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Performance 300 Build

43K views 108 replies 23 participants last post by  Scoop 
#1 ·
Hi all,

After having my Bronco for a good 10 years or so, I figure it's time to actually build myself an engine for it.

I originally planned to rebuild my engine about 3 years ago. I pulled the original engine out (at least, I think it was the original), only to find that it was already bored 30 over. I took the block down to the machine shop and they said that it was so worn out that boring 60 over wasn't enough to clean it up and the block was shot unless I wanted to pay to resleeve it. I figured I'd just find another block and took that one to the scrap yard. It does beg the question how many miles are on my Bronco though. The engine had already been rebuilt and then worn out to the point where it couldn't be rebuilt again. These engines are known for going 300,000 miles or more...

Either way, before I found another block, I lost my job and decided to go back to school for a second degree. After two grueling years, I
graduated last May. So now that I'm back working, firmly established, and moving forward, it's time to build my engine. :thumbup My Bronco's served me faithfully for 75,000 miles through thick and thin, so it deserves it.

I drive it everywhere, every day, to work and back, and out in the mountains to play, so I am keeping that in mind in my build.

I'd like to hit around 9:1 compression (nothing extreme so I can still use regular pump gas), a performance camshaft, larger valves in the head, some port and polishing. I already have a 4bbl carburetor and a good exhaust system, so that should already be good to go. I'd love to hit around ~200hp, ~350tq.
 
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#2 ·
Here's the engine I started with. I bought it off of Craigslist for about $50 (delivered!) several years ago to drop in my Bronco when I pulled the original engine. It drove really well, had good compression, but was horribly noisy. When I bought a parts truck for my NP-435 swap, I dropped that engine in my Bronco (which is in there now) and pulled this one out. I pulled it half way apart to see what was wrong with it, but never found anything. Unfortunately, I got careless with it and left it outside for about a year with no head on it, so it rusted up a bit.





The flywheel is in good shape but rusted. I put a new clutch/flywheel/pressure plate in with the current engine so I may just resurface this one and stash it away.



I do NOT want to forget this when I put it back together! Been there, done that, it sucks.



Forgot it had oil in it, so I had a mess to clean up when I flipped it over:









Despite some rust, the engine turned over really easily. The bearings were nice and silver underneath, and everything looked clean.





For some reason, Supermotors doesn't keep picture orientation any more, so all of my pictures are landscape.
Either way, a 300 crank is extremely heavy.







A couple of the rod bearings were a little worn, but not too bad.



There was very little to no taper on the cylinders, so the pistons popped right out. I was relieved since the last time I removed the pistons from the previous engine, there was so much taper that it took a few hours to get the pistons out. This was about 5 - 10 minutes.



(The oil is from flipping it over)






 
#3 ·
Heard from the machinist yesterday. The crank was reground and cleaned up at 0.010/0.010. The block was in good shape and the cylinders cleaned up at 0.030 over. So it's all good to go to move forward.

So with 4.030" cylinders, I'll have a 304.6ci / 4.99L.

Close enough to be a true 5L. :D
 
#4 ·
1 HP per cube is very reasonable on a good build. There are several six cylinder racing sites out there, I have seen 300 sixes do 9 second quarter mile runs so a streatable one is within reason. You can get away with 9.5 to 10:1 with good fuel, port and polish the ports and polish/ CC the chambers. Stainless back cut valves with reduced stems will help with flow. The most gains will be found in the head work.Clifford Performance makes stroker kits up above 500 CI.
 
#6 ·
I figured you'd be along shortly. :D :beer

445 FE Bronco said:
1 HP per cube is very reasonable on a good build. There are several six cylinder racing sites out there, I have seen 300 sixes do 9 second quarter mile runs so a streatable one is within reason. You can get away with 9.5 to 10:1 with good fuel, port and polish the ports and polish/ CC the chambers. Stainless back cut valves with reduced stems will help with flow. The most gains will be found in the head work.Clifford Performance makes stroker kits up above 500 CI.
I didn't figure 200hp would be very difficult to reach. It's a big engine, and was severally underpowered from the factory. I'd thought about going for more, but I also enjoy my 15 - 17mpg and don't want to eat into that too much. I figure with a healthy engine (my current compression is around 120) and a medium build, I'll have a dependable engine that I really enjoy driving, and still does well on the gas.

