Engine rebuild coming along.
 

They’ve got the crank and pistons in my 70 455 for my gto. I asked what the bearing clearances came in at and they said .0029 mains and .0028 rods with the pistons being an average .003 in the hole. Lat time I think it was like .0025 mains and 0023 rods. I run 15w-40 oil. Hopefully it’s not too loose.

You are fine. The 455 I raced forever was a lot looser than that on the mains. Its a giant 3.25 journal, you don't want to run them tight.

Yes that has happened to me before with clearances too tight and wiped the bearings on the dyno. These are just a little looser than what I was hoping for. At .0023 and .0025 the bearings looked great I guess when they took it apart. I know the oil pressure might be a tad lower.

Go by this chart for the weight oil you should run .

Normal oil temp should not top 240 otherwise you need a cooler.

While your block is at the shop the oil galley plug below the distributor should get removed and a brass or aluminum one installed.

This way if you do want to add a oil temp sensor a 45 or 90 degree fitting can be put in for the sensor to screw into.

I would be happier with .0035 to .004 on those big mains. That where my 455 was set up and it had 75-60 lbs cold, 60 lbs running down the track and never got below 40lbs at idle.
Lasted 30 years too.
I would not want to run a 455 with .0025 on the mains.

Here’s what Federal Mogul wants you to shoot for in terms of bearing clearances for a 3.250” main and a 2.500” rod journals in a competition motor.

The middle of the spec is ideal

I have many times run .0025” on 3.250” crank mains and encountered no issues, nor problems, but your line bore needs to be confirmed to be within .0005” and most times getting this requires the block get line honed by a shop that can hold this .0005” tolerance.

If you don’t want to get your block line honed then I would try to stick to a main clearance of .0028”


Another consideration are the crankshaft oil feed holes.
Far too many shops and back yard builders think that nicely radius chamfers around the oil feed holes are a plus, but they are not.

Anything much more than what’s in this photo is detrimental to supporting the bearings.

I have seen due to my oil temp gauge that 3.250” mains produce higher oil temps and the oil temp comes up faster also.

Oil thinning out too much from excess heat produces the same bad effects as not enough oil once a certain rpm is reached.

This is what lead me on one of my 455s to install duel 2 Qt oil filters .
This alone knocked off 15 degrees of oil temp.

In fact I believe it’s GM that is now having bearing issues on new motors due to this very issue of having too large of a chamfer on there crankshaft oil holes .

Chamfers work both ways.
Too large of a chamfer also allows oil to get pushed back easier into the oil hole feed hole it came out from!

My race 455s back in the day ran low .003’s on the mains if I remember correctly, shifted at 6500 and didn’t have bearing problems. Can’t remember what the rods were. This particular motor I’m doing now is my street car that I occasionally take to the track and shift at 5500. It was line honed back in the day. Sounds like I should be all set with the current .0028 rods and .0029 mains. Looking through some PY past threads on bearing clearances opinions vary. I was hoping for a little tighter but I can imagine trying to get multiple batches of different bearings that technically should be all the same and wading through them trying to find a specific number to get to. Just watched a Steve Morris YT where he was getting different thickness bearings out of the same package. That must be frustrating.
The rods this time were changed to molnars so that’s one reason the rod clearances might of changed on this rebuild from last time. I can’t remember what the oil hole chamfer looks like on my crank…

I played around with 3.25 Main-Rod clearances: prefer 2.5-3.0 mil, and advice above seems better.

The big deal is oil sump to keep pickup happy.

Huh?

I did .0035 mains on my 455. Oil pressure would dip down to 20psi at a 750 rpm idle w a Mellings M54Dvpump. I had to pull the motor a couple years later due to a leaking rear main seal and I swapped in a Butler blueprinted SD pump and billet shaft on their recommendation w the .0035 main clearances. Oil pressure jumped right up to 45 psi at idle and 80 Psi at cruise.

Factory large journal cranks turn into a wet noodle at RPM, flexing all over the place, which would require larger clearances. (bind)

Main saddles flex too, but obviously not as much as the crank.

Sloppy machine work is also a situation where you run larger clearances. (safer)

Larger clearances it's best to run the 80psi spring/80 psi pump.

Higher loads and larger clearances require higher viscosity oils (and more volume/flow). Basing your viscosity on oil psi readings are not an acceptable approach.

Using the above and factoring in how the engine will be used determines the clearances to be used. You can't give 'general' advice on clearances without knowing the above info.

In short, there's a range of clearances that 'can' be used, not one specific value(s).


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This time around I used the butler blueprint 60-70 psi pump and a nitemare pump shaft. I did install the washer that comes with the pump . All my engines in the past have idled around 20 psi at temperature with a standard melling 60 psi pump.

