pump gas build

-

beebeeri000

Rest-O-Moder
Joined
May 25, 2014
Messages
320
Reaction score
2
Location
Vancouver, WA
i was wondering if i could get a little guidance on a pump gas build. im starting of with my '73 225 block crank and head and i was thinking about going with stock connecting rods with flat top pistons and a cam from oregon cam grinders with 234/228 @ .050”, 262/252 adv, .476”/.479” lift, 108 lobe separation. this will be my first time building a slant so i would appreciate any advice. ive also been curious about shaving the block and/or head but i dont wanna increase my compression too much and like most stuff i cant find consistent numbers.
 
i was wondering if i could get a little guidance on a pump gas build. im starting of with my '73 225 block crank and head and i was thinking about going with stock connecting rods with flat top pistons and a cam from oregon cam grinders with 234/228 @ .050”, 262/252 adv, .476”/.479” lift, 108 lobe separation. this will be my first time building a slant so i would appreciate any advice. ive also been curious about shaving the block and/or head but i dont wanna increase my compression too much and like most stuff i cant find consistent numbers.
You don't "find consistent numbers". You have to "measure" what you actually have. "Most times" the slant 6.....and really all of Chrysler's engines of that era fall dismally short of their advertised compression ratios. Usually the slant 6 is down in the 7s. This is because of deck heights taller than spec, combustion chambers bigger than spec. It's just a reality of how they did things. So the best thing is to get it to a competent machine shop and let them inspect and measure everything and go from there.

"All that said" generally speaking the "obligatory" amount to mill the block and or head, is .100". This will generally get compression touching 9:1. But again, measure first.

If it was me, I'd take it off the block, and just have the head lightly milled to clean it up. But you NEED to measure to see where you are first. Hope that helps.
 
Last edited:
i was wondering if i could get a little guidance on a pump gas build. im starting of with my '73 225 block crank and head and i was thinking about going with stock connecting rods with flat top pistons and a cam from oregon cam grinders with 234/228 @ .050”, 262/252 adv, .476”/.479” lift, 108 lobe separation. this will be my first time building a slant so i would appreciate any advice. ive also been curious about shaving the block and/or head but i dont wanna increase my compression too much and like most stuff i cant find consistent numbers.
On the slant in my 83 D150 I cut .047 on the head and did a light clean up cut on the block to get to my target static compression of 8.5
What I did was get the block work done first, cylinders bored, light clean up on the top deck, then installed the crank and 1 and 6 pistons-rods and got the piston recession numbers. Then put that into an on line compression calculator to figure out exactly how much had to be cut on the head to get to my target compression ratio.
You will need to cc the head so you know how big the chambers are, there is a formula,, each .0699 cut from the cylinder head deck removes one cc from the combustion chamber.
KB - Silvolite has a good compression calculator on their web site, so does RB Racing
And when you mention pump gas, are you wanting to run regular or are you OK with Premium?
 
Street or race engine?

I took .080 off my 225 head with a milder Oregon regrind and it runs great on 87 octane. .04 head gasket instead of .02 steel. Street cruiser. Charlie told me there was no down side to increasing compression on a slant.
 
The cam specs you provided seem a little odd. Adv & 050 numbers seem too close.
 
The cam specs you provided seem a little odd. Adv & 050 numbers seem too close.
It appears to be one of those "reverse" grind specials Dutra came up with years ago. Funny thing is, I believe even he admitted later on there were no gains. I know there have been dyno tests that prove there's no advantage.
 
The cam specs you provided seem a little odd. Adv & 050 numbers seem too close.
Thought the same thing, 282/272 would be what I'd expect, unless OCG is using a high tappet-lift reference...don't have the lobe-list handy..
 
It appears to be one of those "reverse" grind specials Dutra came up with years ago. Funny thing is, I believe even he admitted later on there were no gains. I know there have been dyno tests that prove there's no advantage.

And all the simulations I did with Doug a few years ago showed the same thing, no real advantage.

I decked the block 0.60, stock Sealed Power Pistons, took 0.010 off the head to true it up and an OEM steel gasket which gave me 8.8:1. The Oregon Cams 2106 is the best cam if you never plan on reving it more than 3500 RPM and the 819 is the best cam if you want to take away little low end and move it up to 4500. I went with the 2106. Timing is 20 degrees initial and 30 degrees all in. It runs great on any gas you feed it.

