dorcutt
Member
I just picked a 57 truck to add with my 51. The question I have is how do I confirm the engine is the original or not. I tried to add some pictures of both the truck and the block numbers on the engine.
-
We have upgraded our forum software! See here for details.
New truck
- Thread starter dorcutt
- Start date
The FSM will break down the casting and serial #'s, that looks like a later serial # to me, do you really care what year the 235 engine is ? .
Post better pix of the entire engine too, plus the casted in cylinder head # on the left forward top of the head .
Post better pix of the entire engine too, plus the casted in cylinder head # on the left forward top of the head .
dorcutt
Member
Not really Nate, more curious than anything. I’m not sure I would know how to confirm whether or not the engine is original or not. Thanks, Dave
P.S. Will work on pictures
O.K., that's the last and best 235 cylinder head, it resists cracking very well .
Just adjust the valves, set the dwell to 33 degrees on the fly then set the ignition timing to ball on pointer at or below 700RPM .
There shouldn't be any vacuum signal to the distributor @ idle .
These are very fine trucks, I let my '55 2 ton tow truck go in the late 1970's and miss it still......
Just adjust the valves, set the dwell to 33 degrees on the fly then set the ignition timing to ball on pointer at or below 700RPM .
There shouldn't be any vacuum signal to the distributor @ idle .
These are very fine trucks, I let my '55 2 ton tow truck go in the late 1970's and miss it still......
dorcutt
Member
Thanks Nate, I have a little dilemma, this truck has a TH 350 tany in it and an updated starter so it doesn’t have any window to time it like it is on my 51. Nor do I see any marks on the harmonic balancer. Time it by ear ?
Bill Hanlon
Member
You could find a place to mount a pointer near the balancer, use a piston stop to determine TDC and then scribe your own mark on the balancer.
A TH350 eh ? . nice .
I suggest finding a tachometer and vacuum gauge .
Set the idle by ear to the smoothest you can @ 700 ~ 900 RPM then connect the vacuum gauge to the manifold vacuum and slowly move the distributor whilst you watch the vacuum gauge, it'll rise and after a while begin to twitch as you get too much advance ~ back it off slowly until you get the highest steady vacuum signal, snug up the dizzy's pinch clamp and your done .
Don't worry about the exact inches ov vacuum as it depends on the condition of the engine, who built it, where in it's wear cycle and so on it is .
You might get a nice steady 21" of vacuum @ hot idle, you might het 15", as long as it runs out well you're good to go .
Of course, you've already either converted it to some sort of breakerless ignition or bought and learned how to use, a dwell meter ? .
Pertronix or HEI, both are good, open the spark plug gaps to at least .035" (points) or .040" ~ .055" (any breakerless system) .
I suggest finding a tachometer and vacuum gauge .
Set the idle by ear to the smoothest you can @ 700 ~ 900 RPM then connect the vacuum gauge to the manifold vacuum and slowly move the distributor whilst you watch the vacuum gauge, it'll rise and after a while begin to twitch as you get too much advance ~ back it off slowly until you get the highest steady vacuum signal, snug up the dizzy's pinch clamp and your done .
Don't worry about the exact inches ov vacuum as it depends on the condition of the engine, who built it, where in it's wear cycle and so on it is .
You might get a nice steady 21" of vacuum @ hot idle, you might het 15", as long as it runs out well you're good to go .
Of course, you've already either converted it to some sort of breakerless ignition or bought and learned how to use, a dwell meter ? .
Pertronix or HEI, both are good, open the spark plug gaps to at least .035" (points) or .040" ~ .055" (any breakerless system) .
dorcutt
Member
Thanks guys. Good suggestions. I do in fact have a both a tach meter and dwell meter and believe it or not know how to use them. I’ve had good luck with the pertronics on my 51 so will probably upgrade in the future. I had a Tr6 I used it on that worked well so I’m sold.
