A guide to building the lil guy. The Mighty 300

They should. The issue is getting a long enough rod. Already the Buick piston has an almost extreme amount of distance from pin to crown by today's standards. To reduce that any the rod has to be even longer. In my 340 I have 7 inch long rods and the pin is still well below the ring package. 340 rods are a little longer than 300 ones, .427" longer in fact. But when you calculate max rod length using the 300 stroke and deck height you are still going to be somewhere in the 6-1/2" range if not more. So as you say, a stock chevy rod is no help.

The other issue that is very much overlooked is compression chamber volume, design, and squish. And yes those can be overlooked and the engine still run. But it'll run better if they are optimized. It also makes a difference if the builder can or will put in enough time to get the best parts at the best price. If not, then yes, it'd be nice if there was a known package that works acceptably well, but the rods are just half the deal. I'm running 300 alloy heads with zero deck and still have a 22cc dish to keep compression down around 10-1/2:1, and if you eliminate the dish you have to drop the piston down in the bore just enough to turn those small squish areas into ping generators. So you really should drop the compression a bit more to compensate for that, putting you down around 9 or 9-1/2:1 which is OK, but not exactly optimal. So find a hyper with a squish land, enough dish to be around 10:1 at zero deck, and a pin height that gives zero deck with that rod with a pin size that is compatible and not gawdawful heavy and I'm on board with the idea. Up to then it's just another possibly useful but not optimal part that may at some point contribute to a good combination that we haven't found yet. I don't mean to be negative, you are right, the price is very good and with the thick bearings could be useful, especially considering the -.001" size which can help immensely with bearing clearances. But at the same time, without the right piston why wouldn't you just use the stock cast rods and pistons? They do work well and we don't see very many thrown rods at all. If the builder isn't interested in increased performance beyond what a cam swap gives him why would he bother?

Jim

 

I'm thinking about going to the TA Rover heads sometime in the next year on the 300 stroker that I have in the works. It should make a pretty potent package.

To my mind the ultimate street 300 build uses the 350 crank, a set of Carillo NASCAR take-off rods, TA-Rover heads, forged custom pistons, and MAYBE a roller cam. With a blower. If I manage to build that engine I think I can stop there.

Jim

 

In the 350 head thread:

That's good news for us SBB/Rover guys. Does it mean that similar results could be achieved with the Rover heads? Sure would like the answer to that one.

Jim

 

I would just like to know where to find a 300. They seem to be rare lately, and I want to put one in my '63.

 

You just have to ask around. I just did and in only a couple days came up with two. Here's the one I'm not interested in:
https://detroit.craigslist.org/wyn/pts/d/kalamazoo-buick-1965-gs-355-wildcat/6940225155.html
It's $500 for a motor that's stuck (barn find) but it is a 4bbl and it may be OK. Iron head '66 I think. They are out there.

Jim

 

The port is different between the two heads. Rover port is wider and shorter, 350 port is narrower and taller. I know you can hit 270-280 fairly easily with the Rover head. The Rover head has the benefit of a wider port cross section at the pushrod pinch; that's going to be the obstacle with the 350 head. Cant make the 350 port wider without moving the pushrod location, thus requiring offset rockers/lifters.

 

I'm confused?? The distrubutor is in the back and has a nailhead type crossover thermostat pipe?
I thought 300's where SBB based?

 

Good catch, I didn't really look at it more than to see the dust. It was a link forwarded to me. So much for that. You know how to run a Tempest search?

Mike, thanks a lot for the info. We're all still trying to learn as much as we can about these.

Jim

 

Maby the 65GS 401 came from the factory with Wildcat 355 air cleaner??
What a rare blunder it would be. Probably wouldn't clear the hood but it would of been cool.

 

more likely, somebody just grabbed a 300ci air cleaner off of another car.

the Wildcat was a full size car and was never available with a SBB, not even a 340 / 350. large Nailheads or BBB only, depending on year. nothing smaller than a 401ci Nail.