Jim
 
Last edited:
And all the simulations I did with Doug a few years ago showed the same thing, no real advantage.

I decked the block 0.60, stock Sealed Power Pistons, took 0.010 off the head to true it up and an OEM steel gasket which gave me 8.8:1. The Oregon Cams 2106 is the best cam if you never plan on reving it more than 3500 RPM and the 816 is the best cam if you want to take away little low end and move it up to 4500. I went with the 2106. Timing is 20 degrees initial and 30 degrees all in. It runs great on any gas you feed it.

Jim

Yes sir. I remember reading some about it.....and to be CLEAR, I'm not knockin anything Doug has done. That's the only way to find out is to try it. He's probably had more failures trying different things than people will ever have builds. But that's how you learn what works and what doesn't. I would say Doug is a great innovator for sure.

How is he doing since the fire at his place? I understand it was pretty devastating for him.
 
Last edited:
Yes sir. I remember reading some about it.....and to be CLEAR, I'm not knockin anything Doug has done. That's the only way to find out is to try it. He's probably had more failures trying different things than people will have have builds. But that's how you learn what works and what doesn't. I would say Doug is a great innovator for sure.

How is he doing since the fire at his place? I understand it was pretty devastating for him.

After getting to know him before the fire he was absolutely an experimenter. He liked that I could simulate different grinds and he gave me some of his not so great grinds to see if the model predicted failure (it did). He was not afraid to experiment. I have not heard from him since the fire. Wish we could have made the cam we had settled on. I would not have done you any good as it was aimed at people like me that run 2500-3000 max most of the time and targeted the most torque we could muster under 2500 RPM.
 
After getting to know him before the fire he was absolutely an experimenter. He liked that I could simulate different grinds and he gave me some of his not so great grinds to see if the model predicted failure (it did). He was not afraid to experiment. I have not heard from him since the fire. Wish we could have made the cam we had settled on. I would not have done you any good as it was aimed at people like me that run 2500-3000 max most of the time and targeted the most torque we could muster under 2500 RPM.
Yeah, I've always liked my engines a little lumpy. lol You kinda have to give a few things up for that. LOL
 
Now that I look at OGC the 817 is close to what we were thinking our cam would be... 108 LCA with about 198 intake duration and 226 exhaust gave us the most torque under 3000RPM... would like to try that cam now :)
 
And all the simulations I did with Doug a few years ago showed the same thing, no real advantage.

I decked the block 0.60, stock Sealed Power Pistons, took 0.010 off the head to true it up and an OEM steel gasket which gave me 8.8:1. The Oregon Cams 2106 is the best cam if you never plan on reving it more than 3500 RPM and the 819 is the best cam if you want to take away little low end and move it up to 4500. I went with the 2106. Timing is 20 degrees initial and 30 degrees all in. It runs great on any gas you feed it.

Jim
Just how much will a 819 soften the bottom end as compared to a 2106? Maybe I should have gone 2106? I picked the 819 after talking to several people about their builds, though it seems as many people have picked one of those cams as have chosen the other? Mine is gonna be ~8.7-8.8 ish CR in a daily driven D150 with 3.21s
The machine work is done, just gotta CC the heads to verify that I got what I thought I got from the machine shop.
 
i was wondering if i could get a little guidance on a pump gas build. im starting of with my '73 225 block crank and head and i was thinking about going with stock connecting rods with flat top pistons and a cam from oregon cam grinders with 234/228 @ .050”, 262/252 adv, .476”/.479” lift, 108 lobe separation. this will be my first time building a slant so i would appreciate any advice. ive also been curious about shaving the block and/or head but i dont wanna increase my compression too much and like most stuff i cant find consistent numbers.
Call Randy McDowell in ashland Ky. He can tell you exactly what you need to do. He is the best. POWER TECH RACING ENGINES 606 928 3950
 
Just how much will a 819 soften the bottom end as compared to a 2106? Maybe I should have gone 2106? I picked the 819 after talking to several people about their builds, though it seems as many people have picked one of those cams as have chosen the other? Mine is gonna be ~8.7-8.8 ish CR in a daily driven D150 with 3.21s
The machine work is done, just gotta CC the heads to verify that I got what I thought I got from the machine shop.

not significantly, maybe enough you would notice in the real world , maybe.
 
thats just one of the cams i was recommended but its been so long i forgot why i was even looking into it, the only thing im really set on is building it to run on pump gas so i can gas up at just about where ever i go.
 
