Slant Six Build Ideas

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John Martin said:
I never said I was building the engine to the converter. I do realize that the way I’m building the engine will not be much over the original 110hp it was rated at. So with that being said, a high stall converter will take too much power to turn, before anything gets moving.
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IMO, you're lookin at this wrong. You should build the engine for TORQUE. That's where the 225's strong point is. It's ridiculously long stroke for an inline six lends it to some really great low end torque potential. I would try to design the build to have its maximum torque in the 2500 RPM range.

Also, you should keep that same thing in mind choosing a converter. Remember that converter technology is light years from where it was just ten years ago. you can have a converter that'll flash to 5,000 RPM, yet be tight enough to drive on the street everyday without slippage or extra heat buildup and get decent mileage, but flash to 5K when you hem it up for a launch.

Of course, we know you don't need or want a 5K converter. If it was ME, I would look at something like a tight "for a slant six" 3K converter. One that will flash to a MAXIMUM of 3,000 RPM on a hard launch. That's "only" about 1K RPM higher than a stock high stall and with a modern style converter would work very well for what you are wanting to do.

Have you made decisions regrading camshaft or gearing?
 
KosmicKuda said:
Ask 10 guys opinions and you'll get 20 answers.

So here goes. You say you want economy and it's for your parents. No use spending money on fancy stuff like sure grip and hi stall converter. My parents and millions of other parents drove these cars forever bone stock. You can improve on it though.

Charlie said a long time ago that there is no down side to increasing compression and it helps economy and power. So I milled my 225 block .080. (I wanted .100 but my machinist was against it so we compromised) You give some back because composite head gaskets are twice as thick as the original .020 steel.
100% rebuild, bored and honed professionally. I'd have to look but the machine work was 500 something.
Forged crank was checked and polished, no cutting.
Silv-o-lite pistons, King bearings, Hastings moly rings. I bought a kit and picked components eith my machinist.
Gave Oregon Cam a call, told them my intended use and specs and he recommended 2 grinds using my stock blank. I went with the milder because this is a driver afterall. Cost with shipping was 120.
Head rebuilt and had him put hardened exhaust seats in. (He was against that too) I pocket ported and gasket matched myself. Cost for the head work was 400 something.
He refaced my solid lifter rockers for $6 each. (He had a jig)
Installed Rolmaster roller timing chain and degreed cam.
Did a little intake porting and enlarged exhaust outlet before RRR made such a big deal about it.
Rebuilt original BBS Carter with a good kit from Daytona Carb.
Replaced the distributor drive gear myself and set endplay to specs using shims.
Checked oil pump to FSM specs and reused because of known drive gear problems. Also added a distributor drive gear oil squirter for same reason.
Installed brand new larger exhaust system. Going bigger in the future but this was a lucky swap meet find for only $40.
Painted engine red because 64 Valiants had red engines.

Close to 10,000 miles on rebuild finished 4 years ago. Have not changed plugs or points (dwell is still good) Driving to Carlisle I get 23-24 mpg at 65-70 mph on 87 octane. 3 speed manual and 3.23 7-1/4.
It scorched the quarter mile at 18.51
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Now that’s what I’m talking about. Unfortunately, I’m alone on the build as far as professional advice. Much like what you ran into my engine builder does not want to do anything to a slant six. He says, “it’s not a hot rod”.
 
though the guy doing my machine work didn't "laugh in my face" when I took him my slant, I could tell he wasn't "crazy" being that I was wanting something worked on that wasn't a V8. I told him not to laugh when I came in with it. He does do a bunch of 4 banger IH and JD tractor stuff, but most of those aren't there to be "built-up", just rebuilt to run.... When I dropped the heads off (took em 2, hoping at least 1 was usable, after I bowl-hogged them-- I figured I'd wrecked the 1st one) he gave me an "Oh, my GAWD, what happened to the BOWLS on this head"? and I took him the springs, OS valves and stem seals, and told him what I wanted.
A week later when I picked up the block crank and rods/pistons, and "settled up" to that point, I asked him about the heads, and he was in a better "mood" (for lack of a better way to put it) and showed me his progress from where I had left off and seemed a bit more ambitious about the build, and also said that once he had gotten into it, in his opinion I really hadn't done that bad, had more than a "good start" on porting the head I though sure was toast. In his estimation, I am adding "at least 20hp" by the porting job...... (his words, I never asked) just gotta get my replacement set of main bearings so I can get the bottom end wrapped up, and get him a "in the hole" measurement of the piston at TDC so we can figure out how much to shave.... and that the shave would be the last thing we do to that head.
I guess the fact that I kept checking up on him, brought the parts for it as asked for, (didnt keep him waiting) paid for work done "so far" and have been asking Qs along the way, he realized that "I'm serious" about getting this engine together.....
 
