4 bolt main caps #s
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Instructor
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I’m in utah. I’m using one in the Ogden area that’s been around for 35 years. Sadly the one that had been around the longest which was felts, shut their doors.
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Instructor
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wow Mark you must think I’m over here in my garage with a dewalt drill and a harbor freight tap set all while using a wood ruler. Have you tried and succeeded at doing this conversion or is this something you would never do? I think the cool thing about these forums is having people like yourself that can help the community in doing things the right way from experience, if this can’t be done then I won’t try but if it can I don’t see why not?
Last edited by Muzzyzx7rr; Feb 18, 2018 at 12:58 AM.
Burning Brakes
Joined: Feb 2005
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Just a tip, been down this road many times!!
Make absolutely certain the shop is VERY familiar with doing the 4-bolt conversion! If you get a less experienced machinist/shop it's real easy to literally ruin the block.
This has nothing to do with "fitting" the caps, it has to do with drilling the depth on the outer row of holes along the driver side of the casting.
Thanks, Gary in N.Y.
P.S. I would supply 1 OEM outer (short) bolt and tell them to drill the new holes only to the depth on the bolt threads, no deeper!
Make absolutely certain the shop is VERY familiar with doing the 4-bolt conversion! If you get a less experienced machinist/shop it's real easy to literally ruin the block.
This has nothing to do with "fitting" the caps, it has to do with drilling the depth on the outer row of holes along the driver side of the casting.
Thanks, Gary in N.Y.
P.S. I would supply 1 OEM outer (short) bolt and tell them to drill the new holes only to the depth on the bolt threads, no deeper!
Race Director
Joined: Jul 2015
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From: SW Florida.
OK, I just pulled out a couple sets of main caps. the 2-bolt and 4-bolt Mk 4 caps measured within a thousandth of each other from the outside of the register shoulder to the surface the bearing sits in. the gen 5 caps are offset a couple thousandths to 1 side. Muz, you have 10 main caps. 1 assume the 2 bolt caps are numbered so you can tell which one was where? I also assume you have some decent quality mikes and know how to use them? sit down and measure them all and see if and how far off they mike up from the orig caps. those billet caps don't count. they weren't made by GM in the same house where that block was made and and trued up to another same gen block on that same line.
Race Director
Joined: Jul 2015
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From: SW Florida.
vortecpro, why do you want Muzzy's core? I find 3 Mk4 454 near me on craigslist blocks for 300 bucks. and a bunch of gen 5 complete engines for 600. I am pretty sure Philadelphia is not a hotbed for big block chevys. but if so, I can scare you up all the engines you need... Oh, and one guy has a bunch of 781 and 049 heads. 100 bucks a set.
Last edited by derekderek; Feb 18, 2018 at 07:52 AM.
Racer
Joined: Aug 2011
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wow Mark you must think I’m over here in my garage with a dewalt drill and a harbor freight tap set all while using a wood ruler. Have you tried and succeeded at doing this conversion or is this something you would never do? I think the cool thing about these forums is having people like yourself that can help the community in doing things the right way from experience, if this can’t be done then I won’t try but if it can I don’t see why not?
There's no reason to do it, focus on solid modifications that will deliver.
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Instructor
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OK, I just pulled out a couple sets of main caps. the 2-bolt and 4-bolt Mk 4 caps measured within a thousandth of each other from the outside of the register shoulder to the surface the bearing sits in. the gen 5 caps are offset a couple thousandths to 1 side. Muz, you have 10 main caps. 1 assume the 2 bolt caps are numbered so you can tell which one was where? I also assume you have some decent quality mikes and know how to use them? sit down and measure them all and see if and how far off they mike up from the orig caps. those billet caps don't count. they weren't made by GM in the same house where that block was made and and trued up to another same gen block on that same line.
Racer
Joined: Aug 2011
Posts: 493
Likes: 217
vortecpro, why do you want Muzzy's core? I find 3 Mk4 454 near me on craigslist blocks for 300 bucks. and a bunch of gen 5 complete engines for 600. I am pretty sure Philadelphia is not a hotbed for big block chevys. but if so, I can scare you up all the engines you need... Oh, and one guy has a bunch of 781 and 049 heads. 100 bucks a set.
getting ready for a day of core buying today......I guess I'am sick
you probably never seen a guy get excited about a core shiftless set of 781 heads or a nice block as I do
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Race Director
Joined: Jul 2015
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From: SW Florida.
Is a pair of 781 or 049 worth 250 to you? I can get 3 or 4 sets here for 100 apiece. They ship for about 50 a head ups ground. Or do you prefer to eyeball your own cores, and not have shipping raise the cost?
Last edited by derekderek; Feb 18, 2018 at 11:28 AM.
Racer
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I appreciate your help! The shipping is the problem. nd I'am VERY picky.
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Instructor
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My 781’s are beautiful. Mark it would of been awesome to have these heads done by you! Are you just too busy to accept the work or is it too time consuming to do port and blend work and bigger valves on tgese
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Racer
Joined: Aug 2011
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It just would not be cost effective with the shipping each way, really just trying to be realistic on the money end of it.
Thread Starter
Instructor
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that makes sense, well if you are ever in the SLC area let me know, they will be just sitting in our shop waiting to have life breathed back into them😊
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Le Mans Master
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From: Sarver Pa
2021 C1 of the Year Finalist - Modified
muzzy, that number is WAY high. I've done this job 4 times on my Bridgeport, my self. It's not really a big deal. Set the new caps on where you want em, use a centering punch to mark the hole you are going to drill and make sure you use the depth stop. I used the bridgeport to start the tap to keep the threads straight. There's a lot of play in the cap bolt holes so if you are within a couple thou of center it's o-k. They do need to be line honed when finished. I've used factory caps and I used billet Chinese caps. The Chinese caps needed line bored 1st, then line honed, both ways turned out nice.
Thread Starter
Instructor
Joined: Dec 2017
Posts: 239
Likes: 17
muzzy, that number is WAY high. I've done this job 4 times on my Bridgeport, my self. It's not really a big deal. Set the new caps on where you want em, use a centering punch to mark the hole you are going to drill and make sure you use the depth stop. I used the bridgeport to start the tap to keep the threads straight. There's a lot of play in the cap bolt holes so if you are within a couple thou of center it's o-k. They do need to be line honed when finished. I've used factory caps and I used billet Chinese caps. The Chinese caps needed line bored 1st, then line honed, both ways turned out nice.
