Vintage 302 chevy.

Well....things don't look to be as perfect as they seem. I took measurements of the crank saddle to deck, the cam bore to crank saddle and the cam bore to deck. The right bank seems to be close from front to back but the left is terrible The rear numbers on left and right are very similar but the front left numbers are way different than the rear. I did not take a measurement of the inside diameter of the rear main but the front was 2.4915 that was with a caliper not a inside bore gauge.

Nothing spectacular but I used a 6 inch general tools caliper http://www.homedepot.com/p/General-Tools-Fraction-Plus-6-in-3-Mode-Digital-Caliper-147/100651811 and a harbor freight pittsburgh 12 inch digital caliper https://www.harborfreight.com/12-inch-digital-caliper-47261.html. This isn't the most precise way to measure but this gets it in the ball park and definitely shows some inconsistencies.

I think before going back to the machine shop I'll wait for the rotating assembly so I can measure the actual depth of the pistons in the hole so I can tell them how much I want off and where.


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yes have a machine shop verify the measurements and if required you can line hone the mains and deck mill the block decks
 
yes have a machine shop verify the measurements and if required you can line hone the mains and deck mill the block decks

Funny thing is that I already had them align hone and deck it. Before I took it in there it was around 9.018 at all 4 corners and I told them that. I also told them to take a few thousandths off to clean up the decks so the gaskets had a nice clean surface to work with and it seems like they didnt cut anything down at the forward #1 cylinder with the sleeve its still at 9.018 while the other corners are at or around 9.009.
 
If your measurements are correct, It sounds a great deal like you need to find a better machinist to do the work.
the funny thing is that , I'd bet 90% plus of the people who have a machine shop do work like that
would have naturally assumed that the precision machine work was done correctly,
and simply assembled the engine without thinking a second about that work being done correctly.

this is one reason I strongly suggest most serious engine builders may want to have some precision,measuring tools,
and spend the time and effort to check that machine shop work you paid good money for, was in fact, done correctly ,
taking the time too verify the precision machine work was done correctly,
takes a good deal of the time required, in any engine build
(vs slapping parts together out of the box and wondering why it never quite runs up to your expectations)
and yes you probably could use the block in its current condition and find the engine runs,
and most people would never know the engines measurements were not correct or why the engine did not produce power to its full potential,
and the results might be so close that it would hardly matter ,too most car/engine owners.
but that engine block machine work ,being off specs, does not mean its been built correctly either



related threads
http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-68861

http://garage.grumpysperformance.co...ing-parts-and-a-logical-plan.7722/#post-68651

http://garage.grumpysperformance.com/index.php?threads/finding-a-machine-shop.321/#post-59253

http://garage.grumpysperformance.com/index.php?threads/block-prep.125/

http://garage.grumpysperformance.com/index.php?threads/parts-prep-cleaning.6255/#post-51146

http://garage.grumpysperformance.com/index.php?threads/how-to-find-a-decent-machine-shop.800/

http://garage.grumpysperformance.com/index.php?threads/bare-minimum-tools.11026/#post-51843

http://garage.grumpysperformance.com/index.php?threads/machine-shop-sequencing.4460/#post-11720
 
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If your measurements are correct, It sounds a great deal like you need to find a better machinist to do the work.
the funny thing is that , I'd bet 90% plus of the people who have a machine shop do work like that
would have naturally assumed that the precision machine work was done correctly,
and simply assembled the engine without thinking a second about that work being done correctly.

this is one reason I strongly suggest most serious engine builders may want to have some precision,measuring tools,
and spend the time and effort to check that machine shop work you paid good money for, was in fact, done correctly ,
taking the time too verify the precision machine work was done correctly,
takes a good deal of the time required, in any engine build
(vs slapping parts together out of the box and wondering why it never quite runs up to your expectations)
and yes you probably could use the block in its current condition and find the engine runs,
and most people would never know the engines measurements were not correct or why the engine did not produce power to its full potential,
and the results might be so close that it would hardly matter ,too most car/engine owners.
but that engine block machine work ,being off specs, does not mean its been built correctly either



related threads
http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-68861

http://garage.grumpysperformance.co...ing-parts-and-a-logical-plan.7722/#post-68651

http://garage.grumpysperformance.com/index.php?threads/finding-a-machine-shop.321/#post-59253

http://garage.grumpysperformance.com/index.php?threads/block-prep.125/

http://garage.grumpysperformance.com/index.php?threads/parts-prep-cleaning.6255/#post-51146

http://garage.grumpysperformance.com/index.php?threads/how-to-find-a-decent-machine-shop.800/

http://garage.grumpysperformance.com/index.php?threads/bare-minimum-tools.11026/#post-51843

http://garage.grumpysperformance.com/index.php?threads/machine-shop-sequencing.4460/#post-11720

I agree grumpy. Vary rarely do I trust in peoples abilities to provide the quality that I do. Thats just the nature of being a quality control inspector for aircraft, don't trust anyone when it comes to safety.

