A guide to building the lil guy. The Mighty 300

Cam bearings may be back in stock, I just bought a double groove front bearing listed for the 350 and will try it in the 340 as TA doesn't seem to have a listing for the 300/340.

I changed plans for the rockers. This was brought on by reports of failures in the roller bearings in the Procomp lifters caused by snap ring failures and I found that if you smack the shaft with a soft hammer the snap ring will usually snap out, so I decided to go with the 7/16" stud type roller rockers. I ordered a set of inexpensive Chevy trunion type rockers off ebay but felt the contact point on the valve was a little farther outboard than I was comfortable with given the lash caps and the bevel on the valve tips so I sent those back and ordered the TA rockers, I think the number was 1309D (trunion type, 1.6 ratio). Cost was twice as much at a bit under $300 the set but the rockers are stainless rather than aluminum. The fit is a little better but still a bit towards the outside of the valve tip. I think it'll be fine though.

I decided to use the Procomp rollers with the 340 which is getting some remedial work including new head gaskets and main seal work. It also will get a set of late Rover heads, I've cut the dishes deeper to match the Rover chamber size. The procomps can be matched to the Rover rocker shafts by removing the needle bearings and boring them out to the shaft size. That may include offsetting the bore a bit to better center the roller over the valve but I haven't decided on that yet.

The 340 will be getting a TA roller cam in the same grind as the 300 stroker. I did buy one of the V6 cam limiter plates to look at adapting it to the 340 block. When I order the cam I'll ask Tim if I can get it with the square shoulder, which would do away with the need to do machine work on a new and expensive roller cam.

I know the thread is for the 300 but the 340 is so similar that most of it carries over.

Jim

 

Here is a set of stock late Rover (4.0L/4.6L) heads fitted with the PAC-1276 LS drop-in beehive springs and custom modified CC retainers cut to an 11 degree keeper angle. Valves are stock. These will handle .550" of valve lift. Pockets were cut .050 and guides were cut .150" and there is a .015" steel shim under the springs. Spring pressures are about 350 open and 150 closed. The advantage of using these heads rather than the 300 alloy heads is that the chamber volume is the same as the TA-Rover heads so an upgrade is a simple head swap that retains the same compression ratio. Port flow appears to be pretty similar to the 300 alloy heads.

These will be going on my long rod 340 with a roller cam and roller rockers. It is essentially a spare engine at this point and may end up getting a custom underslung blower intake provided I have time enough to build it.

Jim

 

Has anybody had a 300-340 sonic tested to see what the average cylinder wall thickness is?

 

I have, and also bought a Chinese sonic tester which worked reasonably well. Wall thickness tends to approach 3/16" average but can vary quite a bit. Not at all unusual to see 1/8" on one side (hopefully opposite the thrust side). I'd try to avoid going under .100" after boring and honing in any event. I have heard of wall thicknesses as low as .060" but I really wouldn't trust that.

Jim

 

I'd like to use standard bore 3.8 pistons but they are .050 larger than standard 300 bore. Since forced induction is the plan a sonic test is going to be a must.

 

I would agree. Typically you can get by with a .030" overbore without worrying about it but for anything larger a sonic test is a really good idea. My 340 showed .116" @ .030" overbore. I went to .050" and ran 6psi of boost and never had any issues with it. I'm sure you could take that a little further but much more than that would be pushing it.

Jim

 

When I had my 300 block ultrasonic tested and bore .080" over the machinist said I had enough meat to go .120" over comfortably.

Core shift varies from block to block, but the 300's seem to be significantly thicker than the 350's.

 

I just bought a nice industrial ultrasonic tester so I can thoroughly test many points in all the cylinders. It was overly expensive either. Less than $300. Having one block sonic tested at the machine shop is $100.

 

What is the general opinion on the 300 block strength? I'd love to get one of those girdles for the mains like were made for the 350 engines a while back but that boat has sailed. Might have to contact www.sendcutsend.com and order a trial one. I'm not looking to set the world on fire but I'm betting the torque will be quite high at lower rpm under boost.

 

That's been my experience but I haven't dynoed any of my engines yet. The 340 is the same as the 300 but with bigger mains. I made stabilizer plates for that and the stroker 300's, the main intent being just to keep the caps from walking. 1/4" mild steel for the 340 and 11 ga. stainless for the 300's. No bridge across the caps. The bottom end of those blocks are near identical to the 350. I think until you get over something like 750 hp the girdle probably isn't necessary. I'm not pushing that much HP so I didn't bother with it.

Jim

 

i was talking to my machine about using/making 4 bolt main caps. was looking at the mopar 440 design. that would work on the 350 and others.
he said when the 440's get over 600hp, they replace the iron caps with aluminum. they found iron caps were no good after 600 hp.
i'm not a fan of girdles because they are not at the source of problems.

