when i had my 500cfm, the car ran great, it will give you more top end pull, i just didnt like how my plugs would foul, the smell would make your eyes water, but it did pull more at higher speeds 
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- Thread starter MPGmustang
- Start date
I think I know a guy that has a 500cfm on a well prep'd mav... maybe he'll let me try it on the dyno some day just for 'pete's sake' or even run a quarter mile with it some day...
I should ask... nah I'm sure he'll be curious and just hand me the carb and insist I run it!!!
I should ask... nah I'm sure he'll be curious and just hand me the carb and insist I run it!!!
Luke, I honestly think I have plenty of room, I have 50.5-51cc chambers now, as I'm using the 78 head, the desk is only @ .010 so milling the deck would be more difficult than it's worth. it's all in the head now. to get it up to 9.8 (I have roughly 9.25) I'll need .55 more, it equals out to roughly .050 off the head... think it can handle that.Luke76":26rg4t9d said:
Before you start tearing the engine apart, bolt the 500 carb on & dyno it. Since you have a stick trans your loss is just 15% where me with a C4 I loose 25%.
If you have the $$ & time maybe Mike will let you try his new 1.65 roller rockers????
I bet you will hit 150 RWHP.
The 500 you want to borrow has the annular discharge nozzles already installed. Bill
If you have the $$ & time maybe Mike will let you try his new 1.65 roller rockers????
I bet you will hit 150 RWHP.
The 500 you want to borrow has the annular discharge nozzles already installed. Bill
Gene Fiore
Famous Member
Yeah...we could probably work out something to see if my carb would give you the 150hp you are looking for.MPGmustang":ubfd9o98 said:I think I know a guy that has a 500cfm on a well prep'd mav... maybe he'll let me try it on the dyno some day just for 'pete's sake' or even run a quarter mile with it some day...
I should ask... nah I'm sure he'll be curious and just hand me the carb and insist I run it!!!
I'm gonna try some things, I want input on what you all think...
what if...
I get the HHR, and run on the dyno with higher than 91oct gas?? with the higher oct will it 'act' almost like higher compresion with lower oct?
just thought I would ask for what ya'll thoughts are...
so I think I'm lean, plugs are white/clean, I'm gonna put the 61jets back in and run it for a while. I might even need the 31 squiter back but want to see what the jets do.
On the dyno last time the AF was good the whole time, but on the carb rebuild I found the accel pump to be shot and on the wrong pump cam. Gene if your 500 carb can push 150+ I'll probably go get my 350 rebuilt to close to the same. will be intresting to see, hopefully be getting the HHR's today.
OKAY, another off topic, is this worry-some???
I reved the engine realy high lately the tach went past 6k!!! then a big 'BANG' (somewhere on the car IDK where from!) and loss of power, eventually with some cooling down and a day of rest she's back up to her normal power again I've also noticed a changed in MPG but that could be the fact I've been easy with her since... I think I should get a rev limiter to 5500 rpms for my DUI.
I have since taken her back up to 5500-6000 to see the power and it's still there (fun ) I'm thinking it was axle wrap, but it don't make much sence this time, last time I was at the drag strip and at a stop, this time I was 60+mph in 2nd and just high revin'g
what if...
I get the HHR, and run on the dyno with higher than 91oct gas?? with the higher oct will it 'act' almost like higher compresion with lower oct?
just thought I would ask for what ya'll thoughts are...
so I think I'm lean, plugs are white/clean, I'm gonna put the 61jets back in and run it for a while. I might even need the 31 squiter back but want to see what the jets do.
On the dyno last time the AF was good the whole time, but on the carb rebuild I found the accel pump to be shot and on the wrong pump cam. Gene if your 500 carb can push 150+ I'll probably go get my 350 rebuilt to close to the same. will be intresting to see, hopefully be getting the HHR's today.
OKAY, another off topic, is this worry-some???
