dieseldod
ArboristSite Operative
i plan on buying a box of those long 4mm bolts needed for the intake of 272 , any of you guys know the length offhand . thanks
what size 4mm intake bolts do i need to for the 72cc mod on a 61?
- Thread starter dieseldod
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Same length as the bolts in the 61's intake but 4mm.
I dont know the exact length but you should be be able to figure it out with the 61's bolt in your hand.
I dont know the exact length but you should be be able to figure it out with the 61's bolt in your hand.
I think the 61 block bolts to the cylinder and then 2 different bolts go through the carburetor and into the block. On a 272 the bolts go all the way from the elbow to the cylinder
You will need the sleeves as well.
If you are doing the 61 to 268/272 mod you need the 272 intake, complete, as shown. You cannot just use the 61 parts.
The white top 61 I rebuilt had an intake just like the 272 but it is a little smaller inside.
I ended up using the 61's intake and carb on the 272 cylinder after the aftermarket 272 intake refused to seal, it works fine.
The newer orange top 61's have the exact same carb and intake as a 272. The grey top 61's intake/ carb also bolt straight onto a 272 cylinder but the carb is a little smaller.
The 266 had the oddball intake with shorter carb bolts.
I ended up using the 61's intake and carb on the 272 cylinder after the aftermarket 272 intake refused to seal, it works fine.
The newer orange top 61's have the exact same carb and intake as a 272. The grey top 61's intake/ carb also bolt straight onto a 272 cylinder but the carb is a little smaller.
The 266 had the oddball intake with shorter carb bolts.
Huh? 272s should have a 260A, Tilly carb. The early 61-266se should have a 163A. 224 for 266, 234 for 268. Late 61 does show a 254A which is basically the same as the 260.
I don’t have any Walbros here so don’t know those #s.
For intakes, I only show 3 types for these, 61-272
Left to right…
501 53 38 block, 25 10 gasket, Small intake block, through holes, 61s, all models, at least on Barrett’s IPLs
501 80 66, large intake block, 80 68 gasket, 268, 272, 181, 281, 288 through holes
501 51 18 and 49 24 block, 51 19 gasket for 266, all models. Bolted to cylinder.
Your intake wouldn’t seal because it was the wrong one.
Carb side gaskets are the same, 29 64, even with the 1mm difference in carb side openings.
Also, the main bolt length will depend on the intake elbow used.
Only the 266 blocks bolt to the cyl. The other 2 types are through-hole. Block thickness is the same but there are different elbows which require different length bolts…or modified/washered.
dieseldod
ArboristSite Operative
thanks men, thats great.
thanks for that i have a few here to do that will save me a lot of head scratching lol. interesting that the aftermarket intake wouldnt seal , probably buckled hot in mass production. i was going to order some of those from the land of the rising sun.
I have plenty if the large size 80 66 blocks if you need one.
are they not the same intake block on 288 as 272- if i recall they are on one of my builds but I could be wrong
Yes, same block. The smaller block is on the 61s, see above.
If you want to you can use the intake and carb from a 61 on a 272 cylinder, it fits and works fine. They are a touch smaller and it likely hurts top end rpm but they run nicely with the smaller carb.
I put a mildly ported dirt cheap aftermarket 272 cylinder on a ugly old white top 61 with the stock intake and carb, the saw is quite fast.
I couldnt use the aftermarket 272 intake because it was not molded right, only half of the bottom flat part hit the cylinder, it would run fine until the saw got hot then inhale the gasket. Some aftermarket parts are junk.
And, that’s why you need the 80 66 block.
Using the 163A 61 carb will, at least, eliminate the need to change linkage.
Or, if your 61 is newer and has the 254 carb it will be the same as the 260 from a 272.
