Bearing clearance, oil restrictors, and cam questions

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Bearing clearance, oil restrictors, and cam questions Empty Bearing clearance, oil restrictors, and cam questions

Post  Landship_Captain on August 10th 2019, 9:47 pm

This is my first engine build, it's stock stroke AFR 280 headed (85cc chamber version) 472 for a 1979 F150 4x4 (C6, ford 9" rear end, 4.11 gears, 35" tires). I am trying to make the thing accelerate as fast as I can, maybe do a 4wd burnout, and still being able to cruise around in it a decent amount year round. I have +5.8cc flattop forged pistons with intake valve reliefs for AFR heads, forged eagle rods, a stock crank balanced and turned down 0.030" under on rods and mains, and I'm using ARP studs with the stock 2 bolt mains. I'm using king bi metal bearings since it seemed to be what the shop liked.

I recently got my stuff back from the machine shop and repeatedly checked all the clearances with a micrometer and dial bore gauge. The mains all seem to have 0.0020"-0.0021" of clearance except the front/#1 which has something closer to 0.0023" of clearance (I did try moving bearings around between mains and that was the best I got). I had always heard 1 thousandth for every inch but from what I have looked up, people like tighter tolerances for street 460s. So will my mains be good or do I need to do I need a little more clearance and will that slight difference at the front be OK?

My rod bearings are looking to be between 0.002"- and 0.0025" but I was a bit concerned since the rearmost rod bearing journal has about 0.0002" of taper to it (unless I just screwed up my measurements, it's also a pretty cheap micrometer). The others are all very consistent as far as I can tell but I think they all have more clearance than the mains. So are my rods good or does that all need to be addressed?

Another thing that has me concerned is that my bore gauge seems to leave tiny marks in the bearings... Have I ruined my bearings or would those be insignificant enough to ignore? How can I cut down on that later on, do I need to use telescoping bore gauges instead of a dial bore gauge?

As for oil restrictors I can't seem to figure out for sure if I should or should not use them. Do I just need to actually settle on a cam before I decide on them? Do my bearing clearances define my need for them? There anything I can read on selecting them?

As for a cam, I had been talking to Scotty J. via email and he seemed to have something in mind (like this but a bit more lift I think) but he said there was a shortage of solid roller billets and to check back in a couple weeks (3 months ago) and I haven't been able to get a response from him since. Did something happen to him or does he just prefer to be called or what? If I can't get a cam and lifters from him should stick with a SR cam or get a really mean HFT cam (comps glitchy camquest thing pointed me to this 34-250-4).

I suppose I should ask about an oil pump and oil weight as well. What would you guys recommend on those fronts, I was thinking a standard volume oil pump would make more sense but I have heard some people say high volume pumps are always the way to go. I had been told to run 10w30 in the stock engine and didn't see any severe wear when I tore it apart but that seems a bit thin for this build.

Well, thanks for reading my wall of text.

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Bearing clearance, oil restrictors, and cam questions Empty Re: Bearing clearance, oil restrictors, and cam questions

Post  BBFTorino on August 10th 2019, 11:27 pm

Tighter clearances=thinner oil, and be sure to only use a full synthetic oil!
Standard volume oil pump is more than sufficient if you're keeping it under 6500 RPMs
As long as your measurement tools are not gouging/scratching into the metal on the bearings, you are good. It is probably just leaving a mark on the shiney flash coating.
As for a cam, a good hydraulic flat tappet will give you the most trouble free reliability and plenty of torque, which is really what you need for such a big heavy vehicle. I would avoid a solid roller cam for constant street use.
This is just my .02.....and welcome to the site!! Cool

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Bearing clearance, oil restrictors, and cam questions Empty Re: Bearing clearance, oil restrictors, and cam questions

Post  rmcomprandy on August 11th 2019, 11:20 am

I would use the Ford bolts in the main caps and forget about any studs.

The small line in the bearings from the bore gauge won't hurt a thing.

Your clearances are fine for an everyday street type hi-performance engine but,
probably a little tight on the mains for a racing engine.

Use a FLAT tappet hydraulic cam for what you intend doing.
Don't use any kind of restrictors.
That 34-250-4 camshaft is TO BIG for those gears and tire diameter ... use more gear or smaller cam.
A 34-248-4 would be a slightly better Comp Cams catalog "Specialty" camshaft for the application however,
getting something "custom" with a lot of lift and conservative duration would be recommended.

