what size 4mm intake bolts do i need to for the 72cc mod on a 61?

[dieseldod]

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

 

[NSEric]

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.

 

[huskihl]

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 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

 

[singinwoodwackr]

You will need the sleeves as well.

 

[singinwoodwackr]

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.

 

[NSEric]

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.

 

[singinwoodwackr]

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.

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.

 

[singinwoodwackr]

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

Only the 266 blocks bolt to the cyl. The other 2 types are through-hole. Block and hi knees is the same but there are different elbows which require different length bolts…or modified/washered.

 

[dieseldod]

thanks men, thats great.

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.

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.

 

[singinwoodwackr]

I have plenty if the large size 80 66 blocks if you need one.

 

[Gord404]

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