Oil clearances and a surprise

[Small Block Duster]

I'd not worry over that 1 tighter main bearing, but if I did, a bit of crank polish will do. I've polished almost .001" with no issues. And since the full groove mains ought to use more oil, then I would want less mains clearance. For an engine of this power, IMHO few .0001" is not going to change anything.

I was wondering about that. I'll have a talk with the new machinist tomorrow. It would be nice to start assembling it soon. It'll also be nice when I get the pistons and rods back so I can start my rod bearing clearance checks. I'll try to organize the bearing shells so that the clearances are at least above .002" maybe .0021" like the first mock-up.

 

[rumblefish360]

I REALLY like Mr.Gasket’s Ultra Seals. However, any major gasket player should be fine. FWIW, a tip, don’t over tighten the center port bolts! It warps the flange.

I also use a reduced size head on the header bolts. From ARP. I’ll get the part number tomorrow. There a 3/8 head bolt. I cut down a small wrench to fit in easier on the tight spots. While the header is hanging on the end studs, I grab the tight ones first. Blue lock tight should do the trick on holding them in.

 

[famous bob]

I was wondering about that. I'll have a talk with the new machinist tomorrow. It would be nice to start assembling it soon. It'll also be nice when I get the pistons and rods back so I can start my rod bearing clearance checks. I'll try to organize the bearing shells so that the clearances are at least above .002" maybe .0021" like the first mock-up.

Thru out all this , I didn`t read anyone warning you about the rods facing the right way, better check the chamfer on them too.

 

[Small Block Duster]

Thru out all this , I didn`t read anyone warning you about the rods facing the right way, better check the chamfer on them too.

Yes the rods are facing the wrong way, to install them with the top of the piston facing the correct way the non chamfered end of the connecting rod would be against the radiused ( and in this case undercut ) part of the crankshaft. And the spit holes would be facing outward. My biggest worry right now is the shop that I took them to now is breaking the pistons or damaging the piston pin when they press them out to turn them around. I guess I should have had the rods bushed or gotten some Scat rods. Even those were pushing the budget too much. This is a perfect example of spending less money before to spend more money now. I feel dumb for not noticing the connecting rod orientation until we started blueprinting the motor. Also, as you mentioned, the chamfers on the rods seem to be different sizes from each other. I don't think that's a problem as long as they're big enough. The rods were resized. I've gotten advice from a number of you guys here saying that that tight number 2 main at .002" clearance and number one at .0021" is probably okay. We'll see what the rod bearing clearance is when I get them back.

I REALLY like Mr.Gasket’s Ultra Seals. However, any major gasket player should be fine. FWIW, a tip, don’t over tighten the center port bolts! It warps the flange.

I also use a reduced size head on the header bolts. From ARP. I’ll get the part number tomorrow. There a 3/8 head bolt. I cut down a small wrench to fit in easier on the tight spots. While the header is hanging on the end studs, I grab the tight ones first. Blue lock tight should do the trick on holding them in.

Thank you for the advice. I probably would have torqued those center two bolts too tight! I'll get a set or two of those header gaskets. I think my performer RPM heads are dry at the outer bolt hole ends. I think...

I was wondering if it was easier to deal with the headers once they're in the car, such as changing gaskets, with bolts in the outer ends instead of studs? It might give a small amount of maneuvering space. My car is a 75 Duster. It's a slant 6 and it's getting the Schumacher mounts. I'm not sure if those get the engine in exactly the same spot.

 

[rumblefish360]

The swap mounts should put the engine where it needs to be exactly BUT old cars bend, twist, warp and rot out of position so.... a small amount of “Adjustment” maybe needed. Shim kits normally take care of that.

I like to put studs in the heads. At least the front. But both if possible. There in the way a lot when installing headers but since your going in fresh.... I myself would at least get the header in and then install the front stud.

They also make a gasket change easy IF you need to do one.

 

[Small Block Duster]

The swap mounts should put the engine where it needs to be exactly BUT old cars bend, twist, warp and rot out of position so.... a small amount of “Adjustment” maybe needed. Shim kits normally take care of that.
I like to put studs in the heads. At least the front. But both if possible. There in the way a lot when installing headers but since your going in fresh.... I myself would at least get the header in and then install the front stud.

They also make a gasket change easy IF you need to do one.

Thank you. I appreciate the help. I'm going to do everything I can to make sure the header installation and reliability goes as smoothly as possible.

 

[Duane]

Hi guys. You guys have been a lot of help and I appreciate it very much. I don't like starting another post so quickly but I need your advice.

I began to do the initial blueprint to my 360 such as mock-up and checking bearing clearances and the first thing I found was the machine shop had pressed my pistons onto the rods backwards. I understand mistakes happen but this is a pretty amateur mistake and it makes me wonder what else they may have missed. So I took them to another machine shop to have them pressed off and assembled correctly. And hopefully not destroy my pins or my pistons in the process.

Anyway, the main bearing clearance is coming up as high as .0026" on the rear main, #3 and 4 were about 2.4, and the tightest being number 2 main at 2.0 to 2.1. The #2 main bearings showed a little tracking after turning the crank with the caps torqued up. We switched bearing shells from the #2 main to the #1 main and vice versa. #1 main went from 2.3 or 2.4 down to 2.1 or 2.2 and #2 main still close to the same at 2.1 or 2.0. This is after measuring at different ambient temperatures and several times. Also, both get about .0001 smaller from front back on each main. I have full groove p-series main bearings. The thrust is about 3.5 and the crank seems to turn smoothly. I'll know the rod clearance when I get them back. This engine is going to red line at approximately 6500 rpm, mostly street driving and a little racing.

This is a 10 to 1 compression motor. Any information you want to know about it I would be glad to answer. I haven't listed it here to save space.

Back to my question. Everything except the rear main seems awfully tight to me. If it was a small-block Chevy I would probably not run it. But as I have been told, this is a Mopar and I need to think of it in those terms. In your experience, can 360s be run this tight given my operating range and engine set up? I'm still thinking about a high-volume oil pump, but maybe thinner oil than I normally run. Maybe 10w30. I don't know what the rod clearances are yet. I will when I get them back. I don't think they make 9 thousandths under bearings for Mopars. Do you guys think this is an acceptable spec in this case? If not, what do you recommend? Would getting Federal-Mogul bearings and mixing them with the Clevites possibly help change the clearances a little. I've heard that polishing the crank to slightly open up the clearance may not keep the crank journals round. The crank has been freshly machined .010/.010 under and the front 4 main bearing journals are miking out exactly the same.

The machine shop said the crankshaft line bore was good. Do you think it's time to take this to another machine shop and have it line bored and put studs in the same time?

Have you had a successful engine in the past with clearances like mine?

From how to build stroker small block book.

 

[Small Block Duster]

From how to build stroker small block book.

View attachment 1715302502

Thank you, Duane, for the chart. I need to buy that book. The factory specifications are really tight.

Since I last posted my main bearing clearances are .002" to .0024" and my rod bearing clearances are .002" to .0023", with fully grooved main bearings. A little tight but I'm starting to think that it will work.

 

[Duane]

Thank you, Duane, for the chart. I need to buy that book. The factory specifications are really tight.

Since I last posted my main bearing clearances are .002" to .0024" and my rod bearing clearances are .002" to .0023", with fully grooved main bearings. A little tight but I'm starting to think that it will work.

My drag only motor clearances came in at .0019 on the mains and between .0025-.0027 on the rods. I am running it.