mwye0627 44 Report post Posted August 24, 2016 Okay, so not a Monster Big Cam, but I am going with a Trick Flow Stage 2 Cam on a fuel Injected 306 with mildly ported GT40X aluminum heads, 9.6:1 static compression. The specs on the cam are .542" Int / .563" Exh Lift. Duration 224° @ 0.050 Int / 232° @0.050 Exh 112° Lobe Separation angle. Based on past experience, I expect a maximum of 14" of vacuum at idle. It would probably be less, but these Hydraulic Roller cams tend to be a little more forgiving... What would most of you do to address the problem of low vacuum and a power brake booster??? I really don't want to go with the hassle of installing a Hydroboost system, so I guess my options would be a vacuum reservoir or an electric vacuum booster pump. I know that many of the OEM manufacturers are going with electric vacuum pumps, especially on Supercharged or turbocharged engines... How many of you think that a vacuum reservoir with a check valve would be good enough, (especially considering that under deceleration I can expect 18 to 25 inches of vacuum, depending on how hard I was getting on it before lifting)??? Thanks, Mike Quote Share this post Link to post Share on other sites
1969_Mach1 333 Report post Posted August 24, 2016 My 351W makes 14" of vacuum at idle and the X303 cam from Ford Racing. My power brakes work fine for me. Your cam has more valve overlap. Plus you have a small CID engine. I'd guess with that cam in a 306, your idle vacuum will be between 10" and 12" in neutral. You'll probably need something to improve the power brakes. I don't know if a vacuum reservoir or a vacuum pump is a better solution. Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 24, 2016 your compression is too low. what gears and trans do you have? Quote Share this post Link to post Share on other sites
mwye0627 44 Report post Posted August 24, 2016 4R70W trans (2.84:1 First gear) 3.73:1 Rear gear.... Perhaps I will stick with the Trick Flow Stage 1 Cam... I am looking for more bottom end and mid range power... Planning on limiting max RPM to about 5800 Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 24, 2016 these are good with 1.6 rockers . the second one will be slightly milder . if your fuel injection is computer controlled, you are better off with the second cam because of is wider lsa. 221145-10 https://www.summitracing.com/parts/hrs-221145-10 221145-12 https://www.summitracing.com/parts/hrs-221145-12 Quote Share this post Link to post Share on other sites
3pedal 95 Report post Posted August 24, 2016 My guess is you are ok....the 112 LSA is your friend... Quote Share this post Link to post Share on other sites
mwye0627 44 Report post Posted August 24, 2016 I agree... A wider LSA is ALWAYS better for Idle Quality and Vacuum..... Most people would be scared to death of some of the cams we ran in our Pro Mod engines.... 1.085 Lift, 318° duration @ 0.050 a 107° LSA installed with a 109° centerline on a 780 Cu. In. engine Fuel Injected with 15.2 Static Compression and 3 stages of N2O... 2400 HP with everything ON!!! Quote Share this post Link to post Share on other sites
mwye0627 44 Report post Posted August 24, 2016 Thanks for looking up those cams, Barnett... The second one definitely has my interest with the wider LSA... My previous experience has been with the 351W engine... I raced the original 1969 Mustang that I bought in 1973... Heavily reworked Iron Heads... (nothing really good available back then), 12.7:1 static compression, 565 Lift, 232 @ 0.050 duration, symmetrical lobe Solid Flat Tappet camshaft... 110 LSA... I can't remember the installed centerline. I wish I could have found something with better Exhaust specs back then... This was a Lunati Cam... . FMX transmission ( yeah, HEAVY, I KNOW!!!) With Trans-Go manual valvebody Kit... 3200 Stall Converter... 4.56 Traction-Loc rearend - 9" Nodular unit I got from a friend out of a Torino Talledaga... Yes, I knew that car Well... Mid 11 Second car... A LOT of fun at the time!!! Quote Share this post Link to post Share on other sites
1969_Mach1 333 Report post Posted August 25, 2016 I'm definitely not an expert regarding camshafts. But, with respect to idle quality and idle vacuum you have to look at all of the timiing events not just lobe separation angle. Overlap at 0.050" tappet lift, overlap at advertised duration, when the intake valve closes, are the advertised duration specs at 0.004" tappet lift as SAE specifies, or are they at 0.006" tappet lift like Comp and Lunati tend to use, symmetric lobes vs. asymmetric lobes. There's a lot going on there and they are all interrelated. A short duration cam with a 108 deg. LSA can idle just as smooth and with as much vacuum as a long duration cam with a 112 deg. LSA. Quote Share this post Link to post Share on other sites