Otherwise, I'd love to go all out. I've seen some pretty serious numbers being put out by this engine, but my wallet just isn't that big. :toothless

Most of my work will definitely be in the head. It's the bottleneck of this engine. Just need to get it to breath!
 
#7 ·
#8 ·
Hey AB,

congrats on shifting career gears successfully!
Thanks! I owe so much of it to my wife. She encouraged me to do it, and then supported me the whole way through.


If you want a good reference, have a look at this Engine Power series on building a performance Ford Inline 6.

part 1
http://www.powernationtv.com/episode/EP2014-03/part-1-building-an-old-skool-six

part 2
http://www.powernationtv.com/episode/EP2014-04/hopping-up-an-old-skool-six-part-2
Thanks for those videos! I'm going to sit and watch them. They look great.
 
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#9 ·
Definitely following this. Almost considered building an EFI straight to put in place of my 302. Can't wait to see how it turns out.
 
#10 ·
I love that show. Many people forget that all their episodes for as long as they have been on TV in which ever show they were called at the time are all available for viewing online. I go back and watch them all the time. Lots of good information shed in those videos.
 
#12 ·
With the current setup (old stock engine, 4bbl intake, exhaust, performance ignition) it already hauls! And that's with a 3.00 rear end and 32" tires. I drive on the interstate every day and generally leave everyone behind when getting on the on-ramp. :thumbup
They're a good engine. Ford just really under carb'd them.
With a full build, it should leave nothing to be desired.
 
#14 ·
The build in those 2 videos came up to 205hp and 307 ft lbs of Torque. Plus all the extra machining work they did made it stronger and more dependable. I really like that build they did. If I still had my I-6 F150, I would have done the exact same build.
 
#16 ·
YouTube the "Frenchtown Flyer". He is a retired Ford engineer that drag races the 300 six, albeit with a factory crossflow head that was never " released" to the public.

AB, can't wait to see how this goes. Closer to a 5.0 than the 302 lol :goodfinge
 
#17 ·
Hey @AbandonedBronco, you're going to LOVE it .30 over. I had thought we the exact engine build before and for some reason I had thought yours was already bored over like mine. I cant wait to keep watching this build!

Just as an idea.. I had some road rage yesterday and dropped the clutch in first (t-19 tranny though) with the same engine, factory 3.50 gears and 35's and i broke both tires loose:thumbup

Here's a quick exhaust clip
 
#19 ·
Hey @AbandonedBronco, you're going to LOVE it .30 over. I had thought we the exact engine build before and for some reason I had thought yours was already bored over like mine. I cant wait to keep watching this build!

Just as an idea.. I had some road rage yesterday and dropped the clutch in first (t-19 tranny though) with the same engine, factory 3.50 gears and 35's and i broke both tires loose:thumbup

Here's a quick exhaust clip
https://www.youtube.com/watch?v=bQMFbuJtCE4
With as much as I've done, I've still only had a stock engine. Which is cool, because it shows how capable they are in stock form with just bolt ons. But man, I can't wait to see how it'll do with all the goodies on the inside. I probably won't be able to tell the difference with the 30 over with all the other stuff that's going on (head, valves, cam, etc.) but it's sweet to know it's there. :thumbup

That sounds really good!
 
#20 · (Edited)
Update:

Went over to the machinist this morning and spoke with him.
Also, took some pics of the current progress. It's been bored out, but not honed yet. He also said the center line was in spec.









The rods were out of round so they need to be reconditioned. I'd love to go with some forged rods, but for what I'm doing, I don't think what I'm doing necessitates tracking some down.

Otherwise, I was discussing the head. He said he actually recommended the head with the pressed in studs vs. the newer pedestal rockers. He said since I'm using an aftermarket cam, shaved head and/or block, etc. with different dimensions than stock, it would allow a lot greater control over valve adjustment. The pedestal rockers would need shims, which aren't as easy to deal with.

Thoughts on this? I like the design of the pedestal rockers. First, they're bolt-in, so they seem stronger. And second, their motion seems so much smoother. I remember reading multiple times that the older style was prone to stress and cracking.

As for Port and Polishing, he said it generally runs around $600, which seemed a tad high. However, it seems like they do some quality stuff, as they provide flow rate data when they're done.

Next step is to bring a head down as he wants to measure it and see how much to shave/deck to get the preferred compression ratio.

Moving forward!
 
