Messages

1

Matt Shaff's Engine Shop / Gear drive runout?

« on: June 07, 2020, 03:53:49 AM »

Hiya, just checking some stuff before re-assembly. Last year we had the cam dowel come out & I found that the hole in the gear drive cam hub was oversize. I removed the cam, drilled the cam hole larger then reamed it & the hub larger, fitted a bigger dowel & it ran ok. I thought I really ought to look at gear backlash & runout while I have time & the motor is fully apart. Rotating the crank & cam with the gear drive bolted down shows no tight spots but the backlash does change a bit during rotation. I removed the cover again to check runout on the cam gear. It's a maximum of 4 thou (or +2 to -2). Anyone know if this is ok?

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Matt Shaff's Engine Shop / Re: Rod bearing clearance

« on: May 23, 2020, 09:17:47 AM »

Aluminum (MGP).

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Matt Shaff's Engine Shop / Re: Rod bearing clearance

« on: May 23, 2020, 07:07:34 AM »

Thanks for that advice re machining, that's the stuff I just don't know yet. Just referred to my crank figures. After block & caps re-sized & align honed I used King X bearings on them looking for 1 thou and gained a consistent 1.5 thou on all 5 which was actually better. Probably visit machine shop next week, I'd like to know how round the rod bores are too.

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Matt Shaff's Engine Shop / Rod bearing clearance

« on: May 23, 2020, 02:39:46 AM »

My local machine shop checked our crank & gave it a very light polish. The guy said the rod journals are at standard. The bearings used by last year's rebuilder were standard (Clevite CB-743HND) and the previous year's builder were one thou thinner (CB-743HXND). The rod manufacturer (MGP) says we need 3 to 3.5 thou clearance. I assumed that when we first got the engine it had been set up loose for traditional thick oil so that seemed ok. Anyway I used fully synth 10w50 the first year & 15w50 last year with no major issues.

This year I ordered King CR 808HPND in standard but before fitting I thought it would be a good idea to check clearances with last year's bearings. I only have Plastigage. Everything was dry & clean & correctly torqued. I was surprised to find clearances were between 1.5 and 2 thou. Now I could use Clevite thinner bearings as above or King equivalent (STDX type) but firstly availability is not so good and secondly 4 of the bearings will still be a little tight at around 2.5 to 2.75. My question is would it be better to have a thou or two taken off the rod journals now then I can use the bearings I bought & not have the same issue next rebuild? I'm planning on using 10w50 oil as the crank is already set for 3 thou.

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Matt Shaff's Engine Shop / Re: BBC Main Stud Life?

« on: May 19, 2020, 03:19:38 AM »

Thanks for responses. I got my motor second hand and I have no idea on the history of some of the parts. I don't want to harass the guy I bought it off as it looks like he has terminal cancer, he's got enough to worry about. So it's up to my judgement to decide what to renew at the moment.

My machinist commented the studs looked ok but the nuts were not good. I tried some new nuts on the studs but I think the stud threads are past their best as there are tight spots on them. Seeing as we had fretting on the mains, I think now is a good time for a new set of studs (ARP, what else?). I got a tin of ARPs Ultra Torque lube already. Hopefully they will clamp the caps properly and I will feel a bit less anxious as the car goes into stage!

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Matt Shaff's Engine Shop / BBC Main Stud Life?

« on: May 16, 2020, 09:18:40 AM »

On a blown methanol 517ci BBC with 4 bolt steel main caps on an iron Gen IV truck block with aluminum rods, probably around 1000hp and operating at 7000-8000 rpm max, what sort of life expectancy would you give the main studs e.g. in terms of rebuilds, seasons, runs?

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Front Engine Dragsters / Re: World fire up day.

« on: April 10, 2020, 08:25:33 AM »

I'd love to do that, sadly bearings & rings only just arrived so it's going to be a few weeks yet.
But I have lovely neighbours & don't want to annoy them so maybe not.
I might fire up the Cleveland in the Mach1 though. The neighbours are ok with that & I have to move it away from the garage door to work on the altered anyway.
Talking of neighbours, we all went outside our houses at 8pm last night & clapped for 2 minutes in appreciation of the brave nurses & doctors of our NHS.
We did this last Thursday too across Britain. Some people let off fireworks at the same time last night.

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Matt Shaff's Engine Shop / Re: Lost cam dowel - what to do?

« on: March 03, 2020, 01:17:24 PM »

As a post-script, I was drilling a hole at the back of the block for oil drainage as I plan on fitting a wire mesh kit in the valley. Look what fell out of the block while I was drilling:

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Matt Shaff's Engine Shop / Re: Cause of fretting on main caps?

« on: February 23, 2020, 09:19:42 AM »

I would say we only did one run where it was lean. This took off the plug plating much further than any other run we've done, as I said, down to the top of the first thread. Maybe that's when it did the damage. The motor was much hotter than usual after the run. Previously we'd not done more than about half way round the face. I recall the 'timing' bar on the plug ground was usually near or just down from the corner. We didn't realise how bad the pump was til we put a new one on & it's been so rich we have not coloured a plug since. We went from having less & less fuel in the oil to having a shed-load. We won't be running again until April at the earliest.

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Matt Shaff's Engine Shop / Re: Cause of fretting on main caps?

« on: February 08, 2020, 02:09:57 PM »

Tune has been all over the place as we started the season with a failing fuel pump. This got it down to the leanest it's ever been where the plating was off the plugs down to the first thread. Still, it ran 184mph on an 8.4 with an on/off/on/off launch. Then we got a new pump & it went crazy rich even though I changed the pill because I expected it to be rich.

Not had more than 34 degrees advance in it so far.

We have just had the block & caps machined, doweled & line bored by a very experienced machinist. Getting it back on Tuesday.

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Matt Shaff's Engine Shop / Cause of fretting on main caps?

« on: February 07, 2020, 01:11:46 PM »

We only put 13 passes on our blown methanol BBC last season. I was surprised to find serious fretting had occurred on caps 2,3 & 4. 4 was loose in it's register.
As far as I know this did not happen last season when we probably did 20 odd passes. Is there anything I should think about with the tune that may have caused this?

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Matt Shaff's Engine Shop / Re: Removing crank hub spacer

« on: November 30, 2019, 02:08:27 PM »

Grease did not work, I guess its because the area under the front lip was not enough.
So I tapped 2 of the 3/8" holes to 7/16" UNF as I have good taper & bottom taps for that.
Then I fabbed a simple puller from some 1"x1" angle iron with a nut welded under the middle hole & it pulled off nicely.

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Matt Shaff's Engine Shop / Re: Removing crank hub spacer

« on: November 23, 2019, 03:47:29 PM »

Well the bolt did not push the spacer off because it ran out of thread before the flange reached the spacer. Two legged puller won't fit as not enough space between bolt head & spacer.
Looks like 7/16" tap will do holes ok so I may be able to fab a puller tool, but I may give the grease/dowel a try first.

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Matt Shaff's Engine Shop / Re: Removing crank hub spacer

« on: November 21, 2019, 02:00:16 PM »

Hope to get on to it tomorrow or over weekend. If I don't get it off I will post a pic from the front. I need to drain & remove the trans too so best do that first to enable holding the crank still while undoing the bolt.

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Matt Shaff's Engine Shop / Re: Removing crank hub spacer

« on: November 19, 2019, 12:45:49 PM »

Can you get a socket on the bolt?
If you can and the bolt is long enough would the flange on the bolt remove the spacer as you back the bolt out?

I think that is worth trying, socket does go on as I have turned motor over with it before.