I Can tell you as far as the brakes vacuum....I put in a blueprint 383 stroker, similar to yours. After talking to them, they said the same, it should pruduce 10-12" of vacuum, but with an SSBC disc conversion, there isnt any vacuum at idle. JRs72RSis right on target about manufact. vacuum ratings. You will make some sacrifices for SB HP. I lovethe blueprint 383, for the money its a hell of an engine. I installed a Crane cams reseviorand a SSBC pump, get 3 good pumps of the brakes and the vac is gone, and the pump cant keep up, at least not in stop and go city traffic.I found a Hydroboost system on ebay, thats my solution. I put an SSBC rear disc conversion kit in the 70. Id love to have put in the willwood system, but Ive got more than one car in the stable that needs tendin too.....

 

I see you're from Suffolk....just left Virginia last summer...was stationed at Oceana.

So a pump and reservoir and still have vacuum issues? Wow, I've read alot about vacuum problems with high hp and/or big cams but I thought I'd be good since was staying in the low 400 hp range. Looks like I might have an issue. I'll find out when I get back on the road (soon hopefully). What's a hydroboost system consist of?

 

Yep. Retired from the navy.....The engine Ibought was dynoed @ 408 HP 455 TQ. The problem is, You cant have a pump and use the engine's vac at the same time, and a stop valve doesnt work either.Even with a T connector, the pump will run, trying to acquire enough vac from the engine, which it will never do, since the eng will have some vac leaks. The other solution is just to use a pump, then the system is closed and the pump will shut off eventually, when you stop using the brakes, but that takes time, its noisy and vibrates alot, uses up amps, if theres any leaks anywhere, it will start up even at 3 am...and I dont like relying solely on elect. devices especially to stop a car.

The hydroboost replaces the power booster and uses high pressure lines running from the power steering pump to your steering gearbox, thru the hydroboost back to the pump with a low press. line, thereby cutting vacuum completely out. The specs say it should putup to 1200psi to the calipers, all the time.

Give the regular way a chance, you may be fine on vac, but if not there are solutions.

 

Have you tried hooking up a vacuum gauge and running it into the car and tried running around. I push a .512 lift with a 280 duration and have about the same vacuum you have at idle at around 12 - 15. I drive my car daily and I usually have no problem stopping though. I've ran around two weeks with a vacuum gauge in the car and I've noticed that my vacuum is usually around 10 - 12 at low RPM and when I'm coming down from speeds of over 20 mph that I'm having well over 20 in the vacuum range and the brakes work great. As soon as I let off the gas the rpm's pull up the vacuum needed to stop very quickly and it lasts pretty much till I stop.

As for the spark plugs I ran the accel shorty plugs for clearance with my hooker headers.

 

Well...I bought this car for the wife, sooo...she wants the "no fuss brakes". The pressure is there, but not all the time,so its not consistant. Ireally dont mind the inconsistancies much myself, but she does.At times you need to push harder, and it will stop. She is still in the "pump your brakes" when you stop mode, andthat obviously doesnt workwith this set-up. The specs on the cam are
.487Int / .508 Exh & 234 Int / 244 Exh duration @ .050 - 110 degree lobe sep, so it should have some kind of vac at idle, but its just not there.

 

Yep. I went with the Accel shorty plugs.

The gauge is a good idea...I'll do that when I get running again (hopefully within the next two months). Where did you hook it up too?

Speaking of that...I've got the Air Gap intake and not sure where I hook up the vacuum line from the booster. There's a small threaded hole that I plugged because the carb blocks access to it. There are two slightly larger threaded holes aft of the carb, one towards the passenger side and the other on the drivers side. I'll try to find a photo and post it for reference.

 

Here's a pic. Like I said...the hole directly behind the carb is actually blocked by it so it's plugged. You can see the other two holes aft of the carb on either side of the distributor. Which one's used for the booster?

[IMG]local://upfiles/14347/D013AC2D67CF4BC4A0E46807FFE8D2A5.jpg[/IMG]

 

does the front of your carb look like this? The vac booster line comes out at the base of the carb in the middle.

[IMG]local://upfiles/3587/D00FDB8D27C545158D7C8B3087E77098.jpg[/IMG]

 

Are you running a holley style carb with the bowl hanging over the back?

I'm running my advance directly from the vacuum port on the front of my Edelbrock until I finish rebuilding my 750 double pumper. Not the timed advanced or the PCV. If it's an Edelbrock/Carter AFB and you're utilizing the rear vacuum port you can block that and run a nice metal vacuum T from the manifold vacuum that you've plugged. I don't see any reason you should change your current setup unless there's a necessity. But then again, I'm still learning about vacuum and where and from what gets the best results. You can get about 6 - 8 feet of vacuum hose pretty cheaply and cut it how you need it. I ran mine with a t junction and then ran it to a 15 dollar vacuum gauge into the driver's compartment.

 

Yes...the Holley Street Avenger 770. The rear bowl is what blocks that one port on the intake. I'll attach a photo of the carb but it dosen't really show anything. I'll take a better pic tonite and attach it to a reply.

Mine is similar to the Edelbrock in got3ofem's photo. One small and a slightly larger port on the front of the carb with one large port on the back...I think...I'll double check tonite.

I'm also plumbing some aluminum tubing from my fuel pump to the carb dual feed line. I've always used an in-line filter but...there'sthe two filters on the carb at the inlets and there's a filter in the feed line itself...is it overkill to still use an in-line filter?

I appreciate the help. Putting the motor together was easy compared...trying to get the plumbing, wires, etc. back together is kicking my butt!

On another note...did anyone see the picture of my parking brake cables running over my pipes? It's also in the 2nd gen section. Any ideas?



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