slicknapier Posted June 17, 2009 Report Share Posted June 17, 2009 So I finally did a compression test on my straight six and I have no compression in #5 and 6 cylinders. I did the leakdown test a little wrong (not a top dead center), so I really don't know if it's valves, rings, or what. Looking at the cost of rebuilding my motor I think I might switch to a slant. I have a good running slant six with an 833 overdrive trans that I can put in the car to save a little $$$. I would like to eventually build a hopped up flatty for it, but just not now. So my questions are does anybody have any good pics and info to pass along? I did a search and didn't come up with much. Any info is greatly appreciated! thanks, andrew Quote Link to comment Share on other sites More sharing options...
BobT-47P15 Posted June 17, 2009 Report Share Posted June 17, 2009 I'm not sure a slant 6 is an easy swap from a flathead. But, I'll let others who know more talk about that. Quote Link to comment Share on other sites More sharing options...
RobertKB Posted June 17, 2009 Report Share Posted June 17, 2009 If 5 and 6 are both low it could well be the only problem you have is a blown head gasket. Worth checking and a pretty cheap fix. Quote Link to comment Share on other sites More sharing options...
TodFitch Posted June 17, 2009 Report Share Posted June 17, 2009 What ever happened to the old "ring and valve job" that used to be considered normal? Seems like everyone nowadays goes for a whole engine rebuild. Yeah, you should look at and check other stuff when you have the engine open (condition and clearance on bearings, etc.). But I'd be surprised if a DIY ring and valve job would cost more than a few hundred dollars and it would probably give lots of new life to older engines, especially those which have good oil pressure. Quote Link to comment Share on other sites More sharing options...
owrecker Posted June 17, 2009 Report Share Posted June 17, 2009 the one way i used to find out if it was rings or valves was to put squirt a little oil in cylinder then check the compression if the compression was good then its the valves if if not then the rings are bad TOM Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted June 17, 2009 Report Share Posted June 17, 2009 Tod..that day is gone, machinists got everyone cowered to the point that if it is not bored and such it is of no value..these old cars were often re-ringed, inserts etc at 55-75 thousand miles...in the car...from crawling under on a creeper or leaning over the fender..Have helped with a many of these 8 hour overhauls were the heads were the only thing sent out for a quick visit to the machine and back with a 4 hour turn around..(pre-scheduled events) actually a couple of these jobs can be done between re-bores...if the taper is not beyond service standards..sure gives a block long long life service Quote Link to comment Share on other sites More sharing options...
RobertKB Posted June 17, 2009 Report Share Posted June 17, 2009 My ' 53 Plymouth had rings and a valve grind at 72,000 miles. Used the old bearings as they were within factory specs and I had good oil pressure. Car now has 94,000 miles and still has good oil pressure and the compression is good. Does not use oil. As Tim said, job was done with engine in the car and only pulling the pan and head. A very slight ridge was removed before taking out the pistons and cylinders were honed. I plan on doing nothing until my engine tells me it needs further work. Quote Link to comment Share on other sites More sharing options...
slicknapier Posted June 17, 2009 Author Report Share Posted June 17, 2009 Sounds like good advice. Should I start by pulling the head and checking things out, valves, rings etc...My engine has good oil pressure and doesn't seem to use any oil. Maybe I should redo my leakdown test to reconfirm my situation. Just to clarify, remove sparkplugs, get the cylinder I'm checking at TDC, apply air pressure. If it leaks out the exhaust, exhaust valve is bad. Intake leak, intake valve bad, out the breather rings are bad? thanks guys.. Quote Link to comment Share on other sites More sharing options...
Olddaddy Posted June 17, 2009 Report Share Posted June 17, 2009 You can install the slant/6, but you will have to cut the firewall, or move the radiator forward and run an electric fan. I was planning to do it on my 50 Suburban, but decided to stay with the flathead for sentimental reasons. I've got a built slant/6 with 2bbl carb and automatic if you decide to go that route. Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted June 17, 2009 Report Share Posted June 17, 2009 (edited) Actually a slant 6 is 27" long not the 25" that was mentioned earlier. You could make it fit but the cost would be high. The flathead 6 is a really good dependable engine. Here is a chart you can use. Edited June 18, 2009 by Don Coatney Quote Link to comment Share on other sites More sharing options...
slicknapier Posted June 17, 2009 Author Report Share Posted June 17, 2009 thanks...i will do the tests again and keep you guys posted... Quote Link to comment Share on other sites More sharing options...
TodFitch Posted June 18, 2009 Report Share Posted June 18, 2009 Sounds like good advice. Should I start by pulling the head and checking things out, valves, rings etc...My engine has good oil pressure and doesn't seem to use any oil. Maybe I should redo my leakdown test to reconfirm my situation. Just to clarify, remove sparkplugs, get the cylinder I'm checking at TDC, apply air pressure. If it leaks out the exhaust, exhaust valve is bad. Intake leak, intake valve bad, out the breather rings are bad? thanks guys.. Maybe add to that list, out the adjacent cylinder means bad head gasket. I guess I haven't been caught yet with a problem with my head studs (they went to bolts later) so the only thing I don't like about removing and replacing the head is that I have to drain the coolant. And on my 1933 the radiator drain valve (the four letter word starting with "c" for a drain valve does not pass censorship on this site) is located in such a place that there is guaranteed to be some mess. So pulling the head to see what the issue is should not be a huge job. And then you can look at the valves, valve seats, head gasket and ridge at the top of the cylinders. From the description a bad head gasket seems most likely and would be an easy fix. I got a lot of miles out of a "shade tree overhaul" when I first got my car: Just drop the pan, pull the head, examine the parts and replace the obviously broken stuff. In my case I replaced the pistons (broken ring groove tops), rings, and replaced three badly burned exhaust valves. All done in the parking lot of the apartment complex I lived in with no more than hand tools. Ran fine after that. Even drove it from Maryland to California after that. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted June 18, 2009 Report Share Posted June 18, 2009 you talking about the rooster valve eh..looks like petcock is a go though... Quote Link to comment Share on other sites More sharing options...
Brendan D25 Posted June 18, 2009 Report Share Posted June 18, 2009 As Don C. said the slant six is 27" long and you will lose the park brake and maybe have to use the rearend from the donor car if you have one. Nothing is impossible if you have a torch:) but have a closer look at your flathead. Quote Link to comment Share on other sites More sharing options...
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