The Stovebolt Site Forums The Shop Area Engine Shop Chevy 250 engine head swap and cam differences

Hello- I currently have a integral-head style (1974?) 250 in a Land Rover truck. The engine is probably one of the 105 HP rated versions, with EGR valve. For space, asthetic and power reasons, I'd like to replace the head with an earlier 155 HP, non-integral head version. I believe this is physically a straight swap. I assume the integral head block has hydraulic lifters? If so, should I use the existing pushrods if I put a solid lifter head on?

My other question is about the differences in stock cams (if any) used over the years on Chevy 250 engines, both car and truck applications. If there is no difference over the years and between models, I'll probably leave the short block as-is. I was thinking the cams in the 250s fitted to trucks might be different. Or perhaps the cam profiles changed as smog requirements got more strict? Because my truck is heavy and used off-road, I'd rather have torque than high RPM, and would probably never run more than 3800 RPM anyway. The truck is a '67 so there's no problem with doing away with the smog equipment.

I have access to a few 250 engines and would like to do optimize my engine using stock parts. I have ordered the Santucci book, so I appologize if these questions are covered in that text.

Thanks in advance,
Carl

First Welcome to the board.

I don't think you are going to find many that have experience with the integral head, though I believe we have one or two. Hydraulic lifters were standard for 250s that doesn't mean your push rods are going to swap. I'd get a set of push rods with the head.

If you do have an integral, then you have an HEI distributor. The HEI was detuned(?) for smog and I would suspect the cam as well.

You will find that Leo's is a good start, but it won't answer all your questions. If you really want bottom end torque, I'd get a 292. The problem with replacing the 250 with a 292 would be an additional 2 inches in block height and the passenger side motor mount would have to moved forward.

Larry

Welcome carl k, the non integeral heads are not all created equal, the compression can be changed by using differnt casting numbered heads,
inliners.org has a good article on casting numbers and chamber size, if your not stuck on using a head from a 250 you might consider using a head from a 194 cu in motor as the chamber size is smaller and will raise the compression.

there slight differences in the cams but not much i believe. i haven't had a integral head but i know from 63 to the 70's i think they changed slightly. and the sealed power stock replacement ones are slightly different too. which 250's have solid lifters except for aftermarket cams? i thought all the stock ones were hydrolic but i may be wrong i usually am. i think the 230/250/292 heads, noninter of course, are basicly all the same. i think you will be happy with a hi tourqe cam and you will prob get the push rods and lifters with it.

I like the way my slightly bigger cam I installed in my 250 runs, but I don't like the rough idle. Its not very noticeable to anyone but me, but I like it to idle dead smooth, not like its running on 5 cylinders. I may even go back to the stock replacement cam just for that reason. I believe the fuel mileage went down a bit as well.

When I was shopping for cams, I never could find the spec's for OEM cams. I found a few but nothing to write about. I bought a NOS 230 cam off ebay and I can tell you it is smaller then the 250, less lift and duration.

The 194 head does have smaller chambers and will raise the compression, but I have heard the exhaust ports are Siamese just like the intakes and they don't work as good with out a little port work.

Your best bet, in my opinion, would be to swap in a set of 307 Chevrolet flat top pistons, a stock replacement camshaft, a stock 230,250,or 292 head, a stock 292 exhaust manifold, and a stock 292 intake and carburetor. Flat top pistons will give about 9 to 1 compression. The heads are all the same. The 292 manifold has a 2.5" exhaust outlet, the 250 has a 2". And the 292 intake used a bigger Rochester one barrel carburetor.

Joe

Hi All-

Thanks so much for the replies and advice. I was wrong about the lifters, I guess they are all hydraulic.

My Santucci book arrived and it has a lot of answers but still not much for someone trying to put together the optimal 250 using stock components. I have three of these 250 engines besides the one in my truck, and currently no space to really do an entire engine swap, so that's why I was hoping to stick the best stuff onto my 1974 block (currently with integral head), then I can get rid of the remainder. Since these engines went from a rated 155 HP to as low as 95 HP, I know there are some parts combinations that give more power than others (besides the emissions equipment). I will check the head casting numbers to find the one with highest compression (hopefully without AIR ports), and swap it over along with the pushrods. One engine is from a truck so I may see if the cam is good and put that in also. Are all exhaust and intake manifolds pretty much equal?

I am going to check out a rebuilt 292 tomorrow, it's $500 so it might be good as a future transplant when I get space. There's enough space under the hood.

Thanks,
Carl