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Old 05-02-2013, 03:32 PM
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BBC push rod mystery

I have a 1976 GMC truck454. After a (long ago) disassembly of the valve train, I replaced the rockers, cam & lifters with Comp Cams stuff. I thought I had lost the push rods, but just found 'em. Here is the problem: I ordered new magnum rods, 3/8" O.D. as everywhere sez that's the size the 454 uses. But,when I went to install them, they're too big for the guides. But, Comp Cams sez the 5/16 rods are only used i small blocks. I did eventually look at the old rods, sure enough, they're 5/16 O.D. So, *** have I here? I sure don't want to install new guides, as I could booger a head gasket, or two. They (CC) said they wouldn't warranty any parts if I use my old rods. They're straight, etc., just old. Any suggestions not involving Tannerite or Thai hookers?

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Old 05-02-2013, 05:23 PM
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Whoever you talked to at Comp Cams should be fired..

Big blocks have used 5/16 pushrods since the early seventies. In base engines and truck engines. Most common pushrod you will find in a stock 454.

Buy some 3/8 guide plates and you will be running again..
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Old 05-11-2013, 09:46 AM
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Well, as much as I hate to do it, I bought some guide plates for the 3/8 rods I got. I hope I don't incur any head gasket problems as a result, but, I'll take a flying stab at it. I now have the Comp Cams Magnum 3/8" push rods, so I added their guide plates to the mix.
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Old 05-11-2013, 02:56 PM
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The guide plates are installed with the rocker studs, not head bolts so you will not have a head gasket problem. Make sure the push rods are for use with guide plates, some are, some aren't.
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Old 05-11-2013, 03:27 PM
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Since all big block chevys use guide plates pushrods from CC should be hardened ,,USE an adjustable pushrod length checker to make sure you have right length, I used Comp cam ,lifters push rods valve springs.,roller rockers,timing chain and gears,,the pushrods were to short I had to order 125 th longer on intake and 250 th longer on exaust ,the ones that came with cam kit would not work the rubbed my guide plates had tp grind small amount with die grinder then reinstall until I got the clearance I needed,
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Old 05-12-2013, 10:34 AM
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It's a pretty common mistake to end up with 3/8" pushrods on a BBC engine. When looking around at most hi performance suppliers like Jegs or Summit, they carry almost nothing in 5/16" diameter, and tons of 3/8"-7/16" offerings. I didn't even see any 5/16" pushrods offered by Comp, so I'm guessing someone there (unkonledgeable) just spec'd the smallest they carried.
I'm running 7/16" Crower pushrods on my 454. I like the larger diameter, and my Edelbrock heads are setup for the 7/16" already.
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Old 05-12-2013, 12:46 PM
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It's a pretty common mistake to end up with 3/8" pushrods on a BBC engine. When looking around at most hi performance suppliers like Jegs or Summit, they carry almost nothing in 5/16" diameter, and tons of 3/8"-7/16" offerings. I didn't even see any 5/16" pushrods offered by Comp, so I'm guessing someone there (unkonledgeable) just spec'd the smallest they carried.
I'm running 7/16" Crower pushrods on my 454. I like the larger diameter, and my Edelbrock heads are setup for the 7/16" already.
I am running comp 3/8 but when I ordered longer pushrods I got the .130 not the standard.80 they are much stronger,because I am running a milder cam and springs than what you are probably running ,I only have 540 lift.
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Old 05-12-2013, 04:02 PM
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I am running comp 3/8 but when I ordered longer pushrods I got the .130 not the standard.80 they are much stronger,because I am running a milder cam and springs than what you are probably running ,I only have 540 lift.
You're way more lift than my engine. I'm only .518 lift. My cam is designed for 2,000-5,900 rpms. More low end power and torque.
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Old 05-13-2013, 03:31 PM
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Be sure to use sealer on the studs that enter the ports.
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Old 05-15-2013, 07:08 PM
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You're way more lift than my engine. I'm only .518 lift. My cam is designed for 2,000-5,900 rpms. More low end power and torque.
You got me to thinking about intended RPM range ,this is what I have Comp 270 Marine with correct rotation they offer both ,,told me it would run with a 2400 converter and should have 16-18 in vacumn ,I
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Old 05-15-2013, 09:02 PM
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Originally Posted by 496CHEVY3100 View Post
You got me to thinking about intended RPM range ,this is what I have Comp 270 Marine with correct rotation they offer both ,,told me it would run with a 2400 converter and should have 16-18 in vacumn ,I
Those look like great specs for a BBC cam! I've always liked short duration cams with lots of lift in a BBC to make power and torque. I had a Crane cam with 284/284 duration, .528" lift and 114 LSA in my 427, and it had a great powerband, with super lowend response.
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Old 05-15-2013, 09:09 PM
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Had a very disappointing setback today while assembling my 464 BBC. Was down to the last bolt, on the last head, and the final torque increase, when the ARP stud pulled out. The threads in the block stripped out, so had to pull the head to see what happened.
It's the hole that the alignment plug is in, so pulled that also. I can actually get to the backside of the hole and see the damge all the way through. I'll have to order a 7/16-14 helicoil kit to fix it.
Until I get the kit, my assembly is on hold. Tried to buy one locally, but the hardware store wanted $120, and Summit only wanted $22, so I'll wait for Summit.
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Old 05-16-2013, 10:25 AM
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Sorry to hear bad luck, I have good luck with summit shipping,your falcon is looking good you are moving fast ,on the cam I ordered short duration for low end torque since I am running 496 cu in it takes lots of air 225-188 valves 113 cc heads I needed extra lift a 331 rear gear 29in tires .probably will never turn it over 6000 any way reve limiter set at 6 k, if I turn it to 6 it should drop to around 45 on shift that will keep it in power band ,I will run the clock once to get a et,then it will be street driven after that.
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Old 05-16-2013, 10:54 AM
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Just a thought ,did you Mag around bolt hole to check for hairline cracks ,should be OK but it would be better to find it now.
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Old 05-16-2013, 11:24 AM
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Just a thought ,did you Mag around bolt hole to check for hairline cracks ,should be OK but it would be better to find it now.
No, since it's a complete engine I didn't have it down to magnaflux. I don't think it's an issue, as it's been recently rebuilt, and I would hope they would have magged it then.
I'm going to get the helicoil kit from Summit Fri., so hopefully have it repaired then. Need to get some red loctite before then and loctite the insert in place.
I'll switch gears and do some interior work until then. I have a new headliner to put in, and curious what kind of mouse nests I'll find up there when I cut the old one out!

That 496 you've put together should be a killer combo! Lots of grunt, and very streetable setup. I'm running 30" tall cheater slicks, so went with 3.73 ratio rear. I also will run the Falcon mostly on the street, but probably run a couple nostalgia events each summer too.
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