In this case I wasn't relying to heavily on the shops abilities as I was going to check everything anyways. Before I go making a fuss about it to them I'm going to take a little more time measuring and make sure my arguement is valid. I still have some room before its at zero deck and if they can't correct it in one try then I'll be off to another shop.
 
Most machine shops (at least the ones that I've seen) still do not have the equipment to
true up the block off of the crankshaft centerline. Basically, they just restore surfaces.
 
I talked to the shop after work today and they acknowledged that they saw the uneven numbers in the deck heights but I had only requested a light clean up of the deck so thats all they did. I may have been off on my prior numbers but since I didn't record them I guess its partly my fault it came out like it did.
 
I talked to the shop after work today and they acknowledged that they saw the uneven numbers in the deck heights but I had only requested a light clean up of the deck so thats all they did. I may have been off on my prior numbers but since I didn't record them I guess its partly my fault it came out like it did.

I guess stopping work and giving you a phone call was too much of a bother for them.
 
Now for my long winded but fun story of the day, a little off my engine topic but related to my whole car. After getting home from the engine shop I sat down on the couch to relax and followed my normal routine of checking craigslist for car parts. Searched "chevelle" and the very first item on the list was a 68-72 "non-posi" 12 bolt for $500. (I've been on the hunt all summer for a deal on a 12 bolt and have had a couple of $300 chances but one was cut 8 inches and 4hrs away and the other was from an impala that belongs to a guy I work with.) Well I called the guy immediately and agreed to go look at the rear end. On the way I decided to look at the rest of the local ads on craigslist and there was a factory boxed 66 elcamino frame for $450 ironically it was the same guy. So I warned my wife I might end up buying both of these and she approved! Once I got there he ended up having two chevelle 12 bolts the one that wasn't posted had the brackets cut off and leaf spring mounts to work on a nova and he wanted $400 for that since the stock chevelle lower control arm and spring brackets were cut off. After talking with him for a few minutes I looked down at the housing he had originally posted and saw that it had a factory positraction fluid only tag on the fill plug. I pointed it out to him and we confirmed by spinning the yoke that it was indeed a posi. He's had it for years and never noticed it. Being the nice guy I am I gave him a chance too renegotiate the price since it was a posi which he raised to $700. I offered a package deal at $600 on the posi the original $400 for the other 12 bolt which we couldnt confirm if it was open or posi as it wouldn't budge and finally $400 for the frame. So overall $1400 for a factory boxed frame a factory posi 12 bolt and a possible second posi 12 bolt. Not sure if this was a good deal or great haggling but I felt like a winner considering its almost impossible to touch a factory chevelle posi 12 bolt for less than $1500.
 
I guess stopping work and giving you a phone call was too much of a bother for them.

I told them to only contact me by email if possible which they did very well after the ball was rolling. But I was very specific about my instructions and they knew how picky I was because I was always checking up on them. I just failed to tell them to be sure it was square as I thought it was close already.
 
yes and I hope those 12 bolt differentials are in good shape.....Ive almost exclusively,
just accepted the fact that Ill want too look for a dana 60 or ford 9" differential
simply because of my past experiences
 
Thanks all.

What kind of troubles did you have grumpy? I plan to build up the rearend that I use for the drag car. Probably the one with the brackets cut off so I don't have to molest the posi.
 
I got asked why I prefer the dana 60 over the 12 bolt differential, well, I shredded my first stock 12 bolt in my 1969 camaro 375 hp 396 bbc,(yes it had slicks and a 13.7:1 compression, 496 BBC with crower injection,)
so I spent a great deal of cash on a new 12 bolt, and summers brothers axles a a spool, and supposedly stronger bearing and gears, this was back in the early 1970s
and keep in mind all those parts cost me almost as much as I could at the time buy a used 1969 camaro for ...
I had already installed traction bars , better shocks and leaf springs, frame stiffener extensions and a 4 point roll bar, and a much stronger set of u-joints a custom drive shaft, wheel studs, and yoke.
that very expensive differential lasted about 5 months... I swapped too a dana 60, I bought from a salvage yard from a wrecked car, that had a bad engine fire, out of a 1970 hemi cuda, and never had a single issue
here,s a picture of me in 1970 (47 years ago) with a 1969 camaro I installed a BBC-496 with a tunnel ram into, then later CROWER FUEL INJECTION
paulscamarobw.jpg

