Leakfrom intake manifold



:unsure: I noticed coolant leaking from my intake log just below the carb yesterday. It seems to be coming from 2 small cracks in the intake. I understand the heater plate under the carb may be the source of the coolant, but I still have the cracks to deal with. Can these be repaired? If not, what would be involved in putting a 250 head on the 1965 200 block? How much would this increase performance? Would I be alble to reuse my Autolite carb? I appreciate any advice you people can give me.
The plate under the carb is self contained, so if you have a leak by the carb, check your hoses, if they are good, find a replacement water heater plate. Since the intake log is build into the head and there isnt any coolant running through it, I have no idea how you might have gotten cracks in the carb mounting platform. It might be alright to go to the hardware store and put a coolant flush "T" in also for a short fix until you have time (and more knowledge) to fix it the right way. I say might because I dont know if 200's have a problem with icing up when the temperature drops.

If you were to put a 250 head directly onto a '65 200 block you would not gain performance, you would lose it. The 250 has larger combustion chamber size. This can be fixed of course by milling the head to get the new head combustion chamber to be the same size or slightly smaller to make up for the new headgaskets which are slightly thicker then the OE ones.
when you got some free time go check out
it is set for a generic stock 200 6cyl. Hit calculate when you first get there, and it will tell you that this particular 6cyl has 8.7cr. If you imagine that you just bolted on a 250 head bump the Combustion Chamber Volume up to 65 and the gasket thickness up to .045 (ouch CR drops to 7.5)

But after you measure your old head and new head then have a machine shop mill the heads so that you get a 50cc combustion chamber you will get back to a respectable 9.1cr (on this hypothetical engine, your results may vary) Make sure to measure your old head before having the new one milled.

The 250 head will work. The chanber volume is larger than your 200 (62cc vs 52cc) so you will lose some compression if you don't mill the head some (be sure to cc the 250 chambers B4 you mill - don't know what the last guy did).

The 250 head will have a 1.75" carb attach bore. So, the 65 200 Autolite won't fit (1.50" bore). However, there are a number of options here, i.e., the card that came on the 250. When you change the carb you may run into a distributor issue. You will need a carb that fit the 1.75" bore AND supports the dual vac distrubtor. I don't know what choices you have here. Maybe someone else can help.

B4 you spend a lot of time, and money, on a head change (unless your ready to upgrade anyway - whole different subject), replace the spacer (you can eliminate it if you make an adapter from aluminium plate - same type of adapter could be used to mount 1.50 Autolite on the 1.75 head) and fill the cracks in the manifold with JB Weld. The stuff works good in an environment up to 600*, and your intake manifold won't run that hot.

If you have interest in the adapter try this site


Hope this is helpful.