If that's all you want why not leave it stock?
Stock runs on pump gas.
 
Had my fun with a stock engine now I wanna do something else than stock if I had the money I'd boost it

2016:
210/214 @ .050”, 254/254 adv, .434”/.444” lift, 108 sep

819:
219/219 @ .050", 264/264 adv, .437"/.437" lift, 110 lobe sep,

Yours:
234/228 @ .050”, 262/252 adv, .476”/.479” lift, 108 lobe separation

Based on Doug's measured data the 0.444 is more lift than the stock valve can take and if you install larger valves like I did it is just about the optimal lift, any more and you are just hammering the valve train for no real gains. The 110 lobe separation on the 819 is what moves the power band a bit higher in the RPM range and the longer duration of the cam you are looking at does the same but a bit more than the 819 even with the 108 separation.

With the 0.060 off the block, oversized valves (which actually allows the 2016 to keep a similar upper end to the 819 if I recall correctly), 2106, Dutra Duals with the "Y" behind the transmission cross over for peak scavenging at 2500RPM and dual 1 barrels (don't over carb it for low end torque) or a super 6 two barrel I smile and giggle every time I drive the wife Dart. It sound really unique and is a blast to drive around. So much different than the worn out 225 that could barely get out of its own way before we started the project.
 
2016:
210/214 @ .050”, 254/254 adv, .434”/.444” lift, 108 sep

819:
219/219 @ .050", 264/264 adv, .437"/.437" lift, 110 lobe sep,

Yours:
234/228 @ .050”, 262/252 adv, .476”/.479” lift, 108 lobe separation

Based on Doug's measured data the 0.444 is more lift than the stock valve can take and if you install larger valves like I did it is just about the optimal lift, any more and you are just hammering the valve train for no real gains. The 110 lobe separation on the 819 is what moves the power band a bit higher in the RPM range and the longer duration of the cam you are looking at does the same but a bit more than the 819 even with the 108 separation.

With the 0.060 off the block, oversized valves (which actually allows the 2016 to keep a similar upper end to the 819 if I recall correctly), 2106, Dutra Duals with the "Y" behind the transmission cross over for peak scavenging at 2500RPM and dual 1 barrels (don't over carb it for low end torque) or a super 6 two barrel I smile and giggle every time I drive the wife Dart. It sound really unique and is a blast to drive around. So much different than the worn out 225 that could barely get out of its own way before we started the project.

ok ill look into that i forgot to mention that i got a 2bbl intake that im running right now and a set of clifford headers that i was going to y together to a single exit. do you got any recommendations on what valves i should go with?
 
before i order from them would a cam of your size require spring upgrades?

I think he put 340 springs in it.... I think.... I let him do it. When he did the seats and valves he made all the measurements to select the right parts. 0.444 lift is not enough to need anything special. Go on the For B Body Only site and PM 69Bee. He is the machinist that does all my engines.
 
I just got my slant sorted out. It's in an 82 D150, stock bottom end .030 over. The head got oversize valves, a mild bowl cleanup, and shaved to get 8.5 static compression. 2106R cam from OCG. Clifford 4-bbl intake with an Edelbrock AVS 500 carb, Clifford shorty headers (2-into-1, 2-1/2" all the way out back). 3.55 gears with an A833 OD tranny. It took a lot of fiddling with timing and carb adjusting but as of yesterday it finally runs like I expected. The power starts coming on at about 1500-1600 and goes strong up as far as I'd normally take it - about 3000 unless I want to stick my foot in it. When the secondaries kick in you can really tell. I've taken it to 4500-5000 with no gripes from the drivetrain. I'm still tweaking it, but at the moment I'm going to drive it without adjusting it further to make sure it's dialed in under most driving conditions. Oh yeah, this is all on junk 87 pump gas.
 
-
Back
Top