Pump gas compression again

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MOPARMAGA

MOPARMAGA

" The other hard member"
FABO Gold Member
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Location
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Hey there friends,
I want to talk compression limits for pump gas, I have 92 in my area
(communist Seattle)
My build is a 70 dart swinger.
I have a 470 stroker about to be built
1973 chrysler 400 block 630 casting
I have everything aluminum that you can bolt on plus an aluminum 4 core radiator
Hooker ceramic coated 2 inch fenderwell headers
Molnar 3.915 crank
Molnar 6.70 con rods
4032 forged SRP pistons
Trick flow 240 heads
Howards solid f/t cam 260-264 @.050 duration with .616-.620 lift & intake closing at 68 advertised (edm lifters)
Effective crank stroke is 2.93
My static compression is 11.36
If my memory serves me it's 8.70 dcr
188 psi.
These are calculated numbers.
My question for you folks is how did your 11.0:1 - 11.5:1 compression bad *** a-body like pump gas, this car will be street driven some & raced some. I realize it's hard to hear pinging with 3 inch exhaust.
Give me some good news, I've heard it's no problem, then theres the 10.5:1 guys
And just want to give a special shout out to Ken for guiding me on the upcoming build
 
MOPARMAGA said:
Also how did you get your "weinie idiot loser" thing. How do I add something great like that ?
Click to expand...

I got called that on the forum once and just kinda went along with it. You can change your custom title to whatever you want as a gold member. It's on your profile page.
 
RustyRatRod said:
I got called that on the forum once and just kinda went along with it. You can change your custom title to whatever you want as a gold member. It's on your profile page.
Click to expand...
Cool, I just have another goal to reach now
GOLD MEMBER
 
MOPARMAGA said:
Hey there friends,
I want to talk compression limits for pump gas, I have 92 in my area
(communist Seattle)
My build is a 70 dart swinger.
I have a 470 stroker about to be built
1973 chrysler 400 block 630 casting
I have everything aluminum that you can bolt on plus an aluminum 4 core radiator
Hooker ceramic coated 2 inch fenderwell headers
Molnar 3.915 crank
Molnar 6.70 con rods
4032 forged SRP pistons
Trick flow 240 heads
Howards solid f/t cam 260-264 @.050 duration with .616-.620 lift & intake closing at 68 advertised (edm lifters)
Effective crank stroke is 2.93
My static compression is 11.36
If my memory serves me it's 8.70 dcr
188 psi.
These are calculated numbers.
My question for you folks is how did your 11.0:1 - 11.5:1 compression bad *** a-body like pump gas, this car will be street driven some & raced some. I realize it's hard to hear pinging with 3 inch exhaust.
Give me some good news, I've heard it's no problem, then theres the 10.5:1 guys
And just want to give a special shout out to Ken for guiding me on the upcoming build
Click to expand...
When you get it running do a compression check after you shut it off pull out number 1 plug since its easy to get to..You can pick.up a compression tester fairly reasonable...That will tell the tale of what gas to run..Remember..Aluminum heads let's you get by with more compression and lower octane as cast iron does...I'd say anything under 190 you can get by with 93..Do you have an airport close to where you live?..If so you can pick up some Av gas..I'd definitely fire it up and break it in on a higher octane fuel such as Av gas which is plenty enough octane around 100 I believe it is..That would insure that while you're breaking it in and leaning it out you'll have sufficient octane..Remember also that when you first fire it up have your timing light handy and set the timing somewhere around 13-14 initial timing and 34 advanced..
 
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SuperStock426 said:
When you get it running do a compression check after you shut it off pull out number 1 plug since its easy to get to..You can pick.up a compression tester fairly reasonable...That will tell the tale of what gas to run..Remember..Aluminum heads let's you get by with more compression and lower octane as cast iron does...I'd say anything under 190 you can get by with 93..Do you have an airport close to where you live?..If so you can pick up some Av gas..I'd definitely fire it up and break it in on a higher octane fuel such as Av gas which is plenty enough octane around 100 I believe it is..That would insure that while you're breaking it in and leaning it out you'll have sufficient octane..Remember also that when you first fire it up have your timing light handy and set the timing somewhere around 13-14 initial timing and 34 advanced..
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Cool thanks, I do have a gas station on the way to Pacific Raceways that sells trick, also the airport is right behind that gas station. I was talking with Ken, the guy who is going to help me is mopar only & his machinist is a mopar only guy getting ready to retire. So I do have some good help.
But you're absolutely right, it just depends on what the psi is when it runs. Guys at Hughes were telling me that with my cam the optimum pump gas compression would be 12.5 @ 200 psi & other people say 11.0 is to high. It's just the details that make it what it is, so when I break it in ill run her with 100 & see. Thanks again
 
