Heymow - Lawnmower Racing Forum
Engine Help => Briggs OHV & Vanguard => Topic started by: mod 76 on July 23, 2018, 01:06:18 pm
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So I'm preparing to build a 35ci vanny . Bore it from 2.8 to 2.970 so I can drop in the intek pistons . My issue is finding a shop to do the work !!! No one around here does small engines for some reason . I found a quick key boring bar machine with the table for $300. , would that work ?? Does any one have any other ideas or suggestions on how I could.
do this at home .
Or should I just get the 38ci block and not worry about it
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Get the 38,there will be no sleeve left if you bore the 35 that far and use the 23 HP heads,the ports are much higher than the 35 cubic inch heads and they flow lots better That is probably a Quick Way boring bar and if it is in good shape it might be a good deal but if you have never used one it might not be something you want to use without some experience
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I have some machining experience. My last lathe was a 1931 Willard, 16x60 ?? Just a bit to big .. lol ...
I've been reading up on this engine combo on here and it seemed like a pretty standard build that most guys do . And I have looked into just buying the 38ci block ( $350) . And I'm contemplating in getting the 38ci heads from Carrier Performance. I have every intention of running those heads .
My understanding is that the 30ci didn't have a thick enough sleeve @ 2.6" , 35ci @ 2.8" & 38ci @ 2.97" .
I guess I'll have to readjust my aprouch, maybe I miss understood .
And yah @$300 , it's a super deal , most of them go for $800 to $1,500 . And this has a bunch of tooling.
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The table alone might be worth 300 I helped Ryan Kerr and he won the all american with that combination. We ran 14.5 to 1 compression ratio The heads were 22ccs You will need copper head gaskets and O ring the heads, the stock head gaskets won't last one lap
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Ugh, just got the call from the last machine shop near me ( with in a 60 mile radius) they can not machine the bore.
Guess I'll have to buy the 38 block and just run the stock 38 pistons , cause if no one can bore , they can't do a O-ring either...
Thanks for the heads up on the O-ring requirement. I missed that , thought the copper would be enough.
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I forgot to say the 38 block takes a crankshaft with larger main journals too,so you need more than a block ,maybe you can find a whole used engine to rebuild
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mod 76 ,where are you from??
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My apologies for not responding sooner.
I'm in California
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So I found a shop to do the work I needed . He was telling me that he can't re use old pistons , said something about the skirts changing shape after being used , that the bore to piston fitment wouldnt be right , I thought using old pistons were fine !!
So now I'm trying to find a good deal on 40ci intek pistons .
The 38ci heads came in the other day, I did the port work on them last night ... the intake valve was 32.40mm! I thought it was supposed to be 31mm ... any ideas
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I did not get the carrier heads, I ordered new heads off ebay, complete
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Small engine suppliers for cheapest pistons I've found.
Briggs part#793647 std.bore pistons
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I found a place that had them for $50.00 each , part# 793647. That is hands down the cheapest I'll find. I ordered them last night .
Also meant to mention , the machinist said that I don't need to O-ring the motor? He builds racing kart motors , Subaru' s, animal's, ect... does all the QRC stuff , outlaw 500, and does all the resleeving for the local marine shops here .. I told him that I needed it but he said he's run super high compression with out doing it . ???? So I'm a bit at a lose here . He said he uses some kinda " stuff" ?? He forgot the name .. hope her not referring to some liquid/ Indian seal thing ..
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What would be a good piston to cylinder clearance for a new piston ? Like .002 ? And if I used a old piston does that clearance increase ?to acomidate the skirts being distorted a bit from use.
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The machinist got back to me just now and said it's a sealant used on Toyota oil pans ? # 00295-00103 . Said to coat both sides of the head gasket ?? What do you guys think ?
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We never found anything that worked except a copper head gasket and O ring the head,we never tried to O ring the block only the head. It is easy to do,set the head up in a four jaw chuck sharpen a tool bit the shape you want the O ring and tun the lathe by hand .I think the wire was .021 and it should stick out of the groove about .012 to .015"
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Oh , okay . I thought I'd have to do the block . I can do the head then . Is it any type of special wire ? A hoop ? Or just a length of it cut to fit ..
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We used stainless wire and cut to length ,we did try copper and it worked too
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Okay , thanks .. I'll be trying to cut Owings on a salir set of heads this weekend ..
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I wouldn't be afraid to use the old pistons give them .002 to .0025 , I have done it lots of times,why did he say not to use them?
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Back when 352 and 390 fords were popular,if you had a 390 and the pistons were still good and the cylinders needed to be bored i would get a 352 block and bore it .050 and fit the use pistons to it. It was like having a standard bore 390 block but with no wear.
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He just said that the pistons distort over time/use and he wouldn't be able to achieve symmetrical cylinder wall clearance of .003/4.. basically, the skirts are shaped like an egg compared to the top ......
He builds high end kart engines so I just said okay , but it did set the whole project back now ... idk... I've always reused pistons in the past ...
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Okay , the block has been bored and thr new pistons installed . I do notice that the piston is not flush with the deck . It sits about 0.113" / 2.87mm down in the bore . The rods are arc #6275 . Not sure if thats too much , all the rotating assembly's clear internally with no issues.
I thought this combo would give me just about a zero deck height.. ???
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Also , what is the torque on the arp rod bolts ??
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Rod bolt torque is 170 in/lbs lubricated.
At .113 in the hole with the piston,is going to be numb at best you've just added aprox 13cc to combustion area.
The 6276 ARC rod is .128 longer than the one you have,maybe should have used them and cut top o piston
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The piston is down way too far to have much compression,like he said go with the longer rod,13 ccs is almost half the ccs of a stock combustion chamber .
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Ya , i figured it out .. i never thought to check the rod length. I assumed they were right ... thats what i get .. ill be ordering the correct pistons later on ....
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Just out of curiosty,what is the compression height on the pistons you have??
Stock 40ci Intek pistons compression height is .983
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I did a 38ci motor used the Intec pistons and stock length ARC rods and my pistons were in the hole by .053 and with a .016 thick head gasket I came up with around 11 to 1 comp ratio. The Intec piston pin height was about .020 shorter than the factory piston. I can also tell you PVT. sells a rod that is .022 longer than stock if it helps you out.