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If the Cutlass crankshaft has a big "N" on it, use it. Even the lightweight crankshaft will be fine for your build. All the 260 through 403 use the same specs for connecting rods. The 403 are a psychically bigger rod but the dimensions you show are the same. Can your rods not be resized? I have seen reman stock rods on Ebay and places like Summit. Otherwise aftermarket performance rods start at about $500 US a set. It is awesome that direct fit performance rods now exist. Good luck.
I have got a standart crankcshaft 393654. There's no "N" Sign.
I will prefer using light crankshaft version because there is no need to balance. Balancing cost about 500$....
I've found connecting rods remanufactured by Falcon Company. Can somebody tell me how they back to OE-size? I am talking about big end bore diameter?
My connecting rods are junk...
I would still balance it. External balancing will be cheaper. The Speedpro should be a similar weight but still might be a noticeable difference. I would weigh both a stock piston and rod, along with a Speedpro piston and rod on an accurate gram scale.
I would still balance it. External balancing will be cheaper. The Speedpro should be a similar weight but still might be a noticeable difference. I would weigh both a stock piston and rod, along with a Speedpro piston and rod on an accurate gram scale.
I am still Looking for such connecting rods with dimensions : center to center 6,000, big end bore 2,250 , small end bore about 0,980. My Engine was produced by gm. I only have "XC" sign on connecting rods. Maybe somebody have such rods or help me to find in US? I disbelive that was only produced to sevilles Engine. Have a nice day! Johnyy
Unfortunately I tossed all my stock rods. All gasoline Olds 260, Olds 350 and Olds 307 through 84 use the exact same press fit connecting rods. Put a request in the parts wanted section on this site. Good luck.
Hello Guys!
I've bought 8 remanufactured connecting rods in really good price 250$. https://www.cleggengine.com/
Boys from cleggengine are realy helpful,they have a lof of knowledge.
They preapred a set of rods with the same weight like my.
I have another question. I have new valves, valve stem diameter is 0.341 in.
I need to rebuild my valve guides. I found new guides, with inside diameter 0.3450 in. or 0,3430 in.
In my opinion 0,004 in. between valve stem/guides is to much. 0,002.in will be ok? I am talking about valve guides made from iron.
Have a nice day!
The .0343" guides should work. They can hone extra clearance in the new guides, especially needed on the center exhaust guides. I believe you want .0028" minimum clearance on those due to the extra heat off the big crossover port. Especially necessary on a cast iron guide, there are better bronze alternatives. Too many Olds guys have had heads rebuilt and those exhaust valves stick open, which is obviously bad. Good luck.
Hi Guys!I'm going to deliver the heads in the next few days to Machinist Shop, but I have some questions / doubts.
I have 3A heads with chambers 75cc. I need to mill them down to get 68cc.
So 7cc x 0,006 = 0,042 inch.
I have put data in compression calculator - everything seems correct. What do you think? compression ratio caltulator
I also found information about milling intake size 1:1 with head size?
I ve also put 6mm plate and weld the center crossovers.
Last edited by Johny; December 31st, 2022 at 02:28 AM.
CC the heads before getting them cut. They can be more or less than the 75 CC advertised. I found #8 heads to measure 1 to 2 CC less than the 79 CC spec. Most early heads are 2 to 6 CC more than the 64 CC spec, according to Classic Oldsmobile owners. There is very little info on 3A heads, other than they crack and flow the worst of any Olds 350 head. Are you planning on aftermarket composite or the factory stye shim gaskets? If you are using the factory shim style, one to one should work fine. The aftermarket composite are considerably thicker and may need more than the 1 to 1 to properly fit. Good luck.
CC the heads before getting them cut. They can be more or less than the 75 CC advertised. I found #8 heads to measure 1 to 2 CC less than the 79 CC spec. Most early heads are 2 to 6 CC more than the 64 CC spec, according to Classic Oldsmobile owners. There is very little info on 3A heads, other than they crack and flow the worst of any Olds 350 head. Are you planning on aftermarket composite or the factory stye shim gaskets? If you are using the factory shim style, one to one should work fine. The aftermarket composite are considerably thicker and may need more than the 1 to 1 to properly fit. Good luck.
I bought Cylinder head gasket - Fel-pro 8506pt:
Specifications Head Gasket Bore 4.130" Head Gasket Manufactured Thickness .0396" - .0484" Material
And I have bought standart Valley gasket from Fel-pro.
The Felpro head gaskets will be .042" compressed. Remember the amount the piston is below deck will also affect final compression. What cam did you settle on?
Last edited by olds 307 and 403; December 31st, 2022 at 10:47 AM.
The Felpro head gaskets will be .042" compressed. Remember the amount the piston is below deck will also affect final compression. What cam did you settle on?
Camshaft is the last thing I will buy. After I get the end datas about CR, heads flow (portong/bowling) etc.
I want to stay with good low and middle range, good vacuum, flat tappet cam.
Honestly, with a clean up mill on the block and heads, if the 3A currently measure 75 CC, you will be at low 9 to 1 compression. That should be perfect with a mild cam and 89 octane. Are you zero decking the block? Are you getting the 3A heads flowed on a bench?
Honestly, with a clean up mill on the block and heads, if the 3A currently measure 75 CC, you will be at low 9 to 1 compression. That should be perfect with a mild cam and 89 octane. Are you zero decking the block? Are you getting the 3A heads flowed on a bench?
No I don't zero decking.
3a heads will be flow on a bench after porting.
They will get also biger Milodon valves: in take 2,07 exhaust 1,624
Why not to get cr about 10? With 89 octane
Just make sure to have them crack checked. Those 3A heads are known to crack. They will need a lot of bowl and port work to flow any decent numbers. Guys have gotten 400+ HP with 9.5 to 1, good port work, even #8 heads and right cam on an Olds 350.
Can somebody tell me about conecting rods orientation? In Chillton manual for Cadillac's, there was said about oil spurt hole. I don't have any holes.
I bought 8 remanufactured conecting rods from Cleegs Engine.
About my 3a heads my machinist sugessted to mill down 0,018 inch. We will have CR about 9,5 to 1. We will see. So we start 0,018inch and check everythink one more time.
A few days ago I picked up the heads from machinist. They made a lot of work:
- new valve guids
- new valves intake 2,07 and exhaust 1,62
- milling heads 0,018 inch
- milling intake side 0,018 inch
- milling exhaust side
I have measured cylinder head Volume after milling, we get 73cc. ( I had 75,5 before). I put new datas in CR calculator: new CR 9,414:1.
Now i will work on porting ( bowling ).
I am looking for new cam ( flat tap). What would you recommend?
Good idle, god low and middle range, oem converter, th400.
Those heads look really nice, nicest 3A I have ever seen, glad they were crack free. Are you upgrading the converter or changing the rear gear ratio? The factory, guessing 1600 stall in the TH400 and probably low 2 to 1 rear gears will effect cam selection a lot. Also what is your Quadrajet off? The late 70's models are superior to older carbs. Problem is, every year newer, the leaner the idle calibration, which don't like larger camshafts.
Last edited by olds 307 and 403; March 10th, 2023 at 04:56 AM.
Those heads look really nice, nicest 3A I have ever seen, glad they were crack free. Are you upgrading the converter or changing the rear gear ratio? The factory, guessing 1600 stall in the TH400 and probably low 2 to 1 rear gears will effect cam selection a lot. Also what is your Quadrajet off? The late 70's models are superior to older carbs. Problem is, every year newer, the leaner the idle calibration, which don't like larger camshafts.
I have Rochester Quadrajet 4- barrel carb with ID number: 17058213. Its from 1978, 750cfm, produced for Chevy.
Th400 with ID number 78AC018826 with electric kick-down and standard ratio: 1st: 2,48:1 2nd:1,48:1 3rd: 1,00:1
Rear diferential ratio: 2,56 :1 but I will check it tommorow. Car weight 4280lb.
I want to stay with mechanical fuel pump and standard rear ratio. I am thinking about stall converter. What would you recommend?
What camshaft is easiest for you to get, being in Poland? You could go with the 204/214 generic cam or something slightly larger. Converter choice depends on your cam choice. Even for the 204/214 cam, you will want at least a 2000 stall converter.
There are a couple of things to think about. Quench for one, I assume you measured the piston to deck height on your motor? It sounds right with Speedpro flat top pistons. That will give you .062" quench, not ideal. If you go too small on the cam, you may run into pinging issues on 89 our octane. I ran .067" quench and 9.6 to 1 with the Edelbrock 204/214 cam in the advanced position on the Cloyes timing set. I have since degreed that timing set and cam, very close to the factory specs. The first issue I ran into raising compression from 8 to1 to 9.6 to 1 was the Quadrajet. It ran like crap, barely idled, also a 78 403 carb. It needed the idle passages opened up. Cliff Ruggles book explains this procedure and it will probably need it, along with some parts from him. Something like an AEM wideband is a God send to tune the carb through the whole power band. The second issue was the 350 motor liked nothing but 91 octane, unfortunately our best here. I ended up running cold plugs and limiting vacuum advance. Contact Cutlassefi through email at Fastone01 @hotmail.com for advice. What timing set are you planning on? I know people have been happy with the Jegs 2000 to 2300 stall converter on this site.
There are a couple of things to think about. Quench for one, I assume you measured the piston to deck height on your motor? It sounds right with Speedpro flat top pistons. That will give you .062" quench, not ideal. If you go too small on the cam, you may run into pinging issues on 89 our octane. I ran .067" quench and 9.6 to 1 with the Edelbrock 204/214 cam in the advanced position on the Cloyes timing set. I have since degreed that timing set and cam, very close to the factory specs. The first issue I ran into raising compression from 8 to1 to 9.6 to 1 was the Quadrajet. It ran like crap, barely idled, also a 78 403 carb. It needed the idle passages opened up. Cliff Ruggles book explains this procedure and it will probably need it, along with some parts from him. Something like an AEM wideband is a God send to tune the carb through the whole power band. The second issue was the 350 motor liked nothing but 91 octane, unfortunately our best here. I ended up running cold plugs and limiting vacuum advance. Contact Cutlassefi through email at Fastone01 @hotmail.com for advice. What timing set are you planning on? I know people have been happy with the Jegs 2000 to 2300 stall converter on this site.
I bought standard Melling timing set. Non adjustable.
I found a few stall converters 2000-2400 for my th400.
Cutlassefi suggested a custom 214/214 .472/.472 on a 110 LSA for a 9 to 1 Olds 350. In my 70 Cutlass S with a 2350 flash stall in a 2004R with 2.78 gears, it performed very well. It did lose lobes and go flat a year or so later. Make sure you follow the break in procedure and use a high ZDDP oil. I would think both those cams will wake up your Seville quite nicely with a torque converter upgrade. They should both provide adequate vacuum and a good idle. My 214/214 cam had 16" of vacuum at an idle. The first one has more lift and more exhaust duration, probably not a bad thing on our 89 octane with nearly 9.5 to 1 and .062" quench.
I started assembling the engine. I measured rings gaps.
For compression rings the gap is about: 0,017 inch
For oil rings the gap is about: 0,047 inch.
In my opinion gaps are to big.
I have flat tops Pistons +0, 30 , clearance between Pistons/cylinder wall 0,0038 inch
I have bought ring from Hastings 2m697 0,30.
What do you think? Should I order 0,40 or 0,60 rings? Greetings from Poland
You will be fine with the compression rings. Hastings recommends .0035" per inch of bore MINIMUM. So .014" is the minimum or rings could self destruction butting together. You have .003" leeway, a good thing. The oil ring seems high. Mahle recommended .0045" top, .0050" second and .015" oil rails per inch for basic street high performance. They go as high as .0070" per inch of bore. I went more, in the .0060 to .0070" range with my 4.100" bore pistons incase I wanted something like a Torque Storm Supercharger down the line. Hopefully the experts will chime in.
You will be fine with the compression rings. Hastings recommends .0035" per inch of bore MINIMUM. So .014" is the minimum or rings could self destruction butting together. You have .003" leeway, a good thing. The oil ring seems high. Mahle recommended .0045" top, .0050" second and .015" oil rails per inch for basic street high performance. They go as high as .0070" per inch of bore. I went more, in the .0060 to .0070" range with my 4.100" bore pistons incase I wanted something like a Torque Storm Supercharger down the line. Hopefully the experts will chime in.
I have built a few engines in my life. This is first American engine. In my opinion 0,020- 0,025 inch Oil ring gaps will be realy good and enough. Maybe I will buy 040 rings?
I bought crankshaft seal from jeep BS13879. I know that I have to cut wings.
Is this correct way of installing that seal? There is no instruction. I have also bought rings 0,60 from Hastings, in a days I will check gaps.
Have a nice day
Johny
December 1st, 2021, 12:40 PM
