building my first motor, could use some tips.

[91blackcherrytsi]

ive owned a few dsms. so i bought one thats been sitting for years, ive passed by it everyday and finally decided to buy it, we done a compresssion test and found the #1 cyl has none, so im building my first motor, ive collected acl race bearings, a cometic mls head gasket, and arp head studs so far. (thanks extreme psi)

im wondering about pistons and rods now, ive done some research and im kinda leaning toward dsm graveyards 6 bolt rods with evo 9 pistons, ive heard good things about this just wondering what everyone thought about it.

any other engine building tips would be greatly appreciated, thanks guys!

 

[91blackcherrytsi]

Plastigauge you're relying on the supposed/assumed crush properties of a strip of plastic. You also don't get to-the-thousandths measuring ability, you have to guess in between 0.002 and 0.001, for instance, if the strip is crushed wider than one and thinner than the other. It's an old school method of testing clearances back when things could be loose.

Micrometer, you're assuming on the manufacturer's ability to create a sound mechanical instrument and perform quality assurance to ensure that it's reading properly.

Both have the ability to be damaged or become "uncalibrated" over time and use. Of course, plastigauge is a one-time thing, and you have to be very careful that it wasn't already predeformed before you even use it.

It's just that the latter you would think occurs less, considering a strip of plastigauge costs about $7 and covers all sizes of journals, whereas a quality micrometer in 3-4" can run you hundreds, and you'll need 1-2", 2-3", and 3-4", really.

Nowadays, clearances need to be much more tightly controlled as we're producing more specific horsepower per liter, with cylinder pressures much higher than before.

One definite extra pro for using a micrometer is you don't have to spend even a second cleaning the residue off your crank journals or bearings!

Dude that was a brilliant explanation and I'm thankful u took the time to write all that ill definetly have my machinist go ahead and mic them for me

 

[chadillac2820]

Dude that was a brilliant explanation and I'm thankful u took the time to write all that ill definetly have my machinist go ahead and mic them for me

Be sure and request a blueprint

 

[curt-s]

No problem. When they do it, make sure they mic the journals in at least three spots laterally, and every 90 degrees at the minimum, creating 12 measurements per journal. This will give you an idea of your out-of-round and taper. The more measurements, the better, but more costly as it will take up shop time. Somebody may be able to chime in here on an easier way to do that.

As well, with the crank out, have them torque the caps with bearings installed down to spec, and mic the insides as well; top to bottom, both sides, and in the middle. This should give you three measurements per bearing set.

The difference the measurements of the crank and the bearings will be your overall clearance.

It's a lot of measuring, and will take time (and money) but is the best way to make sure you have good stuff to work with.

Micropolishing the crank is a good idea, as it will create a nice smooth surface. This must be done before measuring, obviously.

Balancing the crank is rarely a bad idea (unless the imbalance counteracts the imbalance in the whole assembly, ); balancing the entire rotating assembly is even better, but requires even more specialized equipment. Hope your machinist is good at math Couple of grams here or there quickly adds up to many, many pounds when at 5000 rpm.

As well, get the crank checked for runout, to make sure it's not bent. Nasty things happen with bent cranks. You could do this yourself after you bolt everything up, if you have a good magnetically attachable dial indicator. But if it's bad, you'd have to take it apart again, so a couple bucks for a quick test should be a no-brainer.

Be sure to keep your journals well lubed for any length of storage while you're doing other work. WD-40 does the job pretty good, but I found it dissipates when kept out in the open for extended periods. I suggest a regular coating of oil and keep it in a sealed bag, especially if you're in a moisture intense environment.


*edit*
And as chadillac2820 says, definitely make sure to request the measurements on paper. Don't suffice with the machinist just saying "everything looks good/is in spec".

 

[gabytech]

Listen man I believe u took me the wrong way I wasn't mad at all. I will take everything u said inand use it and I appreciate ## time on it. Considering how explanatory ## first comment was u kinda sounded like a smartass to be honest.

And as far as why am I asking this when I have a few dsm vets as freinds........ would u rather ask 2 peoples opinion or thousands? Makes more sense to me. And again thank you for your time. And I don't plan on shortcutting anything the rotating assembly will be balanced and plasti-gauaged.

I wasnt trying to be a smartass to be honest, Ive just seen this scenario over and over again and it doesn't get old. Im not yet a high performance bible guy and still have lots of stuff to learn, but Ive been doing this for over 10years. Its not the same to make an oil change, brake job, or bolt-on parts to rebuild an engine. Rebuilding an engine, especially high performance engine, requires detailed specs and toleranances to be measured and torqued to specific specs, and even 2 different same engines are built totally different depending on several factors. It's up to you what to do, to each their own, but I would recommend you to have a professional high performance engine builder do the work and stick with minor mechanical jobs and little by little work your way up in knowledge and experience in diy mechanical work. Even most engine repair handbooks are written with a general idea in regular engine rebuilds and not high performance engines which is a totally different ball game... Dont try and save money doing something you have NO REAL clue cause at the end you'll end up spending more and having bigger nightmares than dreams...

BTW, my 1st engine rebuild I ever did, I did it before even going to automotive school, but my next door neighboor was the Sportbike Road Racing Champ and a motorcycle technician. He guided me every step of the way in my build and explained every single detail one by one while doing the rebuild. I basically had no handbook, but had an experienced and professional motorcycle technician by my shoulder supervising every step and correcting me at any mistakes. RIP LUIS NORIEGA, you've been missed since 02, thank you for been my prophet and teacher.. You've been my inspiration every day since...

 

[91blackcherrytsi]

Thanks guys that's the best info I've got yet. I'm gonna see if my machinist has time to put the bottom end together and teach me about this I've known him for years and he builds drag motors. Though they are all v8 fords he's very good at what he does and I think he will have a lot to teach me. gabytech you are right if I want to learn this trade I need to learn it from a pro. It might cost me this time but next time I decide to build ill know. Thanks for all ## help guys

 

[gabytech]

No prob, just giving my 2 cents and glad to help any fellow DSMers, sometimes I tend to come across as a smartass, , when its just the contrary, I dont mind giving any advice and tips, but Im just a blunt guy and call it like I see it...

 

[MNsleeper]

also check Maperformance.com they also do almost everything in house also. so if you have any questions that need answers right away give them a call!

 

[91blackcherrytsi]

I'm the same way gabytech. Its easy to take offense and take stuff the wrong way in forums. Glad u stuck with me though I will keep everyone updated with the process

also check Maperformance.com they also do almost everything in house also. so if you have any questions that need answers right away give them a call!

Alright man thanks ill keep them in mind