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Discussion Starter #1
Hi fellows,

I've been searching for a local machine shop that plate-hones my 400sbc there's none around here that uses torque-plates. I'm concerned about durability and performance problems if I build my motor not using one of those plates.

Machine shops do have torque plates for Asian engines but not for my SBC. Will I have to see the turbo'ed ricers pass me over with resignation?

I'm disappointed.

Jorge
 

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jmr1965,
I'm not expert in this field, but 30 years ago I don't think they had hone plates and there sure were a lot of hot motors back then that were built in the backs of peoples garages using only a hone attached to a drill. I know I drove a few of them. I would say move on to other things, especially considering your location...

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Scott
68 SS BB project car
 

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Jorge,
I have to agree with Scott. We probably plate hone less than 1% of the blocks that we bore. You should not have a problem. If you really want to have the block plate honed, you could buy the plate yourself, they are about $250. I had a customer do exactly that for a weird Buick motor that he wanted plate honed. I knew I would never use the plate again, so he bought it.
Hope this helps,

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Bill Koustenis
Owner
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner
1973 Z-28 ..one family car...Brother bought it new in 73
 

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One thing you might do IF it is bothering YOU THAT MUCH, (anally), is to stack some washers on some headbolts and torque them to each of the five headbolt holes per cylinder and hone away. You might have to cut the washers for clearance, but, what the hey....

The only problem with this is that although you get an upper cylinder sidewall loading, it is not quite like stock, but more then none at all. Of course, you can over torque, tooo....

Just a shade-tree idea, that's all. pdq67
 

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Discussion Starter #5
Thank you for your comments, friends.

I heard/read how important is it so plate-hone the 400SB that I was worried for not having it done so. Many people around here runs 400s competing in the mud and none of them gets it plate-honed; but those are race engines not focused on durability as a street engine is. I just want a good running engine to last many years, but, well.., many times you have to give something.

You have cheered me up to go on with it. I think there are other details like clearances, cooling, oiling, etc, I can pay good attention to for it to last.

Thanks,

Jorge
 

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Do us all a favor and when you get it running, please do a leak down test on it and let us know how it does.

I did a leak down test on a 1 yr old rebuilt stock 400 in my pickup truck, it had %65 leak down on ALL cyls!!!
You wouldn't know it to drive it, there were no apparent problems, but when I pulled the heads, there were light and dark areas on the cyl walls.
I won't build another large bore SB without a block plate.
David

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Check my web page for First Gen Camaro suspension info:
David's Motorsports page
First Gen Suspension Page
67 RS 327 original owner. 69 Camaro Vintage Racer, 65 Lola T-70 Chev SB Can-Am Vintage Racer

[This message has been edited by davidpozzi (edited 08-01-2002).]
 

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David,
I was following this post and I was doing OK until I read your post! Are you suggesting that you should use a plate to hone a 400? Is there something special about a 400 vs a 350? If I read you correctly you were saying to bore a block use a plate and that makes a lot of sense.

billk,
If you read this post please email me.

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Scott
68 SS BB project car
 

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Have a friend that runs a 400SBC in his 77 Nova. Its a super pro car and runs 5.8 in the 1/8 mile with a 1.25 60 ft. time. Watched him build all his engines and he always uses a plate.He freshened a 350 SBC for me and also used a plate. Don't see anything that this would hurt. YMMV
 

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The difference is bore distortion caused by head bolt torqueing due to the 400's siameezed cylinder walls and big bores! That's all.

Yes, it is a good idea to use a hone plate but you can get along without it. You just won't be getting the most out of your engine until the rings hone it round in several/many 1000's of miles of running! My 2 cents. pdq67
 

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I'm not trying to scare anybody.
By the way, mine was .040" over on the bore.

All the performance books recomend using a torque plate on the block with whatever head gasket you plan on running.
The torque plates became a big deal when the 400 came out. I don't think they were used before that on a chevy, but it was found for racing that the torque plates were pretty much neccessity on a 400 and a good idea for any engine. I've heard of people doing valve jobs on heads with a torque plate on the head...

Now, a leakdown guage has a jet the air goes through then it goes to the cylinder so you are measuring a percent of leakage OF THAT SIZE JET. It isn't the most accurate measure of the complete compression loss when the engine is running, I think a blow by measurement is better at that. BUT the leakdown test does give a measurement of relative loss one engine to another.

I measured %65 loss on my cold engine, it all was going out past the rings, I could hear the air in the crankcase blowing. I did it on an engine stand when the engine was out. The rebuilder had welded the front throw on the cast crank so the crank of course broke as soon as the warranty was over!

I didn't see a lot of blow by on this engine, it ran fairly well till it started knocking up front. I would have guessed the leak down was less than %10 by the way it ran.

I'm not saying the engine will not run, but there would probably be a measureable loss in the leak down dept. I'd like to know what the horsepower loss of that would be.

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Check my web page for First Gen Camaro suspension info:
David's Motorsports page
First Gen Suspension Page
67 RS 327 original owner. 69 Camaro Vintage Racer, 65 Lola T-70 Chev SB Can-Am Vintage Racer
 
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