#23 ·
AB the p&p at 600 is probably includes putting the head on a flowbench and matching each runner and valve to be as close in flow as the rest. Haven't been over to my "head and gear" guy in a while but he always gave me good prices because he was a retired engineer and just did it to support his drag racing hobby. Did the p&p include a valve job of at least 3 angles? That would sound more in line with the price as well as a bath in the hot tank.
 
#24 ·
Yeah, he said it came with a flow rate print out when done, so it's going to be more than someone just going in with a grinder and making it look good. This place generally works on race engines, so I imagine they don't screw around.

I am not sure what all is included in the price. It was more of a "how much does a port and polish job usually cost?" "Oh, around $600" while we were discussing a few other things this morning.

I figured I'd get better details when I go in for it. I know the head isn't going to be cheap, but it's the bottle neck of this engine so it needs to be done if the rest of it is going to shine.
 
#27 ·
He said I should be good with pressed in studs since I'm not doing anything crazy like an extreme cam or really changing the valve geometry a lot. However, I'd like to allow this to rev to 5000 - 5500 or so safely, so I may go with the screw-in stud route just for durability.
 
#29 ·
Following with great interest. Thanks to everyone for sharing their experiences with these motors. Keep up the good work!
 
#30 · (Edited)
Alright, spoke with him again this morning when I dropped of my head. He said it was $125 to convert it to screw in studs. sold. Then about $40 for ARP studs. He had some V8 heads he had just done the day before and they looked great.

He's also looking into some larger valves. SI used to regularly have some available but I can't seem to track them down. He's an SI dealer, so he should have a better know how of how to get them.

Intake: Stock: 1.78" Oversized: 1.94"
Exhaust: Stock: 1.56" Oversized: 1.70"





The crank is ground (0.010/0.010) and looks good.
Took some pics, but they didn't turn out very well.

Still, the crank looked great.

He has the head right now so he can accurately measure the cc of each chamber. Then we'll pick out some pistons and calculate the compression ratio.
Every time I pick up a 300 head, I am blown away by just how ridiculously heavy they are.
 
#32 ·
Yeah, I'm sure there are plenty out there. S.I. simply made one specifically for this head/engine, so I was hoping to search them out first.

Otherwise, the stock is:

Intake:
Head: 1.780"
Stem: 0.3419"
Length: 4.81"

Exhaust:
Head: 1.559"
Stem: 0.3419"
Length: 4.81"

So I'm sure I could easily find some that just fit those dimensions.
 
#34 ·
Alright,
Got some information from the builder this morning. He measured the engine and got some real numbers. These are with Silvolite 3118H Pistons.

He's having issues finding anything much more than stock replacement. Thoughts on pistons?

These are his calculations:
Machine 021 off the Deck: 8.4 to 1 compression
Machine Head to 70cc chambers: 8.7 to 1 compression
Zero deck block with 70cc head chambers: 8.8 to 1 compression

Base Engine Inputs
Bore - 4.03
Stroke - 3.98
Rod Length - 6.208
Deck Height - 10

Chamber/Piston Inputs
Chamber CCs in Head - 74.4
Piston Design - Dish Top
Piston Dish ccs - 25
Gasket Thickness - 0.048"
Gasket Bore Dia. - 4.17"
Deck Height Clearance - 0.026"
Piston Ring Depth - 0.266"
Piston Top O.D. - 3.985"
Compression Height. - 1.778"

Calculated Results
Cylinder Size - 50.77 cu.in. - 832.1 CCs - 0.832 L
Engine Size - 304.6 cu.in. - 4992.5 CCs - 4.992 L
Chamber Size - 7.13 cu.in. - 116.8 CCs - 0.117 L
Compression Ratio: - 8.12
Dyn. Comp. Ratio - N/A
Cranking Pressure PSI - N/A
Bore/Stroke Ratio - 1.013
Rod/Stroke Ratio - 1.559
Quench - 0.074

Volume Contributions
Head Chamber - 4.539 cu.in. - 74.4 CCs - 63.7% of Total
Gasket - 0.656 cu.in. - 10.74 CCs - 9.2% of Total
Deck - 0.332 cu.in. - 5.44 CCs - 4.7% of Total
Piston Dish - 1.525 cu.in. - 25 CCs - 21.4% of Total
Piston O.D. - 0.075 cu.in. - 1.24 CCs - 1.1% of Total
 
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