pcguy2u

Still sorting out minor issues on this 75 Vega with a built 350 and I have made some progress. I think the biggest issues were spark plug wires and the 9"x1.75" air filter. Replace with the huge 10" K&N.

The main isssue with this setup is that it's totally undocumented so I really don't know what I'm dealing with.

That brings me to the manifold vaccuum of 10hg. I do understand that the vacuum could be that low depending on the cam and that the cam was touted to be a 280 which seems a bit over the top. Obviously that kind of cam could create and idle vacuum of 10hg, but so could a vacuum leak.

Thought about that for a while and then read somewhere that a significant vacuum leak would cause some sort of a whine or whistle.

Now there is a whine coming from the engine that I have determined is not the alternator - I always thought that sort of whine came from the alternator, but not this time. Could that be coming from the tranny? Tranny seems fine, but I don't know where the sound comes from - no experience there.

If it turns out there is a vacuum leak, does anyone have a proven method of locating it? I have run a mirror/flashlight around the intake manifold to no avail.

Appreciate any help..........

88Z51

Easiest way I know of is to spray some carb cleaner around the intake gasket areas, carb base, etc., and observe any rpm changes. A sudden rpm change in a specific area would indicate a vacuum leak in that area. One tell tale sign is a slow return to idle after reving the engine a bit. Incorrect ignition timing will also cause a low vacuum reading. What kind of issues are you having with the car?

pcguy2u

Don't really know if there are any issues as I have never run this except on the streets. Seems to idle ok at 1050 and it it revs ok, but there is the exhaust lope that would indicate a huge cam and if the cam is really 280/280, the cam might be over the top for the build.

Just trying to avoid embaressing myself on my first outing at Infineon/Sear Point/Race Sonoma or whatever they're calling it these days.

Will try the carb cleaner trick - thanks for that.

Redvette_22

You can also "cup your hands" over the intake of the carb with the engine running. If you have a vacuum leak your engine should still run while covering the top of the carb, then you can search for where the leak is. If the car stalls out you should be good to go and no vacuum leak(s)

383vett

Are you going to be at Sonoma Wednesday? I'll be there. I'll look for you. I'll be in Comp Rod. Willie

pcguy2u

Tried that and it immediately died, but whats the difference between that and closing the choke.

Have some SeaFoam and looking for something to spray it with.

BTW, since I don't know what year the 350 is, how many front seals are there? Would I be better off removing the timing chain cover and bringing it in to match it up or would you buy the seal and return it if it's the wrong one?

pcguy2u

It was my goal to be there last week, but between paint and everything else and now the front seal (no one wants any oil on the track) - small leak, but it looks worse when I rev the engine, so I don't know.

383vett

The last couple of weeks the car count has been pretty low. I had 6 time runs 2 weeks ago. Actually sat out 3 so as not to beat the car up. It would be a good time to go. Good luck with your project. I'll look for you. Willie

pcguy2u

Hey Willie, thanks for that update. I really need to get this sorted out. Any clue about either of the following?

• The all in timing at about 2700 and up won't get to more than 31, must have a limiter. The counter weights look new as do the two silver springs. The last test at 31 was with a replaced silver spring with a gold one. Probably need to try 2 gold and check for a limiter - just not sure what I'm looking at. Likely someone went through all this and found the predetonation required holding the all in down???
• Anyone have any words of wisdom on the removal of the crank/pulley/balancer? Can't be sure of how that all bolts together, but there must be a downside in the R&R.

Also, will the exposed end of the cam show any numbers that will identify its specs?

Many thanks,
Nick

383vett

The distributor only has a set number of degrees it can advance. The springs just allow the advance to come in at a faster or slower rate. There is a slot in the distributor that limits the advance. It's been a while, but I think the slot can be enlarged or different bushings used to change the advance amount (I now tune with a laptop). Without doing that, the only way to achieve your 36 or so degrees is to increase your inital advance 5 degrees. Give that a try. Hopefully, you won't have detonation at lower rpms. If so, try a heavier spring and have full mechanical advance come in at 3200 or so. The end of the cam often has numbers that can be referenced. The pulley is bolted to the balancer by 3 bolts and the center crankshaft bolt. Remove all those and use a puller to remove the balancer. Hope this helps. Willie

pcguy2u

Guess I should find a suitable puller - that bad part is I don't have any room for much between the radiator and the pulley, and the radiator may not be removable without taking the front end off. Hope the puller is low profile.

Is the balancer keyed to the crank?

Just took the beast out for a detonation test and it passed so there appears to be some room for all in timing above the 31˚ that I was able to obtain yesterday. Will pull the distributor while the engine is down.

BTW, the initial timing is already set to 15˚

383vett

Try 19 degrees inital. That will give you 35 degrees which is a good ballpark. You do need a balancer puller, hopefully you will have enough room. The balancer is keyed to the crank snout and is indexed, unlike the LS motors.

pcguy2u

I'll try 19 and leave the distributor alone for the maiden run. A buddy is dropping of the puller and I may have this back together tomorrow??? Maybe Wed night - here's the beast.




I have the option of trailering it on a flatbed - if you had a choice, would you drive it or trailer it?

Thanks again Willie.....

383vett

Your welcome. Definitely trailer if you can, especially if this is the maiden run. Hopefully all will go well, but things break.

chaase