I reved the engine realy high lately
the tach went past 6k!!! then a big 'BANG' (somewhere on the car IDK where from!) and loss of power, eventually with some cooling down and a day of rest she's back up to her normal power again I've also noticed a changed in MPG but that could be the fact I've been easy with her since... I think I should get a rev limiter to 5500 rpms for my DUI.I have since taken her back up to 5500-6000 to see the power and it's still there (fun
) I'm thinking it was axle wrap, but it don't make much sence this time, last time I was at the drag strip and at a stop, this time I was 60+mph in 2nd and just high revin'g
Generally higher oct fuel is of no benefit if the compression is not high enough to need it. That said it won't hurt and you can maybe retune the engine with a bit more advance.
I reved the engine realy high lately
Just a guess but maybe you had valve float at the higher RPM depends what the springs can handle (Open pressure). Than maybe some extra fuel (raw or unburned) was sent though into exhaust were it ignited.
Gene Fiore
Famous Member
X2 on using the high octane fuel...high octane fuel burns slower and unless you have high enough compression it could actually make less power. Oh and HHR's?? Not familiar with that one.
oopps I mean HRR (High Ratio Rockers)... lol
well thought it would be worth a try, I might put some octain booster in to maybe rasie it a few points but guess I'll just skip the full +100oct race fuel...
Bubba, I hope that's all it was honestly, maybe I should invest in some stronger springs for higher RPM's... I know the bottom end is up to it...
well thought it would be worth a try, I might put some octain booster in to maybe rasie it a few points but guess I'll just skip the full +100oct race fuel...
Bubba, I hope that's all it was honestly, maybe I should invest in some stronger springs for higher RPM's... I know the bottom end is up to it...
Not a bad idea if your cam is still pulling at the higher revs. If the springs have had quite a bit of use you could add a shim or two it can be done with head on too. You should be able to pickup an additional 200 to 400 RPM depending on the amount of shim thickness you add i.e. .030 to .060 etc. check for coil spring bind or stack so you have enough clearance between coils at full lift. Just kinda throwing this out there, if your experiencing valve float with the standard rockers, wouldn't moving to the HRR's add to that and possibly make it lower in rpms?
Just wondering before having to disassemble everything twice, not knowing what springs you're running right now.
Edit: not knowing if you switched springs after the new cam, and the condition of yours, I IIWIYS I would consider moving up a level rather than shinning especially with moving to HRR.
Just wondering before having to disassemble everything twice, not knowing what springs you're running right now.
Edit: not knowing if you switched springs after the new cam, and the condition of yours, I IIWIYS I would consider moving up a level rather than shinning especially with moving to HRR.
That's all??? :x wish it was more.... don't think it's worth it, I'll just put a rev limiter on itbubba22349":t8hm94hl said:
the entire engine was rebuilt around the same time, I have since put new lifters in but everything else is the same, I'm running 302 springs now, which i'm told is overkilll for my camchoice, so the valve float makes me curious... If it does lower top rpm limit I'm okay with that. I'll just take off my foot before it gets too high.
I got the new rockers
I'll be installing them Monday Morning.Pick1
Pick2
If you have adjustable rockers than you can also pickup a few more RPM and reduce chances of valve float by adjusting the rockers so the lifter is very close to top of travel. Adjust them to Zero + a 1/4 turn if you can stand a little lifter tick at start up.Well I changed more than I needed obviously and have to retune the whole car...
Changes made:
1) I took the free flow air filter (oil cap) off the front and plugged with a rubber stopper
2) also have the 1.6 rockers on now,
3) then I went to ported vacuum
Results noticed:
1) stopped the PCV bringing in air through that filter making the car richer on idle now
2) the idle vacuum sits lower before with manifold vac it was 7-8 inches, now it's 5 inches but I bet that's more rocker ratio than ported vs manifold.
3) I need the bigger jets in, so I'll be doing that tonight possibly even the bigger squit nozzle or the just try the cam in the number 2 spot.
4) electric choke/idle needs to be adjusted, rockers and ported vacuum changed the way it warms up.
5) little power difference IMO. except the sound, it WAY more throaty
6) less lopey!: it's smoother in lower rpm's... why? I think it's the ported...
Bubba, I went 1/2 turn this time, after I tune it more I'll go back to the rockers and loosen them 1/4 turn, I'm sure that will help too.
I'll also see what mpg has to say about the higher rockers... but the bigger jet will dimish any gains I might have gotten...
