checking my engine out and this is what I found...

[kokonokeys]

I picked up this 1971 S.B. with a 1641 dp with dual carbs. it ran ok when I got it but I wanted to see what I had. The valves were out of adjustment but not horrible and it was in need of a tune up. I pulled the plugs and they are very dark. I would assume they have been there a while but never the less dark. I did a compression check.

Engine cold, valves in adjustment, crank the engine 8 times,

#1=120
#2=120
#3=90
#4=120

I added oil to #3 to see if that would improve the numbers but it made no difference. I even rechecked the valves but they are in adjustment. I know there are different ways to check compression and the numbers will very a bit warm or W.O.T. but this is what I got. I know the numbers are pretty far apart, but give me some thoughts or opinions.

It ran decent before and I plan to tune it up just to see how it runs with some new parts, but what would you do? I realize I am asking for opinions and expect to get a variety of them, but I would like to hear how other people would address this situation if you came across it. Mind you, I am a 9-5 blue collar father of two, who doesn't have thousands laying around for whatever I want. Not that I can't afford a motor, but you get what I mean. Thanks.

[A1steaksauce]

sounds like you got yourself a bad valve in #3. depending on where you are located, and your work space, dropping the motor to toss on a replacement head or get a quickie valve job done wouldn't be too hateful imo.

however that being said i'd also see what sort of numbers you get when it's warm. if #3 goes up and gets somewhat more inline with the other readings then i'd be tempted to just leave it alone. more so if this is just a toy and not a main source of transportation. but i'd be staying on top of the valve adjustments to keep an eye on things

[Schell R32]

yeah A1 has a point...but dont forget the dp heads tend to crack between the vlave way quicker that a 40 or single port....the #3 cyl tends to run the hottest as well and seems to always waste the areas between the valves...i literally have a dozen heads here with cracks between.

[kokonokeys]

sounds like you got yourself a bad valve in #3. depending on where you are located, and your work space, dropping the motor to toss on a replacement head or get a quickie valve job done wouldn't be too hateful imo.

however that being said i'd also see what sort of numbers you get when it's warm. if #3 goes up and gets somewhat more inline with the other readings then i'd be tempted to just leave it alone. more so if this is just a toy and not a main source of transportation. but i'd be staying on top of the valve adjustments to keep an eye on things

I'll do another check with the engine warm and see what I get. It is just a toy so I am thinking that if it runs out ok, I'll drive it for the summer and look into heads over the winter and just keep an eye on the valves as you suggested. Thanks for your input.

yeah A1 has a point...but dont forget the dp heads tend to crack between the vlave way quicker that a 40 or single port....the #3 cyl tends to run the hottest as well and seems to always waste the areas between the valves...i literally have a dozen heads here with cracks between.

When I get to the point where I pull the heads, I'll check for the cracks you are talking about. Are there replacement heads you would steer clear of, or would suggest when I get to that point? I don't mean the Asian built ones, because I know they are not as good quality. Thanks

[A1steaksauce]

you say it's a 1641 running dual carbs, is the bottom end stock as well?

if it turns out that the head is cracked like schell stated and if you wanted a bit more pep, then upgrading to a set of mild CB heads might not be a bad idea. throw in some ratio rockers (if your bottom end is stock, ie stock cam) and enjoy the added hp

that would be the best bang for the buck, and honestly pulling and replacing both heads isn't much more time consuming than doing just one side

[kokonokeys]

you say it's a 1641 running dual carbs, is the bottom end stock as well?

if it turns out that the head is cracked like schell stated and if you wanted a bit more pep, then upgrading to a set of mild CB heads might not be a bad idea. throw in some ratio rockers (if your bottom end is stock, ie stock cam) and enjoy the added hp

that would be the best bang for the buck, and honestly pulling and replacing both heads isn't much more time consuming than doing just one side

I am not sure if the bottom end is stock or not, but I kind of think it is.

who wouldn't want to add more hp. If I am replacing them anyway, I may as well spend a bit more money and get better performance. I just want to make sure I end up with decent quality so I don't waist my money. I will look into CB heads. Thanks again

[A1steaksauce]

I am not sure if the bottom end is stock or not, but I kind of think it is.

who wouldn't want to add more hp. If I am replacing them anyway, I may as well spend a bit more money and get better performance. I just want to make sure I end up with decent quality so I don't waist my money. I will look into CB heads. Thanks again

you can take a peak inside your motor when you pull your heads and have a look around to see what you have. also most cam's are stamped on the face, ie what size they are, so you can always pull the oil pump if you really want to know what you have. personally i'd pull back one of the jugs and take a look around in there with a flashlight. if i see a counterweighted crank and a cam gear that's bolted on instead of riveted i'd go ahead and pull the oil pump to see what i've got in there. if it's riveted on i would just stop there and i wouldn't go that deep into the motor.

stock bottom end with a nice set of heads and ratio rockers will make that thing come alive quite nice.

[kokonokeys]

you can take a peak inside your motor when you pull your heads and have a look around to see what you have. also most cam's are stamped on the face, ie what size they are, so you can always pull the oil pump if you really want to know what you have. personally i'd pull back one of the jugs and take a look around in there with a flashlight. if i see a counterweighted crank and a cam gear that's bolted on instead of riveted i'd go ahead and pull the oil pump to see what i've got in there. if it's riveted on i would just stop there and i wouldn't go that deep into the motor.

stock bottom end with a nice set of heads and ratio rockers will make that thing come alive quite nice.

Thanks for the tip. I'll have a look around when I get to that point. It would be nice to know what I am dealing with. Who knows?.?..Maybe there's a gem there and I just don't know it. Not likely, but we one always hope.

[kokonokeys]

Update:

I went ahead with the tune up as planned. I have been driving it for a couple of days now and everything seems OK. When I start the car cold, (no choke on carbs), it seems to miss a bit, but once it is warm, it idles and runs out smooth. I do notice that it has a very noticeable cough at lower RPM but that may be carb tuning or the 009 that is in it. I haven't found that gremlin yet. I'll be looking into that in the near future. I think I will drive it for the summer and look into the compression deal come fall. That way I can focus on other things that I need to fix, that are not too involved, and I can keep driving it for the summer.

[A1steaksauce]

motor coughing when cold at lower rpm is typical. i don't run the choke on my stock motor and it does that as well. i generally warm her up for a bit in the driveway before i take off down the street

[kokonokeys]

motor coughing when cold at lower rpm is typical. i don't run the choke on my stock motor and it does that as well. i generally warm her up for a bit in the driveway before i take off down the street

Good to know. At least I can check that off my list for things to work on. I will be warming this one up too before I take off somewhere. That is good practice anyway in my opinion. Overall, I am very happy with the results at this point. I have some minor tweaking to do, but that's the fun of owning a classic I think.