MOPARMAGA said:
Cool thanks, I do have a gas station on the way to Pacific Raceways that sells trick, also the airport is right behind that gas station. I was talking with Ken, the guy who is going to help me is mopar only & his machinist is a mopar only guy getting ready to retire. So I do have some good help.
But you're absolutely right, it just depends on what the psi is when it runs. Guys at Hughes were telling me that with my cam the optimum pump gas compression would be 12.5 @ 200 psi & other people say 11.0 is to high. It's just the details that make it what it is, so when I break it in ill run her with 100 & see. Thanks again
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A bit of info to help out...When you do your compression test just yank #1 plug since its easy..Unplug your coil wire..Install your compression gauge..Turn it over at starter speed while opening up the butterflies on the carb til the gauge needle stops climbing..You should be just fine on everything and have a fairly stout engine.
 
I think you’ll be fine with that much cam with proper tuning. Careful with the AV/Gas, it’s got some stuff in it that helps it burn at high altitude that’s pretty aggressive on rubber line and parts. Even the low lead has eight times the lead of regular leaded race gas. Its more of an octane booster, about two gallons to five of premium pump gas. With the timing optimized for full power, it’s probably still going to have an octane requirement of around 95 or better when it come up on the cam at full throttle.. It’s usually more expensive than AV/Gas, but 50/50 race gas to pump gas will get it by during the all out runs without as much potential for making lead deposits/fouling. What kind of ignition are you using? Running a dashboard retard dial isn’t mandatory in this case, but is a nice convenience to have in case you get a load of bad gas.
 
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Garrett Ellison said:
I think you’ll be fine with that much cam with proper tuning. Careful with the AV/Gas, it’s got some stuff in it that helps it burn at high altitude that’s pretty aggressive on rubber line and parts. Even the low lead has eight times the lead of regular leaded race gas. Its more of an octane booster, about two gallons to five of premium pump gas.
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Cool, thanks for the tip. I have heard of some cons, but as a mix it should be okay.
Probably much cheaper than trick racing fuel, I think is over $10 a gallon. Any experience with race gas concentrate ?
 
Garrett Ellison said:
I think you’ll be fine with that much cam with proper tuning. Careful with the AV/Gas, it’s got some stuff in it that helps it burn at high altitude that’s pretty aggressive on rubber line and parts. Even the low lead has eight times the lead of regular leaded race gas. Its more of an octane booster, about two gallons to five of premium pump gas.
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That's about the ratio I mix mine at as well.
 
Yeah, the race gas concentrate is loaded with MTBE. Some users have plug fouling from MTBE accumulating on the spark plugs. The AV/Gas is really the best option as far as cost unless you can buy 100 octane leaded race gas by the drum at bulk cost and run it 50/50 with pump premium. I get mine about two to three gallons at a time in a can and take it to the service station to add before fueling up.
 
Garrett Ellison said:
Yeah, the race gas concentrate is loaded with MTBE. Some users have plug fouling from MTBE accumulating on the spark plugs. The AV/Gas is really the best option as far as cost unless you can buy 100 octane leaded race gas by the drum at bulk cost and run it 50/50 with pump premium. I get mine about two to three gallons at a time in a can and take it to the service station to add before fueling up.
Click to expand...
Av gas has a more precise octane rating than race fuel as well.
 
