY truck already has an hei distributor. Opinioons on the 390 with heated intake mani? of course with that ill need to get the headers.

HI THOMAS : GREAT truck now and will be a greater truck when completed . Here's what I did with my 250 ( which began life as a Mercruiser 165 ) It is .030 over pistons( stock Comp ) , all new bearings , oil pump , etc., Head is cut .080 , 1:84 intakes , stock exhaust valves ,Comp Cams 268-H cam/ hyd.lifters , , unshrouded around valves , multi-angle grind .Did NOT remove intake bosses , but ground them to an airfoil shape ,port-matched in about 1 inch . OFFY intake , 1 inch / 4 hole spacer , Langdon headers ( heated )Road Demon Jr. 525 , 4 barrel mounted transversely .
The car drives VERY strong , Pulls strong @ low RPM and gets decent fuel mileage - Don't forget ZDDP additive for break-in.

Thanks Fleet

I think im going to start off with the head. 1.84 I 1.6 E kit from 12bolt with the lumps.

I was thinking a new cam as well. Can someone help me choose one, im still learning on camshafts. Daily use mostly, might pull a trailer everynow and then.

Well shes torn down






Every compression ring was broke in multiple pieces. Lifters and cam were pretty worn. Anyways she needed some love. If clearences will permit then im sending it to be thermal cleaned. Im ordering parts here soon, should be fun.

Thomas

HEAD ??????? FIRST THING TO DO IS CLEAN / STRIP BLOCK AND HEAD AND SEE WHAT YOU GOT !!!!!!! ALSO STAND THAT CRANK UP, YOU DONT LAY A CRANK ON ITS SIDE...... PAY EXTRA SPECIAL ATTENTION TO THE FIRST 2 CYLINDERS WITH YOUR MIKE. MAG THE HEAD ON DECK SURFACE AND WHERE WATER NECK BOLTS ON. YOU DID NUKMBER THE MAIN CAPS RIGHT ? AND YOUR HOOD YOU HAVE LEANNING UP AGAINST THE METAL BENCH YOU O KNOW THAT HOOD IF ITS GEN. G.M. IS A 1000.00 + HOOD RIGHT ? PUT IT IN THE BED OF YOUR TRUCK ! COVERED !JMO

Ill be sure to stand that up.

Yes i marked everything.

Like i said imn getting it cleaned tomorrow.

Why the first 2?

The hoods toasted. Its in very bad condition.

Thomas

THOSE 67 &8 GM HOODS ARE LIKE GOLD TO US TRUCK GUYS. WHY IS IT BAD ? THE FRONT 2 CYLINDERS WILL BE THE WORST WORN AND THERE COMMON TO HAVE TO GO .060 OVER BORE ON 1ST OVERHAUL TO CLEAN UP AND SOMETIMES EVEN THAT WONT CLEAN IT UP. THATS WHY WHEN YOU SAID YOU HAVE 110 PSI IN ALL CYL.S I THOUGHT YOU MIGHT LIKE TO LEAVE IT ALONE. THATS A GOOD 6 ENGINE AND DIDNT NEED ANY WORK DONE . BUT YOUR INTO IT NOW. LIVE AND LEARN I RECON.

I get it, if its not broke dont fix it. I'm not here for someone to convince me not to work on my truck, im also not here for someone to make me feel guilty when i do work on it. I'm here to get the knowledge on what i want to accomplish. Thanks for some of the helpful hints you have told me but you can stop with the father sounding comments.

I dont plan for this to stay in my truck forever. I plan to experiment with many different powerplants. If i mess up on this block or if something doesnt go right i have v8s that i cant access with no problem.

So I decided on the Clifford 264 cam and lifter kit. Should be fun

That is a nice cam for street use.

I put the same cam in a friends 292 last week and he got the spring kit that required fly cutting the head for the larger springs. They set up for 115# on the seats at 1.70 spring hight. Has a pretty smooth idle, but will blow the tires off from a idle with a turbo 350. I like the cam and would like one in my 250. I have the 262 grind now (Lanati) Have fun with your build...J

Something I wish I had done was drill and tap the crankshaft for a bolt. Sure makes it a easier job to install the balancer.

Awesome build man! Love the truck i have a 72 gmc i am rebuilding hope it looks as noce asyours does! Keep up thegood work!