Richard
Changes made:
1) I took the free flow air filter (oil cap) off the front and plugged with a rubber stopper
2) also have the 1.6 rockers on now,
3) then I went to ported vacuum
Results noticed:
1) stopped the PCV bringing in air through that filter making the car richer on idle now
2) the idle vacuum sits lower before with manifold vac it was 7-8 inches, now it's 5 inches but I bet that's more rocker ratio than ported vs manifold.
3) I need the bigger jets in, so I'll be doing that tonight possibly even the bigger squit nozzle or the just try the cam in the number 2 spot.
4) electric choke/idle needs to be adjusted, rockers and ported vacuum changed the way it warms up.
5) little power difference IMO. except the sound, it WAY more throaty
6) less lopey!
: it's smoother in lower rpm's... why? I think it's the ported...Bubba, I went 1/2 turn this time, after I tune it more I'll go back to the rockers and loosen them 1/4 turn, I'm sure that will help too.
I'll also see what mpg has to say about the higher rockers... but the bigger jet will dimish any gains I might have gotten...
Richard
Richard, sounds like you have a good plan going, but are you not running a PVC valve now? Think that would not be too good can you run a hose into the bottom of the air cleaner for a closed type system?
Bubba,
before: PCV connected to rear of valve cover, oil filler had a free-flow air filter allowing air to come in the front of the engine valve cover to the manifold vacuum via the PCV... basicly the PCV was always on.
After: PCV connected to rear of valve cover, Oil filler plugged with rubber plug. PCV only sucks when it can, not all the time keeping my oil alot cleaner.
I knew I didn't explain it properly earlier... Hope this helped... did I do it right by plugging that oil filler?
before: PCV connected to rear of valve cover, oil filler had a free-flow air filter allowing air to come in the front of the engine valve cover to the manifold vacuum via the PCV... basicly the PCV was always on.
After: PCV connected to rear of valve cover, Oil filler plugged with rubber plug. PCV only sucks when it can, not all the time keeping my oil alot cleaner.
I knew I didn't explain it properly earlier... Hope this helped... did I do it right by plugging that oil filler?
For a street driven vehicle you need a breather on the oil filler to admit clean air into the engine so the pcv can function properly.
If it was a race engine & used a vacuum pump or a crankcase evacuation system you would not even use a pcv valve. Crankcase if under a vacuum provides better ring seal.
Hook yours up for street use. Bill
If it was a race engine & used a vacuum pump or a crankcase evacuation system you would not even use a pcv valve. Crankcase if under a vacuum provides better ring seal.
Hook yours up for street use. Bill
that doesn't make sense then, the air is serirously free flowing, fowling up the little air filter, oil, and making the engine run leaner have have mroe dirt get into the oil faster.
the PCV is still hooked up vacuuming out the gasses from the crank only when there is something to vacuum out.
I see the air filter on the oil filler as vacuum leak at the manifold, going through the valve cover. Now with the rubber stopper on it it's only pulling the obnoxious gasses from the crank case when they are there.
Is this the wrong setup? why have a it setup free flowing way to help ruin your oil/filters?
the PCV is still hooked up vacuuming out the gasses from the crank only when there is something to vacuum out.
I see the air filter on the oil filler as vacuum leak at the manifold, going through the valve cover. Now with the rubber stopper on it it's only pulling the obnoxious gasses from the crank case when they are there.
Is this the wrong setup? why have a it setup free flowing way to help ruin your oil/filters?
The best PVC system is the closed type. This is were the PVC valve is at rear of valve cover and hooked up to the carb base if it has hose fitting there or by adding a plate type fitting below carb etc. The oil cap should be at the opposite end of valve cover and would also need to have a hose fitting than run a hose to the bottom air cleaner this should keep everything clean inside and work correctly. Sounds like you had an open type system your right that it will pull dirt into the engine though the oil cap. A PVC valve is just a controlled vacuum leak but they won't hurt performance one bit and will keep the engine much cleaner inside and have a longer life.
IIRC.You could possibly damage gaskets and seals by blocking off the intake of air to the crankcase.The vacuum can dislodge gaskets enough to cause oil leaks.If I am incorrect in this,someone please correct me.Thanks.
Good luck.Have fun.Be safe.
Leo
