Yup I got burned by the shorter replacement pistons thing. Had no idea til I measured once my short block was already back together. I took a wild ass guess as to how much to mill the block and with 0.030 off the block deck my pistons are still 0.180 down
... With an additional 0.070 off the head my engine measured out exactly 8.4:1 when done. Exactly blueprint spec. I was hoping at the time that with making 0.100" of cast iron dust by milling that it would get me to 9:1 or even slightly more. Goes to show how dismal it would have been if id have just bolted it together without any milling.
I have a long drawn out thread about my build in here somewhere from about 4 years ago
mine is also a forged crank block but with a newer peanut plug head so I could eliminate 6 potential oil leaks ( o rings on spark plug tubes) my build is also in a 1/2 ton truck, I built with very similar goals as you appear to want

The 225-1 and 225-2 HD and XHD truck engines, put into much heavier-duty service than the industrial/agricultural applications, had shot-peened cranks and other upgrades. Valve seat inserts weren't on the list. Here're the '66, '70, '74, '75, and '78 225-1 and 225-2 upgrades:

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Here's another vote for the OCG 2106R cam. I have it in a very similar truck, an 82 D150 with 833OD, 3.55 gears and 29" tires. I shaved the head .060. added oversize valves, and had a mild cleanup done on it. Offy 4-barrel intake with an AVS2 500 on it, Clifford shorties to a single 2.5" exhaust all the way out. IIRC compression is about 8.4 static, 7.8 dynamic.

This combo is surprisingly strong. If I stick my foot in it the truck can easily get a move on. Driving it mildly is just as good. It pulls from idle to about 4500 which is as far as I'm ever likely to spin it. At 75 MPH I'm turning a little over 2200 RPM, just where I wanted it. YMMV of course, but this truck is a hoot to drive now.

I took a bit of a hiatus from the slant project to get the property and equipment winterized, but it's time to get back to work on the mean green leaning tower of power machine. I'm working on my shopping list for what I'll need for machining and reassembly.

Is Hughes' Engine the best source for the O/S valves? Seems like ENGNBLDR is out of the game. The camshaft will be from Oregon, of course.
Is there a preferred place to buy all the other stuff (pistons, lifters, valve seals, etc) from or does it matter much? I'm thinking I'll see what the machine shop has to offer and probably go with that.

I'm not opposed to spending money, but I do like to save where I can, are there any components I can confidently reuse? I know to reuse my crank, connecting rods, and rockers, but what about other stuff (lifters, bearings, etc). Also with taking material out of the deck should I be looking at shorter pushrods, with the RV10 cam should I be looking at different valve springs?

I'm going to start measuring bearing surface tolerances, I'm very much hoping that my crank is still within spec. From what I've interpreted from my FSM, connecting rod tolerances should be 0.0005" - 0.0015" and main bearing tolerances should be close to, but not exceeding 0.001", do those numbers seem correct?

I've also decided to try my hand at some mild porting, which is probably going to look more like polishing than actual porting. Is there really any need to go bananas on porting for an engine that's mostly just going to be a road trip rig? I see no racing in this truck's future so I would imagine increasing air velocity at cruise RPM would be more of a priority than maximizing the maximum airflow capacity.

If I were to go cheaper on valves, I would get 283 chevy intakes (1.72") and I believe 289 Ford exhausts (1.46"). You can these pretty cheap in stainless steel, which is definitely what you want to avoid valve recession without using hardened exh seats. Stock replacement valve springs will work with that cam, but you should get the springs you have checked to make sure they are not worn out. I have no experience with Hughes.

You can go to at least 0.002" (yes, you read that right) on the main and rod bearing clearances, and in fact I run more than 0.0015" when I get cranks machined for all my motors. My bet is your crank is fine if you have never spun a bearing. You can send youf lifters to Oregon for refacing, but they cannot be used on a new or reground cam or you will ruin the cam.

Porting will get you the biggest power gains, from idle all the way up. You will lose nothing down low on a 225, even if you port the max. Just removing material around/behind the valve seats is the biggest gain. Just be careful not to remove too much material between the int and exh ports on the same cylinder, about 1/2" in back of the valves. I'd say 1/16" fine off each surface but not much more. There's a thin spot there where there's a waterjacket. Mostly, it's paring back the big casting junk restrictions 1/4"-3/8" behind the valve seats. You want torque, and this will get you plenty more. Just clean up the casting flash in the main ports and work on the valve guide boss so it looks more tapered into the valve stem.

Can talk more, but this is a start.

Lou

_________________
Home of Slant6-powered fun machines since 1988

I just put a engine together for my truck and all of my clearances were .0023-.0028. I just looked at the race engine that I had built years ago and they were all in the .0020-.0028 range.

A 1/2 thousands is a mighty tight clearance in my mind. I for sure would spin a bearing! I'm sure new modern up to date equipment is capable of holding those tolerances in the factory. We don't have that luxury out here in the Slant 6 world where I live!