 

No I was just joking. Buick used the "Wildcat" moniker on all the air cleaners for a while in the early 60's, sbb or nailhead..
The bottom base even looks to big for the Wildcat 355 air cleaner top..

 

Got the new heads in the other day, they do look good. These are the TA Performance TRS/Rover heads, bare castings. The seats are thicker than I would have expected. I'm pretty sure you could drop in the valves from an iron head and use them if they are long enough in the stem, but there is still enough there to come out to the 2.02/1.60" spec on the webpage. I expect that would involve enlarging the throat as well if going for maximum flow. I don't know how many buyers of these heads are planning on using the smaller valves but I guess that's nit picking. You have a good range of choices. They are obviously set up for stud type rockers in pairs, as the studs don't appear to be exactly inline between the pushrod hole and the valve stem, however I haven't installed any parts to check that. In any case TA has rocker recommendations, a couple of which I think are LS type which should be fine. Those should be adjustable I believe. The spring pocket is also 1/4" larger in diameter, a nice improvement.

The next photo shows the Carillo and Pankl rods I picked up for about $85 a set. The big end has to be narrowed about .040" and a squirt hole added at the inside parting line.

Below that is a 340 crank with the mains cut down to .030" over the 300 journal size. The last photo is a second crank in the lathe to have the journals turned down. The rear seal area will also be turned to match the neoprene rear seals that will go in these two engines.

Both engines will get custom pistons with light weight wrist pins to keep reciprocating weight down. They will be essentially identical except for the rod manufacturer and the big end bearing size.

Jim

 

Very cool! So both of these engines will be 300 block based?

 

That's right Sean. Both will likely need pan spacers as well, probably like I made for my 340. It may make sense to work up a file so they can be waterjet cut.

 

Jim, Chris just needed washers between windage tray and ball peen dimples in shallow part of pan. He used the 350 capscrew rods. You will have more room with the shorter and sleeker rods you have.

 

Remember when you narrow the big end on the rods to try to maintain the sbb offset.

 

Torque the bolts and bore gauge them for roundness/size.

 

Derek, let's discuss this offset a bit. There are actually two to consider, a side offset between the rod's big and small end which I suppose I should measure though I don't think it would be very much, and piston offset which is used to reduce piston thrust. I'm actually not real sure how much good the rod offset does but I guess it might help reduce piston pin wear a little.

Chamfering the oil holes is a good idea, I had looked at that on the first crank, just hadn't done it yet. Main thing is just to bring it back to center though. On the mains that is easy enough to just eyeball it. Rod journals, somewhat trickier.

Jim

 

Steve Reynolds can sell you oil pan spacers. 1/4” alum

 

Hey Jim, sbb rods have a .060" offset from the big hole to the small hole. The extra material is on the chamfered side, if you don't maintain(or get as close as possible) the offset the small end of the rod won't be centered on the wristpin.

On the Carrillo rods, they are more than likely centered and if they are .900" wide all the material will need to be taken off of the non-chamfered side. So you end up with a .055" offset which is within .005" of the .060" factory offset.(probably way closer than what the factory tolerance was)

The Pankl rods may already have a .040" offset so material will need to be removed from both sides. If your Pankl rods are .900" wide you mathematically remove .020" off of the non-chamfered side then divide by 2 the remaining amount to be removed and remove that amount from both sides;

.900 - .845 = .055"

.055" - .020" = .035"

.035" / 2 = .0175" to be removed from the chamfered side.

.0175" + .020" = .0375" to be removed from the non chamfered side.

Fortunately the chamfer is WAY bigger than it needs to be so removing the .0175" from the chamfered side isn't enough to worry about.

To measure the offset of connecting rods, set up an indicator with enough travel to measure at least .100" to be setup on the large end with the small end held or bolted down to a 1-2-3 block. Try to zero it out on the low side then flip the small side on the 1-2-3 block and read the indicator for what the offset is on the big end.