321 GMC inline 6 header

[maguromic]

Ron,

GRP makes a aluminum rod that will clear everything   It’s a 7.700 length GRP part number 18682, takes a cleveite bearing number CB579P. Its made for a Isuzu truck.  If you are worried about rod stretch and durability ask them to make it out of Tantalum 7075 its ballistic aluminum.  I know of at least one car on the salt with a Tantalum set.

I wouldn’t turn down the base circle in your cam as its are already very small and tend to have cam wobble a lot like the early hemi.  Don Garlits once told me that they used to grind their cams with the wobble taken into account on the early hemi.  On mine I made my base circle bigger and put less lift into the cam and put more lift into the rocker arm.

On your head, if you put in on a flow bench you will find that the two center ports will flow about 15% less than the outside ones.  If you are good with a welder think about splitting the exhaust in the center, and to close the combustion chamber up.  Since this a vertical engine it will like chamber like the Pontiac Big Chief head.   Another thing to think about is to add some extra head bolts where the head gasket loves to blow.

If you are turning high RPM their will be spark scatter from running your magneto or distributor in the stock location.  Call Don Ferguson and buy one of his front mount drives and save your self a lot of headaches.

Whole idea is to have fun with it!

[RichFox]

What is the pin dia. on that thing?

[1212FBGS]

interesting thread.... i was just about to do some research after the WF. I want to put pistons and a cam in my 54 vette (blue flame 6) before Christmas. She is a little sluggish and probably over carburetted with those 3 carter YH's. time to freshen it up. I want to keep the stock look with intake and exhaust but i definitely have to toss the pos distributor. Bump the compression, make it breath better with a cam and portwork, and get some reliable spark is the plan. Where is a good place to get pistons, cams, and a magneto?
kent

[power58]

Kent, sounds like a killer vette. I had a friend that had a terrible time finding rebuild kits for the carters in the 70's. Got another friend that has a NOS exhaust manifold for the blue flame, really trick piece. Keep us posted with photos of the rebuild if you can. 

[jimmy six]

Ron, if $$'s are no object call Burns Stainless in Costa Mesa and tell them your plans. They have some experience....Carrillo and Cunningham will make rods to 8" and they will fit with no cam alterations. Long Oliver rods will fit with a turn down of the throw. A good way to add a little stroke.

Ken, Ross has pistons on the shell for Chev 6's. Isky has cams, springs, and retainers. On e-Bay, a guy sells converted HEI's from 194-292's with the extended oil pickup..your best bet. I have his #...Good Luck to all...JD ( just a little experience with 6's)

[Ron Golden]

RichFox, Muguromic, JD,
I made the mistake last December of ordering (and paying for) the rods from a well known manufacturer. I've received the wrong rods once, and been promised the correct ones numerous times. Next week I expect the rods or the return of my money. Then I have to find a reliable rod manufacturer and start over again. I'll call Crower, Cunningham, GRP, etc. and see if a steel rod is available. I talked to one rod manufacturer and he quoted me $1800/set. Thats just a little rich for my budget. I want an 8" rod with a 0.0927" pin. That gives me lots of options for a 400cid style SB Chevy piston from JE. I did find that a set of 308" Hudson rods (8.111" C/C) will work in the GMC if you narrow the big a few thousands.

I'm also trying to keep the actual cam lobe lift within reason by building a set ot 1.91:1 roller rocker arms. That way I'll have more cam-rod clearance....I hope.

Since the max rpm will be 6000 I think the intake is flowing good enough (264 cfm @ 0.600") without getting too big an intake port and losing velocity. I haven't finished the exhaust ports yet since I'm trying to get as much info as possible before I'm completely committed to the port/header.

JD,
How did you do at B'Ville this year?

Thanks guys, Ron

[GH]

Ron, sorry to hear you had problems with the aluminum rods from you know who. Mine seamed to fit just fine, although I don't have the cam in yet.

[Ron Golden]

Gary,


The rods he sent me first were for a 235 Chevy and the side clearance was about 0.080". Did you check yours? Will the rods you have clear the cam?

Did you ever port your cylinder head? I got mine to flow 264 @ 0.0750" lift but will limit the lift to around 0.650". I built a set of 1.91:1 roller rocker arms and hope to be able to have the stock cam reground.

Keep in touch, Ron

[GH]

Ron, my rods didn't have enough side clearance, they had to be milled off. Don't know about cam clearance yet, my cam is not back yet. We are in Cortez Colorado this evening, left Wendover NV this morning. Dropped another valve through a piston in the Stude, ran 234 mph. Cya

[Ron Golden]

Gary,

OUCH!!! Sorry to hear about the dropped valve. Was the 234 mph as fast as you were trying to go, or were you looking for more? Sounds damn fast to me. Running at B'Ville must be one hell of a rush.

By the way, are you having the stock GMC cam reground? Who's grinding it for you?

Keep in touch,

Ron

[GH]

Ron, I was going for 245+ for a record and red hat, that is my goal, then the GMC will go in the Stude. Donnie Johansen is grinding my cam, I purchased a steel cam from Doug Robinson in California. You need to go salt flat racing, once you see it, you will forget about drag racing. Cya

[RichFox]

Hope Donnie gets the cam right.

[GH]

Rich, that's a scary thought..

[RichFox]

I don't think it can happen twice, but I would be real sure I got what I needed before laying out any cash.

[Ron Golden]

Rich,
Sounds like you go bitten like I did. I wonder if it runs in that family?


Gary,
I'm afraid to go to the salt, from what I hear it's almost like being addicted to drugs. By the way, what's the MPH record you'll be shooting for when you run the GMC in the Stude? What RPM do you plan on turning the engine? Keep me up to date on your progress.

Ron