Well my dad and I got a start on building my 302 yesterday at last. I used the original crank out of the motor. It is a 1970 motor. The motor had 92,000 miles on it when pulled. I just had the crank polished and was planning on using std bearings. We put the crank in and plastigauged every main. The front one was right around .002 and the 3 center mains were around .002-.0025 The rear main was at around .003 I am running a high volume melling oil pump with a hardened oil pump drive shaft. Are these clearances tight enough for a new motor? The motor will see 6300 rpm occasionally. I am using clevite 77 bearings. Are they a good street/strip bearing? Thanks in advance, Brandon. Oh ya, hopefully we will be able to get a could of pistons in tonight so I should be able to get connecting rod bearing clearances to!
Help ASAP! Main bearing clearance? Is it o.k.?
1 - 10 of 10 Posts
G
Guest
·Guest
Joined
·
0 Posts
Id have to say that under blue print specs your on the high
side of clearnce [no more than .003]
i think .0015 to .002 would be better for a street engine
your choice of brg`s is fine and pump also
how do the cam bearings look ? are you replacing them ?
as there a factor in oil controll also
if it was me,id just regrind the crank and get matched brgs
and be done with it,takes the question out of it
Dave
side of clearnce [no more than .003]
i think .0015 to .002 would be better for a street engine
your choice of brg`s is fine and pump also
how do the cam bearings look ? are you replacing them ?
as there a factor in oil controll also
if it was me,id just regrind the crank and get matched brgs
and be done with it,takes the question out of it
Dave
You are a little loose on the rear main, but it will live.Are you checking with the plati-gauge with no oil on the bearing front and back? Did the machine shop measure the crank after it was polished if so what was his opinion?better loose that tight ( to a degree) You can also see if you can buy a set of 1 over bearings and use one in the rear main. Robert
Yes, I have new cam bearings, they are durabond brand. I am only 18 and have already spend in excess of 2,000 dollars on the motor so, buying a set of bearings just for the one is out of the question. With a high volume pump I should be fine, according to the machine shop were I spent $1800 in machine work and parts! Also the machine shop chafered the oil holes in the crank, so I think that will help? I just want your guys opinions because my dad and I think it is a little iffy. But being 18 and not being able to drive my car since may, I am a little ancy to drive it again. But I do want to do it right. So should I leave it or do something with it? :: Edit: we did check the clearances with out oil on any of the bearing, front and back.
Joined
·
4,971 Posts
In excess of $2k for a run of the mill rebuilt 302? What exactly did the machine shop do for $1800 plus parts (besides make a lot of money)? I'm assuming that your $1800 figure includes some new aluminum heads?
Machine shop services should not be that expensive unless you're a woman.
$100 will get your block hot tanked, magnafluxed, and installation of new cam bearings. $10 a cylinder for boring and honing. $100 to turn and polish the crank, and if desired add in another $150 for balancing.
Machine shop services should not be that expensive unless you're a woman.
$100 will get your block hot tanked, magnafluxed, and installation of new cam bearings. $10 a cylinder for boring and honing. $100 to turn and polish the crank, and if desired add in another $150 for balancing.
$2000 invested and you are worried about another $50 for a set of bearings,now is not the time to get cheap. You plasti-gauge bearing with no oil on the bearings oil will mess up the readings. Hang in there take your time and you will be ok. It is great to see a young man of your age diving into a project like this.
Joined
·
10,587 Posts
No worries....I've run 289/302's with .003" on the mains and 0045" on the rods to 7500 rpm all season long with no failures.
Only thing I'd be concerned about is too much oil getting to the top end (which would lower oil pressure with the looser crank clearances). I always installed restrictors in my engines. Running the HV pump is fine.
What does the thrust clearance measure? Are you running fully grooved main bearings (Clevites generally are)?
Only thing I'd be concerned about is too much oil getting to the top end (which would lower oil pressure with the looser crank clearances). I always installed restrictors in my engines. Running the HV pump is fine.
What does the thrust clearance measure? Are you running fully grooved main bearings (Clevites generally are)?