_________________
2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Don't forget push-rod length when cutting substantial amounts off the deck and/or head. It may be necessary to have custom pushrods to allow for proper adjustment and geometry.

CJ

_________________
Part of Tyrde-Browne Racing

With what you're talking about there should be more than enough adjustments in the valve train without custom length pushrods.
"Stroker scamp" (rarely on here) aka "rusty rat rod" on FABO has one he cut the head like 0.175" (not a misprint) and has a much more radical cam and he talks often about not having to get custom pushrods. He practically lives at the FABO site.

I have cut many heads, and you can open up the rockers enough with that kind of cut, BUT if you street drive it much the rockers will be beyond their "tight" range and loosen up and you will drop/bend pushrods. You might get around this with rocker locknuts, but I have always done pushrods. Best to figure out how much you want to mill, then decide on the pushrods. Anything up to about 0.100" head/block mill will likely be fine. Also, if you have a regrind cam, that usually gets ground on the back side of the lobe some, so that will offset the milling by a little at least.

Lou

_________________
Home of Slant6-powered fun machines since 1988

I'm hoping to start porting tomorrow. I took a look at the head to come up with a plan of attack but it's left me a bit confused, either I'm missing something or Mopar created this head to flow the least amount of air possible. In the following responses are pictures I took of an intake and exhaust valve seat, as well as highlighted copies detailing what I think should be removed. If my understanding of porting principles is correct, that means I need to remove the acre of metal highlighted in red without touching the area highlighted in green. Is this correct? I almost can't fathom having to remove that much material.

Additionally, the valves seem very very close to the edge of the combustion chamber. I will be installing oversized valves (some of the existing seats have been compromised due to corrosion) but will they even fit? seems like a mighty tight fit.

Back to porting. I'm planning on porting in the bowl area and only polishing up the rest of the runner. I'd really prefer to not cut into a coolant passageway or mess up something with the valve guide. Is there enough material in the bowl area for some "spirited" porting, anything I should watch out for around the area of the valve stem?

Yes, the casting vs. machining around the bowl and valve entry is often terrible. In short, you can remove the red parts. You can get the seats rough cut for the new OS valves first before you port, but it's not necessary. If you wait to cut the seats and do porting first, it might actually be a nice limiter for your porting in the red area. You will gain a lot of HP and torque and lose nothing. What OS valve sizes? Yes, you have room for a lot more than stock and there is plenty of lateral room, although you need to worry about cylinder bores too. What bore size will you have on this engine? 1.70/1.44 are usually economical (if there is still a supplier), fit stock bore, and flow well. 1.72/1.50 SB chevy are also pretty easy to get but need 0.060" overbore to give the exh clearance to the bore or a ground out bore notch. Make sure to get stainless valves and then you don't need hardened seats. Look for 283 Chevy. You don't need to do much but smooth the port. You can take off quite a bit around the guides too to smooth the air path. Make sure NOT to do a lot between each pair of int and exh ports as there is a thin spot in the water jacket casting there.

I can talk more, but need to sign off now...

Lou

_________________
Home of Slant6-powered fun machines since 1988

I'm well under way in porting+polishing, all that's left now is some polishing. I'm hoping to use the 1.70/1.44 valves from Hughes' engine. I'm glad I waited to get the new seats cut, I ended up slightly nicking every single seat. I may still get the new size rough cut so I can do a final round to get the seat area perfect. I did also put a decent gouge in the edge of one of the combustion chambers, I wasn't being careful enough about the angle of my sanding disc while polishing. The gouge is around 0.030" deep, a decent amount, but hopefully that will get eaten away during the milling process (I'm expecting to take about 0.070 to 0.100 total off of the head and deck). Unfortunately for me, my local Canadian Tire doesn't carry a bit that's suitable for polishing that hill area in the combustion chamber, the spark plug opening, or the runner area, so I'll need to look elsewhere for an appropriate bit in order to finish this up.
After I'm done this I'll be checking the tolerances of the bottom end then it should be ready for machining.

I had a few other thoughts while immersed in the lull of porting. Are there any advantages at all to polishing the connecting rods, crankshaft counterweights, and block walls? I've seen people do this with the claim of increasing oil drainback or helping the rotating assembly "cut through" oil in the pan.
Also, are crank scrapers a good idea? I've seen a few people mention them on the forum before. I've also heard that the camshaft relies on oil being flung up to it from the crankshaft for lubrication, which I crank scrapper would naturally block.

I like the concept of removing as much parasitic loss as possible, but do any of those thoughts translate to good ideas in an engine that sees daily-driver conditions?

Looking good. Don't get too close to the seats when grinding because you need a little metal for heat conduction away from the seats. Yes, good you waited before getting seats enlarged. You can touch them up, or just go with it. You will get substantial gains either way.

Lou

_________________
Home of Slant6-powered fun machines since 1988