crowerin1.jpg

Crower_Injectors.jpg


Now, I'm older, much more experienced, have a lot more tools, a better shop,
I've had 47 years to learn from almost 200, successful, engine and car builds,
and made my share of mistakes and learned from it all,
I'm bit heavier, and still wasting a great deal of money on cars,
and yes, it took me almost 40-47 additional years too get that far
garage25.jpg

garage11.jpg

P1000311.JPG

2940a_IMG.jpg

garage8.jpg
 
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I got asked why I prefer the dana 60 over the 12 bolt differential, well, I shredded my first stock 12 bolt in my 1969 camaro 375 hp 396 bbc,(yes it had slicks and a 13.7:1 compression, 496 BBC with crower injection,)
so I spent a great deal of cash on a new 12 bolt, and summers brothers axles a a spool, and supposedly stronger bearing and gears, this was back in the early 1970s
and keep in mind all those parts cost me almost as much as I could at the time buy a used 1969 camaro for ...
I had already installed traction bars , better shocks and leaf springs, frame stiffener extensions and a 4 point roll bar, and a much stronger set of u-joints a custom drive shaft, wheel studs, and yoke.
that very expensive differential lasted about 5 months... I swapped too a dana 60, I bought from a salvage yard from a wrecked car, that had a bad engine fire, out of a 1970 hemi cuda, and never had a single issue
here,s a picture of me in 1970 (47 years ago) with a 1969 camaro I installed a BBC-496 with a tunnel ram into, then later CROWER FUEL INJECTION
paulscamarobw.jpg

crowerin1.jpg

Crower_Injectors.jpg


Now, I'm older, much more experienced, have a lot more tools, a better shop,
I've had 47 years to learn from almost 200, successful, engine and car builds,
and made my share of mistakes and learned from it all,
I'm bit heavier, and still wasting a great deal of money on cars,
and yes, it took me almost 40-47 additional years too get that far
garage25.jpg

garage11.jpg

P1000311.JPG

2940a_IMG.jpg

garage8.jpg

What ended up breaking on the high dollar rearend you built?
 
I twisted the splines on the axles, cracked a main bearing cap, and cracked several pinion gear teeth,
that also resulted in metallic trash that ruined the ring gear
keep in mind this was not a posi but a spool, so I just gave up on the 12 bolt
now I,d point out I had 5.13 gears and a tubed rear and damn big slicks,
but I was not in my opinion launching that hard,maybe a 4000 rpm launch,
with a manual trans and the clutch had to be slipping at least marginally,
to lessen the impact shock loads on the rear differential,
as I only replaced a couple muncies, over several years.
(and if youve raced much back in the time frame the USED SALVAGE YARD muncies cost about $120-$140 EACH)
I WISH THAT WAS THE CASE NOW (BUT THAT WAS ABOUT A WEEKS PAY)
the front tires were off the ground for only maybe 30-45 feet and I doubt they got 6" or so,
it was a very nice controlled launch , I don,t remember the 60 ft times but the car ran in the high tens back when that was not too common.
(early 1970s)the 1968 corvette I eventually transferred the engine into had a good deal more suspension work and a full roll cage,
and a shortened dana 60, fully tubed rear and bigger slicks and was noticeably faster low 10,s at 135 mph
now by todays standards the cars were not impressive but back then they were at least semi competitive,
in the run what you brought style racing that we did then.
yes I.m fully aware lots of guys run 12 bolts successfully, even in heavy cars ,
but I just had no success and decided to avoid them.
 
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I understand grumpy. Why keep dumping money into something thats not working for you. I'm not going to be making the kind of torque you were but the shock load is what I worry about with the high rpm.

Cnc motorsports has a 5% off everything coupon this weekend so the pistons might be getting ordered.
 
You are not reusing the pistons? Why?
I built a high compression 302 SBC. With your 492 heads, you will need asymmetrical dome pistons.
Mine used 12.5:1 TRW symmetrical dome pistons and 186 Chevy heads, which have nearly identical combustion chambers as your 492s.
The side of the high dome will hit the head near the spark plug toward the exhaust valve, especially with your heads being angle-milled.
Also, weigh the old piston first so you can come close with the new ones for an easier job of balancing.
 

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You are not reusing the pistons? Why?
I built a high compression 302 SBC. With your 492 heads, you will need asymmetrical dome pistons.
Mine used 12.5:1 TRW symmetrical dome pistons and 186 Chevy heads, which have nearly identical combustion chambers as your 492s.
The side of the high dome will hit the head near the spark plug toward the exhaust valve, especially with your heads being angle-milled.
Also, weigh the old piston first so you can come close with the new ones for an easier job of balancing.

Bored .040 over so I had to get new pistons. Arias recommended that I replace them anyways. I got the icon ic803-040, smaller dome (12.7 cc) but its got some nice features. I would like to have a bigger dome but without going custom there isn't much to choose from.
 
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