The endplay is .006 so I think I am o.k. there. No, they are not fully grooved. Is that a bad thing? They are only grooved on the top side. Oh ya, I was going to make my oil pan hold another quart of oil also. I didn't have any oil on the bearings when I plastigauged it either. Here is where the money went: The block was TruDecked (basically decked using a jig to align the deck with the crank and cam), cooked, bored, cam bearings installed. I used DOOE-C cast iron heads. New valve guides, hardened seats on the exhaust side, grind valves, and machine for screw in studs and guide plates, machined .020 for compression, drill steam ports in heads. Pistons put on the rods, rods reconditioned and shotpeened, crank polished, oil holes chafered. Compete rotating assembly balanced. Part include, speed pro hyper pistons, arp rod bolts, arp screw in studs, guideplates, comp cam, lifters, melling high volume oil pump, cloyes street true roller timing chain, clevite 77 rod and main bearings, hastings chrome moly rings, comp valve spring, retainer, and lock kit matched to the cam, exhaust seats, valve guides arp rod bolts, and postitive stop valve seals. Then from other places I bought a weiand stealth intake, windage tray, head bolt washers to use 351w heads on a 302, mechanical oil pressure and water temp gauges, copper collecter gaskets, flowtech headers, stainless steel swirl polished valves (brand new on e-hay for $100 :
, and a set of harland sharp roller rockers which I found at a swap meet with 2,000 miles on them for $75 including polylocks! All I have to buy now is a set of pushrods, and ford racing polished aluminum valve covers. This is why I didn't want to pay another $150 to get a reground crank, as the machine shop couldn't grind cranks, because he doesn't have the machine yet. Compression ratio should be around 9.5:1. Probaby something that I missed also.
, and a set of harland sharp roller rockers which I found at a swap meet with 2,000 miles on them for $75 including polylocks! All I have to buy now is a set of pushrods, and ford racing polished aluminum valve covers. This is why I didn't want to pay another $150 to get a reground crank, as the machine shop couldn't grind cranks, because he doesn't have the machine yet. Compression ratio should be around 9.5:1. Probaby something that I missed also.
Joined
·
10,587 Posts
I prefer fully grooved bearings but that's just a personal preference since I liked to spin my engines. The rest of your combo sounds fine although you didn't spec the cam. With a racing solid lifter cam and 13:1 compression, I made about 1.4 hp/ci out of a couple of engines similar to yours. Ran low 11's in the race car. That was with stock rods and iron heads.
If you've put everything together right, you should have a fine performing, reliable engine. BTW, I've always had good luck with the inexpensive SVO hardened pushrods. The ones currently in the race car cost 28 bucks. Make sure, if you increase oil pan capacity, that you properly modify/locate the pump pickup as well as provide inertia control for the oil. If you retain a front sump, control upon acceleration (especially at the track if drag racing) is very important. I always ran a modified Bronco pan on my engines since the race car doesn't have the stock steering or crossmember. Worked fine with the Boss windage tray. Earlier efforts in my street car utilized a basic Milodon pan with a longer pickup.
Good luck with your project!
If you've put everything together right, you should have a fine performing, reliable engine. BTW, I've always had good luck with the inexpensive SVO hardened pushrods. The ones currently in the race car cost 28 bucks. Make sure, if you increase oil pan capacity, that you properly modify/locate the pump pickup as well as provide inertia control for the oil. If you retain a front sump, control upon acceleration (especially at the track if drag racing) is very important. I always ran a modified Bronco pan on my engines since the race car doesn't have the stock steering or crossmember. Worked fine with the Boss windage tray. Earlier efforts in my street car utilized a basic Milodon pan with a longer pickup.
Good luck with your project!
The specs on the cam are 224 degrees of duration at .050 on the intake, and 230 exhaust. 110 lsa. .509 lift on the intake, and .512 on the exhaust. How much more oil do I need. Can I just add a piece onto the side of my existing pan. I can't really afford an oil pan right now. Do you have a part number on those pushrods, or know where I can get them? I have .002 clearance on the mains, is that tight enough? I am thinking it will be o.k.
1 - 10 of 10 Posts
Join the discussion
Join now to ask and comment!