MOPARMAGA said:
Hey there friends,
I want to talk compression limits for pump gas, I have 92 in my area
(communist Seattle)
My build is a 70 dart swinger.
I have a 470 stroker about to be built
1973 chrysler 400 block 630 casting
I have everything aluminum that you can bolt on plus an aluminum 4 core radiator
Hooker ceramic coated 2 inch fenderwell headers
Molnar 3.915 crank
Molnar 6.70 con rods
4032 forged SRP pistons
Trick flow 240 heads
Howards solid f/t cam 260-264 @.050 duration with .616-.620 lift & intake closing at 68 advertised (edm lifters)
Effective crank stroke is 2.93
My static compression is 11.36
If my memory serves me it's 8.70 dcr
188 psi.
These are calculated numbers.
My question for you folks is how did your 11.0:1 - 11.5:1 compression bad *** a-body like pump gas, this car will be street driven some & raced some. I realize it's hard to hear pinging with 3 inch exhaust.
Give me some good news, I've heard it's no problem, then theres the 10.5:1 guys
And just want to give a special shout out to Ken for guiding me on the upcoming build
Click to expand...
Do you still have those Pro Comp rods?
 
SuperStock426 said:
Do you still have those Pro Comp rods?
Click to expand...
Yes, I still have those too, I'm going to for my next build offset gring a 383 crank to 3.550 stroke & find some pistons I think a 1.60 compression height I can't remember off the top of my head, I did the math the other day, in a year or so I'll see about just making a street engine with a 4 speed & my 440 source heads for just a put around in my 99 dakota r/t.
 
Garrett Ellison said:
Yeah, the race gas concentrate is loaded with MTBE. Some users have plug fouling from MTBE accumulating on the spark plugs. The AV/Gas is really the best option as far as cost unless you can buy 100 octane leaded race gas by the drum at bulk cost and run it 50/50 with pump premium. I get mine about two to three gallons at a time in a can and take it to the service station to add before fueling up.
Click to expand...
MOPARMAGA said:
Yes, I still have those too, I'm going to for my next build offset gring a 383 crank to 3.550 stroke & find some pistons I think a 1.60 compression height I can't remember off the top of my head, I did the math the other day, in a year or so I'll see about just making a street engine with a 4 speed & my 440 source heads for just a put around in my 99 dakota r/t.
Click to expand...
Have you done any research on those rods?
 
MOPARMAGA said:
Also, I talked myself out of putting better bolts in after everything it cost the same as molnar
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I wish Manley still made rods for 440s..They were good rods..In my 440 build I am putting in my Demon I purchased Eagle rods..I haven't had any dealings with Pro Comp so I can't comment on them..I'd look around for some info on people who has run them..They may be an ok rod to use.
 
SuperStock426 said:
Have you done any research on those rods?
Click to expand...
I have yet to find anyone who's ever ran them, they've been in Buisness for a while
The actual name is speedmaster 79.
I did a thread on them because I was talking to my builder & he showed me a brand new eagle rod & it was boxed in flimsy cardboard & in a plastic bag, rods looked identical in quality but the only difference is eagle inscribed on them & had rap bolts, so if you subtract the cost of the rap bolt you'd be left with the price of the pro comp/ speedmaster rods, I thought it was funny. Originally I bought them because I was just going to go mild with my build but then I was like, half measures availed me nothing so went a bit more radical & I want to trust them I really do but... I guess the molnars could break too but atleast I know I spent more on them
 
SuperStock426 said:
I wish Manley still made rods for 440s..They were good rods..In my 440 build I am putting in my Demon I purchased Eagle rods..I haven't had any dealings with Pro Comp so I can't comment on them..I'd look around for some info on people who has run them..They may be an ok rod to use.
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Yeah, see I've never been the guy who just takes things as I was told. On summit there description says they're x-rayed & shot peened, the finish is dead on to other 5-600 dollar rods. So maybe I just say screw it, give them a try & hell if they last ill advertise for them. But it's alot of money to toss aside if they go pop
 
MOPARMAGA said:
Yeah, see I've never been the guy who just takes things as I was told. On summit there description says they're x-rayed & shot peened, the finish is dead on to other 5-600 dollar rods. So maybe I just say screw it, give them a try & hell if they last ill advertise for them. But it's alot of money to toss aside if they go pop
Click to expand...
Check both ends for tolerances and try them..
 
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