Get a good torque converter to match the camshaft.

A good quality 10w-30 or 10W-40 oil is fine.
After break-in I would recommend AmsOil "Premium Protection" 10W-40 as it is specially formulated for hydraulic lifters and a flat tappet camshaft.

I would use a high pressure, standard volume oil pump ... like a Kaase pump or another special pump similar to that.

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Bearing clearance, oil restrictors, and cam questions Empty Re: Bearing clearance, oil restrictors, and cam questions

Post  Landship_Captain on August 11th 2019, 2:49 pm

BBFTorino wrote:Tighter clearances=thinner oil, and be sure to only use a full synthetic oil!
Standard volume oil pump is more than sufficient if you're keeping it under 6500 RPMs
As long as your measurement tools are not gouging/scratching into the metal on the bearings, you are good. It is probably just leaving a mark on the shiney flash coating.
As for a cam, a good hydraulic flat tappet will give you the most trouble free reliability and plenty of torque, which is really what you need for such a big heavy vehicle. I would avoid a solid roller cam for constant street use.
 This is just my .02.....and welcome to the site!! Cool

Thanks!
I'm glad a standard volume pump will work since I should be able to use a rear sump pan from later trucks with it this way. I want to eventually de-lift or reduce the lift on the thing and just cut or use flared fenders and those pans look like they would have the best clearance for that.

For the cam, that's a good point, I was hoping to try and lighten the truck eventually but I have no idea how much I can really do there. I had been a bit concerned about the solid roller maintenance too, I wasn't looking forward to religiously checking lash in the middle of winter.




rmcomprandy wrote:I would use the Ford bolts in the main caps and forget about any studs.

The small line in the bearings from the bore gauge won't hurt a thing.

Your clearances are fine for an everyday street type hi-performance engine but,
probably a little tight on the mains for a racing engine.

Use a FLAT tappet hydraulic cam for what you intend doing.
Don't use any kind of restrictors.
That 34-250-4 camshaft is TO BIG for those gears and tire diameter ... use more gear or smaller cam.
A 34-248-4 would be a slightly better Comp Cams catalog "Specialty" camshaft for the application however,
getting something "custom" with a lot of lift and conservative duration would be recommended.

Get a good torque converter to match the camshaft.

A good quality 10w-30 or 10W-40 oil is fine.
After break-in I would recommend AmsOil "Premium Protection" 10W-40 as it is specially formulated for hydraulic lifters and a flat tappet camshaft.

I would use a high pressure, standard volume oil pump ... like a Kaase pump or another special pump similar to that.

Damn, I figured I would be fine with bolts but I didn't trust the original ones since they were a bit beat up so I sprang for the studs... That whole engine was a bit funky when I tore it apart, it had 7 d6ve rods, 4 or 5 of which have the number 7 stamped into them, and one c8ve rod. All the gaskets looked like someone just forced birds to build nests out of permatex and cork and the intake manifold was sealed to the block and water passages with what appeared to be a half a tube of silicone calk...

Ahh good, two votes for the marks being fine! I couldn't really feel them but it still had me worried.

Yeah, I suppose an HFT cam seems to be the way to go then.

If you don't mind me asking, what situations would you use restrictors in? My searches just got me conflicting answers in really old forum threads.

Stupid question, by more gear you mean even lower not taller right?

Ok, I will will look into that camshaft and try to do more reading on camshaft selection. As for custom grinds who all does those? I know Scotty J. does but I'm not sure who else.

Yeah, I knew I would need a new torque converter... The old one had the studs in it stripped out a bit. Is it just about the specifications or are there brands to avoid or favor?

Cool, I will keep that oil in mind. I had used Valvoline full synthetic but that was more because it was always cheap and easy to find and the aforementioned birds nest gaskets leaked like crazy until I replaced them.

Thanks for the help!

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Bearing clearance, oil restrictors, and cam questions Empty Re: Bearing clearance, oil restrictors, and cam questions

Post  rmcomprandy on August 11th 2019, 7:20 pm

Oil restrictors to the cam bearings ... NEVER;
except maybe the front one because that cam bearing gets oil from another place.

Restrictors to the upped end with any stock block is done with lifter bushings or restricting pushrods.

MORE gear = higher numerically.

Lots of us on this forum will provide custom ground camshafts if wanted.

That fully synthetic oil is NOT cheap but, is one of the best for that application.

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