I think I will just ask for the machine work to be done and build it in my garage. So I will do .080” shaved off the block, mill the head flat, bore/hone the cylinders to clean up the block. I may as well ask for new cam bearings then.
 
Oh no doubt... Mine IS being "Built" in my home garage.... by nobody other than ME.
but I am having more machine work done to it than I have had done to the 1st 2 Slant engines I overhauled ~30 years ago..... 1st time asking for the block and head to be milled more than "just enough to assure a good seal".... (my block only took 6-thou for that to happen, I went 30-thou) 1st time porting a head, 1st time CC'ing one, 1st time I am dealing with O/S valves, on any engine I have built, V8s included.... I don't have a mill or a boring bar or the tools/fixture to press piston pins, or anything like that..... so I have to rely on a machine shop for all of that.

and most here will tell you not to shoot in the dark and guess how much to shave off block and/or head..... measure as you go or you might get to where it will not run on pump 87. Be careful there. myself I'm going for "all I can get" and still run pump 87. 89 and 92 are incrementally way too much more than what 87 costs now a days... IDK what ever happened to a 10 cent differential. Sometimes I see 60-cents more for premium vs 87.... for EVERY gallon, and that would be on EVERY fillup.. no thanks. I'd have to double power and MPG both, to make that worthwhile. having to run premium will make a 20MPG combo seem like a 13-14MPG combo if you "could have" run 87. Make sense?
though MPG isn't the end-all, cure all for me, I am going for the best I can get "for what it is"
I don't have an exact number yet// but between the block and head, I'm guessing I will wind up at around 80-thou shaved between the block and head combined but the actual number remains to be seen.

20-thou of milling will only put you back to stock compression because of the bigger thickness of any aftermarket head gasket you will find..... the original was a shim steel that was only 20-thou thick. most currently available head gaskets for a slant 6 are 2x that.
 
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John Martin said:
Sorry to start a new thread again, but I had to start over and ask my question again due to getting a rude answer the first time.

I want to build an economy slant six that is reliable and can be driven every day. The build will start with a 1972 225 slant six. The car it is going into has air conditioning and power steering.

My goals are to make up the power used to drive the accessories and to get about 20mpg. Car will be used mostly around town and I would like to use 3.23 gears. I was also thinking of installing a higher stall torque converter as well.

I am planning on a Melling oil pump, flow-kooler water pump, electronic ignition. I would like to keep it outwardly stock looking.

I would like to swap a camshaft. I was looking at AussieSpeed’s Evil Stick, Comp Cams, and Erson RV10.


Thanks in advance
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Well gosh and here I was giving you more good help in your new thread never realizing "I" was the one who made you go hide under the kitchen table. Sorry you got all hurt over something that was considered tongue in cheek like a bunch of guys sittin around a shop. Feel free to use any of my free advice, but I'll bow out since I'm not appreciated. Remember, not everybody is like you, everyone is different. Good luck with your build. It sounds like a good one. Just know, no one gets paid for years of experience and advice around here.
 
I edited my post because I had the head milled, not the block.

My machinist was an old timer who started in 1962. I picked my head up on Easter (5 yrs ago?) because his shop building was 10 steps from his house and he had no fixed hours. He worked on EVERYTHING. Car engines, motorcycle engines, fancy import engines, tractors, diesels, etc. He had honing plates for small and big block Mopars.
He said his son's first car was a slant six and they couldn't kill it. (They tried) We sat around for an hour when I picked up my head and we just talked about stuff. He said when Dyno Don was passing through he'd drop off heads to get them freshened up back in the day. My head was one of the last things he did as unfortunately he passed away suddenly less than 2 weeks later. I really should check to see if his son continued the business.

John, I document the engine build here if you're interested:
Not Fast, just "Less Slow"
I should probably update it.
 
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KosmicKuda said:
I edited my post because I had the head milled, not the block.

My machinist was an old timer who started in 1962. I picked my head up on Easter (5 yrs ago?) because his shop building was 10 steps from his house and he had no fixed hours. He worked on EVERYTHING. Car engines, motorcycle engines, fancy import engines, tractors, diesels, etc. He had honing plates for small and big block Mopars.
He said his son's first car was a slant six and they couldn't kill it. (They tried) We sat around for an hour when I picked up my head and we just talked about stuff. He said when Dyno Don was passing through he'd drop off heads to get them freshened up back in the day. My head was one of the last things he did as unfortunately he passed away suddenly less than 2 weeks later. I really should check to see if his son continued the business.