 

Just a heads up to guys looking for long tube headers for 64-67 cars with 300-340 engines. The Sanderson Shorty headers can easily be converted to long tube headers. They have done the hard part with the clearance near the ports and the thick heavy flanges. Once I finish my modifications to my headers I'll get a set and do a tutorial on how to turn them in to long tubes.

 

Long tubes are fine but you will get more out of them if you can make the tubes equal length,

Jim

 

Great thread. A little overwhelming at times with info. I've read through it a few times but then... squirrel.
I'm building a '64 300 to replace my '65 300 that I have in my '91 Toyota Pickup that I dropped it in about 13 years ago. It had about 80k when it when in and is a bit tired. I want to go with the '64 for the aluminum heads and intake for weight savings. However I do plan on making this a stroker as I have a good 350 crank just hanging around and yes just for the sake of making a stroker out of it. I plan on using the cam and lifters I had put in the '65 as it sounds great and is a good know set. Hydraulic cams and lifters are hit or miss these days and this set is obviously good. It is a Isky 270-HL-HYD. 270 duration, 109 lobe center with .470/.470 lift. I see a million options on this post for rods, pistons etc. I'm not going for crazy power here but don't want to waste time/money. While money isn't an issue for this build I just don't need to go crazy as I'm not looking for a particular HP goal. My machinist said it will probably be easiest to have a set a pistons made which I'm fine with. A few questions for some of you guys with experience with building a stroker with a 350 crank are:
Easiest rod to use? I know the stock ones need to be clearanced. Do that or use something else if we're doing custom pistons.
Larger valves for the '64 heads? Have V6 ones cut down or is there another option? Plan on doing just some mild porting/clean up and port matching.

I will be also be running fuel injection on a '64 4 barrel intake that I will machine to a single plane.
I guess I'm looking for a concise list to give my machinist of what one of you would do if you were to build this motor to save him from having to read through this whole thread /do a bunch of homework. He has read the Hot Rod article and the BritishV8 articles.
Hope this makes sense.
Sean

 

On Chris's Stroker we used the 73-80 350 capscrew rods. The only clearance issues were the windage tray dropped with washers and a little ball peen work in the front of the oil pan in the shallow part. Speed-Pro Hyper Ford 2.5 sohc 4 cylinder pistons which are 3.78 stock . 1.19 pin height and around 10.3 compression. Rods were bushed down to piston pin press fit with steel bushings. It's been running great for about 10 years now. I wanted larger valves like I did years ago. 1.74 IN and 1.5 EX from Ford 2.3 sohc 4 cylinder. Beehive springs from Alex's Parts. Budget constraints prevented that. He used 3.4 Chevy V6 valves cut down to be the biggest he could fit with stock seats. 1.69 IN and 1.39 EX. Z28 Chevy valve springs. Crower 50233 cam retarded 4 degrees.

 

You can also use later 3800 V6 supercharged pistons and bush the rods, About the same compression but floating pins. I was thinking of trying SBC 305 overbore pistons and 6" SBC rods modified to same thickness and offset as Buick rods but I like the long rods. Jim Blackwood used Nascar take out rods . He has all the specs for that.

 

Sean, I'd suggest you consider using the late Rover heads (4.0, 4.6L) as they flow nearly as well as the 300 alloys, are better castings, and are a more modern chamber design. They have the same volume as the TA/Rover heads which gives you the option of doing that upgrade later as well. For that you need a piston with a 35cc dish and zero deck.

More info is available here:

https://www.mgexp.com/forum/mg-engine-swaps-forum.40/comprehensive-300-buick-build-thread.4463289/

Jim

 

Also there is a new single plane coming available from Australia that looks good, has injector ports already as well:

https://www.mgexp.com/forum/mg-engine-swaps-forum.40/interest-for-the-willpower-intake.4339676/

There has been talk about it possibly being available through TA but IDK if that's gone anywhere yet.

Jim

 

Should you wish to go that far it's possible to build this engine with a roller cam and lifters making it compatible with modern oils. On my stroker I used the TA heads and roller with the stud type rockers then went further with beehive springs and titanium valves that I bought used and modified to fit. The Carillo rods I used were 6.2" ex-nascar off ebay for about $100. Used a somewhat smaller rod bearing and wrist pin but that also let me further reduce the reciprocating weight. Then the 26Lb TA flywheel is an especially nice touch to end up with a very free revving engine.

Jim

 

Thanks Jim. Going to keep the stock aluminum 300 heads as that's what I already have. Also going to keep the cam I had in my previous engine. It's already broken in with those lifters and is good. We stock oil with zinc so it isn't a problem. Again, not looking for power just a good runner using what I have.