20 at hot idle ( under 1000 ) is plenty as long as by 2000 it slams right up to 40 to 45 psi.

Dyno day this Friday.
.040 over 455
9.73-1
236/244 @ .050,,,, .580 lift HR
Stock iron port matched intake
Cliff quadrajet
#64 heads cnc port to 254 cfm by Dave
Dyno headers but will switch to my rare oversized manifolds with 3” head pipes
MSD RTR
Internally balanced

With headers I’m expecting around 495 hp .

I'll give you 30 more hp based on my engine.

.060 over 350/413 stroker
9.34 to 1
224/230 @.050 .502/.510 lift HR
Torker-I port matched intake
6X-4 heads - stock
Hooker Dyno headers
MSD RTR

442 LbFt@4300 and 453HP@5600

Back in 2019 it made 491 hp at 5200 rpm and 570 trq. with the headers. So other than a slightly bigger bore the biggest difference is going from the HFT ram air 4 sized cam and rhoads v max lifters to a HR …its a little more duration and the lift went from .530 to .580. That’s why I’m not expecting much of a power increase.
I’m hoping the power loss going from headers to the rare manifolds and 3” pipes is a little less this time as last time it was regular ram air manifolds and 2.5” head pipes and lost about 15 -17ish horsepower. Maybe this time I’ll only lose about 10 ish.

So they got the engine running and they called and said it’s missing a little on the pull and around 5300 it would just shut down and then come back to life. They happened to have another Pontiac RTR msd dist with a bronze gear and tried that one . It ran fine with that one. I asked them to switch modules possibly to see if mine is bad. Ugh. He did say it made a little over 500 hp but didn’t have any other details at the moment. If they’re not interested in switching modules I’ll probably just buy another module have them install it and see if it works. If it doesn’t, I’ll probably just buy another ready to run and send this one off to MSD to fix it and then sell it I guess.
Once my dist is in it a running right I’ll go up ,, make some pulls and then put on my qjet, make a pull and then install the iron manifolds and see what it does for power.

Who is dynoing the motor?

The same people that put it together for me,, redline performance engines. They don’t want to pull the module or anything out of the other distributor and I don’t blame them so I’m just gonna get another distributor coming. I’ve got a small body DUI distributor, but I’d have to get a different poly gear for it for the roller cam. And I kind of like the rev limiter part on the MSD so I’ll just stick with another one of those. I think the module alone is like 180 and I’m not even sure if that’s the problem. I’ll just send this one into MSD and let them fix it at their leisure.

So I’m not going over to the dyno shop tomorrow now… no sense until I get a dist I own in there and running correctly.

It's criminal what MSD/Holley distributors cost now, need a mortgage for those things...


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Would be satisfying if an HEI was dropped-in and made more TQ @RPM.

Explain how that would be possible?

Crazy how people are so religious of HEI, makes zero sense to me. Coil in cap is a big drawback, as is the large base/cap. And that's not even beginning to talk about the modules.


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Will they switch over to the RARE manifolds on the dyno for a comparison?

A Progression Ignition dizzy would be nice in this application. Full timing control via phone app/BT and built in rev limiter: https://progressionignition.com/prod...ap-distributor

Yes,,,as soon as they get the new dist in and running correctly I will go over with my qjet and manifolds. Once the engine has total timing dialed ( which will be around 33 as usual) Ill throw on my qjet and try that. Last time it made a couple of more HP than the 850 holley dyno carb. Then we;ll remove the headers and try the oversized manifolds with the 3" headpipes from RARE.

I thought about that a few years ago but sounded like wizardry thats over my head. Im not very technical savvy.
New dist should be at the shop monday. Not sure whats wrong with the old one...only 5 years old. Hopefully MSD can fix it and then Ill sell it i guess.

The new MSD programmable 6AL, now called the 'Ultra 6AL+', with programmable timing now does bluetooth:

https://www.msdignition.com/products...eet/parts/6523


Then it wouldn't matter what dizzy you use...

EDIT: It's smaller too, at 3.3" x 5.2" .

EDIT 2: It has an integrated MAP sensor and CAN-BUS capable. Comes in black too:

https://www.msdignition.com/products...et/parts/65233

**Apologize for some previous tone of comments, I've been under the weather...

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Mains, did you do this to them ? Or leave them as is ?
It matters.

HEI ? You will not get any more power out of a HEI vs a points triggered MSD. proven it.
Less to go wrong and no apps to screw up.
You can get HEI for other makes too. Some Ford racer I know run them. Coil on cap and all that. I ark them why and they look at me like I am nuts. HEI has this reputation I do not get.