John, I document the engine build here if you're interested:
Not Fast, just "Less Slow"
I should probably update it.
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I will check it out.
I have heard of decking the block of an engine to sit flush with the top of the pistons at TDC is good way to improve performance.
 
John Martin said:
I have heard of decking the block of an engine to sit flush with the top of the pistons at TDC is good way to improve performance.
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Yeah but on a slant youll find the pistons are something like .16-.17 down in the hole. Too much to zero deck.
 
It's also a good idea to deck regardless, because Chrysler's machining tolerance were anything but accurate. Most times, the decks are tall as well as crooked, so it pays to have one decked, even if all you want it the stock height. The last slant six block I had decked, opposing corners were over .020" different from one another.
 
Bad news! The donor has turned out to be a Jasper short block with a cast crank! It has the 1972 intake, exhaust, head and oil pan, but the rest is not worth it now. I guess I will be using the 70 block, crank, and rods I had laying around.

New plan is to bore and hone for .030” to clean up the cylinders, add new bearings, and now to clean up the crankshaft in that block.
 
John Martin said:
Bad news! The donor has turned out to be a Jasper short block with a cast crank! It has the 1972 intake, exhaust, head and oil pan, but the rest is not worth it now. I guess I will be using the 70 block, crank, and rods I had laying around.

New plan is to bore and hone for .030” to clean up the cylinders, add new bearings, and now to clean up the crankshaft in that block.
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What issue do you have with the cast crank motor? The last years cast crankshafts are really light. I am using a last year 87 cast crank motor as the base for the performance slant in my 68 Barracuda.
 
my68barracuda said:
What issue do you have with the cast crank motor? The last years cast crankshafts are really light.
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I like the strength of the forged crank, its just a preference. Since it’s a Jasper engine it’s a hodge-podge of core parts.
 
So I have a Comp Cams High Energy 220/220 cam and lifters on the way. I would have bought an Erson RV10 cam but they gave me a runaround about gotta PO number to buy from them so I took my business else where.
 
John Martin said:
I like the strength of the forged crank, its just a preference. Since it’s a Jasper engine it’s a hodge-podge of core parts.
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The cast crank can handle 500 plus HP. I am actually LOOKING for a cast crank 225. I have a forged crank engine I'll swap you straight across.
 
John Martin said:
So I have a Comp Cams High Energy 220/220 cam and lifters on the way. I would have bought an Erson RV10 cam but they gave me a runaround about gotta PO number to buy from them so I took my business else where.
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You need to be really careful here. The Comp slant six camshafts have a bad reputation for chewing up camshaft gears.
 
KosmicKuda said:
Yeah but on a slant youll find the pistons are something like .16-.17 down in the hole. Too much to zero deck.
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Mine was .175" in the hole. This is the engine I put the head on that was milled .155" lol. Compression i still dang near 10:1 even with the pistons that far in the hole. lol
 
Yall, I think this guy has me on ignore. Will one of yall please tell him about the Comp camshaft gear problem please? The last thing I want to happen is for him to have a destroyed engine over his hurt feelins. Thanks.
 
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John Martin said:
So I have a Comp Cams High Energy 220/220 cam and lifters on the way. I would have bought an Erson RV10 cam but they gave me a runaround about gotta PO number to buy from them so I took my business else where.
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i would be careful with the comp cams in a slantie, they have a bad reputation for chewing up camshaft gears
 
diymirage said:
i would be careful with the comp cams in a slantie, they have a bad reputation for chewing up camshaft gears
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I will be getting it inspected by the engine builder I’m taking the head to. If he says it’s no good I will be returning it.
 
John Martin said:
Sorry to start a new thread again, but I had to start over and ask my question again due to getting a rude answer the first time.

I want to build an economy slant six that is reliable and can be driven every day. The build will start with a 1972 225 slant six. The car it is going into has air conditioning and power steering.

My goals are to make up the power used to drive the accessories and to get about 20mpg. Car will be used mostly around town and I would like to use 3.23 gears. I was also thinking of installing a higher stall torque converter as well.

I am planning on a Melling oil pump, flow-kooler water pump, electronic ignition. I would like to keep it outwardly stock looking.

I would like to swap a camshaft. I was looking at AussieSpeed’s Evil Stick, Comp Cams, and Erson RV10.


Thanks in advance
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So where or what is the question ?
 
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