Engine run 1st time for me, now issues

[Speedbumpauto]

When did a 77 Chevy 350 engine stop having a bypass in the water pump?

[geezer#99]

The hired hand!
Would he be the one with the specs on who's leaned over the motor tweaking the carb when you first started it?

[geezer#99]

Originally Posted by Speedbumpauto

When did a 77 Chevy 350 engine stop having a bypass in the water pump?

They did have one but without a bypass like your heater core provides you get hot spots in the heads. Water pump bypass doesn't help with that.

[yossarian19]

Originally Posted by nvrdone

Check your timing. If timing is off it will cause low vacuum and hot running

Yep.

[Speedbumpauto]

No offense, but I think the heater bypass idea is bad info. Chevy trucks like ours were offered without a heater from the factory. Did they have hot spots? I don't think the designer/engineers would have allowed that or at least if it seemed to be a problem, they wouldn't have allowed the same design to be used for 40 years. I have built and/or seen hundreds or even thousands of open street rods and T buckets without heaters that have small block Chevys and I've never witnessed this problem or the fix shown. I'm open to new thinking but I'd like to see a little proof.

[geezer#99]

Originally Posted by Speedbumpauto

No offense, but I think the heater bypass idea is bad info. Chevy trucks like ours were offered without a heater from the factory. Did they have hot spots? I don't think the designer/engineers would have allowed that or at least if it seemed to be a problem, they wouldn't have allowed the same design to be used for 40 years. I have built and/or seen hundreds or even thousands of open street rods and T buckets without heaters that have small block Chevys and I've never witnessed this problem or the fix shown. I'm open to new thinking but I'd like to see a little proof.

All the factory heater delete vehicles I've encountered had some sort of bypass.
However like you I've seen many street rods without any bypass, but at the same time heard lots of complaints about running hotter than expected.
I've tried running them that way but with a bypass they ran cooler.

[Speedbumpauto]

As to the original overheating question, I just can't see the bypass or lack thereof, being a problem as the T stat is (hopefully) fully open, directing as much hot coolant as it's design allows to the radiator. In this situation, I can't see where a bypass located in the front of the manifold where the T stat opening is can help at all. As a matter of question, seems it could hurt as it is only directing heated coolant back to the water pump without the advantage of going through a heat exchanger. IMO, Yoshi needs to look in another direction to solve his heating problem.

[OrrieG]

Good point, I assumed that since the radiator coolant was getting hot the t stat was operating correctly. Seems like very simple first dianostic would be to mark the current distributor position, then adjust timing (probably advance) to see if vacuum increases. In the old days I would go for maximum vacuum and best running then back it off a few degrees. Doesn't cost anything and if does not help you have a mark to reset the dist to where it was. If you have to really crank it then might be off by a tooth, they will run retarded a tooth, but not too good advanced one, lots of carb backfires.

[Speedbumpauto]

Agree. Quick and dirty with minimal tools, even just your ear if it's trained.

[yoshi]

Ok quick update before I head home, piston stop fitted turned engine put mark where it stopped. Turned engine the other way, stopped at 4 deg (after) on the timing plate.

[Speedbumpauto]

True TDC is the point exactly in the center between your mark on the balancer where it stopped in one direction and your mark where it stopped in the other direction. Measure 1/2 way between those marks and scribe a line on the balancer. That is true TDC in reference to the timing mark or pointer on the timing cover you used to make the marks on the balancer when you rotated the engine in each direction. Now you can accurately check the timing with a light.

[yoshi]

Ok home now, I reckon the mark must be in the centre of the engine @ TDC. I checked the fan & it was drawing air from the engine bay through the rad. In my hast to get it wired up ready for starting the engine I wired it up the wrong way! Oh well you live & learn & no one was injured! I got some 3/8 fittings & some hose to fit a bypass but was unable to as it's 1/2" doh!

[yoshi]

Cooling seems to be sorted now by moving the rad into the engine bay & pulling air through. Dolphin gauges are showing needle between 180-210, but at least the rad didn't empty itself this time. Cap is 20lb. Timing was set at 32 deg on Saturday. I haven't got a timing gun yet, when I turn the dizzy slightly anti clockwise the vacuum increases a little & the rpm increases too, and the opposite if I turn it clockwise.

[geezer#99]

Excellent!
Don't get too carried away with that 20 lb rad cap. That style of rad doesn't like more than 12 to 14 lbs.

[yoshi]

Do you think it's worth me upping the fan to a 14"?

[geezer#99]

I'd wait and see if you need it, once you get your front end all togethor. Get your timing set and carb tuned and go from there.
Where in the uk do you live?

[yoshi]

Most easterly point, about 2hrs from london

[geezer#99]

Reason I asked was to know how close to sea level you live.
That info can effect your tune.
I see your dizzy is lacking a vac advance. You might need vac advance to optimize your tune. Depends how your carb reacts to mixture adjustments.

[yoshi]

Actually where my truck is at the moment http://www.itv.com/news/anglia/topic/lowestoft/

[Highsider]

Originally Posted by geezer#99

Don't get too carried away with that 20 lb rad cap. That style of rad doesn't like more than 12 to 14 lbs.

In my post above, I forgot to mention I am using a new 7-pound radiator cap which is the stock rating, to get that 190 degree result.
It does dump a considerable amount of coolant into the overflow tank, but it all draws back in when it cools.
I am very pleased!

[yoshi]

Ok so cooling sorted (fingers crossed) it wasn't breathing when I fired up to check cooling so that's good. I can't see or feel any vacuum leaks. So where do I go from here? Remove timing chain cover to check timing?

[geezer#99]

What exactly is it doing?

[yoshi]

Low vacuum about 5-6

[geezer#99]

Big cam, lack of timing does that.
What rpm are you idling at?
What's your base timing?

[yoshi]

When we finished on Saturday it was timed up at 32 deg, no rev counter yet. http://youtu.be/S4oyeQrtClA