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Discussion Starter · #1 ·
I have a 54 dodge pickup with a flathead in it,
supposed to be very fresh, twin carters on an Offenhauser intale, Phillips performance 3 into one manifolds, phillips performance breathers, Mild Cam, Balanced etc. etc.
the problem is, this thing falls flat on its face, timing is set at TDC initial, and reaches about 18 degrees total timing, Ive syncved the carbs using a unisync., replaced every possible ignition component..tried the timing all over the place...stumbles like timing is out, but it seems to hold rock steady, ...heres my question..It only has about 11 inches of vacuum at an idle ...peaks at about 15...is this too low? ive heard a solid running flathead should have 20 inches, but im not sure with the twin carbs and the cam...im wondering if the cam timing could be off a tooth, when i got the truck the timing was out, and the guy had adjusted as far as he could ..and it was still too advanced..I had to loosen the secong adjusting bolt under the distributer on the flathead dodge and move that adjustment in order to move the distributer far enough to get this thing in time. doesnt seem bad with no load... but with any load this engine falls very flat ...stumbles studders misses all over the place....any opinion would be very welcome
Thanks
Al
 

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Has the block been ported and relieved, or just a stock rebuild with all the performance goodies added with no mods or enhancements to the engines breathing. Those engines have very low compression, around 6:1, so any little issue is probably magnified because of this. Its possible that the cam could be off a tooth, but the total timing advance seems too low to me. Many times people change cams and intakes and other things on these older engines, and then try to tune them using the stock tune-up specs.....and it usually doesn't work too good.
 

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Discussion Starter · #3 ·
i doubt much has been done...its probably stock other than the cam...Ive had a few flatheads in the past, and have never chased one like this...i was going to pull the timing cover this weekend and have a look...but its alot of messing around...and I want to make sure it even might be the problem...any idea of what this thing should have for vacuum?...Ive tried the initial timming all the way up to 10 degrees BTDC...and still no difference..the manual shows the stock compression at 8.5 to one...I called the guy that i bought the truck off and he assured me the engine is fresh...he has been honest to this point so I have no reason to doubt him...but he did say he could never get the thing to run properly after the rebuild....it ran faily poorly when I got it and the valves hadnt been set ...I have set the valves and it has amplified the problem...again it makes me wonder about cam timing...with the valves set..am i opening the valves even earlier now.
 

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Al, you might want to try and do a compression test, just to see if it is abnormally high or low. This might reveal to you that a valve timing issue is indeed the culprit. Again, it wont be an absolute smoking gun, but it could give you further insight as to what is going on in that area. And perhaps narrow down the things to check out, and help you resolve this....
 

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Yes, it will affect it. I suggested it to help narrow the search. As you pointed out, it is low considering what you know to be true about the engine. Again, not an absolute smoking gun, but it is kinda' pointing in that direction. Also, these engines are gear drive, if I remember correctly, and it is an easy mistake to get the teeth off when assembling the engine,as compared to engines that have timing chains.
 

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Discussion Starter · #7 ·
thanks,
I have a 360 waiting in the wings to go into this truck...I want a drivable rod..I have a 29 model A all stock if I want something hard to drive,
but I want this thing running properly before it comes out, I want to be able to sell the drive train to someone and still sleep at night, I guess Ill pull it down this weekend and see what ive got...I hate doing it because the truck has really nice paint...and accidents happen
 

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Al, im sure your comfortable with the diagnoses that you have performed on the engine yourself, like ignition timing and valve adjustment and carb tuning. And going off the info the previous owner gave you regarding the condition of the engine and 8-1/2:1 compression, as you discovered, the compression test didn't really confirm that with your readings of 95 lbs. So, you can draw several conclusions from this, either the overall compression is much lower than he stated to you, or that there is some valve timing issues to investigate as we have been discussing. I would ask the previous owner to confirm his earlier statement one last time before I tore into the engine about the 8-1/2:1 compression, and how he arrived at this. All the literature I have ever seen for these Flatheads have shown their compression to been much lower. So just to eliminate that possibility all together, I think you should seek to discuss it with him one more time before you tear into it. Good luck.
 

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Discussion Starter · #11 ·
it wasnt the previous owner that gave me the 81/2 number ...I got that number from an original factory service manual that I have for the truck...i do beleive that the engine is fresh...when i pulled the side covers to set the valve lash, the paint under the cover was new...so it wasnt just a repaint..the lifter gallery was very clean, and the lifters di appear to be new...he also told me that he had to put a new crank in it because of a crack foung when the original was checked, hes not an engine guy..he had it done at a shop...but if he is telling stories..i think its because someone has lied to him about whats been done, this guy comes across as a straight shooter...and EVERYTHING else on the truck is new...this guy put some real money into this thing
 

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flat dodge

sounds like part of the problem could be carbs,they must be crect geting not just 2 stock 1s also acelerator linkage must be good no slop, if both carbs open befor acel pumps squirt this will creat a bog,or high float levels etc. to much fuel can wash the cylenders creating low comp . sqirt oil in all cyl roll over a few times then do comp test,carc at idel then full open. block off fuel linto carbes befor test to be sure cylenders not washed, even start and run till it stops out of fuel. you might even block off 1 carb after and test run after. good luck cliff
 

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Discussion Starter · #13 ·
yes i agree...as far as the jets go im not sure whats in there..these carbs are the carter ball n ball style...they have three settings for the accelerator pumps, I have tried them all, with no real change they seem to be dumping enough fuel...I tried disconnecting one and it was definitely starving., but the plugs do show signs of getting carboned up...not wet but sootty black .im not really a carb guy and when you read how to set the idle mixtures it says till it runs smooth...well that doesnt really help with dual carbs...I have them now at about 3/4 turn from a gentle seat...I have no idea if this is right., but it idles not bad...the engine does sound very cammy...however with the two three into one manifolds, and it running like crap..it would sound cammy.the Offenhauser dual carb linkage is junk..really hard to keep tight, but it seems to be holding...i have tried about everything I can think of on this thing...you would think a Flathead would be easy
 

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Discussion Starter · #14 · (Edited)
well heres what I found..Thought I would try one more thing before getting into the engine, I made up a blocker plate, and removed one carb, still ran like crap...went to put the carb back on and realized that the Offenhoauser intake had no vacuum ports to match the vacuum ports in the bottom of the carb..removed botn carbs, drilled the intake, removes the mickey mouse spacers that had been installed below the carbs, and reinstalled with some new gaskets, re sync'd and runs like a charm...havent done a compression check again, or checked vacuum, but it runs great, so neither one of those things where high on my priority list...putting on some miles was
thanks for your input on this, im no dummy, but this thing had me frustrated. not being the one to put it together, sometimes troubleshooting can be tough...this forum will be a great help...
 
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