Stayinline

A MACHINE SHOP HAS TO DRILL THE CRANK FOR A BALANCER BOLT, YOU CANT DO IT BY HAND.

I have drilled my crank by hand for a damper bolt & so has a prior engine shop I know w/no problems.
Cast iron is easy to drill. Drill as straight as you can & use some sort of guide to help you drill it straight.

It is best to have it done by a competent shop or person.

MBHD

IF YOU HAVE A LATHE, TAKE TIME TO DESIGN AND MAKE A DRILL FIXTURE THEN IT COULD BE DONE BUT ITS NOT AS ACCURITE AS DRILLING IN A LATHE. I GUESS ITS A QUESTION OF HOW PATICULAR YOU ARE, FOR ME I LIKE TO DO IT ONCE AND DO IT RIGHT AND BE DONE WITH IT.

Well thanks to everyone so far. Ive called a couple people to pick there brains. Thanks for all the help.

Thomas

ENJOY THE BUILD AS WHEN YOU GET IT DONE ALL YOU CAN DO IS DRIVE IT. ALSO 1 MORE THING YOU NEED TO DO "FOR SURE" TO YOUR HEAD, YOU MUST INSTALL HARDENED EXHAST VALVE SEATS SO YOU CAN RUN UNLEADED GAS........

Looks like im going .060 over. I was told 307 flat top pistons. Why?

Will these work?

http://www.summitracing.com/parts/slp-w295ap60

So how should I calculate to zero deck my block.

What is the stock deck height? With stock 250 pistons I got 9.105 of total height and with 307 pistons I got 9.120 of total height.

You will need to actually mock the crank back up in the block and check each rod and piston to verify the deck height.

if you go ..060 you know you,ll need a 3 or 4 core radiator to keep it cool right ? with 307 flat top pistons you dont have to 0 deck your block. you,ll still have 9-1 compression and thats plenty with todays gas. go higher and you,ll have to pull timming out of it to keep from spark knocking. just clean up block deck and head surface and run flat top 307 pistons you,ll be happy with it. jmo

Easiest is to check the front and rear cylinder for DH. Then mill the deck accordingly. That means assembling the piston rod combo and putting in the crank and dropping all into the block. Then take measurements. It aint easy but good to do.
I don't think the .060 pistons will cause overheating problems, bigger than that, yes.

.040 AND MY 2 CORE RAD IN MY 71 CHEVY PICKUP WASNT A GOOD COMBO BUT I LIVE IN THE HILLS OF E.TN. AND I WORK MY TRUCK. I HAD TO GO 160 THERMOSTAT AND 3 CORE RAD WITH A FIXED 5 BLADE FAN TO KEEP IT BELOW 190 DEGREES

Anyone have a clifford intake they wouldnt want to get rid of.

CLIFFORD IS FOR HIGHER RPM,S A OFFY IS A BETTER ALL AROUND MANIFOLD IMO. JUST A THOUGHT

From what i read there isnt much of a noticeable difference. The clifford seems easier to do a port injection set up if i choose to and it looks better in my opinion. Both i need an set of aftermarket headers.

Thomas

I have had both the Offy & Clifford intake manifolds on 250 engines w/different combos & the Offy is better for low end torque & makes for a better driver day to day type manifold.

The Offy makes for a better street manifold I can speak from personal experience on 250 engines, daily driver type senarios, not engine dynos, can't say for a 292, I would think a 292 engine can deal w/a Clifford far better than a 194 CI engine.

A person here tried both manifolds w/a stock 250 engine & the results were close,, but this is on a stock engine, when you run a bigger camshaft, bigger ports, bigger valves etc, the Offy will shine more so in the lower RPM's..

I other words, if you over cammed an engine ran less than optimal compression, made the intake ports big & used large intake valves, the Clifford will be an absolute pig as compared to to an Offy intake, especially if your engine is 250 CI or less, I can only imagine what an over cammed ,low compression big port 194 ci engine would be like w/a Clifford manifold. horrendous!!!!

If you look @ the Clifford intake runners, they are HUGE! When you have huge runners, the port velosity goes down tremendously & when this happens, you lose torque & other important parameters for a strong healthy engine.

MBHD

Get whichever intake you can find the cheapest.

They both make great street intakes. The Clifford will make more HP above about 4K rpm.

I HAVE A SET OF N.O.S. CHEVY 6 SPLIT HEADERS FOR YOUR 67-72 PICKUP I,D SELL YA