Bill/Nate not being a master mechanic not shure how to confirm TDC. I know there is a power stroke and and exhaust stroke so I think I have to look at the valves position to confirm. Can you guys confirm the best way to find TDC. This thing is stretching my brain a bit which I’m enjoying. Many thanks, Dave
Bill/Nate not being a master mechanic not shure how to confirm TDC. I know there is a power stroke and and exhaust stroke so I think I have to look at the valves position to confirm. Can you guys confirm the best way to find TDC. This thing is stretching my brain a bit which I’m enjoying. Many thanks, Dave
Bill Hanlon
Member
A piston stop is basically a bolt with a rounded tip. It screws into #1 spark plug hole. The tip of the bolt extends slightly into the cylinder.
Start with the #1 piston down in the hole quite a bit. Verify that piston is down using a soda straw.
Install the piston stop.
SLOWLY/GENTLY rotate the crankshaft clockwise until the piston contacts the piston stop.
Find a place on the engine very near the harmonic damper/crank pulley to put a fine mark. I used a center punch to make a dimple and then touched the dimple with a single paint brush bristle and white paint.
Mark the adjacent point on the damper/pulley with a fine paint mark.
SLOWLY/GENTLY rotate the crankshaft counter clockwise until the piston contacts the piston stop.
Mark the adjacent point on the damper/pulley with a fine paint mark.
Remove the piston stop.
TDC is exactly in the middle between the two marked points on the pulley. Use a center punch, dremmel tool, engraving tool or such to mark the pulley/damper to mark the pulley. Paint the mark.
Getting additional markings requires measuring the diameter of the damper/pulley where you marked it. Let's say it was 8 inches. Then solve for arc length (A) using the formula A = Diameter * 3.14 * degrees /360. So 5 degrees advanced would be 0.348888888889 inches clockwise from the TDC mark on the pulley. Or you may be able to find a way to mount a metal pointer to the block or timing cover and use it. Just make sure the zero point on the pointer is adjacent to the TDC mark you made above.
Hot Rod Magazine's web site has a pretty good article about this here How to Accurately Determine Piston TDC - Hot Rod Network although the head is removed and they are using a small block Chevy V8. Procedure is the same.
Start with the #1 piston down in the hole quite a bit. Verify that piston is down using a soda straw.
Install the piston stop.
SLOWLY/GENTLY rotate the crankshaft clockwise until the piston contacts the piston stop.
Find a place on the engine very near the harmonic damper/crank pulley to put a fine mark. I used a center punch to make a dimple and then touched the dimple with a single paint brush bristle and white paint.
Mark the adjacent point on the damper/pulley with a fine paint mark.
SLOWLY/GENTLY rotate the crankshaft counter clockwise until the piston contacts the piston stop.
Mark the adjacent point on the damper/pulley with a fine paint mark.
Remove the piston stop.
TDC is exactly in the middle between the two marked points on the pulley. Use a center punch, dremmel tool, engraving tool or such to mark the pulley/damper to mark the pulley. Paint the mark.
Getting additional markings requires measuring the diameter of the damper/pulley where you marked it. Let's say it was 8 inches. Then solve for arc length (A) using the formula A = Diameter * 3.14 * degrees /360. So 5 degrees advanced would be 0.348888888889 inches clockwise from the TDC mark on the pulley. Or you may be able to find a way to mount a metal pointer to the block or timing cover and use it. Just make sure the zero point on the pointer is adjacent to the TDC mark you made above.
Hot Rod Magazine's web site has a pretty good article about this here How to Accurately Determine Piston TDC - Hot Rod Network although the head is removed and they are using a small block Chevy V8. Procedure is the same.
dorcutt
Member
Thanks Bill. Good explanation. Question how long should I make the piston stop?
Bill Hanlon
Member
I'd buy one.
Here is one from Summit Racing Summit Racing® Piston Stops SUM-900189
It needs to thread into the spark plug hole and be adjustable once it is in to just barely keep the piston from reaching TDC.
dorcutt
Member
Thanks, got it. will look it up
dorcutt
Member
Thanks Nate. Will have to dig out my vacuum gage.