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#61
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7/16 is preferable, especially on a stock block. What do you have ? |
#62
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My block is at the machinist and he finally got the thrust surface cut. This was a challenge as it is very difficult to measure how much to cut off the new thrust cap. He is currently doing the line hone. The new 4 bolt caps are much harder to machine than the cast saddles in the block so this is also a challenge to prevent cutting to much off the block side during the line hone. To further complicate this process the front and rear caps are the original cast caps. The steel caps came about .050 too small compared to the correct bore size. The steel caps were put in a mill and the bore was rough cut to reduce the amount to be honed during the line hone. After line hone then it will move to boring the cylinders and moving one bank over about .015" to get more material on the thrust side.
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Tim Corcoran |
#63
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I don't understand why steel caps are used instead of ductile iron. It seems the ductile would machine easier. Is the iron cap a lot weaker than steel? I have a block headed to the shop for 4 bolt caps and was planning to use ductile caps.
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#64
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Do you have cast iron caps? Have you talked to your machinist yet about the thrust register will need to be machined on the new thrust cap? A lot of machinists won't even take the job, they are used to chevy main caps that don't have dowel pins and the process is much easier. Some say that going to 4 bolt mains doesn't do much unless they are splayed and that two bolt mains are stronger than most believe. I personally don't have the expertise to weigh in on that. I can tell you I'm going to have a big bill for putting these new four bolt steel caps and the line hone. He won't be able to give me a price until he knows how many hours he has into it.
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Tim Corcoran |
#65
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Well, if one has a 2 bolt non drilled block IMO it makes no sense to run straight 4 bolt caps.
Few things, the front cap is cheap, might as well run a steel front cap. If a IA2 has 7/16 splayed caps we know they are better. And there would be no reason to run a 1/2 outer bolt and its greater torque pulling on the weaker stock block. I bought my 400 block from Dan W. I thought it was a drilled and tapped 400 block and sent him straight PE caps. In conversation I found out it was a non drilled block. Even though Dan was partway through with the straight caps, thrust was cut, I called KRE and had them send him splayed caps. And it cost me a extra 200$ for Dan to do splayed. Lot more Fing around. But he did have the jig for drilling the splayed caps. Dan had another customer who could used the straight caps as they fit his block even though cut. Splayed id the way to go. They help out with cap walk. Bolts pulling from 2 directions. Milodon makes ductile iron for Pontiac,s in 3" and 3.25" mains, straight and splayed. You only have to cut .030 off a Mildon cap and they are ductile iron so the line bore has to be much easier for the machinist. https://www.milodon.com/main-caps/main-caps.php Last edited by Dragncar; 12-15-2023 at 05:42 AM. |
#66
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Sounds like you have a great guy doing the work for you. Had the same done to mine except I had splayed put on, what a mess when its not done right. Best of luck to you this coming season.
John |
#67
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__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#68
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Tim Corcoran |
#69
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GT |
#70
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I am not installing splayed caps, the block is pre drilled for 4 bolts. All pre-drilled outer bolts are 1/2"
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Tim Corcoran |
#71
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I would imagine he is cutting with the cap installed on the block to the factory one already there matching them up. That would create a correct fit .
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Be carefull of the feet you step on today.They may be attached to the a$$ you kiss tomorrow. |
#72
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Tom 1963 Lemans -428 +.030, SD Perf KRE heads, turbo 350, 9" Ford 3:90, 11.01@121 1956 Chieftain gasser, 461 stroked 400, SD Perf ported E-heads, turbo 400, Dana 3:70 10.40@125 |
#73
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__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#74
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Allot of good experienced people on this board in many different trades. Sometimes people assume they are knowledgeable in areas they play in part time and don't know they are communicating with someone that's knowledge on the subject is based on real life experience from many years hands on. Keyboard has more than likely never installed aftermarket main caps on a block. It can make you seem like you have though.
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Be carefull of the feet you step on today.They may be attached to the a$$ you kiss tomorrow. |
The Following User Says Thank You to chiefbigb For This Useful Post: | ||
#75
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__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#76
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Tim Corcoran Last edited by Tim Corcoran; 12-21-2023 at 12:53 AM. |
#77
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get it close enough for one face to match? Then it gets cut for the right thickness? |
#78
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The thrust register on the new cap is done and the line hone is complete. Next up is boring and honing the block for the new Ross pistons.
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Tim Corcoran |
The Following User Says Thank You to Tim Corcoran For This Useful Post: | ||
#79
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Quote:
__________________
“It takes considerable knowledge just to realize the extent of your own ignorance.” Dr. Thomas Sowell |
#80
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I am a Cummins and caterpillar master machinist. Worked for dealers and oems since 1990. Mostly did deck repair at remote locations. Not allot gets fixed anymore just swing engines in long block form. I do more wiring and emissions work these days. Still play with the Pontiac engines. There are a couple in progress similar to what Tim is working on out there now.
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Be carefull of the feet you step on today.They may be attached to the a$$ you kiss tomorrow. |
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