Rsmach1 71 Report post Posted August 25, 2016 A vacuum pump https://m.summitracing.com/parts/sum-760152 Or you can just convert to manual disc's as I'm doing. 1 RPM reacted to this Quote Share this post Link to post Share on other sites
Rsanter 152 Report post Posted August 26, 2016 I would start with a large vacume resavoir as that will never hurt. You can rob those off of a cougar or other large ford car and mount them under the fender. Then if that is not good enough you can always add in the pump Bob 1 fordguy69 reacted to this Quote Share this post Link to post Share on other sites
3pedal 95 Report post Posted August 26, 2016 Thats a good pump but noisy...it will correct your PB problem...doesn't help a automatic shift properly though...to make my life easier I sold the pump and installed a smaller cam...I'm very happy now....think before you act..either one of those cams barnet pulled up will work great .... Quote Share this post Link to post Share on other sites
Ash 145 Report post Posted August 27, 2016 Could I please ask those of you in the know about the vacuum my engine will create, it's been a concern in the back of my mind for a while. I'm not experienced enough with cams to know for sure. Comp did me a custom grind to my car and engine specs. Stroked 428CJ to 462ci, Fast EZI-EFI, Edelbrock Performer RPM heads, Blue Thunder 427MR intake and FPA headers along with 6 speed TR6060 trans and 3.91 9 inch. They came out with this: I'm in the process of doing my body work. I picked up an electric vacuum pump a while back, new but not used at the right price, just in case I needed it. Now would be the ideal the time for me to make provisions to hide it under a fender if I do in fact need it. Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 27, 2016 That has 65 degrees of overlap so you may need one . Hard to say for sure but it is definitely near the fringe . If you don't drive in stop and go traffic you should be fine however. . Quote Share this post Link to post Share on other sites
Ash 145 Report post Posted August 27, 2016 Possibly is enough to say to me install it the vacuum pump. Thanks, Barnett. Even if I don't need it, I'll make allowances it to fit it in case that I do. Quote Share this post Link to post Share on other sites
3pedal 95 Report post Posted August 27, 2016 Nice combo Ash...I agree with Barnett...but the 114 LSA may save your Power Brakes...gotta have at least 13 inches at idle...hmmmm Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 27, 2016 Nice combo Ash...I agree with Barnett...but the 114 LSA may save your Power Brakes...gotta have at least 13 inches at idle...hmmmm Actually, one of the main criteria that determines the amount of vacuum is the overlap. If it is 65, it is 65 whether the LSA is 114 or 112 or 110 or 108 etc. If all other tings remained the same, it would have more vacuum with a 108 LSA it it had only 55 degrees of overlap. Quote Share this post Link to post Share on other sites
3pedal 95 Report post Posted August 27, 2016 Barnett...I am speaking to his combination...all the numbers make up the team... Quote Share this post Link to post Share on other sites
barnett468 418 Report post Posted August 27, 2016 Barnett...I am speaking to his combination...all the numbers make up the team... Ahhh, yes, 65 overlap has less vacuum on a smaller displacement engine, however, he is still nearing the fringe where a definitive answer is difficult to give, so better to be safe than sorry and have a plan for insufficient vacuum in advance. Quote Share this post Link to post Share on other sites
Ash 145 Report post Posted August 27, 2016 Appreciate the feedback guys. As I said, I didn't know the answer myself, so I appreciate you helping out. The vacuum unit that I got is not that big and should hide easily under the drivers side fender. I was going to fit an electric power steering pump there but I figure the shorter the hoses on a vacuum pump is better compared to the hydraulic hose length on a power steering pump. So the steering pump can go on the passenger side. Quote Share this post Link to post Share on other sites
