2F Head - Chevy Valve Conversion HELP (1 Viewer)

[CRUISERMHK]

Hi all, I know this topic has been discussed to death, pro's, con's etc. I know I need a valve job so I'm heading down this path on my Aug 85 along with a 0.040 overbore, 0.035 head shave, Delta 500s cam grind, header, EFI.

What I cant find are specific details. Which valves, guides, etc.

I have a local machinist who has a very good reputation in engine building. He has not done this upgrade and the problem is trying to find the appropriate parts. He is more old school and searching the net is a struggle. Rather than pay him to struggle, I'm trying to use resources to help with the parts find and guide.

1. Which valves exactly. 305 V8 has 1.500 and 1.840 with 11/32 stems. Some mention LS valves which are almost 2.000 inches. Do those fit?
2. Valve guides? Replace or ream the original larger? Buying a specific Ream is costly for a one time job.

I wish I was somewhere close to machine shops with experience but I live where I live in Kansas and don't have a lot of options. So if you can help me with some resources, I'd appreciate it.

Robin M. in MHK

 

[Pighead]

I did a valve job on a Late F head last year, probably different from yours. My machinist decided on SBI 01762R for the intakes and 11361-8 for exhaust. Used new guides.

 

[3_puppies]

Jim C posted about this many years ago in the 40 section, maybe in FAQ

 

[White Stripe]

I don't know if .035 head shave will be worth it. I would consider more. And some basic head porting.

 

[SteveH]

I did a .030 head shave and found no measurable increase in compression. I would either do more, or skip it.

 

[Spike Strip]

Post #4

Head comparisons..(FAQ)

While Dhondagod was at my house over the weekend we were chattin about different heads for 2f's. H recently had a head gasket blow in his early 2F and got a good look at his head. I knew that I had a later model head sitting around (probably around 87 ish) with a casting number 61040 and...

forum.ih8mud.com

 

[CRUISERMHK]

I want to put a bow on this thread and share what I've learned. Thanks for all the replies.

In the end, it came down to the valve guides. 2F guides are basically 8 mm, spec 8.01-8.03 mm (0.3154-0.3161 in).
Per spec, IN valve stems 7.970-7.985 (0.3134-0314), EX 7.960-7.975 mm (0.3134-0.314 in).

SBC valve stems are 11/32 in (0.3438). A special ream would be necessary to use the existing guides and my machine shop didn't have one and prohibitive to buy for maybe one job. Didn't find 11/32 guides that would fit the 2F head without more machining.

Searching found 4.8 LS valves had 0.313 in (8 mm) valve stems. IN head dia 1.89 in (2F 1.811 in), EX dia 1.55 in (2F 1.476 in). Length 4.9-4.88, close and can be handled in the valve adjustment. IN Melling V1934 EX Melling V1935. Side note, you can get 2.0 in LS intake valve and machinist thought it would fit but I elected to go with the smaller LS of 1.89 in

Valve guides were within factory spec and oil clearance was as well. Toyota valve stem seals fit perfectly with no need to machine the guides as with the SBC.

What did it cost? I'm not sure about the head alone because I did complete engine rebuild machining. Doing what I did would likely just be a standard head job with new valves, seats and springs. Converting to SBC would have required more machining steps and likely more cost.

My machine work besides the head included
Bored 0.40 over and decked the block 0.040.
Crank polished, was within standard spec.
Balancing
Delta Cam regrind 505 S
Hot tanked along with other parts
Total Machine Cost $2400, head included. Parts are separate

Cheers!
Robin

 

[CruiserTrash]

I want to put a bow on this thread and share what I've learned. Thanks for all the replies.

In the end, it came down to the valve guides. 2F guides are basically 8 mm, spec 8.01-8.03 mm (0.3154-0.3161 in).
Per spec, IN valve stems 7.970-7.985 (0.3134-0314), EX 7.960-7.975 mm (0.3134-0.314 in).

SBC valve stems are 11/32 in (0.3438). A special ream would be necessary to use the existing guides and my machine shop didn't have one and prohibitive to buy for maybe one job. Didn't find 11/32 guides that would fit the 2F head without more machining.

Searching found 4.8 LS valves had 0.313 in (8 mm) valve stems. IN head dia 1.89 in (2F 1.811 in), EX dia 1.55 in (2F 1.476 in). Length 4.9-4.88, close and can be handled in the valve adjustment. IN Melling V1934 EX Melling V1935. Side note, you can get 2.0 in LS intake valve and machinist thought it would fit but I elected to go with the smaller LS of 1.89 in

Valve guides were within factory spec and oil clearance was as well. Toyota valve stem seals fit perfectly with no need to machine the guides as with the SBC.

What did it cost? I'm not sure about the head alone because I did complete engine rebuild machining. Doing what I did would likely just be a standard head job with new valves, seats and springs. Converting to SBC would have required more machining steps and likely more cost.

My machine work besides the head included
Bored 0.40 over and decked the block 0.040.
Crank polished, was within standard spec.
Balancing
Delta Cam regrind 505 S
Hot tanked along with other parts
Total Machine Cost $2400, head included. Parts are separate

Cheers!
Robin

Another data point … I think I’m probably closer to $3000 for similar machine work.

Cleaning, hot tank, etc
Block bored 1.00mm (0.040) over, and deck trued up
Head - only some valves replaced as needed, stock sizes, stem seals replaced, deck and manifold surfaces only taken down enough to true them up, springs were good
Crank taken to .25mm under
Flywheel machined
Whole rotating assembly dynamic balanced
Delta RV grind on a NOS Toyota cam

Parts also separate and I’m doing the build. So probably $2800-2900 in machine work.

 

[LAMBCRUSHER]

do NOT go over the 1.5/1.84" valves. I had a head built spec'ing those, and my machinist friend did me a "favor" by sticking the larger valves and stiffer springs in, and it was not the favor I wanted. I also used a KC284? I think delta grind- again, not the grind that I really wanted. I am wishing I had stated to my machinist friend that this was a very specific recipe, and to NOT go above and beyond during the commissioning phase, and also wishing I had got a fresh stock profile cam. The motor pulls- that's not the ish; the ish is that it is TOO HONKIN LOUD, and rattles my teeth in their sockets, and makes my neighbors hate my truck. Also, it drinks like a Scotsman. The lift and duration specs on the cam grind might be good at a glance for power, but because it was ground from a stock cam, the ramp speed is too fast and the stiff springs can't keep up if I'm too liberal with the go foot. I'm afraid it may, or even maybe already has bent some push rods. If I could go back in time, like I say, I'd have gone new stock profile cam with those 305 valves - stainless on the exhaust side, at least, and some appropriate springs that are not too stiff, and not too loose. These heads are not cheap when you can find them, so don't "ruin" yours by chasing horses. HTH

 

[LAMBCRUSHER]

If you can, contact JimC, and offer to pay him for advice. He's one of the pioneers of the chevy valve "upgrade" and knows these motors better than most of us know ourselves.

 

[CruiserTrash]

Somewhere there's a post comparing cam specs between stock and several aftermarket grinds. Just did a search but I can't find it. I can't recall if Delta's "RV" was the same as their "KC284" or if those are different profiles.

 

[LAMBCRUSHER]

Somewhere there's a post comparing cam specs between stock and several aftermarket grinds. Just did a search but I can't find it. I can't recall if Delta's "RV" was the same as their "KC284" or if those are different profiles.

I can’t recall either. It was about 12 years ago; maybe more.