Hey fellas! I was running a good distance from home when my primary power valve let go ( Holley 94 ) but I had to get home. I remedied the power valve but now it's just not running like it was. Exhaust tone not the same, sleepy on accel from cruising speed and just doesn't have the power it did. I've set the distributor timing with the 3/8" method, checked my points gap, checked the timing, compression test shows 125-127 psi on all cylinders. BUT, vacuum gauge bounces between 14-19 Hg/in. at idle and now I'm drawing a vacuum at the dipstick tube. Any ideas on where to go from here? Thanks for your time, greatly appreciated! Jim Sgrig
If you have vacuum at the dipstick tube, you would have to have an intake gasket and/or manifold leak.
No PCV, vacuum fluctuates between 14-19 Hg/in. According to the chart it says loose valve guides. Would they have worn out that fast from raw fuel?
Would that give me the funky vacuum gauge readings? I did replace the gasket when I adjusted the valves and it ran fine. It’s only been since the raw fuel through the power valve port. The valves really started to rattle during the rest of the trip home after the PV went bad. Could a few valve guides wear enough to create enough clearance to cause an internal vacuum leak?
I have no experience with FlatHeads but an engine is an engine. Question, how could you get vacuum at dip stick to begin with? What I mean is, are you not using a breather cap? If not maybe you sucked in the intake gasket?
I thought that at first too, until it dawned on me with the Flathead style valve guides. Flatheads will suck air past/through broken or worn valve guides…
Pulled the intake…good seal all around. While grasping the valves and shaking side to side by hand on the intake valves that were at the bottom of the cam lobes and I get noticeable lateral movement and you can see the stem move while peering down the intake port. Seems excessive to me. Is there a spec for lateral movement or play? I’ve also noticed it has the 2 piece guides with the tulip valves. While prying down on the guides through the port, they move quite easily. Is this normal? It does have the adjustable lifters. How high are the guides supposed to sit above the floor of the port? I’ve go what looks like 1/8-3/16” above. Is THIS normal? I want to thank everyone for their input up to this point, more would be greatly appreciated! Thanks fellas!
Yes, they are… I’m concerned with the amount of lateral movement in the valve stems and the ease at which I can pry the guides down. I don’t know how normal this is… I’m gonna hafta buy a manual I suppose….
Yes it is normal for the valve guides to stick up in the ports. On race engines we cut them down on a lathe to match the bottom of the port to eliminate air restrictions.
Well, I’ve ordered the valve changeover kit from Reds…disassembly will start this evening. I’ll be installing a new clutch while it’s down… Thanks everyone for their input, greatly appreciated!!
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