1975 engine pinging/tapping noises

[Jmack223]

Hey guys!

So I've just put my bus engine back together. Now I have this pigging/tapping noise whenever there is load on the engine. I can rev it up with no noise oat all but as soon as I put it in gear and give it some gas this very loud tapping starts.

Sounds like it could be the valves but shouldn't I still hear it when the engine is revved up in neutral? Could it be the exhaust? Blent valves? Only happens with load so I'm not sure what to think of it. Thanks guys!


Also I could not do a proper timing as I could not find my timing gun. I have fiddled with it for hours and tried it really retarded so I doubt it coul be dentination

[ccpalmer]

Possibly the CV joints making noise?
_________________
'71 Westy

[Lil Lulu]

Exhaust leak? Check the header to head connetors.
_________________
'65 Beetle "Lil' Lulu"- Ruby Red
1600 stock from '71 bus

'72 Deluxe - Niagara Blue w/pastelwiess Camper Special 2L dual 40 Webers 002

'74 Hightop Weekender "Dixie" 1800 34 Del singles

[Wildthings]

Best not to run your engine without having timed it with a gun at full revs. At least check and set the timing very carefully statically at 7.5° BTDC following the advice in Muir's idiot book.

You do have a timing scale don't you?

[raygreenwood]

I know I say this a lot but its worth asking. I am assuming this is a type 4?

What was done? Rebuild? Just a refresh? Did you change the cam or oil pump?
Is so.....what was the gap between highest point of the cam gear and any points on the pump? Ray

[Randy in Maine]

[Jmack223]

[Tcash]

If you have solid lifters adjust your valves first.
Link:solid or Hyd

This is a bug, but it will give you the idea.
You want to set yours to 5 deg ATDC (after top dead center).

Link


After you have static timed it. Start the engine and with a gloved hand, pull one plug wire off the dist. cap at a time and see if the noise goes away.
The noise goes away you have a problem with that cylinder.
If you want to try and make it home.

FI engine: You could pull the injector wire on that cylinder and tape it off so it is not spraying fuel into that cylinder and pull the spark plug so it is not building compression.

Good Luck

[Randy in Maine]

You don't need the RPM gauge, just a real timing light and the timing scale.

[Wildthings]

[Tcash]

Good Point Wildthings.
I did not take into account that the 75 distributor vacuum can has the Retard function.

75 specs
Advance/Retard Range: Vacuum: 8-11deg Adv @ 7.9 In. Hg, 11-13deg Ret @7.9 In. Hg; Centrifigual: 11-17deg @ 2000 rpm, 21-25deg @ 3600 rpm

An initial dynamic timing of 5 deg atdc.
With the Retard(later) range being 11-13 deg. would be subtracted from the initial 5 deg atdc.

Therefore starting the engine up, retard hose disconnected the timing would be 6-8 deg btdc. Connecting the hose would retard(later) the timing to 5 deg atdc

atdc(later)--------------tdc--------------------(sooner)btdc
---------------5-4-3-2-1-0-1-2-3-4-5-6-7-8----------------

So Static timing would be 6-8 deg. btdc.

[Tcash]

double post

[Jmack223]

Thanks for all the good info guys! I'm going to do the timing as soon as I get back!

[udidwht]

The video above is not how one should time their engine...it'll get the engine started but one still needs to be certain what the distributor is putting out at full advance which is critical given you don't drive down the highway at 7.5 degrees advance.

This is a major issue with Youtubers...putting out less than complete honest straight forward answers.
_________________
1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires