My 340 build

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I'll guess that if you put in the thumpr at 102, cylinder pressure will be in the 200+ range. Just my 2 ccents.

I'd look for something that is in the 285-290 advertised, 235ish at .050, cut on an 110 and installed at 110. That should reduce pressure.

Might call Brian at IMM or a good grinder like Bullet and ask. The static compression is going to be an issue for pump gas.
 
Thanks for the input guys, so i was inable to order a cam at the moment due to miney so that was a bust...but a buddy of mine came by with a present though he brought a xe274h cam over brand new and told me i could have it since hes got a completely different setup hes going for and doesnt need it. Is that can anygood at all? Just curious and he didnt have a cam card on it
 
MoparMark91 said:
So i just checked and i it takes 55-60 lbs to rotate crankshaft everything is lubed up now...that dont sound right am i correct guys?
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you're probably ok , new engine's before break'n are a tad tight. mostly from the new rings and cylinder finish.
 
MoparMark91 said:
So maybe i should nit run the xe268h and just bite the bullet and buy the voodoo
Hmm? Any opinions or input guys buttoning it up Wednesday
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As stated, get a custom cam. I know you have one already but a custom cam is well worth the wait and effort. Bullet used to be the go to for me, but they are NOT what they used to be since Tim Langley left. I have since started using custom cams from Lunati, Mike is the guy to talk to over there. He will talk to you in simple terms and make it understandable. I am by no means a cam expert, but I know I can call Mike anytime and will make it understandable for me. You give him your engine specs, fuel info, vehicle info, gearing and what you will be using it for primarily and he will give you his opinion and advice on what to use. Great guy, great company and great product.

I have a Scat rotating assembly 408 all forged with CNC 220 BPE aluminum heads, with a street/strip ported Eddy Airgap intake with a Lunatic solid flat cam, rather big one, Running MSD pro billet ready to run distributor and getting a custom carb built by Dom with Thumper Carbs. Running a built 727 with a 10 converter and way to tall of gear with a 3.55 but also have a 4.10 chunk to throw in it when the time is needed.

I am very grateful to all the guys on here for their advice and suggestions. There is a hell of allot of quality and knowledgeable people on here. They will steer you right.
 
I'm having the same problem with my slant build. Because I chose non turbo pistons and am going to zero deck height the block, my static compression is going be pretty high. About 9.7. With the camshaft I have, my dynamic is going to be 8.8. Caint do that on pump gas. So I am having to back up and punt on the cam. Need something with at least 68* IVC event. What I have now ain't even close. lol
 
fishmens67 said:
you're probably ok , new engine's before break'n are a tad tight. mostly from the new rings and cylinder finish.
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Really? That stiff is normal? As soon as i remove rods and pistons the crankshaft spins nice. My rod bearings measured .001 chamfer correctly orientated to crank,ring end gap spot on everything is squeaky clean...i did have a lot of assemly lube on bearings and 30 weight oil on cylinders and pistons to ease install. Has anyone ever had such a stiff rotation? Looked up countless times, cant find nothing read every book and shop manual i have but still nothing that helps with info, could possibly a rod on the wrist pin being getting hung up, im just tring to brainstorm:BangHead:
 
MoparMark91 said:
Really? That stiff is normal? As soon as i remove rods and pistons the crankshaft spins nice. My rod bearings measured .001 chamfer correctly orientated to crank,ring end gap spot on everything is squeaky clean...i did have a lot of assemly lube on bearings and 30 weight oil on cylinders and pistons to ease install. Has anyone ever had such a stiff rotation? Looked up countless times, cant find nothing read every book and shop manual i have but still nothing that helps with info, could possibly a rod on the wrist pin being getting hung up, im just tring to brainstorm:BangHead:
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I've never in my life seen a new engine take as little as 25 LB FT. But now I will admit, I've not measured that on very many at all......but I've built a LOT of engines. I don't know where the 25 figure came from, but I think it's way too light.
 
RustyRatRod said:
I've never in my life seen a new engine take as little as 25 LB FT. But now I will admit, I've not measured that on very many at all......but I've built a LOT of engines. I don't know where the 25 figure came from, but I think it's way too light.
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Rob, Every short block I've ever built has been under 30 ft-lbs with most being 24-25 ft-lbs. 55-60 would be more like a stiff, fully assembled flat tappet engine.
 
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I have never measure turning torque, but is it a smooth 60lbs or herky jerky? Does it turn with tight spots?
 
IQ52 said:
Rob, Every short block I've ever built has been under 30 ft-lbs with most being 24-25 ft-lbs. 55-60 would be more like a stiff, fully assembled flat tappet engine.
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Well, I may well be off base. Won't be the last time. LOL
 
It doesnt seem like its catching but is just excessive force to do full rotation, like i feel things should be smoother, when i took out number 7 piston it was a little tough. Should i possible do light hone job to see if it will help? I believe i have enough piston to wall clearance after checking with with calipers on piston and cylinder. Kind of a stand stilm scratching my head right now
 
RustyRatRod said:
I've never in my life seen a new engine take as little as 25 LB FT. But now I will admit, I've not measured that on very many at all......but I've built a LOT of engines. I don't know where the 25 figure came from, but I think it's way too light.
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I cant find the measurement in a shop manual but there has git to be some sort of guideline
 
MoparMark91 said:
I cant find the measurement in a shop manual but there has git to be some sort of guideline
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If you are second guessing the short block build, it's just as easy to pull it apart and double check everything.
all you lose is a couple hours.
 
fishmens67 said:
If you are second guessing the short block build, it's just as easy to pull it apart and double check everything.
all you lose is a couple hours.
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I have it back apart and double checked everything, crankshaft spins great honestly .001 on rods and .0015 on mains with plastiguage. Rings gapped good, been brainstorming for a bit chamfer and rods oriented the right way.
 
I would put each piston in the proper cylinder and check the movement.
 
I pulled one at a time and checked rotation and seemed okay other than number 7 was a little tougher. I guess i could assemble it 1 by 1 and if everything checks out run it. My piston to wall clearance is good too.
 
JMO, those are VERY tight clearances. Too tight for my liking. I like .0025 crank and .0015 min on rods, closer to .002 preferred.

Could be part of the reason it seems tough to turn.

If you run it tight, you need to make sure the oil is up to temp before romping on it.
 
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crackedback said:
JMO, those are VERY tight clearances. Too tight for my liking. I like .0025 crank and .0015 min on rods, closer to .002 preferred.

Could be part of the reason it seems tough to turn.
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Yeah im not too happy about the clearances but it says its in spec?
 
MoparMark91 said:
Yeah im not too happy about the clearances but it says its in spec?
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In spec to what? The factory drive it around town spec?

The general rule on performance oriented builds is you want .001 clearance per inch of journal sizing. Similar to the piston ring gap computation setting approach.
 
crackedback said:
In spec to what? The factory drive it around town spec?

The general rule on performance oriented builds is you want .001 clearance per inch of journal sizing. Similar to the piston ring gap computation setting approach.
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So if its a 3.58 stroke then it should be around .003?
 
Journal diameter.... same approach as used to figure out piston ring gap sizing.
 
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