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is there any reason why my engine wouldn't built enough vacuum ?
i heard that it is the case only with high lift cam, which is far from the case (lol) in my engine.
I'd start by checking for a vacuum leak. The easiest way to do that is idling the engine in park, then spraying starter fluid around the lines and base of the carb without getting any into the carb. If the engine revs, you have a leak.
Triple check the line going to the booster itself and the seal on the booster, too.
If you've also triple checked the vacuum line from the back of the intake to the booster itself then it's time to invest in an aftermarket device that makes vacuum.
On a side, yet on topic note, I'm pretty sure XJ's had a football sized "bottle" that "stored" vacuum to prevent such problems.
It was located on the front passenger side- near the bumper.
There has to be an explanation or an issue that hasn't been resolved. I have the same 7" dual diaphragm booster on my jtruck and the 327 makes plenty of vacuum for it. I have no trouble stopping my 35s.
44bz wrote:There has to be an explanation or an issue that hasn't been resolved. I have the same 7" dual diaphragm booster on my jtruck and the 327 makes plenty of vacuum for it. I have no trouble stopping my 35s.
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your engine is a 4 barrel high comp or 2 barrel low comp ?
44bz wrote:There has to be an explanation or an issue that hasn't been resolved. I have the same 7" dual diaphragm booster on my jtruck and the 327 makes plenty of vacuum for it. I have no trouble stopping my 35s.
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your engine is a 4 barrel high comp or 2 barrel low comp ?
Mine is originally a 2bbl motor but I'm running a 4bbl intake and carb.
tara wrote:i spoke with an old mechanic guy who said that he thinks that the problem is that my engine doesn't produce enough vaccum for dual booster and that the original 9" single booster require less vaccum. so he advised to installed a 9" single or add avaccum electric pump to help, what do you guys think ???
another possibilty : i got a vaccum leak somewhere before the booster so the vaccum is not strong enough and the booster cannot work correctly
Bigger boosters don't require higher vacuum levels. Just a higher volume of vacuum, which a gas v8 will easily do, provided the nipple the vacuum is being pulled from isnt tiny. The 360's and 258's had a pretty large (3/8" I think) vacuum line coming from the intake to the booster.
tara wrote:so you got the original low comp pistons ? is it a great improvement to have 4 barrels ?
lucky you to found this intake
I believe I do have the lower compression engine. The motor currently in it came out of a 66 or 67 Wagoneer. It already had the 4bbl intake on it though. I haven't ever driven a 327 with a 2bbl carb so I can't really comment on the pros/cons. The original 327 had a 2bbl intake and a 4bbl carb by way of an adaptor when I bought it. I pulled that in favor of a 4bbl intake I found on eBay years ago but the truck was down for several years while I rebuilt it.
this morning, just in case test the check valve booster and surprised this brand new (tested by technicians, lol) looked faulty. tried to blow in both holes and nothing : blocked.
so i installed another one, and now pedal is normal (not hard like before). but still slow to return. when i try to lock the wheels, only the front are locking, is that normal ?
braking is still not optimal from what i can feel, but it is better though
tara wrote:this morning, just in case test the check valve booster and surprised this brand new (tested by technicians, lol) looked faulty. tried to blow in both holes and nothing : blocked.
so i installed another one, and now pedal is normal (not hard like before). but still slow to return. when i try to lock the wheels, only the front are locking, is that normal ?
braking is still not optimal from what i can feel, but it is better though
I know earlier you stated the rear brakes were too tight, did you adjust them out? Maybe they are adjust just a bit too much?
tara wrote:yes, i have checked them. one wheel was dragging. Now everything is fine, drums can turn freely with no drag
Thats good, but if they are adjusted out too far, then it requires more movement from the wheel cylinder for them to make contact with the drum. Which could result in less braking from the rear.
tara wrote:so you got the original low comp pistons ? is it a great improvement to have 4 barrels ?
lucky you to found this intake
I believe I do have the lower compression engine. The motor currently in it came out of a 66 or 67 Wagoneer. It already had the 4bbl intake on it though. I haven't ever driven a 327 with a 2bbl carb so I can't really comment on the pros/cons. The original 327 had a 2bbl intake and a 4bbl carb by way of an adaptor when I bought it. I pulled that in favor of a 4bbl intake I found on eBay years ago but the truck was down for several years while I rebuilt it.
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what carb do you got ? are you happy with it ? i found a 4 bbl intake and wonder if i should try it. it is pricey too
tara wrote:what carb do you got ? are you happy with it ? i found a 4 bbl intake and wonder if i should try it. it is pricey too
I have a Holley truck avenger (TA470). It's been fine but I don't really need an off-road carb.
I'm glad I swapped for the 4bbl intake. The prices have definitely gone up tho. I paid $150 4 or 5 years ago and just a few months ago one went over $400 on eBay. Seems ridiculous to me but unfortunately I guess that's where prices are now. There's a good looking one on eBay now, but pricey as you said.
a STUPID QUESTION : do i have to clean all the brake bleeder vacuum pump after using it ? i got also two MC which won't be used, do i have to clean them ? remove the dot 4 ? how ?