Im assuming they used them as is. Half grooved I believe. That some type of extra oil hole?

I didn’t know this existed, very cool and great to see MSD offering a programmable ignition but it’s about the same price as the Progression Distributor, $478 vs $529 Still great to see others offering easy programmable ignition though!

I agree with post 22.

Coils run cooler and last longer when there external.

With big diameter caps the tip of the rotor spends more time between each terminal.
This time is only milliseconds, but has an effect as Rpm’s go up, and especially above 5000.

This added distance means the spark leaving the tip of the rotor arc’s more before it get to the cap terminal, and especially if coils are used that kick out more then 45,000 volts.

A well set up stock points Dizzy modded to take another set of points while keeping it’s vacuum advance losses nothing over a HEI .

Can you explain this? By another do you mean an additional or a non-stock set of points? Thanks!

And with MSD you have to buy a box and a dizzy. It’s hard to beat the PI distributor if you’re looking for a programmable option at a good price.

Some people want to run a box anyway. My concern would be if the company goes under in 3 years or something, then what?

Then of course phones are constantly updating their' software, and there's a chance the app could get buggy, or not work at all. You would be forced to hold on to an old phone just to tune it.

MSD isn't going anywhere, and the R&D gets tons of money. They offer a desktop app too, which many racers use, and it's the same software the GRID uses.

I like the fact that the Progression body is basically a knock-off Pro Billet, but vendors are starting to go more toward hall effect triggers for a number of reasons, wish both vendors would switch over.

I also like the fact that the knock-off Pro Billets use a compatible cap & rotor, MSD/Holley has ridiculous pricing at $68 for each, and you can use the knock-off caps & rotors for like $40 for both. Sure beats $140 for a simple tune up.

I just got a Summit cap & rotor, and it fits the Dual Spark too. Nice.


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Its not a extra oiling hole. On the mains where the 3 holes intersect into one, the shot of oil does not come from the middle of the hole. It comes from the hole on the tab side of the bearing.
So, if you leave say a Clevite bearing alone the main shot of oil had to hit the back of the bearing, move over and get through the stock hole. Thats one thing on a stock engine. But on a engine that will be spun up it can starve a rod bearing, not good.
Even the FM bearings with the slot need this done. The slot still partially covers the hole where oil comes from. My my current engine has FM main bearings and the slot with the added hole looks kinda like a golf club or "L". I just could not find the pictures for it.
I have always done this and never spun a bearing in my life.

To very briefly reply to post 32, it’s a very involved mod that use to be done before Accel came out with there duel point dizzy for Pontiacs in the mid 70s.

You need to rob the breaker plate from another one.
Cut it down to fit into the dizzy and tack weld it below the original breaker plate .

Move the condenser to outside the dizzy.

Drill and tap holes to mount the second set of points directly opposite the original one and then shim the added set of pints up to make it about the same height as how the original one sits in relation to the cam.

OK, got it. Its a homemade dual point that you could build yourself before they were readily available for the Pontiac V8. Thanks!

Dyno results…. 514 hp with headers,,, 510 hp with rare oversized manifolds and their 3”headpipes. Rear main started to leak a little bit seemed like so. I didn’t take the motor with me. They’re gonna look at it. I used the best gasket company, graphite rear main.

Nice numbers!

Even the BSFC numbers.

Well done!! That'll be a fun ride

Nice, Scott! Interesting the negligible hp/tq differences between headers and R.A.R.E. manifolds. Good stuff.

How far up into ME are you? Is your nearest track NE Speedway?

Last time I was using standard ram air manifolds with 2.5” headpipes and I think it lost about 15 hp over headers . I was really surprised this time it only lost 4hp with the better manifolds and 3” pipes over headers.. It made the same 570 trq as it did last time but got a decent bump in hp. Peak rpms is now 200 rpms higher with the new HR cam.

The closest track to me is new Oxford dragway,about 50 miles.

Looking at the 2019 dyno sheets it looks like it’s a little lower oil pressure this time. Maybe a 8 psi average lower now through out the pull. The mains are .0028 but the rod clearance is .0029,, last time it was like. .0023 rods. That might be causing the lower pressure. Idling today was around 19-20 psi at 800 rpm at temp.

It now has a Cloyes double roller racing Z timing chain. Whats does the Z add over the standard racing double roller?

What oil viscosity?

15w 40 cenpeco

Outstanding results!!! Really impressive for iron heads and intake manifold. Even better with RA manifolds

Nice! Good job

Not bad for a junky old quadrajet,,, or so I’m told.

That’s a great build!! Congrats

Looking at the 2 dyno sheets it looks like switching to the manifolds and pipes richend up the air fuel ratio some.